Hi-Fi & Home Cinema GLOSSARY

Digital television

2008-07-09T00:30:00.000-07:00

Digital television (DTV) is the sending and receiving of moving images and sound by means of discrete (digital) signals, in contrast to the analog signals used by analog TV. Introduced in the late 1990s, this technology appealed to the television broadcasting business and consumer electronics industries as offering new financial opportunities.

Digital television is more flexible and efficient than analog television. When properly used by broadcasters, digital television allows higher-quality images and sound and more programming choices than analog does. However a digital signal does not necessarily carry a higher-quality image or sound than an analog signal.

Technical information

Formats and bandwidth

With digital television, two formats--HDTV and SDTV--of TV programme are broadcast.

High-definition television (HDTV), which is usually used over DTV, uses one of two formats: 1280 × 720 pixels in progressive scan mode (abbreviated 720p) or 1920 × 1080 pixels in interlace mode (1080i). Each of these utilizes a 16:9 aspect ratio. (Some televisions are capable of receiving an HD resolution of 1920 × 1080 at a 60 Hz progressive scan frame rate — known as 1080p60 — but this format is not standard and no broadcaster is able to transmit these signals over the air at acceptable quality yet.)

Standard definition TV(SDTV), by comparison, may use one of several different formats taking the form of various aspect ratios, depending on the technology used in the country of broadcast. For 4:3 aspect-ratio broadcasts, the 640 × 480 format is used in NTSC countries, while 720 × 576 (rescaled to 768 × 576) is used in PAL countries. For 16:9 broadcasts, the 704 × 480 (rescaled to 848 × 480) format is used in NTSC countries, while 720 × 576 (rescaled to 1024 × 576) is used in PAL countries. However, broadcasters may choose to reduce these resolutions to save bandwidth (e.g., many DVB-T channels in the United Kingdom use a horizontal resolution of 544 or 704 pixels per line).[1] The perceived quality of such programming is surprisingly acceptable because of interlacing—the effective vertical resolution is halved to 288 lines.

Each DTV channel is permitted to be broadcast at a data rate up to 19 megabits per second, or 2.375 megabytes per second. However, the broadcaster does not need to use this entire bandwidth for just one broadcast channel. Instead the broadcast can be subdivided across several video subchannels of varying quality and compression rates, including non-video datacasting services that allow one-way high-bandwidth streaming of data to computers.

A broadcaster may opt to use a standard-definition digital signal instead of an HDTV signal, because current convention allows the bandwidth of a DTV channel (or "multiplex") to be subdivided into multiple subchannels, providing multiple feeds of entirely different programming on the same channel. This ability to provide either a single HDTV feed or multiple lower-resolution feeds is often referred to as distributing one's "bit budget" or multicasting. This can sometimes be arranged automatically, using a statistical multiplexer (or "stat-mux"). With some implementations, image resolution may be less directly limited by bandwidth; for example in DVB-T, broadcasters can choose from several different modulation schemes, giving them the option to reduce the transmission bitrate and make reception easier for more distant or mobile viewers.

Reception

There are a number of different ways to receive digital television. One of the oldest means of receiving DTV (and TV in general) is using an antenna (known as an aerial in some countries). This way is known as Digital Terrestrial Television (DTT). With DTT, viewers are limited to whatever channels the antenna picks up. Signal quality will also vary.

Other ways have been devised to receive digital television. Among the most familiar to people are digital cable and digital satellite. In some countries where transmissions of TV signals are normally achieved by microwaves, digital MMDS is used. Other standards, such as DMB and DVB-H, have been devised to allow handheld devices such as mobile phones to receive TV signals. Another way is IPTV, that is receiving TV via Internet Protocol, relying on DSL or optical cable line. Finally, an alternative way is to receive digital TV signals via the open Internet. For example, there is a lot of P2P Internet Television software that can be used to watch TV on your computer.

Some signals carry encryption and specify use conditions (such as "may not be recorded" or "may not be viewed on displays larger than 1 m in diagonal measure") backed up with the force of law under the WIPO Copyright Treaty and national legislation implementing it, such as the U.S. Digital Millennium Copyright Act. Access to encrypted channels can be controlled by a removable smart card, for example via the Common Interface (DVB-CI) standard for Europe and via Point Of Deployment (POD) for IS or named differently CableCard.

Interaction

Interaction happens between the TV watcher and the DTV system. It can be understood in different ways, depending on which part of the DTV system is concerned. It can be an interaction with the STB only (to tune to another TV channel or to browse the EPG).

Modern DTV systems are able to provide interaction between the end-user and the broadcaster through the use of a return path. With the exceptions of coaxial and fiber optic cable, which can be bidirectional, a dialup modem, Internet connection, or other method is typically used for the return path with unidirectional networks such as satellite or antenna broadcast.

In addition to not needing a separate return path, cable also has the advantage of a communication channel localized to a neighborhood rather than a city (terrestrial) or an even larger area (satellite). This provides enough customizable bandwidth to allow true video on demand.

Advantages to conversion

DTV has several advantages over analog TV, the most significant being that digital channels take up less bandwidth (and the bandwidth needs are continuously variable, at a corresponding cost in image quality depending on the level of compression). This means that digital broadcasters can provide more digital channels in the same space, provide high-definition television service, or provide other non-television services such as multimedia or interactivity. DTV also permits special services such as multiplexing (more than one program on the same channel), electronic program guides and additional languages, spoken or subtitled. The sale of non-television services may provide an additional revenue source. In many cases, viewers perceive DTV to have superior picture quality, improved audio quality, and easier reception than analog.

Disadvantages to conversion

Impact on existing analog technology
The analog switch-off ruling, which so far has met with little opposition from consumers or manufacturers, would render all non-digital televisions obsolete on the switch-off date unless connected to an external off-the-air tuner, analog or digital cable, or a satellite system. An external converter box can be added to non-digital televisions to lengthen their useful lifespan. Several of these devices have already been shown and, while few were initially available, they are becoming more available by the day. Once connected to the converter unit, operation of non-digital units is achievable and, in most cases, rich in new features (in comparison to previous analog reception operation). At present, analog switchoff is scheduled for February 17, 2009 in the United States and August 31, 2011 in Canada.

Some existing analog equipment will be less functional with the use of a converter box. For example, television remote controls will no longer be effective at changing channels, because that function will instead be handled by the converter box. Similarly, video recorders for analog signals (including both tape-based VCRs and hard-drive-based DVRs) will not be able to select channels, limiting their ability to automatically record programs via a timer or based on downloaded program information. ATSC-capable VCRs are likely to be far less common than their NTSC counterparts, with most current offerings being VCR/DVD combo units. Also, older handheld televisions, which rely primarily on over-the-air signals and battery operation, will be rendered impractical since the proposed converter boxes are not portable nor powered with batteries.

Portable radios which feature the ability to listen to television audio on VHF channels 2-13 would also lose this ability, while television stations which formerly broadcast on Channel 6 (with analog FM audio on 87.75 MHz) would no longer be heard on standard FM broadcast band radios. These stations would lose the ability for commuters to listen to their broadcasts.

Were any new TVs to contain only an ATSC tuner, this could prevent older devices such as VCRs and video game consoles with only an analog RF output from connecting to the TV. Connection would require an analog to digital converter box, which is the opposite as what is currently being sold. Such a box would also likely introduce additional delay into the video signal. Fortunately, analog inputs suitable for connection to VCRs have remained available on all current digital-capable TV's.

Compression artifacts and allocated bandwidth

DTV images have some picture defects that are not present on analog television or motion picture cinema, because of present-day limitations of bandwidth and compression algorithms such as MPEG-2.
When a compressed digital image is compared with the original program source, some hard-to-compress image sequences may have digital distortion or degradation. For example:quantization noise,incorrect color,blockiness,a blurred, shimmering haze.

Broadcasters attempt to balance their needs to show high quality pictures and to generate revenue by using a fixed bandwidth allocation for more services.

Buffering and preload delay

Unlike analog televisions, digital televisions have a significant delay when changing channels, making "channel surfing" more difficult. Different devices need different amounts of preload time to begin showing the broadcast stream, resulting in an undesirable and annoying audio echo effect when two televisions in adjacent rooms of a house are tuned to the same channel.

Effects of poor reception

Changes in signal reception from factors such as degrading antenna connections or worsening weather conditions may gradually reduce the quality of analog TV. The nature of digital TV results in a perfect picture initially, until the receiving equipment starts picking up noise or losing signal. Some equipment will show a picture even with significant damage, while other devices may go directly from perfect to no picture at all (and thus not show even a slightly damaged picture). This latter effect is known as the digital cliff or cliff effect.

For remote locations, distant analog channels that were previously acceptable in a snowy and degraded state may be anything from perfect to completely unavailable. The use of lower power (typically one-fifth that of analog broadcasts in the US) and higher frequencies will add to these problems, especially in cases where a clear line-of-sight from the receiving antenna to the transmitter is not available. Many intermittent signal fading conditions, such as the rapid-fade effect caused by reflections of UHF television signals from passing aircraft, will produce not intermittently-snowy video but potential intermittent loss of the entire signal.

Limitations

The greatest DTV detail level currently available is 1080i, which is a 1920x1080 interlaced widescreen format. Interlacing is done to reduce the image bandwidth to one-half of full-frame quality, which gives better frame update speed for quick-changing scenes such as sports, but at the same time reduces the overall image quality and introduces image flickering and "crawling scanlines" because of the alternating field refresh.

Full-frame progressive-scan 1920x1080 (1080p) requires up to twice the data bandwidth currently available in the DTV channel specification. 1080p may become an option in the future, as image compression algorithms improve, allowing more detail to be sent via the same channel bandwidth allocations to be used now.

The limitations of interlacing can be partially overcome through the use of advanced image processors in the consumer display device, such as the use of Faroudja DCDi and using internal framebuffers to eliminate scanline crawling.

Surround sound

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Multichannel audio denominates the techniques for enriching (expanding and deepening) the sound reproduction quality, of a recorded source, with additional, recorded sound channels reproduced via additional, discrete speakers. The three-dimensional (3D) sphere of human hearing can be virtually achieved with audio channels above and below the listener. To that end, the multichannel surround sound application encircles the audience (left-surround, right-surround, back-surround), as opposed to "screen channels" (center, [front] left, and [front] right), i.e. ca. 360° horizontal plane, 2D).

The first, documented use of surround sound was in 1940, for the Disney studio's animated film Fantasia. Its multichannel audio application was called 'Fantasound', comprising three audio channels and speakers; the sound was diffused throughout the cinema, initially, by an engineer using some 54 loudspeakers; the surround sound was achieved using the sum and the difference of the phase of the sound.

Surround sound technology is used in both cinema and "home theater" systems, video game consoles, and personal computers, et cetera. Commercial surround sound formats include videocassettes, Video DVDs, and HDTV broadcasts encoded as Dolby Pro Logic, Dolby Digital, or DTS. Other commercial formats include the competing DVD-Audio (DVD-A) and Super Audio CD (SACD) formats; and MP3 Surround. Cinema 5.1 surround formats include Dolby Digital, DTS, and Sony Dynamic Digital Sound (SDDS).

Mostly, film production companies and video game creators are the principal users of surround sound; however, some consumer camcorders have such capability, either in-built or discrete. Some AV receivers, stereophonic systems, and computer soundcards contain integral digital signal processors and / or digital audio processors to simulate surround sound from a stereophonic source.

Creating surround sound

Surround sound is created several ways. The first, and simplest, method is using a surround sound recording microphone technique and / or mixing-in surround sound for playback on an audio system using speakers — encircling the listener — to play audio from different directions. A second approach is processing the audio with psychoacoustic sound localization methods to simulate a two-dimensional (2-D) sound field with headphones. A third approach, based on Huygens' principle, attempts reconstructing the recorded sound field wavefronts within the listening space, an "audio hologram" form. One form, wave field synthesis (WFS), produces a soundfield with an even error field over the entire area. Commercial WFS systems, made by the Swiss companies sonic emotion and Iosono, require a many loudspeakers and much computing power.

The Ambisonics form, also based on Huygens' principle, gives an exact sound reconstruction at the central point; less accurate away from center point. There are many free and commercial software available for Ambisonics, which dominates most of the consumer market, especially musicians using electronic and computer music. Moreover, Ambisonics products are the standard in surround sound hardware sold by Meridian Audio, Ltd. In its simplest form, Ambisonics consumes few resources, however, this is not true for recent developments, such as Near Field Compensated Higher Order Ambisonics. Some years ago it was shown that, in the limit, WFS and Ambisonics converge.

Finally, surround sound also can be achieved by mastering level, from stereophonic sources as with Penteo, which uses FFT analysis of a stereo recording to break individual sounds to component panorama positions, then positions them, accordingly, into a five-channel field.

Mapping channels to speakers

In most cases, surround sound systems rely on the mapping of each source channel to its own loudspeaker. Matrix systems recover the number and content of the source channels and apply them to their respective loudspeakers. With discrete surround sound, the transmission medium allows for (at least) the same number of channels of source and destination; however, one-to-one, channel-to-speaker, mapping is not the only way of transmitting surround sound signals.

The transmitted signal might encode the information (defining the original sound field) to a greater or lesser extent; the surround sound information is rendered for replay by a decoder generating the number and configuration of loudspeaker feeds for the number of speakers available for replay. This "replay device independent" encoding is analogous to encoding and decoding an Adobe PostScript file, where the file describes the page, and is rendered per the output device's resolution capacity. The Ambisonics and WFS systems use audio rendering; the Meridian Lossless Packing contains elements of this capability.

Bass management

Surround replay systems may make use of bass management, the fundamental principle of which is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of handling it, whether the latter are the main system loudspeakers or one or more special low-frequency speakers called subwoofers.

There is a notation difference before and after the bass management system. Before the bass management system there is a Low Frequency Effects (LFE) channel. After the bass management system there is a subwoofer signal. A common misunderstanding is the belief that the LFE channel is the "subwoofer channel". The bass management system may direct bass to one or more subwoofers (if present) from any channel, not just from the LFE channel. Also, if there is no subwoofer speaker present then the bass management system can direct the LFE channel to one or more of the main speakers.

Low Frequency Effects (LFE) channel

The Low Frequency Effects channel, or LFE, is a source of some confusion in surround sound. The LFE channel was originally developed to carry extremely low "sub-bass" cinematic sound effects (e.g., the loud rumble of thunder or explosions) on their own channel. When loud sub-bass effects are on a different channel, this allows theaters to control the volume of the sub-bass effects, so that it suits the size of their sound reproduction system and the acoustic environment of their cinema. Independent control of the sub-bass effects also reduced the problem of intermodulation distortion in analog movie sound reproduction.

In the original movie theater implementation, the LFE was a separate channel fed to one or more subwoofers. However, home replay systems may not have a separate bass speaker (subwoofer) that is able to handle the sub-bass effects. As a result, modern home surround decoders and systems often include a bass management system that allows bass on any channel (main or LFE) to be fed only to the loudspeakers that can handle low-frequency signals. The salient point here is that the LFE channel is not the "subwoofer channel"; there may not even be a subwoofer, and if there is it may be handling a good deal more than effects.

Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system. They argue that all available channels have a full frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel, underlining its redundancy for its original purpose.

LFE is sometimes expanded as Low-frequency Enhancment.

Surround sound specifications

The descriptions of surround sound specifications below distinguish between the number of discrete channels encoded in the original signal and the number of channels reproduced for playback. The number of channels reproduced for playback can be changed by using matrix decoding. A distinction is also made between the number of channels reproduced for playback and the number of speakers used to reproduce (each channel may refer to a group of speakers). The graphics to the right of each specification description represent the number of channels, not the number of speakers.

3.0 Channel Surround (analog matrixed: Dolby Surround)

Extracts 3 audio channels from a specially encoded two-channel source:Two channels for speakers at the front—left (L) and right (R).One channel for surround speaker or speakers at the rear—surround (S).Describes the numerous matrixed (pre- Pro Logic) surround processors.

Placement: (three speakers in total) Three identical speakers placed equidistant around a central listening position. If two rear speakers are used they should also be placed at ear height, slightly behind the listening position, and should be of bi-polar construction.

4.0 Channel Surround (analog matrixed/discrete: Quadraphonic)

Extracts four audio channels from either a specially encoded two-channel source or a four-channel source:Two channels for speakers at the front—left (L) and right (R).Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).Describes the early matrixed systems and discrete Quadraphonic surround systems. Source media, usually LP record or tape, is often branded four channel stereo.

Placement: Quadraphonics is a system designed for music only. All speakers should be at an ±45˚. All speakers should be at ear height.

4.0 Channel Surround (analog matrixed: Dolby Pro Logic)

Extracts four audio channels from a specially encoded two-channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).One channel for both surround speakers at the rear—mono surround channel (S).Describes the Dolby Pro Logic matrixed surround system. Source media, usually VHS, Laser Disc, television broadcast or CableTV/Satellite is often branded with "Dolby Surround" logo. This is the encoding used on the analog optical track for theatrical motion picture films.

Placement: (Five speakers in total) The front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear-high as possible. Surround channel speakers should be placed at ear height, slightly behind the listening position, and should be of bi-pole construction.

5.1 Channel Surround (3-2 Stereo) (analog matrixed: Dolby Pro Logic II)

Extracts Five audio channels from either a specially encoded two-channel or a stereo source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).Describes the Dolby Pro Logic II matrixed surround system. Source media is often gaming systems including Playstation 2, GameCube and Wii games branded with "Pro Logic II" logo.

5.1 surround sound may also be referred to as 3-2 stereo. This defines the configuration that has been standardised for numerous surround sound applications. The term 3-2 refers to 3 front speakers and 2 rear speakers.
Placement: 5.1 speaker layouts should conform to the ITU-R BS.775 standard, despite the myth that music and video content require different placements. The ITU standard states that the left and right speakers are located at ±30˚, while the rear speakers should be positioned approximately ±110˚. There is speculation that rear loudspeakers at ±150˚ provide "more exciting surround effects".

5.1 Channel Surround (70 mm 6-Track) (analog magnetic)

Delivers six audio channels from a 6 channel source:Four channels for speakers at the front-left (L), left center (LC), right center (RC), and right (R).One channel for speaker at the center-center (C)One channel for surround speaker at the rear-monaural surround (S).

5.1 Channel Surround (3-2 Stereo) (analog magnetic: Dolby Stereo "Baby Boom")

Delivers five audio channels and 1 LFE channel from a 6 channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).

5.1 Channel Surround (3-2 Stereo) (digital discrete: Dolby Digital, DTS, SDDS)

Delivers Five discrete audio channels and 1 LFE channel from a 6 channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).Describes the Dolby Digital, Digital Theater System (DTS), and Sony Dynamic Digital Sound (SDDS) systems. Source media, usually DVD and sometimes Laser Disc or satellite/digital cable is often branded with "Dolby Digital" and/or DTS logos.DTS uses a higher data rate than Dolby Digital, so DTS can achieve higher fidelity.

Placement: 5.1 speaker layouts should conform to the ITU-R BS.775 standard, despite the myth that music and video content require different placements. The ITU standard states that the left and right speakers are located at ±30˚, while the rear speakers should be positioned approximately ±110˚. There is speculation that rear loudspeakers at ±150˚ provide "more exciting surround effects".

6.1 Channel Surround (analog matrixed: Dolby Pro Logic IIx)

Extracts six audio channels and one low-frequency channel from either a specially encoded two-channel or stereo source. Expands a back surround channel from a 5.1 channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the sides—side left (LS) and side right (RS).One channel for surround speakers at the rear—back surround channel (BS).One low-frequency channel to drive a sub-woofer.Describes the Dolby Pro Logic IIx matrixed surround system. Source media is the same as both Dolby Pro Logic and Dolby Pro Logic II.

Placement: The front speakers should be placed at the edges of the screen, toed in to face the central listening location. The center speaker should be placed behind the screen (when using projection) or over or under a TV. Side channel speakers should be placed to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed slightly behind the listening position, and should have a normal high-quality monopolar construction. All speakers should be at ear height.

6.1 Channel Surround (digital partially discrete: Dolby Digital EX)

Delivers five audio channels, one extracted audio channel and one LFE channel from a six channel source:Two discrete channels for speakers at the front—left (L) and right (R).One discrete channel for speaker at the center—center (C).Two channels for surround speakers at the sides—left surround (LS) and right surround (RS). The discrete LS and RS channels are dematrixed into LS, RS, and back surround (BS).One channel for surround speakers at the rear—back surround channel (BS).One low-frequency effects channel (LFE).Describes the Dolby Digital EX discrete/matrixed hybrid Surround system. Source media, usually DVD is often branded with "Dolby Digital EX" logo. This format is used in some theatrical motion picture films.

6.1 Channel Surround (digital discrete: DTS-ES)

Delivers six discrete audio channels and 1 LFE channel from a seven channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the sides—side left (LS) and side right (RS).One channel for surround speakers at the rear—back surround channel (BS).One low-frequency effects channel (LFE).Describes the DTS ES discrete Surround system. Source media, usually DVD is often branded with "DTS ES" logo. In theatrical motion picture film, this format does not exist, and the name "DTS-ES" refers to the above hybrid format used for Dolby Digital EX.

7.1 Channel Surround (digital discrete: Dolby Digital Plus, DTS-HD, Dolby TrueHD)

Delivers seven audio channels and one LFE channel from an 8 channel source:Two channels for speakers at the front—left (L) and right (R).One channel for speaker at the center—center (C).Two channels for surround speakers at the sides—left surround (LS) and right surround (RS).[9]Two channels for surround speakers at the rear—left back (LB) and right back (RB).One low-frequency effects channel (LFE).Describes the Dolby Digital Plus discrete Surround system. Source media, usually HD DVD and sometimes Blu-Ray is often branded with "Dolby Digital Plus" and/or "DTS-HD" logos.

Layout variation for 7.1 widescreen cinema format:Four channels for speakers at the front—left (L), Center-left (CL), right (R) and Center-Right (CR).One channel for speaker at the center—center (C).Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).

This variation is becoming increasingly popular in home entertainment systems, as well as for large cinema auditoria where the screen width is such that the additional channels are needed to cover all angles between the loudspeakers satisfactorily for all seats in the auditorium.

For music, speaker placement is unknown.
Placement: The front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Side channel speakers should be placed on side walls, to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

10.2 Channel SurroundMain article: 10.2

10.2 is the surround sound format developed by THX creator Tomlinson Holman of TMH Labs and University of Southern California (schools of Cinema/Television and Engineering). Developed along with Chris Kyriakakis of the USC Viterbi School of Engineering, 10.2 refers to the format's promotional slogan: "Twice as good as 5.1". Advocates of 10.2 argue that it is the audio equivalent of IMAX.

10.2 augments the LS (left surround) and RS (right surround) channels by two point surround channels that can more finely manipulate sound—allowing the mixer to shift sounds in a distinct 360° circle around the movie watcher.

The 14 discrete channels are:
- Five front speakers: Left Wide, Left, Center, Right and Right Wide

- Five surround channels: Left Surround Diffuse, Left Surround Direct, Back Surround, Right Surround Diffuse and Right Surround Direct

- Two LFE channels: LFE Left, LFE Right

-Two Height channels: Left Height, Right Height

The .2 of the 10.2 refers to the addition of a second subwoofer. The system is bass managed such that all the speakers on the left side use the left sub and all the speakers on the right use the right sub. The Center and Back Surround speaker are split among the two subs. The two subs also serve as two discrete LFE (Low Frequency Effects) channels. Although low frequencies are not localizable, it was found that splitting the bass on either side of the audience increases the sense of envelopment.

22.2 Channel Surround

22.2 is the surround sound component of Ultra High Definition Video (Super Hi-vision TV with 4320 scanning lines), and has been developed by NHK Science & Technical Research Laboratories. As its name suggests, it uses 24 speakers. These are arranged in three layers: A middle layer of ten speakers, an upper layer of nine speakers, and a lower layer of three speakers and two sub-woofers. The system was demonstrated at Expo 2005, Aichi, Japan, the NAB 2006 conference, Las Vegas, and at IBC 2006, Amsterdam, Netherlands.

Infinite Channel Surround (Ambisonics)

Ambisonics is a series of recording and replay techniques using multichannel mixing technology that can be used live or in the studio. Any number of speakers in any physical arrangement can be used to recreate a sound field. With 6 or more speakers arranged around a listener, a 3-dimensional ("periphonic", or full-sphere) sound field can be presented. Ambisonics was invented by Michael Gerzon (among other researchers) of the Mathematical Institute, Oxford.

Panor-Ambiophonic (PanAmbio) 4.0/4.1Main article: Ambiophonics

PanAmbio combines a stereo dipole and crosstalk cancellation in front and a second set in back of the listener (total of four speakers) for 360° 2D surround reproduction. Four channel recordings, especially those containing binaural cues, create speaker-binaural surround sound. 5.1 channel recordings, including movie DVDs, are compatible by mixing C-channel content to the front speaker pair. 6.1 can be played by mixing SC to the back pair.

Notation

This notation, e.g. "5.1", reflects the number of full range channels; including a ".1" to reflect the limited range of the LFE channel.

E.g. 5 full-range channels + 1 LFE channel = 5.1
It can also be expressed as the number of full-range channels in front of the listener, separated by a slash from the number of full-range channels beside or behind the listener, separated by a decimal point from the number of limited-range LFE channels.

E.g. 3 front channels + 2 side channels + an LFE channel = 3/2.1

This notation can then be expanded to include the notation of Matrix Decoders. Dolby Digital EX, for example, has a sixth full-range channel incorporated into the two rear channels with a matrix. This would be expressed:
3 front channels + 2 rear channels + 3 channels reproduced in the rear in total + 1 LFE channel = 3/2:3.1

Note: The term stereo, although popularised in reference to two channel audio, can also be properly used to refer to surround sound, as it strictly means "solid" sound. However this is no longer a common usage and "stereo sound" is almost exclusively used to describe two channel left and right sound.

Dolby Pro Logic

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Dolby Pro Logic is a surround sound processing technology designed to decode soundtracks encoded with Dolby Surround. Dolby Surround Stereo was originally developed by Dolby Laboratories in 1976 for analog cinema sound systems. The format was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were earlier introduced and was then replaced by the newer and improved Pro Logic system in 1987. However, the term "Dolby Surround" is still used to describe the encoding technology or matrix-encoded soundtrack, whereas Pro Logic refers to the decoding technology/processor. It is the domestic equivalent of the theatrical Dolby Stereo technology used in movie cinemas in the 1970s and '80s. The two technologies are mostly identical but a change in marketing was needed so as not to confuse cinema stereo which is at least four channels of audio with home stereo which is only two. Thus Dolby Pro-Logic is the consumer version of theatrical Dolby stereo.

Dolby Pro Logic

Dolby Surround/Pro Logic is based on basic matrix technology. When a Dolby Surround soundtrack is created, four channels of sound are matrix-encoded into an ordinary stereo (two channel) sound track by using phase shift techniques. A Pro Logic decoder/processor "unfolds" the sound into the original 4.0 surround—left and right, center, and a single limited frequency-range mono rear channel—while systems lacking the decoder play back the audio as standard Stereo.

Although Dolby Surround was introduced as an analog format, all Dolby Digital decoders incorporate a digitally implemented Dolby Surround Pro Logic decoder for digital stereo signals that carry matrix-encoded Dolby Surround.

Dolby Pro Logic II
In 2000, Dolby introduced Dolby Pro Logic II (DPL II), an improved implementation of Dolby Pro Logic. DPL II processes any high quality stereo signal source into "5.1"—five separate full frequency channels (left, center, right, left surround and right surround) plus one low-frequency-effects (deep bass) channel. Dolby Pro Logic II also decodes 5.1 channels from stereo signals encoded in traditional four-channel Dolby Surround. DPL II implements greatly enhanced steering compared to DPL, and as a result, offers an exceptionally stable sound field that simulates 5.1 channel surround sound to a much more accurate degree than the original Pro Logic.
Because of the limited nature of the original DPL, many consumer electronics manufactures introduced their own processing circuitry, such as the "Jazz", "Hall", and "Stadium" modes found on most common home audio receivers. DPL II forgoes this type of processing and replaces it with simple servo (negative feedback) circuits used to derive five channels. In addition to five full range playback channels, Pro Logic II introduced a Music mode which would not add any processing to the left and right channels, but will still extract a center channel and two surround channels, providing a net effect of a wider center channel.
The Pro Logic II system also features a mode designed specifically for video gaming, and it is frequently used in game titles for Sony's PlayStation 2, Nintendo's GameCube and Wii as an alternative to digital technologies like Dolby Digital, LPCM or DTS.

Dolby Pro Logic IIx

A newer Dolby Pro Logic IIx system is also now available, which can take stereo and Dolby Surround (sometimes called Dolby Stereo Surround) source material and up-convert it to 6.1, or 7.1 channel surround sound. Dolby Pro Logic IIx also takes signals intended for Dolby Pro Logic II, and up-converts them to a 6.1 or 7.1 channel surround sound.
Software encoding
The liba52 decoder library for AC3 and A52 digital sound optionally exports stereo sound compatible with Dolby Surround and Pro Logic.
The Handbrake software for Mac OS X is capable of downmixing Dolby Digital AC-3 5.1 to Stereo for Dolby Pro Logic I & II for surround playback

Pro Logic vs Dolby Surround
Dolby Surround is the encoding counterpart to Dolby Pro Logic's decoding technology, but early home implementations of Dolby Surround decoding went by the name Dolby Surround which can cause some confusion. Dolby Surround and Dolby Pro Logic decoders are similar in principle, as both use matrix technology to extract extra channels from stereo-encoded audio. However, Pro Logic uses advanced algorithms, superior to the earlier home Dolby Surround system and similar to the original cinema Dolby Stereo processors, in order to not only extract the extra channels, but to also improve steering and discreteness between the channels.

Digital cinema

2008-07-08T23:04:00.000-07:00

Digital cinema refers to the use of digital technology to distribute and project motion pictures. The final movie can be distributed via hard drives [ex. Utilizing the CRU-Dataport DX115 removable disk drive carriers + DX115 carrier USB/SATA adapter], DVDs or satellite and projected using a digital projector instead of a conventional film projector. Digital cinema is distinct from high-definition television and in particular, is not dependent on using television or HDTV standards, aspect ratios, or frame rates. Digital projectors capable of 2K resolution began deploying in 2005, and since 2006, the pace has accelerated. HDTV and pre-recorded HD disks could put pressure on movie theaters to offer something to compete with the home HD experience.

In this article, 2K and 4K refer to images with 2048 and 4096 horizontal pixel resolution, respectively.

Technology

To match or improve the theater experience of movie audiences, a digital cinema system must provide high quality image, sound, subtitles, and captions. Theater managers require server controls for managing and displaying content in multiple theaters, and studios want their content encrypted with secure delivery, playback, and reporting of play times to the distribution company.

The Digital Cinema Initiatives (DCI), working in conjunction with members of the SMPTE standards committee, has published a system specification for digital cinema that was agreed upon by the major studios. Briefly, the specification calls for picture encoding using the ISO/IEC 15444-1 "JPEG2000" (.jp2) standard and use of the CIE XYZ color space at 12 bits per component encoded with a 2.6 gamma applied at projection, and audio using the "Broadcast Wave" (.wav) format at 24 bits and 48 kHz or 96 kHz sampling, controlled by an XML-format Composition Playlist, into an MXF-compliant file at a maximum data rate of 250 Mbit/s. Details about encryption, key management, and logging are all discussed in the specification as are the minimum specifications for the projectors employed including the color gamut, the contrast ratio and the brightness of the image.

Digital cinema conforming to the DCI Standard is referred to within the film industry as D-Cinema while all other forms of digital cinema are referred to as E-Cinema. Thus, while D-Cinema is a defined standard, though one that is still partly being framed by SMPTE as of 2007, E-Cinema may be anything, ranging from a DVD player connected to a consumer projector to something that approaches the quality of D-Cinema without conforming to some of the standards. Even D-Cinema itself has evolved over time before the DCI standards were framed. However, the current DCI standards were made with the intention of standing the test of time, much like 35 mm film which has evolved but still retained compatibility over a substantial part of a century.

Digital capture

As of 2007 the most common acquisition medium for digitally projected features is 35 mm film scanned and processed at 2K or 4K via digital intermediate. Most digital features to date have been shot at 1920x1080 HD resolution using cameras such as the Sony CineAlta, Panavision Genesis or Thomson Viper. New cameras such as the Arriflex D-20 and Silicon Imaging's SI-2K can capture 2K resolution images, and the Red Digital Cinema Camera Company's Red One can record 4k RAW. Thus the future of digital cinema can be expected to have as a standard 4K capture and 4K projection. Currently in development are other cameras capable of recording 4K RAW, such as Dalsa Corporation's Origin, and cameras capable of recording 5k RAW, such as the RED EPIC, and cameras capable of recording 3k RAW (for budget filmmakers) such as the RED SCARLET.

Digital post-production

Film is scanned from camera-original film negatives into a digital format on a scanner or high-resolution telecine. Data from digital motion picture cameras may be converted to a convenient image file format for work in a facility. All of the files are 'conformed' to match an edit list created by the film editor, and are then color corrected under the direction of the film's staff. The end result of post-production is a digital intermediate used to record the motion picture to film and/or for the digital cinema release.

Digital mastering

When all of the sound, picture, and data elements of a production have been completed, they may be assembled into a Digital Cinema Distribution Master (DCDM) which contains all of the digital material needed for a show. The images and sound are then compressed, encrypted, and packaged to form the Digital Cinema Package (DCP).

Digital cinema distributors

Technicolor, Deluxe Entertainment Services Group Inc., XDC and Access Integrated Technologies are the leading companies in digital distribution. Other companies currently distributing digital cinema include Kodak, DTS, Ascent Media, Dolby, Arts Alliance Media and Motion Picture Solutions.

Digital projection

There are currently two types of projectors for digital cinema. Early DLP projectors, which were deployed primarily in the U.S., used limited 1280×1024 resolution which are still widely used for pre-show advertising but not usually for feature presentations. The DCI specification for digital projectors calls for three levels of playback to be supported: 2K (2048×1080) at 24 frames per second, 4K (4096×2160) at 24 frames per second, and 2K at 48 frames per second.

Three manufacturers have licensed the TI-developed DLP Cinema technology. Christie Digital Systems, Barco and NEC. Christie is the maker of the CP2000 line of 2K DCI-compliant Digital Cinema Projectors, and long established in traditional film projector technology throughout the U.S. and is the market leader in terms of units sold and deployed internationally. NEC manufactures the Starus NC2500S, NC1500C and NC800C 2K projectors for large, medium and small screen respectively and the Starus Digital Cinema Server system, as well as other equipment to connect PCs, analog/digital tape decks and satellite receivers, DVD, and off-air broadcast, etc. for pre-show and special presentations. While NEC is a relative newcomer to Digital Cinema, Christie is the main player in the U.S. and Barco takes the lead in Europe and Asia.

The other soon-to-be-deployed-technology is from Sony and is labeled "SXRD" technology. Their projector provides 4096x2160 resolution.

Other manufacturers have been developing digital projector technology, but these have not yet been deployed into motion picture theaters and are not commercially available in versions that conform to the DCI specification.
As of July 2007, there are some cinemas in Singapore showing digital 4K films to public using Sony's CineAlta 4K digital projector. They are located at Golden Village Cinema in Vivocity (Hall 11), Eng Wah Cinema in Suntec (Hall 3), Shaw Cinema in Bugis (Hall 1 & 3) and at Cathay Cineplex (Hall 7).

In September 2007, Muvico Theaters Rosemont 18 in Rosemont, Illinois became the first theater in North America to have Sony's CineAlta 4K digital projectors for all 18 screens. Muvico Theaters intends on opening more theaters in the last quarter of 2008 and well into 2009 all utilizing Sony's CineAlta 4K digital projector.

Live broadcasting to movie theaters
Digital cinemas can deliver live broadcasts from performances or events. For example, there are regular live broadcasts to movie theaters of Metropolitan Opera performances.

Current developments

As of October 2007, there are over 5000 DLP-based Digital Cinema Systems installed.
By October 2007, DG2L Technologies was reported to have supplied 1500 Digital Cinema Systems to UFO Moviez Ltd. in India and Europe.

As of July, 2007, 1400 screens in the U.S. have been equipped with digital cinema projectors including a dozen theaters where the Sony 4K projector has been installed. In continental Europe, XDC is servicing over 300 screens in 10 countries, where Germany has the leading territory with over 100 installations.

The UK is home to Europe's first DCI compliant fully digital multiplex cinemas, Odeon Hatfield and Odeon Surrey Quays (London) have a total of 18 digital screens and were both launched on Friday 9 February 2007.

In June 2007, Arts Alliance Media announced the first European commercial digital cinema VPF agreements (with Twentieth Century Fox and Universal Pictures).

As of March 2007, with the release of Disney's Meet the Robinsons, about 600 screens have been equipped with 2K digital projectors that are equipped with Real D Cinema's stereoscopic 3D technology, marketed under the Disney Digital 3-D brand.

In mid 2006, about 400 theaters have been equipped with 2K digital projectors with the number increasing every month.

In February 2005, Arts Alliance Media was selected to roll out the UK Film Council’s Digital Screen Network (DSN), a $20M contract to install and operate Europe’s largest 2K digital cinema network. By March 2007, 230 of the 241 screens had been installed on schedule, with the remaining 11 to be installed later in 2007 when cinemas have completed building works or construction.

Chicken Little from Disney, with its experimental release of the film in digital 3D, increased the number of projectors using the 2K format. Several digital 3D films will surface in 2006 and several prominent filmmakers have committed to making their next productions in stereo 3D.

By early 2006, Access Integrated Technologies (AccessIT) had announced agreements with nearly all of the major film studios and several exhibitors that enable the company to roll-out its end-to-end digital cinema systems. In August 2006, the Malayalam digital movie Moonnamathoral was distributed via satellite to cinemas; thus becoming the first Malayalam digital film to be so distributed. This was done using the end-to-end digital cinema system developed by Singapore based DG2L Technologies.

On May 1, 2008, Public Radio International (PRI) spearheaded the first-ever digital cinema event in public media by working with Ira Glass and Chicago Public Radio on This American Life Live![5]. The event was presented exclusively in select theatres by National CineMedia's (NCM) Fathom, in partnership with BY Experience and Chicago Public Radio, and in association with Public Radio International.

Economics

Savings in distribution

Digital distribution of movies has the potential to save money for film distributors. A single film print can cost around US$1200[citation needed] (or $30,000 for a 1-time print of an 80-minute feature[7]), so making 4000 prints for a wide-release movie might cost $5 million. In contrast, at the maximum 250 megabit-per-second maximum data rate defined by DCI for digital cinema, a typical feature-length movie could fit comfortably on an off the shelf 300 GB hard drive—which cost as low as $70—which could even be returned to the distributor for reuse after a movie's run. With several hundred movies distributed every year, industry savings could potentially reach $1 billion or more.

Alternative content

An added incentive for exhibitors is the ability to show alternative content such as live special events, sports, pre-show advertising and other digital or video content. Some low-budget films that would normally not have a theatrical release because of distribution costs might be shown in smaller engagements than the typical large release studio pictures. The cost of duplicating a digital "print" is very low, so adding more theaters to a release has a small additional cost to the distributor. Movies that start with a small release could scale to a much larger release quickly if they were sufficiently successful, opening up the possibility that smaller movies could achieve box office success previously out of their reach.

Greater protection for content

A last incentive for digital distribution is the possibility of greater protection against piracy. With traditional film prints, distributors typically stagger the film's release in various markets, shipping the film prints around the globe. In the subsequent markets, pirated copies of a film (i.e. a cam) may be available before the movie is released in that market. A simultaneous worldwide release would mitigate this problem to some degree. Simultaneous worldwide releases on film have been used on The Da Vinci Code, Lord of the Rings: Return of the King, Star Wars: Revenge of the Sith, Charlie's Angels: Full Throttle and Mission: Impossible III amongst others. With digital distribution, a simultaneous worldwide release would not cost significantly more than a staggered release.

Costs

On the downside, the initial costs for converting theaters to digital are high: up to $150,000 per screen or more. Theaters have been reluctant to switch without a cost-sharing arrangement with film distributors. Recent negotiations have involved the development of a Virtual Print License fee which the studios will pay for their products which allows financiers and system developers to pay for deployment of digital systems to the theaters, thus providing investors a certain payback.

While a theater can purchase a film projector for US$50,000 and expect an average life of 30–40 years, a digital cinema playback system including server/media block/and projector can cost 3–4 times as much, and is at higher risk for component failures and technological obsolescence. Experience with computer-based media systems show that average economic lifetimes are only on the order of 5 years with some units lasting until about 10 years before they are replaced.

Archiving digital material is also turning out to be both tricky and costly. In a 2007 study, the Academy of Motion Picture Arts and Sciences found the cost of storing 4K digital masters to be "enormously higher - 1100% higher - than the cost of storing film masters." Furthermore, digital archiving faces challenges due to the insufficient temporal qualities of today's digital storage: no current media, be it optical discs, magnetic hard drives or digital tape, can reliably store a film for a hundred years, something that properly stored and handled film can do.[8]

History

Digital media playback of hi-resolution 2K files has at least a twenty year history with early RAIDs feeding custom frame buffer systems with large memories. Content was usually restricted to several minutes of material.
Transfer of content between remote locations was slow and had limited capacity. It wasn't until the late 1990s that feature length projects could be sent over the 'wire' (Internet or dedicated fiber links).

There were many prototype systems developed that claim a first in some form of digital presentation. However, few of these had a significant impact on the advance of the industry. Key highlights in the development of digital cinema would likely include: demonstrations by TI of their DMD technology, real-time playback of compressed hi-resolution files by various vendors, and early HD presentations from D5 tape to digital projectors.

Standards development

The Society of Motion Picture and Television Engineers began work on standards for digital cinema in 2001. It was clear by that point in time that HDTV did not provide a sufficient technological basis for the foundation of digital cinema playback. (In Europe and Japan however, there is still a significant presence of HDTV for theatrical presentations. Agreements within the ISO standards body have led to these systems being referred to as Electronic Cinema Systems (E-Cinema)).

Digital Cinema Initiatives (DCI) was formed in March 2002 as a joint project of the motion picture studios (Disney, Fox, MGM, Paramount, Sony Pictures Entertainment, Universal and Warner Bros. Studios) to develop a system specification for digital cinema. In cooperation with the American Society of Cinematographers, DCI created standard evaluation material (the ASC/DCI StEM material) and developed tests of 2K and 4K playback and compression technologies. DCI published their specification in 2005.

Claims to significant events

One claim for the first digital cinema demonstration comes from JVC. On March 19, 1998, they collaborated on a digital presentation at a cinema in London. Several clips from popular films were encoded onto a remote server, and sent via fibre optic for display to a collection of interested Industry parties.

The Last Broadcast made cinematic history on October 23, 1998, when it became the first feature to be theatrically released digitally, via satellite download to theaters across the United States. An effort headed by Wavelength Releasing, Texas Instruments, Digital Projection Inc. and Loral Space, it successfully demonstrated what would become a template for future releases. In 1999, it was repeated utilizing QuVIS technology across Europe, including the Cannes Film Festival, making The Last Broadcast the first feature to be screened digitally at the Cannes Film Festival.

Several feature films were shown in 1999 using DLP prototype projectors and early wavelet based servers. For example, Walt Disney Pictures Bicentennial Man was presented using a Qubit server manufactured by QuVIS of Topeka, Kansas. DVD ROM was used to store the compressed data file. The DVD ROMs were loaded into the QuBit server hard drives for playout. The file size for Bicentennial Man was 42 GB with an average data rate of 43 Mbit/s.
In 2000, Walt Disney, Texas Instruments and Technicolor with the cooperation of several U.S. and international exhibitors, began to deploy prototype Digital Cinema systems in commercial theatres. The systems were assembled and installed by Technicolor using the TI mark V prototype projector, a special Christie lamp housing, and the QuBit server with custom designed automation interfaces.

Technicolor manufactured the DVDs for uploading on these test systems and was responsible for sending technicians out to the locations for every new feature film that was played. The technicians would typically spend ten or so hours to load the files from the DVD to the QuBit, set up the server to play the files, and then set up the projector. A full rehearsal screening of the feature was mandatory as was the requirement to have back up DVDs and backup QuBits available should something fail.

The systems were eventually replaced or upgraded after TI made improvements to the projectors and Technicolor developed a purpose-built digital cinema server in a venture with Qualcomm, the engineering giant from San Diego best known for advanced mobile phone technology. The new systems were called AMS for Auditorium Management Systems and were the first digital cinema servers designed to be user friendly and operate reliably in a computer-hostile environment such as a projection booth. Most importantly, they provided a complete solution for content security.

The AMS used removable hard disk drives as the transport mechanism for the files. This eliminated the time required to upload the DVD ROMs to the local hard drives and provided the ability to switch programs quickly. For security, the AMS used a media block type system that placed a sealed electronics package within the projector housing. The server output only 3DES encrypted data and the media block did the decryption at the point just before playout.

The first secure encrypted digital cinema feature was Star Wars Episode II: Attack of the Clones. The system functioned well but was eventually replaced because of the need to create a standard data package for D-cinema distribution.

Universal Pictures used their film Serenity as the first DCI-compliant DCP to be delivered shown to an audience at a remote theater, although it was not distributed this way to the public. Inside Man was their first DCP cinema release, and was transmitted to 20 theatres in the United States along with two trailers.

In April 2005, DG2L Technologies announced that it had been awarded the multi-million dollar contract for the world's largest satellite based MPEG4 digital cinema deployment to be done in India, which encompassed 2000 theaters for UFO (United Film Organizers), a subsidiary of the Valuable Media Group. In Mar 2006, United Film Organizers Moviez (UFO Moviez), had reached a significant milestone—surpassing 30,000 shows using the DG2L Cinema System platform. This figure increased to 100,000 shows in August 2006. In September 2006, UFO Moviez acquired 51% stake in DG2L Technologies in a deal estimated at around $50 million.

Stereo 3-D images
In late 2005, interest in digital 3-D stereoscopic projection has led to a new willingness on the part of theaters to co-operate in installing a limited number of 2K stereo installations to show Disney's Chicken Little in 3-D film. Seven more digital 3-D movies are slated for 2006 or 2007 release (including Beowulf, Monster House and Meet the Robinsons). The technology combines digital projectors with the use of polarized glasses and screens. DLP technology is well-suited for stereo 3-D as it can handle the higher frame rates required for flicker free presentations.

Digital Theater System

2008-07-08T20:19:00.000-07:00

DTS (also known as Digital Theater Systems), owned by DTS, Inc. (NASDAQ: DTSI), is a multi-channel digital surround sound format used for both commercial/theatrical and consumer grade applications. It is used for in-movie sound both on film and on DVD, and during the last few years of the Laserdisc format's existence, several releases had DTS soundtracks.

History

One of the company's initial investors was film director Steven Spielberg, who felt that theatrical sound formats up until the company's founding were no longer state of the art, and as a result were no longer optimal for use on projects where quality sound reproduction was of the utmost importance. Work on the format started in 1991, four years after Dolby Labs started work on its new codec, Dolby Digital. The basic and most common version of the format is a 5.1 channel system, similar to a Dolby Digital setup, which encodes the audio as five primary (full-range) channels plus a special LFE (low-frequency effect) channel, for the subwoofer.

Note however that encoders and decoders support numerous channel combinations and stereo, four-channel and four-channel+LFE soundtracks have been released commercially on DVD, CD and Laserdisc.

Other newer DTS variants are also currently available, including versions that support up to seven primary audio channels plus one LFE channel (DTS-ES). DTS's main competitors in multichannel theatrical audio are Dolby Digital and SDDS, although only Dolby Digital and DTS are used on DVDs and implemented in home theater hardware. Spielberg debuted the format with his 1993 production of Jurassic Park, which came slightly less than a full year after the official theatrical debut of Dolby Digital (Batman Returns). In addition, Jurassic Park also became the first home video release to contain DTS sound when it was released on LaserDisc in January 1997, two years after the first Dolby Digital home video release (Clear and Present Danger on Laserdisc) which debuted in January of 1995.

In theatrical use, information in the form of a modified time code is optically imaged onto the film. An optical LED reader reads the timecode data off the film and sends it to the DTS processor which uses this timecode to synchronize the projected image with the soundtrack audio. The actual audio is recorded in compressed form on standard CD-ROM media at a bitrate of 1,103 kbit/s. The processor also acts as a transport mechanism, as it holds and reads the audio discs. Newer units can generally hold three discs, allowing a single processor/transport to handle two-disc film soundtracks along with a third disc containing sound for theatrical trailers. In addition, specific elements of the imprinted timecode allow identifying data to be embedded within the code, ensuring that a certain film's soundtrack will only run with that film. DTS provided the Digital Audio for IMAX until 2001, when Dolby took over.

DTS and Dolby Digital (AC-3), DTS's chief competitor in the cinema and home theater market, are often compared due to their similarity in product goals. In theatrical installations, AC-3 audio is placed between sprocket holes, leaving the audio content susceptible to physical damage due to film wear and mishandling. DTS audio is stored on a separate set of CD-ROM media, whose greater storage capacity affords the potential to deliver better audio fidelity. However, the separation of print film and audiotrack is both a blessing and a curse. AC-3 (and SDDS) reside entirely on the 35 mm film itself, simplifying distribution by eliminating an extra (optional) deliverable. But DTS's CD-ROM media is not subject to the usual wear and damage suffered by the film print during the normal course of the movie's theatrical screening. Disregarding the separate CD-ROM assembly as a potential point of failure, the DTS audiopath is comparatively impervious to film degradation, excepting that the film-printed timecode is completely destroyed.

In the consumer (home theater) market, AC-3 and DTS are close in terms of audio performance. When the DTS audio track is encoded at its highest legal bitrate (1,536 kbit/s), technical experts rank DTS as perceptually transparent for most audio program material (i.e., indistinguishable to the uncoded source in a double blind test.) Dolby claims its competing AC-3 codec achieves similar transparency at its highest coded bitrate (640 kbit/s). However, in program material available to home consumers (DVD, broadcast and subscription Digital TV), neither AC-3 nor DTS run at its highest allowed bitrate. DVD and broadcast (ATSC) HDTV cap AC-3 bitrate at 448 kbit/s. But even at 448 kbit/s, consumer audio gear already enjoys better audio performance than theatrical (35 mm movie) installations, which are limited to even lower bitrates. When DTS-audio was introduced to the DVD specification, studios authored DVD-movies at DTS's full bitrate (1,536 kbit/s). Later movie titles were almost always encoded at a reduced bitrate of 768 kbit/s, ostensibly to increase the number of audio-tracks on the movie disc. At this reduced rate (768 kbit/s), DTS no longer retains audio transparency.

AC-3 and DTS are sometimes judged by their encoded bitrates. DTS proponents claim that the extra bits give higher fidelity and more dynamic range, providing a richer and more lifelike sound. But no conclusion can be drawn from their respective bitrates, as each codec relies on different coding tools and syntax to compress audio. When the DTS and AC-3 audiotracks on the same DVD are compared, some movies exhibit noticeable differences. A DTS track is often louder with less hiss, even at the same relative playback volume.

DTS as a codec

DTS is an enhanced copy of a French patent called LC Concept, first used in 1990 for the movie Cyrano de Bergerac which received the best sound award at the César Awards in 1991.

On the consumer level, DTS is the oft-used shorthand for the DTS Coherent Acoustics codec, transportable through S/PDIF and used on DVDs, CDDAs, LDs and in wave files. This system is the consumer version of the DTS standard, using a similar codec without needing separate DTS CD-ROM media.

There are significant technical differences between commercial/theatrical and home variants: the former being a traditional ADPCM compression system and the latter a sophisticated hybrid perceptual and signal-redundancy compressor based on ADPCM called APTX-100.

DTS playback

Both music and movie DVDs allow delivery of DTS audio tracks. But DTS was not part of the original DVD specification (1997), so early DVD players did not recognize DTS audio tracks at all. The DVD specification was revised to allow optional inclusion of DTS audio tracks. The DVD title must carry one or more primary audio tracks in AC-3 or LPCM format (in Europe, MPEG-1 is also an allowed primary track format). The DTS audio track, if present, can be selected by the user. Modern DVD players can now decode DTS natively with no problem, or pass it through to an external decoder. Nearly all standalone receivers and many integrated ("home theater in a box") DVD player/receivers manufactured today can decode DTS.

For PC playback, many software players support the decoding of DTS. The VideoLAN project has created a decoding module for DTS called libdca (formerly libdts), which is the first open source implementation of DTS. The Sony Playstation 3 and Xbox 360 are capable of DTS decoding and output via Toslink or HDMI as LPCM. However on the 360, this feature is only found on new the Elite model and newer models available since. Only the Playstation 3 console has the ability to decode DTS-HD Master Audio or High Resolution since the newest firmware update, ver. 2.30 and up. The Xbox 360 can only output the core bitstream at 1.5 Mbit/s via LPCM or Toslink.

DTS variants

In addition to the standard 5.1 channel DTS Surround codec, the company has several other technologies in its product range designed to compete with similar systems from Dolby Labs. The primary new technologies are:

DTS 70 mm

This is a process designed specifically for playback in motion picture theaters equipped with 70mm projection and 6-track stereophonic surround sound. It is believed that this is the digital equivalent of the 70mm Dolby Stereo 6-Track analog mixing process. It works the same way that 35 mm DTS does, only the size of the print stock is bigger. The 6-track audio data is played on special compact discs in synchronization with the picture that is projected on a screen. The 6-track system plays on a properly organized 5.1 system: left, right, center, LFE speaker, and split surrounds.

DTS-ES

DTS-ES (DTS Extended Surround) includes two variants, DTS-ES Matrix and DTS-ES Discrete 6.1, depending on how the sound was originally mastered and stored. DTS-ES Discrete provides 6.1 discrete channels, with a discretely recorded (non-matrixed) center-surround channel; in home theater systems with a 7.1 configuration, the two rear-center speakers play in mono. DTS-ES Matrix provides 5.1 discrete channels with a matrixed center-surround audio channel. DTS-ES commonly works on a matrix system, whereby processors that are compatible with the ES codec look for and recognize "flags" built into the audio coding and "un-fold" the rear-center sound from data that would otherwise be sent to rear surround speakers.

This is notated as DTS-ES 5.1. Less frequently, DTS-ES data can be encoded with a discrete sixth audio channel (the rear-center), meaning that the audio data for the sixth channel is stored separately from the other information, and is not embedded or matrixed among other channels. This is notated as DTS-ES 6.1, as the center rear is completely discrete from the other channels. ES capable processors can recognize the discrete sixth channel, and play it back if connected to the necessary speaker(s). In contrast, Dolby's competing EX codec, which also boasts a center rear channel, can only handle matrixed data and does not support a discrete sixth channel. DTS-ES is backward compatible with standard DTS setups, so non-ES equipment which does not recognize the flags or with ES enabled equipment that lack the extra speaker connections, sound plays back in 5.1 as if it were standard DTS. Only a few DVD titles have been released with DTS-ES Discrete.

DTS NEO:6

DTS NEO:6, like Dolby's Pro Logic IIx system, can take stereo content and convert the sound into 5.1 or 6.1 channel format.

DTS 96/24

DTS 96/24 allows the delivery of 5.1 channels of 24-bit, 96 kHz audio and high quality video on the DVD-Video format. Prior to the invention of DTS 96/24, it was only possible to deliver two channels of 24-bit, 96 kHz audio on DVD-Video. DTS 96/24 can also be placed in the video zone on DVD-Audio discs, making these discs playable on all DTS compatible DVD players.

DTS-HD High Resolution Audio

DTS-HD High Resolution Audio, like DTS-HD Master Audio, is an extension to the original DTS audio format. It delivers up to 7.1 channels of sound at 96 kHz sampling frequency and 24 bit depth resolution. DTS-HD High Resolution Audio is selected as an optional surround sound format for Blu-ray Disc and HD DVD with constant bit rates up to respectively 6.0 Mbit/s and 3.0 Mbit/s. It is supposed to be an alternative for DTS-HD Master Audio where disc space may not allow it.

DTS-HD Master Audio

DTS-HD Master Audio, previously known as DTS++ and DTS-HD, supports a virtually unlimited number of surround sound channels, can downmix to 5.1 and two-channel, and can deliver audio quality at bit rates extending from DTS Digital Surround up to lossless (24-bit, 192 kHz). DTS-HD Master Audio is selected as an optional surround sound format for Blu-ray and HD DVD, where it has been limited to a maximum of 8 discrete channels. DTS-HD MA supports variable bit rates up to 24.5 Mbit/s on a Blu-ray Disc and up to 18.0 Mbit/s for HD-DVD, with 6 channel encoded at up to 192 kHz or 8 channels encoded at 96 kHz/24 bit. In case more than 6 channels are used, a "Channel Remapping" function allows for remixing the soundtrack to compensate for a different channel layout in the playback system compared to the original mix. Currently the Japanese version Pioneer BDP-LX80 supports bitstream digital output of the format along with the Samsung BD-P1400 (through a firmware update). All Blu-ray and HD DVD players can decode the DTS "core" resolution soundtrack at 1.5 Mbit/s, however. DTS-HD Master Audio and Dolby TrueHD are the only technologies that deliver compressed lossless surround sound for these new disc formats, ensuring the highest quality audio performance available in the new standards. (N.B.: DTS Coherent Acoustics coding system has been selected as mandatory audio technology for both the Blu-ray Disc (BD) and High Definition Digital Versatile Disc (HD DVD).

Others

- DTS Connect: This is a real-time encoding technology for interactive media available on the computer platform only. It converts any audio signals on a PC into the 5.1-channel DTS format and transports it via a single S/PDIF cable. It is found on soundcards with CMedia CMI8788/CMI8770 Soundcontroller and onboard audio with Realtek ALC883DTS/ALC889A/ALC888DD-GR and SoundMAX AD1988 chip.

- DTS Interactive: This is a realtime DTS stream encoder. It is a part of DTS Connect, and can be found on stand alone devices (e.g., Surround Encoder, HD DVD / Blu-ray Player). Nearly a dozen titles on the PlayStation 2 feature the "DTS Interactive" realtime stream encoder, such as Grand Theft Auto: Vice City, and Terminator 3: Rise of the Machines.

- DTS Surround Sensation: A relatively new development, previously known as DTS Virtual. It allows a virtual 5.1 surround sound to be heard through a standard pair of headphones.

Dolby

2008-07-07T03:26:00.000-07:00

History

Dolby Labs was founded by Ray Dolby in England in 1965. He moved the company to the United States (San Francisco, California) in 1976. The first product he made was Type A Dolby Noise Reduction, a simple compander. One of the features that set Dolby's compander apart was that it treated only the quiet sounds that would be masked by tape noise. Dolby marketed the product to record companies.

Dolby was persuaded by Henry Kloss of KLH to manufacture a consumer version of his noise reduction. Dolby worked more on companding systems and introduced B-type in 1968. Dolby did not manufacture consumer products outright; it licensed the technologies to consumer electronics manufacturers.

Dolby also sought to improve film sound. As the corporation's history explains:Upon investigation, Dolby found that many of the limitations in optical sound stemmed directly from its significantly high background noise. To filter this noise, the high-frequency response of theatre playback systems was deliberately curtailed… To make matters worse, to increase dialogue intelligibility over such systems, sound mixers were recording soundtracks with so much high-frequency pre-emphasis that high distortion resulted.

The first film with Dolby sound was A Clockwork Orange (1971), which used Dolby noise reduction on all pre-mixes and masters, but a conventional optical sound track on release prints. Callan (1974) was the first film with a Dolby-encoded optical soundtrack. In 1975 Dolby released Dolby Stereo, which included a noise reduction system in addition to more audio channels (Dolby Stereo could actually contain additional center and surround channels matrixed from the left and right). The first film with a Dolby-encoded stereo optical soundtrack was Lisztomania (1975), although this only used an LCR (Left-Center-Right) encoding technique. The first true LCRS (Left-Center-Right-Surround) soundtrack was encoded on the movie A Star Is Born in 1976. In less than ten years, 6,000 cinemas worldwide were equipped to use Dolby Stereo sound. Dolby reworked the system slightly for home use and introduced Dolby Surround, which only extracted a surround channel, and the more impressive Dolby Pro Logic, which was the domestic equivalent of the theatrical Dolby Stereo.

Dolby developed a digital surround sound compression scheme for the cinema. Dolby Stereo Digital (now simply called Dolby Digital) was first featured on the 1992 film Batman Returns. Introduced to the home theater market as Dolby AC-3 with the 1995 laserdisc release of Clear and Present Danger, the format did not become widespread in the consumer market, partly because of extra hardware that was necessary to make use of it, until it was adopted as part of the DVD specification. Dolby Digital is now found in the HDTV (ATSC) standard of the USA, DVD players, and many satellite-TV and cable-TV receivers.

On February 17, 2005, the company became public, offering stock for sale on the New York Stock Exchange under the symbol DLB.
On March 15, 2005, Dolby celebrated forty years of enhancing entertainment at the ShoWest 2005 Festival in San Francisco.
On January 8, 2007, Dolby announced the arrival of an entirely new product called Dolby Volume at the International Consumer Electronics Show (CES). This product enables users to maintain a steady volume while switching through channels or program elements (i.e., loud TV commercials).
Dolby Labs has been good to its founder. Ray Dolby is a member of the Forbes 400 with an estimated net worth of 2.7 Billion in 2007.

Technologies

Analog audio noise reduction

Dolby A/B/C/S-Type NR: professional and consumer noise reduction systems for tapes and analog cassettes.Dolby SR (Spectral Recording): professional four-channel noise reduction system in use since 1986, which improves the dynamic range of analog recordings and transmissions by as much as 25 dB.

Dolby SR is utilized by recording and post-production engineers, broadcasters, and other audio professionals. It is also the benchmark in analog film sound, being included today on nearly all 35 mm film prints. On films with digital soundtracks, the SR track is used in cinemas not equipped for digital playback, and it serves as a backup in case of problems with the digital track.

Dolby FM: noise reduction system for FM broadcast radio. Dolby FM used Dolby B, combined with 25 microsecond pre-emphasis. This system integrated into a small number of receivers, and was used by a few radio stations in the late 1970s and early 1980s. The system is no longer used, however.

Dolby HX Pro: single-ended system used on high-end tape recorders to increase headroom. The recording bias is varied with respect to the high frequency component of the signal being recorded. It does nothing to the actual audio that's being recorded, and doesn't require a special decoder. Any HX Pro recorded tape will have, in theory, better sound on any deck.

Audio encoding/compression

Dolby Digital (also known as AC-3): is a lossy audio compression format. It supports channel configurations from mono up to six discrete channels (referred to as "5.1"). This format first allowed and popularized surround sound. It was first developed for movie theater sound and spread to Laserdisc and DVD. It has been adopted in many broadcast formats including all North American digital television (ATSC), DVB-T, direct broadcast satellite, cable television, DTMB, IPTV, and surround sound radio services. It was also part of Blu-ray and HD DVD standards. Dolby Digital is used to enable surround sound output by most video game consoles. Several personal computers support converting all audio to Dolby Digital for output. Dolby Digital EX: introduces a matrix-encoded center rear surround channel to Dolby Digital for 6.1 channel output.

This center rear channel is often split to two rear back speakers for 7.1 channel output.Dolby Digital Plus: audio codec based on Dolby Digital that is backward compatible, but more advanced. The DVD Forum has selected Dolby Digital Plus as a standard audio format for HD DVD video. It supports datarates up to 6 Mbyte/s, an increase from Dolby Digital's 640 kbit/s maximum. Dolby Digital Plus is also optimized for limited datarate environments such as Digital broadcasting. Dolby-E selected hardware.

Dolby E: professional coding system optimized for the distribution of surround and multichannel audio through digital two-channel post-production and broadcasting infrastructures, or for recording surround audio on two audio tracks of conventional digital video tapes, video servers, communication links, switchers, and routers. The Dolby E signal does not reach viewers at home. It is transcoded to Dolby Digital at lower datarate for final DTV transmission.Dolby Stereo (also known as Dolby Analog): original analog optical technology developed for 35 mm prints and is encoded with four sound channels: Left/Center/Right (which are located behind the screen) and Surround (which is heard over speakers on the sides and rear of the theatre) for ambient sound and special effects. This technology also employs A-type or SR-type noise reduction, listed above with regards to analog cassette tapes. See also Dolby SurroundDolby TrueHD: Dolby's current lossless coding technology. It offers bit-for-bit sound reproduction identical to the studio master. Over seven full-range 24-bit/96 kHz discrete channels are supported (plus a LFE channel, making it 7.1 surround) along with the HDMI interface. It has been selected as the mandatory format for HD DVD and as an optional format for Blu-ray Disc. Theoretically, Dolby True HD can support more channels, but this number has been limited to 8 for HD DVD and Blu-ray Disc.

Audio processingDolby Headphone: simulates 5.1 surround sound in a standard pair of stereo headphones. Dolby Virtual Speaker: simulates 5.1 surround sound in a setup of two standard stereo speakers. Dolby Pro Logic, Dolby Pro Logic II, Dolby Pro Logic IIx: expands stereo content to surround soundAudistry: sound enhancement technologies Dolby Volume: reduces volume level changes.

Central processing unit

2008-07-07T02:57:00.000-07:00

A Central Processing Unit (CPU), or sometimes just called processor, is a description of a class of logic machines that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage. The term itself and its initialism have been in use in the computer industry at least since the early 1960s (Weik 1961). The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation has remained much the same.

Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, computer. However, this costly method of designing custom CPUs for a particular application has largely given way to the development of mass-produced processors that are suited for one or many purposes. This standardization trend generally began in the era of discrete transistor mainframes and minicomputers and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in everything from automobiles to cell phones to children's toys.

History of CPUs

Prior to the advent of machines that resemble today's CPUs, computers such as the ENIAC had to be physically rewired in order to perform different tasks. These machines are often referred to as "fixed-program computers," since they had to be physically reconfigured in order to run a different program. Since the term "CPU" is generally defined as a software (computer program) execution device, the earliest devices that could rightly be called CPUs came with the advent of the stored-program computer.

The idea of a stored-program computer was already present during ENIAC's design, but was initially omitted so the machine could be finished sooner. On June 30, 1945, before ENIAC was even completed, mathematician John von Neumann distributed the paper entitled "First Draft of a Report on the EDVAC." It outlined the design of a stored-program computer that would eventually be completed in August 1949 (von Neumann 1945). EDVAC was designed to perform a certain number of instructions (or operations) of various types. These instructions could be combined to create useful programs for the EDVAC to run. Significantly, the programs written for EDVAC were stored in high-speed computer memory rather than specified by the physical wiring of the computer. This overcame a severe limitation of ENIAC, which was the large amount of time and effort it took to reconfigure the computer to perform a new task. With von Neumann's design, the program, or software, that EDVAC ran could be changed simply by changing the contents of the computer's memory.

While von Neumann is most often credited with the design of the stored-program computer because of his design of EDVAC, others before him such as Konrad Zuse had suggested similar ideas. Additionally, the so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design using punched paper tape rather than electronic memory. The key difference between the von Neumann and Harvard architectures is that the latter separates the storage and treatment of CPU instructions and data, while the former uses the same memory space for both. Most modern CPUs are primarily von Neumann in design, but elements of the Harvard architecture are commonly seen as well.

Being digital devices, all CPUs deal with discrete states and therefore require some kind of switching elements to differentiate between and change these states. Prior to commercial acceptance of the transistor, electrical relays and vacuum tubes (thermionic valves) were commonly used as switching elements. Although these had distinct speed advantages over earlier, purely mechanical designs, they were unreliable for various reasons. For example, building direct current sequential logic circuits out of relays requires additional hardware to cope with the problem of contact bounce. While vacuum tubes do not suffer from contact bounce, they must heat up before becoming fully operational and eventually stop functioning altogether. Usually, when a tube failed, the CPU would have to be diagnosed to locate the failing component so it could be replaced. Therefore, early electronic (vacuum tube based) computers were generally faster but less reliable than electromechanical (relay based) computers.

Tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the (slower, but earlier) Harvard Mark I failed very rarely (Weik 1961:238). In the end, tube based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems. Most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs (see below for a discussion of clock rate). Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, limited largely by the speed of the switching devices they were built with.

Discrete transistor and IC CPUs

The design complexity of CPUs increased as various technologies facilitated building smaller and more reliable electronic devices. The first such improvement came with the advent of the transistor. Transistorized CPUs during the 1950s and 1960s no longer had to be built out of bulky, unreliable, and fragile switching elements like vacuum tubes and electrical relays. With this improvement more complex and reliable CPUs were built onto one or several printed circuit boards containing discrete (individual) components.

During this period, a method of manufacturing many transistors in a compact space gained popularity.The integrated circuit (IC) allowed a large number of transistors to be manufactured on a single semiconductor-based die, or "chip." At first only very basic non-specialized digital circuits such as NOR gates were miniaturized into ICs. CPUs based upon these "building block" ICs are generally referred to as "small-scale integration" (SSI) devices. SSI ICs, such as the ones used in the Apollo guidance computer, usually contained transistor counts numbering in multiples of ten. To build an entire CPU out of SSI ICs required thousands of individual chips, but still consumed much less space and power than earlier discrete transistor designs. As microelectronic technology advanced, an increasing number of transistors were placed on ICs, thus decreasing the quantity of individual ICs needed for a complete CPU. MSI and LSI (medium- and large-scale integration) ICs increased transistor counts to hundreds, and then thousands.

In 1964 IBM introduced its System/360 computer architecture which was used in a series of computers that could run the same programs with different speed and performance. This was significant at a time when most electronic computers were incompatible with one another, even those made by the same manufacturer. To facilitate this improvement, IBM utilized the concept of a microprogram (often called "microcode"), which still sees widespread usage in modern CPUs (Amdahl et al. 1964). The System/360 architecture was so popular that it dominated the mainframe computer market for the decades and left a legacy that is still continued by similar modern computers like the IBM zSeries. In the same year (1964), Digital Equipment Corporation (DEC) introduced another influential computer aimed at the scientific and research markets, the PDP-8. DEC would later introduce the extremely popular PDP-11 line that originally was built with SSI ICs but was eventually implemented with LSI components once these became practical. In stark contrast with its SSI and MSI predecessors, the first LSI implementation of the PDP-11 contained a CPU composed of only four LSI integrated circuits (Digital Equipment Corporation 1975).

Transistor-based computers had several distinct advantages over their predecessors. Aside from facilitating increased reliability and lower power consumption, transistors also allowed CPUs to operate at much higher speeds because of the short switching time of a transistor in comparison to a tube or relay. Thanks to both the increased reliability as well as the dramatically increased speed of the switching elements (which were almost exclusively transistors by this time), CPU clock rates in the tens of megahertz were obtained during this period. Additionally, while discrete transistor and IC CPUs were in heavy usage, new high-performance designs like SIMD (Single Instruction Multiple Data) vector processors began to appear. These early experimental designs later gave rise to the era of specialized supercomputers like those made by Cray Inc.

MicroprocessorsMain article: Microprocessor The integrated circuit from an Intel 8742, an 8-bit microcontroller that includes a CPU running at 12 MHz, 128 bytes of RAM, 2048 bytes of EPROM, and I/O in the same chip. Intel 80486DX2 microprocessor in a ceramic PGA package.

The introduction of the microprocessor in the 1970s significantly affected the design and implementation of CPUs. Since the introduction of the first microprocessor (the Intel 4004) in 1970 and the first widely used microprocessor (the Intel 8080) in 1974, this class of CPUs has almost completely overtaken all other central processing unit implementation methods. Mainframe and minicomputer manufacturers of the time launched proprietary IC development programs to upgrade their older computer architectures, and eventually produced instruction set compatible microprocessors that were backward-compatible with their older hardware and software. Combined with the advent and eventual vast success of the now ubiquitous personal computer, the term "CPU" is now applied almost exclusively to microprocessors.

Previous generations of CPUs were implemented as discrete components and numerous small integrated circuits (ICs) on one or more circuit boards. Microprocessors, on the other hand, are CPUs manufactured on a very small number of ICs; usually just one. The overall smaller CPU size as a result of being implemented on a single die means faster switching time because of physical factors like decreased gate parasitic capacitance. This has allowed synchronous microprocessors to have clock rates ranging from tens of megahertz to several gigahertz. Additionally, as the ability to construct exceedingly small transistors on an IC has increased, the complexity and number of transistors in a single CPU has increased dramatically. This widely observed trend is described by Moore's law, which has proven to be a fairly accurate predictor of the growth of CPU (and other IC) complexity to date.

While the complexity, size, construction, and general form of CPUs have changed drastically over the past sixty years, it is notable that the basic design and function has not changed much at all. Almost all common CPUs today can be very accurately described as von Neumann stored-program machines. As the aforementioned Moore's law continues to hold true, concerns have arisen about the limits of integrated circuit transistor technology. Extreme miniaturization of electronic gates is causing the effects of phenomena like electromigration and subthreshold leakage to become much more significant. These newer concerns are among the many factors causing researchers to investigate new methods of computing such as the quantum computer, as well as to expand the usage of parallelism and other methods that extend the usefulness of the classical von Neumann model.

CPU operation

The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions called a program. Discussed here are devices that conform to the common von Neumann architecture. The program is represented by a series of numbers that are kept in some kind of computer memory. There are four steps that nearly all von Neumann CPUs use in their operation: fetch, decode, execute, and writeback.

The first step, fetch, involves retrieving an instruction (which is represented by a number or sequence of numbers) from program memory. The location in program memory is determined by a program counter (PC), which stores a number that identifies the current position in the program. In other words, the program counter keeps track of the CPU's place in the current program. After an instruction is fetched, the PC is incremented by the length of the instruction word in terms of memory units. Often the instruction to be fetched must be retrieved from relatively slow memory, causing the CPU to stall while waiting for the instruction to be returned. This issue is largely addressed in modern processors by caches and pipeline architectures (see below).

The instruction that the CPU fetches from memory is used to determine what the CPU is to do. In the decode step, the instruction is broken up into parts that have significance to other portions of the CPU. The way in which the numerical instruction value is interpreted is defined by the CPU's instruction set architecture (ISA). Often, one group of numbers in the instruction, called the opcode, indicates which operation to perform. The remaining parts of the number usually provide information required for that instruction, such as operands for an addition operation. Such operands may be given as a constant value (called an immediate value), or as a place to locate a value: a register or a memory address, as determined by some addressing mode. In older designs the portions of the CPU responsible for instruction decoding were unchangeable hardware devices. However, in more abstract and complicated CPUs and ISAs, a microprogram is often used to assist in translating instructions into various configuration signals for the CPU. This microprogram is sometimes rewritable so that it can be modified to change the way the CPU decodes instructions even after it has been manufactured. Block diagram of a simple CPU.

After the fetch and decode steps, the execute step is performed. During this step, various portions of the CPU are connected so they can perform the desired operation. If, for instance, an addition operation was requested, an arithmetic logic unit (ALU) will be connected to a set of inputs and a set of outputs. The inputs provide the numbers to be added, and the outputs will contain the final sum. The ALU contains the circuitry to perform simple arithmetic and logical operations on the inputs (like addition and bitwise operations). If the addition operation produces a result too large for the CPU to handle, an arithmetic overflow flag in a flags register may also be set.

The final step, writeback, simply "writes back" the results of the execute step to some form of memory. Very often the results are written to some internal CPU register for quick access by subsequent instructions. In other cases results may be written to slower, but cheaper and larger, main memory. Some types of instructions manipulate the program counter rather than directly produce result data. These are generally called "jumps" and facilitate behavior like loops, conditional program execution (through the use of a conditional jump), and functions in programs. Many instructions will also change the state of digits in a "flags" register. These flags can be used to influence how a program behaves, since they often indicate the outcome of various operations. For example, one type of "compare" instruction considers two values and sets a number in the flags register according to which one is greater. This flag could then be used by a later jump instruction to determine program flow.

After the execution of the instruction and writeback of the resulting data, the entire process repeats, with the next instruction cycle normally fetching the next-in-sequence instruction because of the incremented value in the program counter. If the completed instruction was a jump, the program counter will be modified to contain the address of the instruction that was jumped to, and program execution continues normally. In more complex CPUs than the one described here, multiple instructions can be fetched, decoded, and executed simultaneously. This section describes what is generally referred to as the "Classic RISC pipeline," which in fact is quite common among the simple CPUs used in many electronic devices (often called microcontrollers). Classic because when first RISC pipelines were designed at Stanford and U C Berkley by Hennesy and Patterson's students respectively they contained similar pipeline stages which have been termed "Classical" pipeline. ).

Integer range

The way a CPU represents numbers is a design choice that affects the most basic ways in which the device functions. Some early digital computers used an electrical model of the common decimal (base ten) numeral system to represent numbers internally. A few other computers have used more exotic numeral systems like ternary (base three). Nearly all modern CPUs represent numbers in binary form, with each digit being represented by some two-valued physical quantity such as a "high" or "low" voltage.

Related to number representation is the size and precision of numbers that a CPU can represent. In the case of a binary CPU, a bit refers to one significant place in the numbers a CPU deals with. The number of bits (or numeral places) a CPU uses to represent numbers is often called "word size", "bit width", "data path width", or "integer precision" when dealing with strictly integer numbers (as opposed to floating point). This number differs between architectures, and often within different parts of the very same CPU. For example, an 8-bit CPU deals with a range of numbers that can be represented by eight binary digits (each digit having two possible values), that is, 28 or 256 discrete numbers. In effect, integer size sets a hardware limit on the range of integers the software run by the CPU can utilize.

Integer range can also affect the number of locations in memory the CPU can address (locate). For example, if a binary CPU uses 32 bits to represent a memory address, and each memory address represents one octet (8 bits), the maximum quantity of memory that CPU can address is 232 octets, or 4 GiB. This is a very simple view of CPU address space, and many designs use more complex addressing methods like paging in order to locate more memory than their integer range would allow with a flat address space.

Higher levels of integer range require more structures to deal with the additional digits, and therefore more complexity, size, power usage, and general expense. It is not at all uncommon, therefore, to see 4- or 8-bit microcontrollers used in modern applications, even though CPUs with much higher range (such as 16, 32, 64, even 128-bit) are available. The simpler microcontrollers are usually cheaper, use less power, and therefore dissipate less heat, all of which can be major design considerations for electronic devices. However, in higher-end applications, the benefits afforded by the extra range (most often the additional address space) are more significant and often affect design choices. To gain some of the advantages afforded by both lower and higher bit lengths, many CPUs are designed with different bit widths for different portions of the device. For example, the IBM System/370 used a CPU that was primarily 32 bit, but it used 128-bit precision inside its floating point units to facilitate greater accuracy and range in floating point numbers (Amdahl et al. 1964). Many later CPU designs use similar mixed bit width, especially when the processor is meant for general-purpose usage where a reasonable balance of integer and floating point capability is required.

Clock rate

Most CPUs, and indeed most sequential logic devices, are synchronous in nature. That is, they are designed and operate on assumptions about a synchronization signal. This signal, known as a clock signal, usually takes the form of a periodic square wave. By calculating the maximum time that electrical signals can move in various branches of a CPU's many circuits, the designers can select an appropriate period for the clock signal.

This period must be longer than the amount of time it takes for a signal to move, or propagate, in the worst-case scenario. In setting the clock period to a value well above the worst-case propagation delay, it is possible to design the entire CPU and the way it moves data around the "edges" of the rising and falling clock signal. This has the advantage of simplifying the CPU significantly, both from a design perspective and a component-count perspective. However, it also carries the disadvantage that the entire CPU must wait on its slowest elements, even though some portions of it are much faster. This limitation has largely been compensated for by various methods of increasing CPU parallelism.

However architectural improvements alone do not solve all of the drawbacks of globally synchronous CPUs. For example, a clock signal is subject to the delays of any other electrical signal. Higher clock rates in increasingly complex CPUs make it more difficult to keep the clock signal in phase (synchronized) throughout the entire unit. This has led many modern CPUs to require multiple identical clock signals to be provided in order to avoid delaying a single signal significantly enough to cause the CPU to malfunction. Another major issue as clock rates increase dramatically is the amount of heat that is dissipated by the CPU. The constantly changing clock causes many components to switch regardless of whether they are being used at that time. In general, a component that is switching uses more energy than an element in a static state. Therefore, as clock rate increases, so does heat dissipation, causing the CPU to require more effective cooling solutions.

One method of dealing with the switching of unneeded components is called clock gating, which involves turning off the clock signal to unneeded components (effectively disabling them). However, this is often regarded as difficult to implement and therefore does not see common usage outside of very low-power designs.[10] Another method of addressing some of the problems with a global clock signal is the removal of the clock signal altogether. While removing the global clock signal makes the design process considerably more complex in many ways, asynchronous (or clockless) designs carry marked advantages in power consumption and heat dissipation in comparison with similar synchronous designs. While somewhat uncommon, entire CPUs have been built without utilizing a global clock signal. Two notable examples of this are the ARM compliant AMULET and the MIPS R3000 compatible MiniMIPS. Rather than totally removing the clock signal, some CPU designs allow certain portions of the device to be asynchronous, such as using asynchronous ALUs in conjunction with superscalar pipelining to achieve some arithmetic performance gains. While it is not altogether clear whether totally asynchronous designs can perform at a comparable or better level than their synchronous counterparts, it is evident that they do at least excel in simpler math operations. This, combined with their excellent power consumption and heat dissipation properties, makes them very suitable for embedded computers (Garside et al. 1999).

CD-ROM

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CD-ROM (an abbreviation of "Compact Disc read-only memory") is a Compact Disc that contains data accessible by a computer. While the Compact Disc format was originally designed for music storage and playback, the format was later adapted to hold any form of binary data. CD-ROMs are popularly used to distribute computer software, including games and multimedia applications, though any data can be stored (up to the capacity limit of a disc). Some CDs hold both computer data and audio with the latter capable of being played on a CD player, whilst data (such as software or digital video) is only usable on a computer (such as PC CD-ROMs). These are called Enhanced CDs.

Although many people use lowercase letters in this acronym, proper presentation is in all capital letters with a hyphen between CD and ROM. It was also suggested by some, especially soon after the technology was first released, that CD-ROM was an acronym for "Compact Disc read-only-media", or that it was a more 'correct' definition. This was not the intention of the original team who developed the CD-ROM, and common acceptance of the 'memory' definition is now almost universal. This is probably in no small part due to the widespread use of other 'ROM' acronyms such as Flash-ROMs and EEPROMs where 'memory' is usually the correct term.

Media

CD-ROM discs are identical in appearance to audio CDs, and data is stored and retrieved in a very similar manner (only differing from audio CDs in the standards used to store the data). Discs are made from a 1.2 mm thick disc of polycarbonate plastic, with a thin layer of aluminium to make a reflective surface. The most common size of CD-ROM disc is 120 mm in diameter, though the smaller Mini CD standard with an 80 mm diameter, as well as numerous non-standard sizes and shapes (e.g. business card-sized media) are also available. Data is stored on the disc as a series of microscopic indentations ("pits", with the gaps between them referred to as "lands"). A laser is shone onto the reflective surface of the disc to read the pattern of pits and lands. Because the depth of the pits is approximately one-quarter to one-sixth of the wavelength of the laser light used to read the disc, the reflected beam's phase is shifted in relation to the incoming beam, causing destructive interference and reducing the reflected beam's intensity. This pattern of changing intensity of the reflected beam is converted into binary data.

Standards

There are several formats used for data stored on compact discs, known collectively as the Rainbow Books. These include the original Red Book standards for CD audio, White Book and Yellow Book CD-ROM. The ECMA-130 standard, which gives a thorough description of the physics and physical layer of the CD-ROM, inclusive of Cross-interleaved Reed-Solomon coding CIRC and Eight-to-Fourteen Modulation, can be downloaded from.

ISO 9660 defines the standard file system of a CD-ROM, although it is due to be replaced by ISO 13490. UDF format is used on user-writeable CD-R and CD-RW discs that are intended to be extended or overwritten. The bootable CD specification, to make a CD emulate a hard disk or floppy, is called El Torito. Apparently named this because its design originated in an El Torito restaurant in Irvine, California.

CD-ROM format

A CD-ROM sector contains 2352 bytes, divided into 98 24-byte frames. The CD-ROM is, in essence, a data disk, which cannot rely on error concealment, and therefore requires a higher reliability of the retrieved data. In order to achieve improved error correction and detection, a CD-ROM has a third layer of Reed-Solomon error correction.[1] A Mode-1 CD-ROM, which has the full three layers of error correction data, contains a net 2048 bytes of the available 2352 per sector. In a Mode-2 CD-ROM, which is mostly used for video files, there are 2336 user-available bytes per sector. The net byte rate of a Mode-1 CD-ROM, based on comparison to CDDA audio standards, is 44.1k/s×4B×2048/2352 = 153.6 kB/s. The playing time is 74 minutes, or 4440 seconds, so that the net capacity of a Mode-1 CD-ROM is 682 MB.

A 1x speed CD drive reads 75 consecutive sectors per second.

CD sector contents

A standard 74 min CD contains 333,000 blocks or sectors.

Each sector is 2352 bytes, and contains 2048 bytes of PC (MODE1) Data, 2336 bytes of PSX/VCD (MODE2) Data, or 2352 bytes of AUDIO.

The difference between sector size and data content are the Headers info and the Error Correction Codes, that are big for Data (high precision required), small for VCD (standard for video) and none for audio.

If extracting the disc in RAW format (standard for creating images) always extract 2352 bytes per sector, not 2048/2336/2352 bytes depending on data type (basically, extracting the whole sector). This fact has two main consequences:

Recording data CDs at very high speed (40x) can be done without losing information. However, as audio CDs do not contain a third layer of error correction codes, recording these at high speed may result in more unrecoverable errors or 'clicks' in the audio.On a 74 minute CD, one can fit larger images using RAW mode, up to 333,000 × 2352 = 783,216,000 bytes (747~ MiB). This is the upper limit for RAW images created on a 74 min or 650~ MiB Red Book CD. The 14.8% increase is due to the discarding of error correction dataPlease note that an image size is always a multiple of 2352 bytes (the size of a block) when extracting in RAW mode.

Manufacture

Pre-pressed CD-ROMs are mass-produced by a process of stamping where a glass master disc is created and used to make "stampers", which in turn are used to manufacture multiple copies of the final disc with the pits already present. Recordable (CD-R) and rewritable (CD-RW) discs are manufactured by a similar method, but the data is recorded on them by a laser changing the properties of a dye or phase change material in a process that is often referred to as "burning".

Capacity

A standard 120 mm CD-ROM holds up to 703.1 MiB (737 million bytes) of data (not counting error correction/detection data). To put this storage capacity into context, the average novel contains 100,000 words. Assume that average word length is 10 letters and that each letter occupies one byte. A novel therefore might occupy 1,000,000 bytes (1000 kB, without layout information). One CD can therefore contain around 700 novels. If each novel occupies at least one centimetre of bookshelf space, then one CD can contain the equivalent of seven metres of bookshelf. However, textual data can be compressed by more than a factor of ten, using compression algorithms, so a CD-ROM can accommodate close to 100 metres of bookshelf space.

In comparison a single layer DVD contains 4.4 GiB of data, approximately 6 times the amount of a CD-ROM.

CD capacities are always given in binary units, although decimal SI prefixes are usually used: a "700 MB" CD has a nominal capacity of about 700 MiB. DVD capacities, on the other hand, are given in decimal units: a "4.7 GB" DVD has a nominal capacity of about 4.38 GiB.

CD-ROM drives

CD-ROM discs are read using CD-ROM drives, which are now almost universal on personal computers. A CD-ROM drive may be connected to the computer via an IDE (ATA), SCSI, S-ATA, Firewire, or USB interface or a proprietary interface, such as the Panasonic CD interface. Virtually all modern CD-ROM drives can also play audio CDs as well as Video CDs and other data standards when used in conjunction with the right software.

Laser and Optics

CD-ROM drives employ a near-infrared 780 nm laser diode. The laser beam is directed onto the disc via an opto-electronic tracking module, which then detects whether the beam has been reflected or scattered.

Transfer rates

The rate at which CD-ROM drives can transfer data from the disc is gauged by a speed factor relative to music CDs: 1x or 1-speed which gives a data transfer rate of 150 kilobytes per second in the most common data format. By increasing the speed at which the disc is spun, data can be transferred at greater rates. For example, a CD-ROM drive that can read at 8x speed spins the disc at up to 4000 rpm (compared to the 500 rpm maximum for 1x speed), giving a transfer rate of 1.2 megabytes per second. Above 12x speed, vibration and heat can become a problem. CD-ROM drives above this speed tackle the problem in several ways. Constant angular velocity (CAV) drives spin the disc at a constant rate, leading to faster data transfer when reading from the outer parts of the disc, but slower towards the centre. 20x was thought to be the maximum speed due to mechanical constraints until Samsung Electronics introduced the SCR-3230, a 32x CD-ROM drive which uses a ball bearing system to balance the spinning disc in the drive to reduce vibration and noise. As of 2004, the fastest transfer rate commonly available is about 52x or 10,350 rpm and 7.62 megabytes per second, though this is only when reading information from the outer parts of a disc. Future speed increases based simply upon spinning the disc faster are particularly limited by the strength of polycarbonate plastic used in CD manufacturing, though improvements can still be obtained by the use of multiple laser pickups as demonstrated by the Kenwood TrueX 72x which uses seven laser beams and a rotation speed of approximately 10x.

CD-Recordable drives are often sold with three different speed ratings, one speed for write-once operations, one for re-write operations, and one for read-only operations. The speeds are typically listed in that order; ie a 12x/10x/32x CD drive can, CPU and media permitting, write to CD-R discs at 12x speed (1.80 MiB/s), write to CD-RW discs at 10x speed (1.50 MiB/s), and read from CD discs at 32x speed (4.80 MiB/s).

The 1x speed rating for CD-ROM (150 KiB/s) is different than 1x speed rating for audio CD (172.3 KiB/s) and is not to be confused with the 1x speed rating for DVDs (1.32 MiB/s).

CinemaScope

2008-07-05T00:07:00.000-07:00

CinemaScope was a widescreen movie format used from 1953 to 1967. Anamorphic lenses allowed the process to project film up to a 2.66:1 aspect ratio, twice as wide as the conventional format of 1.33:1. Although CinemaScope was shortly made obsolete by new technological developments, the anamorphic presentation of films initiated by CinemaScope in the 1950s has continued to this day.

History

Origins

A French professor named Henri Chrétien developed and patented a new film process that he called Anamorphoscope in the late 1920s. It was this process that would later form the basis for CinemaScope. Chrétien's process was based on lenses that employed an optical trick which produced an image twice as wide as that produced with conventional lenses. In New York, a premiere of Chrétien's new process impressed the major Hollywood film studios of the time, who were eager to win back lost audiences from television’s allure.

Twentieth Century Fox bought the rights of the Anamorphoscope. (Predecessor company Fox Film Corporation had experimented with another widescreen process, Fox Grandeur, in 1929-1931.) However, the format needed more development before it would be ready to use. The first of Chrétien's lenses were quickly transported to Hollywood where they were further analyzed. From this analysis the basis of CinemaScope was formed.

Twentieth Century Fox's pre-production of The Robe was halted so that the film could be changed to CinemaScope, what Fox president Spyros Skouras called the future of filmmaking. Fox's famous advertising slogan "Movies are Better than Ever" gained credibility with the ground breaking 1953 film The Robe. With the introduction of CinemaScope, the movie industry was able to re-assert its distinction from its new competitor — television.

Early implementations

A promotional picture advertising The Robe and CinemaScope. The small box in the center represents a regular-width screen. The curvature of the screen has been greatly exaggerated; unlike Cinerama screens, CinemaScope screens were rectangular.

The comedy How To Marry A Millionaire was the first film to be shot in CinemaScope. However, The Robe was released first. Fox utilized its influential people to promote CinemaScope. With the success of The Robe and How To Marry A Millionaire, the process became a hot property in Hollywood. Fox licensed the process to many of the major film studios including Columbia, Universal, MGM and Walt Disney Productions. Disney created one of the best-regarded examples of early CinemaScope productions with the live-action epic 20,000 Leagues Under the Sea.

Due to initial uncertainty a number of films were shot simultaneously with anamorphic and regular lenses. Despite early success with the process, Fox did not stick to their claim of shooting every production with the process. CinemaScope as a trade name was reserved for "A" productions, while "B" productions in black and white commenced in 1956 at Fox under the trade name, "RegalScope."

Rival processes

CinemaScope itself was a response to early "realism" processes Cinerama and 3-D. Cinerama was relatively unaffected by CinemaScope, as it was a quality-controlled process that played in select venues, similar to the current IMAX films of recent years. 3-D was hurt, however, by studio advertising surrounding CinemaScope's promise that it was the "miracle you see without glasses." Technical difficulties in presentation spelt the end for 3-D, but studio hype was quick to hail it a "victory" for CinemaScope.

Earlier in 1953, a rival technique now known as "flat" widescreen appeared. In this process, a fully exposed 1.37:1 Academy ratio-area is cropped in the projector to a widescreen aspect ratio by the use of an aperture plate, also known as a soft matte. Aware of Fox's upcoming CinemaScope productions, Paramount introduced this technique in March's release of Shane with the 1.66:1 aspect ratio, although the film was not shot with this ratio originally in mind. Universal-International followed suit in May with a 1.85:1 aspect ratio for Thunder Bay. By summer of 1953, Paramount, Universal, MGM, Columbia, and even Fox, under the banner of "Panoramic Productions" had switched from filming flat shows in a 1.37:1 format, and used variable flat widescreen aspect ratios in their filming.

The fundamental technique that CinemaScope was built on was not patentable because the anamorphoscope had been known for centuries. Anamorphosis had been used in visual media such as Hans Holbein's painting, The Ambassadors (1533), as early as the sixteenth century. Some studios sought to develop their own systems rather than pay Fox.

In response to the demands for a higher fidelity spherical widescreen process, Paramount created an optical process, VistaVision, which shot horizontally on the 35 mm film reel, and then printed down to standard 4-perf vertical 35 mm. Thus, a finer grained negative was introduced, and consequently less grainy prints. The first Paramount release in VistaVision was White Christmas. VistaVision died out in the late 1950s, with the introduction of finer grained film stocks.

RKO used the Superscope process in which the standard 35 mm image was cropped in post-production to create a widescreen image.

Another process called Techniscope was developed by Technicolor Inc. in the early 1960s, using normal 35 mm cameras modified for two perforations per frame instead of the regular four and later converted into an anamorphic print. Techniscope was mostly used in Europe, especially with lower budget films.
Many European countries and studios used the standard anamorphic process for their widescreen films, identical in technical specifications to CinemaScope, and renamed to avoid the copyrights of Fox. Some of these include Euroscope, Franscope, and Naturama (the latter used by Republic Pictures). In 1952-53 Warner Brothers also planned to develop an identical anamorphic process called Warnerscope, but after the premiere of CinemaScope, Warners decided to license it from Fox instead.

Technical difficulties

Although CinemaScope was capable of producing a 2.66:1 image, the addition of multi-channel COMMAG sound reduced this to 2.55:1. Theater owners, however, were dissatisfied with contractually having to install three or four-track magnetic stereo, and because of the technical nature of sound installations, drive-in theaters had trouble presenting stereophonic sound at all. Due to these conflicts, Fox revoked their policy of stereo-only presentations, and added an optical soundtrack, while keeping the magnetic for those theaters that chose to present their films with stereophonic sound. The addition of the optical soundtrack reduced the width of the presented aspect ratio further to 2.35:1.

A general problem with expanding the image meant that there could be visible graininess and brightness problems. To combat this, larger formats were developed (initially a too-costly 55 mm for Carousel and The King and I) - and then abandoned (both films were eventually reduction printed at 35 mm, although the aspect ratio was kept at 2.55:1). Later Fox re-released The King and I in the 65/70 mm format. The initial problems with grain and brightness were eventually reduced thanks to improvements in film stock and lenses.

CinemaScope lenses were detrimented by barrel distortion when the anamorphic power was decreased, and objects approached close to the camera. Close-up shots would slightly over-stretch an actor's face, and telephoto shots would appear as if they were being rolled over a bump in the middle of the picture. This problem was avoided at first by composing wider shots, but as anamorphic technology lost its novelty, directors and cinematographers sought compositional freedom from these limitations. Issues with the lenses made it difficult to photograph animation using the CinemaScope process. Nevertheless, many animated short films and a few features were filmed in CinemaScope during the 1950s, including Disney's Lady and the Tramp (1955).

Decline

Panavision, who initially made their fortune manufacturing anamorphic adapters for CinemaScope theaters, innovated the CinemaScope process by including a dual rotating element which was controlled by a focus ring in order to keep the plane of focus at a constant anamorphic ratio of 2x. This prevented the over-stretching effect found in Cinemascope; closeups would look much more natural, and the "bump effect" previously mentioned was also avoidable.[citation needed] After screening a demo reel comparing the two systems, many US studios adopted the Panavision anamorphic lenses. The Panavision technique was considered more attractive to the industry because it was more affordable than CinemaScope and was not owned/licensed-out by a rival studio. By the mid-1960s even Fox had begun to abandon CinemaScope for Panavision (famously at the demand of Frank Sinatra for Von Ryan's Express). Fox eventually capitulated completely to third-party lenses by 1967. In Like Flint, a spy spoof with James Coburn, was Fox's final film in CinemaScope.

Modern references

While the lens system has been retired for decades, Fox has used the trademark in recent years on at least three films - Down with Love, which was shot with Panavision optics but used the credit as a throwback to the films it references, and the Don Bluth films Anastasia and Titan A.E. at Bluth's insistence. Nonetheless, these films are not true CinemaScope as they use modern lenses. CinemaScope's association with anamorphic projection is still so embedded in mass consciousness that all anamorphic prints are now referred to, generically as "'Scope" prints.

In the Broadway musical "Hairspray" (2002) and the New Line Cinema film version of the musical (2007), there is a reference to the CinemaScope format in the song "(The Legend of) Miss Baltimore Crabs."

Compact Disc

2008-07-04T23:32:00.000-07:00

A Compact Disc (also known as a CD) is an optical disc used to store digital data, originally developed for storing digital audio. The CD, available on the market since late 1982, remains the standard playback medium for commercial audio recordings to the present day, though they have recently lost some ground to digital distribution.

Standard CDs have a diameter of 120 mm and can hold up to 80 minutes of audio. There is also the Mini CD, with diameters ranging from 60 to 80 mm; they are sometimes used for CD singles, storing up to 24 minutes of audio.
The technology was later adapted and expanded to include data storage (CD-ROM), write-once audio and data storage (CD-R), rewritable media (CD-RW), Super Audio CD (SACD), Video Compact Discs (VCD), Super Video Compact Discs (SVCD), PhotoCD, PictureCD, CD-i, and Enhanced CD. CD-ROMs and CD-Rs remain widely used technologies in the computer industry. The CD and its extensions have been extremely successful: in 2004, worldwide sales of CD audio, CD-ROM, and CD-R reached about 30 billion discs. By 2007, 200 billion CDs had been sold worldwide.

History

The compact disc is a successful spin-off of the much less successful Laserdisc technology. In 1979, Sony and Philips Consumer Electronics set up a joint task force of engineers to design a new digital audio disc. The task force, led by prominent members Kees Schouhamer Immink and Toshitada Doi (土井利忠), progressed the research into laser technology and optical discs that had been started by Philips in 1977. After a year of experimentation and discussion, the taskforce produced the Red Book, the Compact Disc standard. Philips contributed the general manufacturing process, based on video Laserdisc technology. Philips also contributed Eight-to-Fourteen Modulation (EFM), which offers both a long playing time and a high resilience against disc defects such as scratches and fingerprints, while Sony contributed the error-correction method, CIRC. The Compact Disc Story, told by a former member of the taskforce, gives background information on the many technical decisions made, including the choice of the sampling frequency, playing time, and disc diameter. According to Philips, the Compact Disc was thus "invented collectively by a large group of people working as a team."

The first CD that was pressed in Hanover was a recording of Herbert von Karajan conducting the Alpine Symphony by Richard Strauss. In August 1982 the real pressing was ready to begin in the new factory, not far from the place where Emil Berliner had produced his first gramophone record 93 years earlier. (Deutsche Grammophon, Berliner’s company, had by now become a part of PolyGram.) CDs and Sony's CD player CDP-101 reached the market on October 1, 1982 in Japan, and early the following year in the United States and other markets. This event is often seen as the "Big Bang" of the digital audio revolution. The new audio disc was enthusiastically received, especially in the early-adopting classical music and audiophile communities and its handling quality received particular praise. As the price of players sank rapidly, the CD began to gain popularity in the larger popular and rock music markets. The first artist to sell a million copies on CD was Dire Straits, with their 1985 album Brothers in Arms. In 1986 Queen became the first artist to have their entire catalogue converted to the format.

The CD was originally thought of as an evolution of the gramophone record, rather than primarily as a data storage medium. Only later did the concept of an "audio file" arise, and the generalising of this to any data file. From its origins as a music format, Compact Disc has grown to encompass other applications. In June 1985, the CD-ROM (read-only memory) and, in 1990, CD-Recordable were introduced, also developed by Sony and Philips.

Physical details

A Compact Disc is made from a 1.2 mm thick disc of almost pure polycarbonate plastic and weighs approximately 16 grams. A thin layer of aluminium or, more rarely, gold is applied to the surface to make it reflective, and is protected by a film of lacquer. The lacquer is normally spin coated directly on top of the reflective layer. On top of that surface, the label print is applied. Common printing methods for CDs are screen-printing and offset printing.

CD data is stored as a series of tiny indentations (pits), encoded in a tightly packed spiral track molded into the top of the polycarbonate layer. The areas between pits are known as "lands". Each pit is approximately 100 nm deep by 500 nm wide, and varies from 850 nm to 3.5 µm in length.

The spacing between the tracks, the pitch, is 1.6 µm. A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser through the bottom of the polycarbonate layer. The change in height between pits and lands results in a difference in intensity in the light reflected. By measuring the intensity change with a photodiode, the data can be read from the disc.

The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, Non-return-to-zero, inverted (NRZI) encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a zero. This in turn is decoded by reversing the Eight-to-Fourteen Modulation used in mastering the disc, and then reversing the Cross-Interleaved Reed-Solomon Coding, finally revealing the raw data stored on the disc.

While CDs are significantly more durable than earlier audio formats, they are susceptible to damage from daily usage and environmental factors. Pits are much closer to the label side of a disc, so that defects and dirt on the clear side can be out of focus during playback. Discs consequently suffer more damage because of defects such as scratches on the label side, whereas clear-side scratches can be repaired by refilling them with plastic of similar index of refraction, or by careful polishing. Early music CDs were known to suffer from "CD rot" or "laser rot" where the internal reflective layer itself degrades. When this occurs the CD may become unplayable.

Disc shapes and diameters

The digital data on a CD begins at the center of the disc and proceeds outwards to the edge, which allows adaptation to the different size formats available. Standard CDs are available in two sizes. By far the most common is 120 mm in diameter, with a 74 or 80-minute audio capacity and a 650 or 700 MB data capacity. This diameter has also been adopted by later formats, including Super Audio CD, DVD, HD DVD, and Blu-ray Disc. 80 mm discs ("Mini CDs") were originally designed for CD singles and can hold up to 21 minutes of music or 184 MB of data but never really became popular. Today nearly all singles are released on 120 mm CDs, which is called a Maxi single.

"Shaped CD"

Novelty shaped CDs are also available in a number of shapes and sizes, and are mostly used for marketing. A common variant is a "business card" CD, a CD-single with portions removed at the top and bottom to more closely resemble the form-factor of a business card.

Logical formats

Audio CD

The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. The document is known colloquially as the "Red Book" after the color of its cover. The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel. Four-channel sound is an allowed option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; mono source material is usually presented as two identical channels on a 'stereo' track.

The selection of the sample rate was primarily based on the need to reproduce the audible frequency range of 20 Hz - 20 kHz. The Nyquist–Shannon sampling theorem states that a sampling rate of at least double the maximum frequency of the signal to be recorded is needed, resulting in a 40 kHz rate. The exact sampling rate of 44.1 kHz was inherited from a method of converting digital audio into an analog video signal for storage on U-matic video tape, which was the most affordable way to transfer data from the recording studio to the CD manufacturer at the time the CD specification was being developed. The device that turns an analog audio signal into PCM audio, which in turn is changed into an analog video signal is called a PCM adaptor. This technology could store six samples (three samples per each stereo channel) in a single horizontal line. A standard NTSC video signal has 245 usable lines per field, and 59.94 fields/s, which works out at 44,056 samples/s/stereo channel. Similarly, PAL has 294 lines and 50 fields, which gives 44,100 samples/s/stereo channel. This system could either store 14-bit samples with some error correction, or 16-bit samples with almost no error correction.

There was a long debate over whether to use 14 bit (Philips) or 16-bit (Sony) quantization, and 44,056 or 44,100 samples/s (Sony) or around 44,000 samples/s (Philips). When the Sony/Philips task force designed the Compact Disc, Philips had already developed a 14-bit D/A converter, but Sony insisted on 16 bit. In the end, 16 bits and 44.1 kilosamples per second prevailed. Philips found a way to produce 16-bit quality using their 14-bit DAC by using four times oversampling.

Storage capacity and playing time

The partners aimed at a playing time of 60 minutes with a disc diameter of 100 mm (Sony) or 115 mm (Philips).[9] Sony vice-president Norio Ohga suggested extending the capacity to 74 minutes to accommodate Wilhelm Furtwängler's 1951 performance of Beethoven’s 9th Symphony at the Bayreuth Festival.

The extra 14 minute playing time subsequently required changing to a 120 mm disc. Kees Immink, Philips' chief engineer, however, denies this, claiming that the increase was motivated by technical considerations, and that even after the increase in size, the Furtwängler recording was not able to fit onto the earliest CDs.

According to a Sunday Tribune interview, the story is slightly more involved. At that time (1979) Philips owned Polygram, one of the world’s largest distributors of music. Polygram had set up a large experimental CD plant in Hanover, Germany, which could produce huge numbers of CDs having, of course, a diameter of 115 mm. Sony did not yet have such a facility. If Sony had agreed on the 115 mm disc, Philips would have had a significant competitive edge in the market. Sony decided that something had to be done. The long playing time of Beethoven's Ninth imposed by Ohga was used to push Philips to accept 120 mm, so that Philips’ Polygram lost its edge on disc fabrication.

The 74-minute playing time of a CD, which was much longer than the 15 to 20 minutes per side possible with long-playing vinyl albums, was often used to the CD’s advantage during the early years when CDs and LPs vied for commercial sales. CDs would often be released with one or more bonus tracks, enticing consumers to buy the CD for the extra material. However, attempts to combine double LPs onto one CD occasionally resulted in an opposing situation in which the CD would actually offer fewer tracks than the LP equivalent. An example is the 1987 album Kiss Me, Kiss Me, Kiss Me by The Cure, which states in the CD liner notes: "The track Hey You!!! which appears on the double album and cassette has been omitted so as to facilitate a single compact disc." The 2006 re-release of this album saw the re-inclusion of the missing track.[12] Another example is the original late-1980s Warner Bros. Records reissue of Fleetwood Mac's Tusk album, which substituted the long album version of "Sara" with the shorter single version. Enough complaints were lodged to eventually convince Warner Bros. to remaster the album in the mid-1990s with the original contents intact.

Main physical parameters

The main parameters of the CD (taken from the September 1983 issue of the audio CD specification) are as follows :

- Scanning velocity: 1.2–1.4 m/s (constant linear velocity) – equivalent to approximately 500 rpm at the inside of the disc, and approximately 200 rpm at the outside edge. (A disc played from beginning to end slows down during playback.)

- Track pitch: 1.6 µm

- Disc diameter 120 mm

- Disc thickness: 1.2 mm

- Inner radius program area: 25 mm

- Outer radius program area: 58 mm

- Center spindle hole diameter: 15 mm

The program area is 86.05 cm² and the length of the recordable spiral is (86.05 cm² / 1.6 µm) = 5.38 km. With a scanning speed of 1.2 m/s, the playing time is 74 minutes, or around 650 MB of data on a CD-ROM. If the disc diameter were only 115 mm, the maximum playing time would have been 68 minutes, i.e., six minutes less. A disc with data packed slightly more densely is tolerated by most players (though some old ones fail). Using a linear velocity of 1.2 m/s and a track pitch of 1.5 µm leads to a playing time of 80 minutes, or a capacity of 700 MB. Even higher capacities on non-standard discs (up to 99 minutes) are available at least as recordables, but generally the tighter the tracks are squeezed the worse the compatibility.

Data structure

The smallest entity in a CD is called a frame. A frame consists of 33 bytes and contains six complete 16-bit stereo samples (2 bytes × 2 channels × six samples: equals 24 bytes). The other nine bytes consist of eight Cross-Interleaved Reed-Solomon Coding error correction bytes and one subcode byte, used for control and display. Each byte is translated into a 14-bit word using Eight-to-Fourteen Modulation, which alternates with 3-bit merging words. In total there are 33 × (14 + 3) = 561 bits. A 27-bit unique synchronization word is added, so that the number of bits in a frame totals 588 (of which only 192 bits are music).

These 588-bit frames are in turn grouped into sectors. Each sector contains 98 frames, totaling 98 × 24 = 2352 bytes of music. The CD is played at a speed of 75 sectors per second, which results in 176,400 bytes per second. Divided by 2 channels and 2 bytes per sample, this results in a sample rate of 44,100 samples per second.

For CD-ROM data discs, the physical frame and sector sizes are the same. Since error concealment cannot be applied to non-audio data in case the CIRC error correction fails to recover the user data, a third layer of error correction is defined, reducing the payload to 2048 bytes per sector for the Mode-1 CD-ROM format. To increase the data-rate for Video CD, Mode-2 CD-ROM, the third layer has been omitted, increasing the payload to 2336 user-available bytes per sector, only 16 bytes (for synchronization and header data) less than available in Red-Book audio.

"Frame"

For the Red Book stereo audio CD, the time format is commonly measured in minutes, seconds and frames (mm:ss:ff), where one frame corresponds to one sector, or 1/75th of a second of stereo sound. Note that in this context, the term frame is erroneously applied in editing applications and does not denote the physical frame described above. In editing and extracting, the frame is the smallest addressable time interval for an audio CD, meaning that track start and end positions can only be defined in 1/75 second steps.

Logical structure

The largest entity on a CD is called a track. A CD can contain up to 99 tracks (including a data track for mixed mode discs). Each track can in turn have up to 100 indexes, though players which handle this feature are rarely found outside of pro audio, particularly radio broadcasting. The vast majority of songs are recorded under index 1, with the pre-gap being index 0. Sometimes hidden tracks are placed at the end of the last track of the disc, often using index 2 or 3. This is also the case with some discs offering "101 sound effects", with 100 and 101 being index 2 and 3 on track 99. The index, if used, is occasionally put on the track listing as a decimal part of the track number, such as 99.2 or 99.3. (Information Society's Hack was one of very few CD releases to do this, following a release with an equally-obscure CD+G feature.) The track and index structure of the CD carried forward to the DVD as title and chapter, respectively.

Manufacturing tolerances

Current manufacturing processes allow an audio CD to contain up to 80 minutes (variable from one replication plant to another) without requiring the content creator to sign a waiver. Thus, in current practice, maximum CD playing time has crept higher by reducing minimum engineering tolerances, while still maintaining acceptable standards of reliability.

CD-Text

CD-Text is an extension of the Red Book specification for audio CD that allows for storage of additional text information (e.g., album name, song name, artist) on a standards-compliant audio CD. The information is stored either in the lead-in area of the CD, where there is roughly five kilobytes of space available, or in the subcode channels R to W on the disc, which can store about 31 megabytes.

CD + Graphics

Compact Disc + Graphics (CD+G) is a special audio compact disc that contains graphics data in addition to the audio data on the disc. The disc can be played on a regular audio CD player, but when played on a special CD+G player, can output a graphics signal (typically, the CD+G player is hooked up to a television set or a computer monitor); these graphics are almost exclusively used to display lyrics on a television set for karaoke performers to sing along with.

CD + Extended Graphics

Compact Disc + Extended Graphics (CD+EG, also known as CD+XG) is an improved variant of the Compact Disc + Graphics (CD+G) format. Like CD+G, CD+EG utilizes basic CD-ROM features to display text and video information in addition to the music being played. This extra data is stored in subcode channels R-W. Very few, if any, CD+EG discs have been published.

Super Audio CD

Super Audio CD (SACD) is a read-only optical audio disc format aimed at providing much higher fidelity digital audio reproduction than the Red Book audio CD. Introduced in 1999, it was developed by Sony and Philips Electronics, the same companies that created the Red Book audio CD. SACD was in a format war with DVD-Audio, but neither has yet managed to replace audio CDs. SACD has the advantage over DVD-Audio in that most SACD discs are hybrids: they also contain a standard audio CD layer which is playable in existing CD players.

CD-MIDI

Compact Disc MIDI or CD-MIDI is a type of CD where MIDI format is used to store music performance data which upon playback is performed by electronic instruments that synthesize the audio that is heard. Hence unlike Red Book audio CD, these recordings are not audio.

CD-ROM

For its first few years of existence, the Compact Disc was purely an audio format. However, in 1985 the Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data computer data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive.

Video CD

Video CD (aka VCD, View CD, Compact Disc digital video) is a standard digital format for storing video on a Compact Disc. VCDs are playable in dedicated VCD players, most modern DVD-Video players, personal computers, and some video game consoles.

The VCD standard was created in 1993 by Sony, Philips, Matsushita, and JVC and is referred to as the White Book standard.

Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise, and does not deteriorate further with each use, which may be preferable.

352x240 (or SIF) resolution was chosen because it is half the vertical, and half the horizontal resolution of NTSC video. 352x288 is similarly one quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution.

Super Video CD

Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video on standard compact discs. SVCD was intended as a successor to Video CD and an alternative to DVD-Video, and falls somewhere between both in terms of technical capability and picture quality.

SVCD has two-thirds the resolution of DVD, and over 2.7 times the resolution of VCD. One CD-R disc can hold up to 60 minutes of standard quality SVCD-format video. While no specific limit on SVCD video length is mandated by the specification, one must lower the video bit rate, and therefore quality, in order to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring significant quality loss, and many hardware players are unable to play video with an instantaneous bit rate lower than 300 to 600 kilobits per second.

Photo CD

Photo CD is a system designed by Kodak for digitizing and storing photos on a CD. Launched in 1992, the discs were designed to hold nearly 100 high quality images, scanned prints and slides using special proprietary encoding. Photo CD discs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well. They are intended to play on CD-i players, Photo CD players and any computer with the suitable software irrespective of the operating system. The images can also be printed out on photographic paper with a special Kodak machine.

Picture CD

Picture CD is another photo product by Kodak, following on from the earlier Photo CD product. It holds photos from a single roll of color film, stored at 1024×1536 resolution using JPEG compression. The product is aimed at consumers. Software to view and perform simple edits to images is included on the CD.

CD-i

The Philips "Green Book" specifies the standard for interactive multimedia compact discs designed for CD-i players. This format is unusual because it hides the initial tracks which contains the software and data files used by CD-i players by omitting the tracks from the disc's TOC (table of contents). This causes audio CD players to skip the CD-i data tracks. This is different from the CD-i Ready format, which puts CD-i software and data into the pregap of track 1.

Enhanced CD

Enhanced CD, also known as CD Extra and CD Plus, is a certification mark of the Recording Industry Association of America for various technologies that combine audio and computer data for use in both compact disc and CD-ROM players.

The primary data formats for Enhanced CD disks are mixed mode (Yellow Book/Red Book), CD-i, hidden track, and multisession (Blue Book).

Broadband

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In telecommunications

Broadband in telecommunications is a term that refers to a signaling method that includes or handles a relatively wide range of frequencies, which may be divided into channels or frequency bins. Broadband is always a relative term, understood according to its context. The wider the bandwidth, the greater the information-carrying capacity. In radio, for example, a very narrow-band signal will carry Morse code; a broader band will carry speech; a still broader band is required to carry music without losing the high audio frequencies required for realistic sound reproduction.

A television antenna described as "normal" may be capable of receiving a certain range of channels; one described as "broadband" will receive more channels. In data communications a modem will transmit a bandwidth of 56 kilobits per seconds (kbit/s) over a telephone line; over the same telephone line a bandwidth of several megabits per second can be handled by ADSL, which is described as broadband (relative to a modem over a telephone line, although much less than can be achieved over a fiber optic circuit, for example).

In data communications

Broadband in data communications can refer to broadband networks or broadband Internet and may have the same meaning as above, so that data transmission over a fiber optic cable would be referred to as broadband as compared to a telephone modem operating at 56,000 bits per second.

However, broadband in data communications is frequently used in a more technical sense to refer to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission, regardless of actual data rate. In network engineering this term is used for methods where two or more signals share a medium.

In video

Broadband in analog video distribution is traditionally used to refer to systems such as cable television, where the individual channels are modulated on carriers at fixed frequencies. In this context, baseband is the term's antonym, referring to a single channel of analog video, typically in composite form with an audio subcarrier. The act of demodulating converts broadband video to baseband video.

However, broadband video in the context of streaming Internet video has come to mean video files that have bitrates high enough to require broadband Internet access in order to view them.
Broadband video is also sometimes used to describe IPTV Video on demand.

In DSL

The various forms of Digital Subscriber Line (DSL) services are broadband in the sense that digital information is sent over a high-bandwidth channel above the baseband voice channel on a single pair of wires.

In Ethernet

A baseband transmission sends one type of signal using a medium's full bandwidth, as in 100BASE-T Ethernet. Ethernet, however, is the common interface to broadband modems such as DSL data links, and has a high data rate itself, so is sometimes referred to as broadband. Ethernet provisioned over cable modem is a common alternative to DSL.

Bluetooth

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Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmissions over short distances from fixed and/or mobile devices, creating wireless personal area networks (PANs). The intent behind the development of Bluetooth was the creation of a single digital wireless protocol, capable of connecting multiple devices and overcoming issues arising from synchronization of these devices. Bluetooth provides a way to connect and exchange information between devices such as mobile phones, telephones, laptops, personal computers, printers, GPS receivers, digital cameras, and video game consoles over a secure, globally unlicensed Industrial, Scientific, and Medical (ISM) 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.

Uses

Bluetooth is a standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device.[2] Bluetooth enables these devices to communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, as long as the received transmission is powerful enough. Bluetooth device class indicates the type of device and the supported services of which the information is transmitted during the discovery process.

Bluetooth profiles

In order to use Bluetooth, a device must be compatible with certain Bluetooth profiles. These define the possible applications and uses of the technology.

List of applications

More prevalent applications of Bluetooth include :

- Wireless control of and communication between a mobile phone and a hands-free headset. This was one of the earliest applications to become popular.Wireless networking between PCs in a confined space and where little bandwidth is required.

- Wireless communications with PC input and output devices, the most common being the mouse, keyboard and printer.Transfer of files between devices with OBEX.

- Transfer of contact details, calendar appointments, and reminders between devices with OBEX.

- Replacement of traditional wired serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices.

- For controls where infrared was traditionally used.

- Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices.

- Two seventh-generation game consoles, Nintendo's Wii[4] and Sony's PlayStation 3 use Bluetooth for their respective wireless controllers.

- Dial-up internet access on personal computer or PDA using a data-capable mobile phone as a modem.

Bluetooth vs. Wi-Fi in networking

Bluetooth and Wi-Fi have different applications in today's offices, homes, and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers. Both are versions of unlicensed spread spectrum technology.

Bluetooth differs from Wi-Fi in that the latter provides higher throughput and covers greater distances, but requires more expensive hardware and higher power consumption. They use the same frequency range, but employ different modulation techniques. While Bluetooth is a replacement for a variety of applications, Wi-Fi is a replacement only for local area network access. Bluetooth can be thought of as wireless USB[citation needed], whereas Wi-Fi is wireless Ethernet[citation needed], both operating at much lower bandwidth[citation needed] than cable networking systems. However, this analogy is not entirely accurate since any Bluetooth device can, in theory, host any other Bluetooth device—something that is not universal to USB devices, therefore it would resemble more a wireless FireWire.

Bluetooth devices

Bluetooth exists in many products, such as telephones, printers, modems and headsets. The technology is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones (i.e. with a Bluetooth headset) or byte data with hand-held computers (transferring files).

Bluetooth simplifies the discovery and setup of services between devices. Bluetooth devices advertise all of the services they provide. This makes using services easier because there is no longer a need to set up network addresses or permissions as in many other network.

Wi-Fi

Wi-Fi is more like a traditional Ethernet network, and requires configuration to set up shared resources, transmit files, and to set up audio links (for example, headsets and hands-free devices). It uses the same radio frequencies as Bluetooth, but with higher power resulting in a stronger connection. Wi-Fi is sometimes called "wireless Ethernet." This description is accurate as it also provides an indication of its relative strengths and weaknesses. Wi-Fi requires more setup, but is better suited for operating full-scale networks because it enables a faster connection, better range from the base station, and better security than Bluetooths.Bluetooth and Wi-Fi have different applications in today's offices, homes, and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers. Both are versions of unlicensed spread spectrum technology.

Bluetooth differs from Wi-Fi in that the latter provides higher throughput and covers greater distances, but requires more expensive hardware and higher power consumption. They use the same frequency range, but employ different modulation techniques. While Bluetooth is a replacement for a variety of applications, Wi-Fi is a replacement only for local area network access. Bluetooth can be thought of as wireless USB, whereas Wi-Fi is wireless Ethernet, both operating at much lower bandwidth than cable networking systems. However, this analogy is not entirely accurate since any Bluetooth device can, in theory, host any other Bluetooth device—something that is not universal to USB devices, therefore it would resemble more a wireless FireWire.

Bluetooth devices

Wi-Fi

Computer requirements

A typical Bluetooth USB dongle An internal notebook Bluetooth card (14×36×4 mm)A personal computer must have a Bluetooth adapter in order to be able to communicate with other Bluetooth devices (such as mobile phones, mice and keyboards). While some desktop computers and most recent laptops come with a built-in Bluetooth adapter, others will require an external one in the form of a dongle.Unlike its predecessor, IrDA, which requires a separate adapter for each device, Bluetooth allows multiple devices to communicate with a computer over a single adapter.

Operating system support

Apple has supported Bluetooth since Mac OS X v10.2 which was released in 2002.
For Microsoft platforms, Windows XP Service Pack 2 and later releases have native support for Bluetooth. Previous versions required users to install their Bluetooth adapter's own drivers, which were not directly supported by Microsoft. Microsoft's own Bluetooth dongles (packaged with their Bluetooth computer devices) have no external drivers and thus require at least Windows XP Service Pack 2.

Linux has two popular Bluetooth stacks, BlueZ and Affix. The BlueZ stack is included with most Linux kernels and it was originally developed by Qualcomm. The Affix stack was developed by Nokia. FreeBSD features Bluetooth support since its 5.0 release. NetBSD features Bluetooth support since its 4.0 release. Its Bluetooth stack has been ported to OpenBSD as well.

Specifications and features

The Bluetooth specification was developed in 1994 by Jaap Haartsen and Sven Mattisson, who were working for Ericsson Mobile Platforms in Lund, Sweden. The specification is based on frequency-hopping spread spectrum technology.
The specifications were formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1998. Today it has a membership of over 7000 companies worldwide. It was established by Ericsson, IBM, Intel, Toshiba, and Nokia, and later joined by many other companies.

Bluetooth 1.0 and 1.0B

Versions 1.0 and 1.0B had many problems, and manufacturers had difficulty making their products interoperable. Versions 1.0 and 1.0B also included mandatory Bluetooth hardware device address (BD_ADDR) transmission in the Connecting process (rendering anonymity impossible at the protocol level), which was a major setback for certain services planned for use in Bluetooth environments.

Bluetooth 1.1

Ratified as IEEE Standard 802.15.1-2002.Many errors found in the 1.0B specifications were fixed.Added support for non-encrypted channels.Received Signal Strength Indicator (RSSI).

Bluetooth 1.2

This version is backward-compatible with 1.1 and the major enhancements include the following:Faster Connection and DiscoveryAdaptive frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence.Higher transmission speeds in practice, up to 721 kbit/s, as in 1.1.Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better support for concurrent data transfer.Host Controller Interface (HCI) support for three-wire UART.Ratified as IEEE Standard 802.15.1-2005.

Bluetooth 2.0

This version, specified on November 10, 2004, is backward-compatible with 1.1. The main enhancement is the introduction of an Enhanced Data Rate (EDR) for both data (ACL) and voice (eSCO) packets. The nominal signalling rate of EDR is about 3 megabits per second, although the practical data transfer rate is 2.1 megabits per second. This additional throughput is obtained by using a different modulation scheme for radio transmission of the data payload. Standard or Basic Rate transmission uses the Gaussian Frequency Shift Keying (GFSK) method, while EDR uses a combination of GFSK and Phase Shift Keying (PSK).

According to the 2.0 specification, EDR provides the following benefits :

- Three times faster transmission speed — up to 10 times in certain cases (up to 2.1 Mbit/s).

- Lower power consumption through a reduced duty cycle.

- Simplification of multi-link scenarios due to more available bandwidth.

The Bluetooth Special Interest Group (SIG) published the specification as "Bluetooth 2.0 + EDR" which implies that EDR is an optional feature. In some cases it is not clear whether a product claiming to support "Bluetooth 2.0" actually supports the EDR higher transfer rate. At least one commercial device, the HTC TyTN pocket PC phone, states "Bluetooth 2.0 without EDR" on its data sheet.

Bluetooth 2.1

Bluetooth Core Specification Version 2.1 is fully backward-compatible with 1.1, and was adopted by the Bluetooth SIG on July 26, 2007. This specification includes the following features :

- Extended inquiry response : provides more information during the inquiry procedure to allow better filtering of devices before connection. This information includes the name of the device, a list of services the device supports, as well as other information like the time of day, and pairing information.

- Sniff subrating : reduces the power consumption when devices are in the sniff low-power mode, especially on links with asymmetric data flows. Human interface devices (HID) are expected to benefit the most, with mouse and keyboard devices increasing the battery life by a factor of 3 to 10. It lets devices decide how long they will wait before sending keepalive messages to one another. Previous Bluetooth implementations featured keep alive message frequencies of up to several times per second. In contrast, the 2.1 specification allows pairs of devices to negotiate this value between them to as infrequently as once every 5 or 10 seconds.

- Encryption Pause Resume : enables an encryption key to be refreshed, enabling much stronger encryption for connections that stay up for longer than 23.3 hours (one Bluetooth day).Secure Simple Pairing: radically improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. It is expected that this feature will significantly increase the use of Bluetooth.Near Field Communication (NFC) cooperation: automatic creation of secure Bluetooth connections when NFC radio interface is also available. For example, a headset should be paired with a Bluetooth 2.1 phone including NFC just by bringing the two devices close to each other (a few centimeters). Another example is automatic uploading of photos from a mobile phone or camera to a digital picture frame just by bringing the phone or camera close to the frame.

Future of Bluetooth

- Broadcast Channel : enables Bluetooth information points. This will drive the adoption of Bluetooth into mobile phones, and enable advertising models based around users pulling information from the information points, and not based around the object push model that is used in a limited way today.

- Topology Management : enables the automatic configuration of the piconet topologies especially in scatternet situations that are becoming more common today. This should all be invisible to the users of the technology, while also making the technology just work.

- Alternate MAC PHY : enables the use of alternative MAC and PHY's for transporting Bluetooth profile data. The Bluetooth Radio will still be used for device discovery, initial connection and profile configuration, however when lots of data needs to be sent, the high speed alternate MAC PHY's will be used to transport the data. This means that the proven low power connection models of Bluetooth are used when the system is idle, and the low power per bit radios are used when lots of data needs to be sent.

- QoS improvements : enable audio and video data to be transmitted at a higher quality, especially when best effort traffic is being transmitted in the same piconet.

High-speed Bluetooth

On 28 March 2006, the Bluetooth Special Interest Group announced its selection of the WiMedia Alliance Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) version of UWB for integration with current Bluetooth wireless technology.

UWB integration will create a version of Bluetooth wireless technology with a high-speed/high-data-rate option. This new version of Bluetooth technology will meet the high-speed demands of synchronizing and transferring large amounts of data, as well as enabling high-quality video and audio applications for portable devices, multi-media projectors and television sets, and wireless VOIP.

At the same time, Bluetooth technology will continue catering to the needs of very low power applications such as mouse, keyboards, and mono headsets, enabling devices to select the most appropriate physical radio for the application requirements, thereby offering the best of both worlds.

Bluetooth 3.0

The next version of Bluetooth after v2.1, code-named Seattle (the version number of which is TBD) has many of the same features, but is most notable for plans to adopt ultra-wideband (UWB) radio technology. This will allow Bluetooth use over UWB radio, enabling very fast data transfers of up to 480 Mbit/s, while building on the very low-power idle modes of Bluetooth.

Bluetooth low energy

On June 12, 2007, Nokia and Bluetooth SIG announced that Wibree will be a part of the Bluetooth specification as an ultra low power Bluetooth technology.[15] Expected use cases include watches displaying Caller ID information, sports sensors monitoring your heart rate during exercise, as well as medical devices. The Medical Devices Working Group is also creating a medical devices profile and associated protocols to enable this market. Battery life for devices using Bluetooth low energy technology is designed to be up to one year.

Blu-ray (2)

2008-07-04T22:40:00.000-07:00

Technical specifications

Laser and optics

Blu-ray Disc uses a "blue" (technically violet) laser operating at a wavelength of 405 nm to read and write data. Conventional DVDs and CDs use red and near infrared lasers at 650 nm and 780 nm respectively.
The blue-violet laser's shorter wavelength makes it possible to store more information on a 12 cm CD/DVD sized disc. The minimum "spot size" on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, increasing the numerical aperture from 0.60 to 0.85 and making the cover layer thinner to avoid unwanted optical effects, the laser beam can be focused to a smaller spot. This allows more information to be stored in the same area. For Blu-ray Disc, the spot size is 580 nm. In addition to the optical improvements, Blu-ray Discs feature improvements in data encoding that further increase the capacity. (See Compact disc for information on optical discs' physical structure.)

Hard-coating technology

Because the Blu-ray Disc data layer is closer to the surface of the disc, compared to the DVD standard, it was at first more vulnerable to scratches. The first discs were housed in cartridges for protection. Advances in polymer technology eventually made the cartridges unnecessary.

TDK was the first company to develop a working scratch protection coating for Blu-ray Discs. It was named Durabis. In addition, both Sony and Panasonic's replication methods include proprietary hard-coat technologies. Sony's rewritable media are spin-coated with a scratch-resistant and antistatic coating. Verbatim's recordable and rewritable Blu-ray Disc discs use their own proprietary hard-coat technology called ScratchGuard.

Software standards

Codecs

Codecs are compression schemes that store audio and video more efficiently, either giving longer play time or higher quality per megabyte. There are both lossy and lossless compression techniques.

The BD-ROM specification mandates certain codec compatibilities for both hardware decoders (players) and the movie-software (content). For video, all players are required to support MPEG-2, H.264/AVC, and SMPTE VC-1. MPEG-2 is the codec used on regular DVDs, which allows backwards compatibility. H.264/AVC was developed by MPEG and VCEG as a modern successor of MPEG-4. VC-1 is another MPEG-4 derivative codec mostly developed by Microsoft. BD-ROM titles with video must store video using one of the three mandatory codecs. Multiple codecs on a single title are allowed.

The choice of codecs affects the producer's licensing/royalty costs, as well as the title's maximum runtime, due to differences in compression efficiency. Discs encoded in MPEG-2 video typically limit content producers to around two hours of high-definition content on a single-layer (25 GB) BD-ROM. The more advanced video codecs (VC-1 and H.264) typically achieve a video runtime twice that of MPEG-2, with comparable quality.

MPEG-2 was used by many studios, including Paramount Pictures (which initially used the VC-1 codec for HD DVD releases) for the first series of Blu-ray discs that were launched throughout 2006. Modern releases are now often encoded in either H.264/AVC or VC-1, allowing film studios to place all content on one disc, reducing costs and improving ease of use. Using these codecs will also free many GB of space for storage of bonus content in HD (1080i/p) as opposed to the SD (480i/p) typically used for most titles. Some studios (such as Warner Bros.) have released bonus content on discs encoded in a different codec than the main feature title; for example the Blu-ray release of Superman Returns uses VC-1 for the feature film and MPEG-2 for bonus content (presumably because it is simply ported from the DVD release).

For audio, BD-ROM players are required to support Dolby Digital AC-3, DTS, and linear PCM. Players may optionally support Dolby Digital Plus, and lossless formats Dolby TrueHD and DTS-HD Master Audio. BD-ROM titles must use one of the mandatory schemes for the primary soundtrack. A secondary audiotrack, if present, may use any of the mandatory or optional codecs.

For users recording digital television programming, the recordable Blu-ray Disc standard's initial data rate of 36 Mbit/s is more than adequate to record high-definition broadcasts from any source (IPTV, cable/satellite, or terrestrial). Blu-ray movies have a maximum data transfer rate of 54 Mbit/s, a maximum AV bitrate of 48 Mbit/s (for both audio and video data), and a maximum video bitrate of 40 Mbit/s. This compares to HD DVD movies which have a maximum data transfer rate of 36 Mbit/s, a maximum AV bitrate of 30.24 Mbit/s, and a maximum video bitrate of 29.4 Mbit/s.

Java software support

At the 2005 JavaOne trade show, it was announced that Sun Microsystems' Java cross-platform software environment would be included in all Blu-ray Disc players as a mandatory part of the standard. Java is used to implement interactive menus on Blu-ray Discs, as opposed to the method used on DVD video discs, which uses pre-rendered MPEG segments and selectable subtitle pictures, which is considerably more primitive and less seamless. Java creator James Gosling, at the conference, suggested that the inclusion of a Java Virtual Machine as well as network connectivity in some BD devices will allow updates to Blu-ray Discs via the Internet, adding content such as additional subtitle languages and promotional features that are not included on the disc at pressing time. This Java Version is called BD-J and is a subset of the Globally Executable MHP (GEM) standard. GEM is the world-wide version of the Multimedia Home Platform standard.

Region codes Regions for Blu-ray standard

A : Americas; East and Southeast Asia; U.S. territories; Bermuda.

B : Africa, Europe, Oceania; Middle East; Kingdom of the Netherlands; British overseas territories, French territories; Greenland.

C : Central and South Asia; Mongolia, Russia, and People's Republic of China.

Blu-ray Discs may be encoded with a region code, intended to restrict the area of the world in which they can be played, similar in principle to the DVD region codes, although the used geographical regions differ. Blu-ray Disc players sold in a certain region may only play discs encoded for that region. The purpose of this system is to allow motion picture studios to control the various aspects of a release (including content, date, and in particular price) according to the region. Discs may also be produced without region coding, so they can be played on all devices.
This places the countries of the major Blu-ray manufacturers (Japan, Korea, Malaysia) in the same region as North America. As of early 2008, about two-thirds of all released discs were region-free.

In the Blu-ray region coding system, the United States is placed in region A while regions B and C are used for countries which can experience localization delays before U.S. titles are officially released. The opposite, though, is sometimes true and a few new titles such as Harry Potter and the Goblet of Fire and Running Scared were released in certain European countries before the U.S. release. In response to the DVD region system, multi-region and region-free DVD players became dominant in certain markets; certain Blu-ray player models have been modified to allow for playback of Blu-ray discs from Regions A and B and DVD discs from Regions 1 and 2.

Digital rights management (DRM)

The Blu-ray Disc format employs several layers of digital rights management. AACS decryption process
Advanced Access Content System (AACS) is a standard for content distribution and digital rights management. It is developed by AS Licensing Administrator, LLC (AACS LA), a consortium that includes Disney, Intel, Microsoft, Matsushita (Panasonic), Warner Bros., IBM, Toshiba and Sony.

Since appearing in devices in 2006, several successful attacks have been made on the format. The first known attack relied on the trusted client problem. In addition, decryption keys have been extracted from a weakly protected player (WinDVD). However, even though some AACS cryptographic keys have been compromised, new releases will use new, uncompromised keys.

BD+ was developed by Cryptography Research Inc. and is based on their concept of Self-Protecting Digital Content.[50] BD+ is effectively a small virtual machine embedded in authorized players. It allows content providers to include executable programs on Blu-ray Discs. Such programs can:examine the host environment, to see if the player has been tampered with. Every licensed playback device manufacturer must provide the BD+ licensing authority with memory footprints that identify their devices.verify that the player's keys have not been changed.execute native code, possibly to patch an otherwise insecure system.transform the audio and video output. Parts of the content will not be viewable without letting the BD+-program unscramble it.

If a playback device manufacturer finds that its devices have been hacked, it can potentially release BD+-code that detects and circumvents the vulnerability. These programs can then be included in all new content releases.
The specifications of the BD+ virtual machine are available only to licensed device manufacturers. A list of licensed adopters is available from the BD+ website.

BD+ was made available for content publishers in June 2007. The first titles using BD+ were released in October the same year. Players from Samsung and LG had problems playing back those titles until the manufacturers updated their firmware, but this problem was later identified as being related to BD-Java use, not BD+.[52] BD+ protection was fully circumvented with the release 6.4.0.0 of AnyDVD HD program.

BD-ROM Mark is a small amount of cryptographical data that is stored physically differently from normal Blu-ray Disc data. Bit-by-bit copies that do not replicate the BD-ROM Mark are impossible to decode. A specially licensed piece of hardware is required to insert the ROM-mark into the media during replication. Through licensing of the special hardware element, the BDA believes that it can eliminate the possibility of mass producing BD-ROMs without authorization.

Blu-ray

2008-07-04T22:26:00.000-07:00

Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage media format. Its main uses are high-definition video and data storage. The disc has the same dimensions as a standard DVD or CD.
The name Blu-ray Disc is derived from the blue laser (violet coloured) used to read and write this type of disc. Because of its shorter wavelength (405 nm), substantially more data can be stored on a Blu-ray Disc than on the DVD format, which uses a red (650 nm) laser. A dual layer Blu-ray Disc can store 50 GB, almost six times the capacity of a dual layer DVD.

Blu-ray Disc was developed by the Blu-ray Disc Association, a group of companies representing consumer electronics, computer hardware, and motion picture production. As of July 2, 2008 more than 650 Blu-ray Disc films have been commercially released in the United States and more than 410 Blu-ray Disc titles have been released in Japan.

During the high definition optical disc format war, Blu-ray Disc competed with the HD DVD format. On February 19, 2008, Toshiba — the main company supporting HD DVD — announced it would no longer develop, manufacture and market HD DVD players and recorders, leading almost all other HD DVD supporters to follow suit, effectively ending the format war.

History

In 1998, commercial HDTV sets began to appear in the consumer market; however, there was no commonly accepted, inexpensive way to record or play HD content. In fact, there was no medium with the storage required to accommodate HD codecs, except JVC's Digital VHS and Sony's HDCAM. Nevertheless, it was well known that using lasers with shorter wavelengths would enable optical storage with higher density. When Shuji Nakamura invented practical blue laser diodes, it was a sensation, although a lengthy patent lawsuit delayed commercial introduction.

Origins

Sony started two projects applying the new diodes: UDO (Ultra Density Optical) and DVR Blue (together with Pioneer), a format of rewritable discs which would eventually become Blu-ray Disc (more specifically, BD-RE). The core technologies of the formats are essentially similar.

The first DVR Blue prototypes were unveiled at the CEATEC exhibition in October 2000. Because the Blu-ray Disc standard places the data recording layer close to the surface of the disc, early discs were susceptible to contamination and scratches and had to be enclosed in plastic cartridges for protection. In February 2002, the project was officially announced as Blu-ray, and the Blu-ray Disc Association was founded by the nine initial members.

The first consumer devices were in stores on April 10, 2003. This device was the Sony BDZ-S77; a BD-RE recorder that was made available only in Japan. The recommended price was US$3800; however, there was no standard for pre-recorded video and no movies were released for this player. The Blu-ray Disc standard was still years away as a newer, more secure DRM system was needed before Hollywood studios would accept it, not wanting to repeat the failure of the Content Scramble System used on DVDs.

Blu-ray Disc format finalized

The Blu-ray Disc physical specifications were finished in 2004. In January 2005, TDK announced that they had developed a hard coating polymer for Blu-ray Discs The cartridges, no longer necessary, were scrapped. The BD-ROM specifications were finalized in early 2006. AACS LA, a consortium founded in 2004, had been developing the DRM platform that could be used to securely distribute movies to consumers. However, the final AACS standard was delayed, and then delayed again when an important member of the Blu-ray Disc group voiced concerns. At the request of the initial hardware manufacturers, including Toshiba, Pioneer and Samsung, an interim standard was published which did not include some features, like managed copy.

Launch and sales developments

The first BD-ROM players were shipped in the middle of June 2006, though HD DVD players beat them in the race to the market by a few months.
The first Blu-ray Disc titles were released on June 20, 2006. The earliest releases used MPEG-2 video compression, the same method used on DVDs. The first releases using the newer VC-1 and AVC codecs were introduced in September 2006. The first movies using dual layer discs (50 GB) were introduced in October 2006.

The first mass-market Blu-ray Disc rewritable drive for the PC was the BWU-100A, released by Sony on July 18, 2006. It recorded both single and dual layer BD-R as well as BD-RE discs and had a suggested retail price of US$699.

Competition from HD DVD

The DVD Forum (which was chaired by Toshiba) was deeply split over whether to develop the more expensive blue laser technology or not. In March 2002, the forum voted to approve a proposal endorsed by Warner Bros. and other motion picture studios that involved compressing HD content onto dual-layer DVD-9 discs. In spite of this decision, however, the DVD Forum's Steering Committee announced in April that it was pursuing its own blue-laser high-definition solution. In August, Toshiba and NEC announced their competing standard Advanced Optical Disc. It was finally adopted by the DVD Forum and renamed HD DVD the next year, after being voted down twice by Blu-ray Disc Association members, prompting the U.S. Department of Justice to make preliminary investigations into the situation.

HD DVD had a head start in the high definition video market and Blu-ray Disc sales were slow at first. The first Blu-ray Disc player was perceived as expensive and buggy, and there were few titles available. This changed when PlayStation 3 launched, since every PS3 unit also functioned as a Blu-ray Disc player. At CES 2007 Warner proposed Total Hi Def which was a hybrid disc containing Blu-ray on one side and HD DVD on the other but it was never released. By January 2007, Blu-ray discs had outsold HD DVDs, and during the first three quarters of 2007, BD outsold HD DVDs by about two to one. Finally, by February 2008, Toshiba announced it was pulling its support for the HD DVD format, leaving Blu Ray as the victor in the video wars.

Some analysts believe that Sony's PlayStation 3 video game console played an important role in the format war, believing it acted as a catalyst for Blu-ray Disc, as the PlayStation 3 used a Blu-ray Disc drive as its primary information storage medium. They also credited Sony's more thorough and influential marketing campaign. More recently several studios have cited Blu-ray Disc's adoption of the BD+ anti-copying system as the reason they supported Blu-ray Disc over HD DVD.

End of the format war

In January 2008, a day before CES 2008, Warner Brothers, the only major studio still releasing movies in both HD DVD and Blu-ray Disc format, announced it would release only in Blu-ray Disc after May 2008. This effectively included other studios which came under the Warner umbrella, such as New Line Cinema and HBO, though in Europe HBO distribution partner the BBC announced it would, while keeping an eye on market forces, continue to release product on both formats. This led to a chain reaction in the industry, including major U.S. retailers such as Best Buy, Wal-Mart, and Circuit City dropping HD DVD in their stores.

A major European retailer, Woolworths, dropped HD DVD from its inventory. Netflix and Blockbuster, major DVD rental companies, said they would no longer carry HD DVDs. Following these new developments, on 19 February 2008, Toshiba announced it would be ending production of HD DVD devices,[34] allowing Blu-ray Disc to become the industry standard for high-density optical disks. Universal Studios, the sole major movie studio to back HD DVD since inception, shortly after Toshiba's announcement, said "while Universal values the close partnership we have shared with Toshiba, it is time to turn our focus to releasing new and catalog titles on Blu-ray Disc. "Paramount Studios, which started releasing movies only in HD DVD format during late 2007, also said it would start releasing in Blu-ray Disc. Both studios announced initial Blu-ray lineups in May 2008. With this, all major Hollywood studios now support Blu-ray.

Former HD DVD supporter Microsoft has stated that they are not currently pursuing a Blu-ray Disc drive for the Xbox 360, and will instead focus on their digital downloads from the Xbox Live Marketplace.
Blu-ray Disc began making serious strides as soon as the format war ended. Nielsen VideoScan sales numbers showed that with some titles, such as 20th Century Fox's "Hitman," up to 14% of total disc sales were from Blu-ray, although the average for the first half of the year was around 5%. Shortly after the format war ended, a study by The NPD Group found that awareness of Blu-ray Disc had reached 60% of U.S. households, with most experts predicting the business will take off in a significant fashion in the fourth quarter of 2008, when BD Live software and players--which offer a variety of Web-enabled features, from downloadable trailers to chat and instant-messaging functions--start hitting the market.

A preliminary conclusion has been made by the Singulus Technologies AG, German manufacturer of optical disc equipment and world's only provider of such services as mastering, molding and replication. According to Stefan Baustert Blu-ray is being adopted faster than the DVD format 11 years ago at the same period of its development. This conclusion was made due to the fact that Singulus Technologies has received orders for 21 Blu-ray dual-layer machines only during this year's first quarter, while only 17 DVD machines of this type were made in the same period 11 years ago.

Bass

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Bass or Basses may refer to:

Music and other sound

- Low frequency part of the sound spectrum (see also Low Frequency Effects, (LFE))
- ss (musical term), describing bass in terms of tone and musicality

Musical instruments

- Bass (instrument), one of several instruments in the bass range
- Double bass, the largest and lowest pitched bowed string instrument
- Electric upright bass, the electric version of a double bass
- Bass guitar, generally with a solid body
- Acoustic bass guitar, with a hollow body
- Bass drum, a large drum
- Tuba, often called "the bass" in the context of brass instruments
- Bass clarinet a clarinet with a lower sound
- Bass cornett, a low pitched wind instrument
- Bass flute, an instrument one octave lower than a fluteBass sarrusophone, a low pitched double reed instrumentBass saxophone

Musical genres

Drum and bass, a type of electronic dance music
Miami bass, a type of hip hop music
Ghettotech, or Detroit Bass, a form of electronic dance music
Techno Bass, a blend of Miami bass and Detroit techno
Drill 'n bass, a form of electronic dance music

Other musical areas

- Bass (vocal range), a male singer who sings in the deepest vocal range
- Figured bass, a kind of integer musical notationF clef or bass clef
- Bass note, the lowest note in a chord
- Bassline, an instrumental part which is in the bass range"Basses", is the third movement of Mike Oldfield's Tubular Bells 2003 album

People with the surname Bass

- Bass (surname)

Places

- Bass Rock, wildlife sanctuary off the coast of Scotland
- Bass, Victoria, a town in Australia
- Division of Bass, a federal electoral division, in Australia
- Division of Bass (state), state electoral division, in Australia
- Bass Strait, in Australia
- Bass Pyramid, island in Bass Strait
- Basses, Vienne a Commune of the Vienne department in France
- Bass, West Virginia
-Bass River (disambiguation)

Other

- Bass (fish), various freshwater and saltwater species
- Bass (beer), a British brand of beer
- Beneath a Steel Sky, a videogame
- Bass diffusion model, a mathematical marketing model
- Bass (Mega Man), a character in the video game Mega Man
- Bass Armstrong, a character from the video game Dead or AliveG. H. Bass, a shoemaker, especially of loafers
- Bass Anglers Sportsmen Society (B.A.S.S.)

Analog

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Analog or analogue may refer to :

(1) Analog signal, a variable signal continuous in both time and amplitude (as opposed to digital or discrete, e.g. analog wristwatch vs digital wristwatch) Analog circuits, circuits which use analog signalsAnalog transmission, a transmission using analog signalsAnalog Transducer is a sensor that measures continuous information.Analog television encodes television picture and sound information and transmits it as an analog signalAnalog recording stores signals as a continual wave in/on a medium.Analog synthesizer, a synthesizer that uses analog circuits and analog computer techniques to generate sound electronically.

(2) An analog (noun) refers to an object, concept or situation which in some way resembles a different situation. Analogue (literature), a literary work that shares motifs, characters or events with another, but is not directly derived from itAn analogyAnalog (chemistry), a structural derivative of a parent compound that often differs from it by only a single element.

Titles and names

Analog Science Fiction and Fact, the current title of the magazine originally named Astounding StoriesA.N.A.L.O.G. (Atari News And Lots Of Games), a magazine focusing on Atari computersAnalog (program), a computer program that analyzes log files from web serversAnalog Devices, a semiconductor companyThe Analogs, a Polish street-punk bandAnalogue, a 2005 album by Norwegian band a-haAnalogue, a British theatre companyThe Federal Analog Act, a section of the DEA Controlled Substances Act

Amplifier (2)

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Other amplifier types

Carbon microphone

One of the first devices used to amplify signals was the carbon microphone (effectively a sound-controlled variable resistor). By channeling a large electric current through the compressed carbon granules in the microphone, a small sound signal could produce a much larger electric signal. The carbon microphone was extremely important in early telecommunications; analog telephones in fact work without the use of any other amplifier. Before the invention of electronic amplifiers, mechanically coupled carbon microphones were also used as amplifiers in telephone repeaters for long distance service.

Magnetic amplifier

A magnetic amplifier is a transformer-like device that makes use of the saturation of magnetic materials to produce amplification. It is a non-electronic electrical amplifier with no moving parts. The bandwidth of magnetic amplifiers extends to the hundreds of kilohertz.

Rotating electrical machinery amplifier

A Ward Leonard control is a rotating machine like an electrical generator that provides amplification of electrical signals by the conversion of mechanical energy to electrical energy. Changes in generator field current result in larger changes in the output current of the generator, providing gain. This class of device was used for smooth control of large motors, primarily for elevators and naval guns.
Field modulation of a very high speed AC generator was also used for some early AM radio transmissions.

Johnsen-Rahbek effect amplifier

The earliest form of audio power amplifier was Edison's "electromotograph" loud-speaking telephone, which used a wetted rotating chalk cylinder in contact with a stationary contact. The friction between cylinder and contact varied with the current, providing gain. Edison discovered this effect in 1874, but the theory behind the Johnsen-Rahbek effect was not understood until the semiconductor era.

Mechanical amplifiers

Mechanical amplifiers were used in the pre-electronic era in specialized applications. Early autopilot units designed by Elmer Ambrose Sperry incorporated a mechanical amplifier using belts wrapped around rotating drums; a slight increase in the tension of the belt caused the drum to move the belt. A paired, opposing set of such drives made up a single amplifier. This amplified small gyro errors into signals large enough to move aircraft control surfaces. A similar mechanism was used in the Vannevar Bush differential analyzer.

Optical amplifiers

Optical amplifiers amplify light through the process of stimulated emission.

Miscellaneous types

There are also mechanical amplifiers, such as the automotive servo used in braking.Relays can be included under the above definition of amplifiers, although their transfer function is not linear (that is, they are either open or closed).Also purely mechanical manifestations of such digital amplifiers can be built (for theoretical, didactical purposes, or for entertainment), see e.g. domino computer.Another type of amplifier is the fluidic amplifier, based on the fluidic triode.

Amplifier

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Generally, an amplifier is any device that changes, usually increases, the amplitude of a signal. The "signal" is usually voltage or current.
In popular use, the term today usually refers to an electronic amplifier, often as in audio applications. The relationship of the input to the output of an amplifier — usually expressed as a function of the input frequency — is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain. A related device that emphasizes conversion of signals of one type to another (for example, a light signal in photons to a DC signal in amperes) is a transducer, or a sensor. However, a transducer does not amplify power.

Figures of merit

The quality of an amplifier can be characterized by a number of specifications, enumerated below.

Gain

The gain of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels. (When measured in decibels it is logarithmically related to the power ratio: G(dB)=10 log(Pout/Pin)).

Bandwidth

The bandwidth (BW) of an amplifier is the range of frequencies for which the amplfier gives "satisfactory performance". The "satisfactory performance" may be different for different applications. However, a common and well-accepted metric are the half power points (i.e. frequency where the power goes down by half its peak value) on the power vs. frequency curve. Therefore bandwidth can be defined as the difference between the lower and upper half power points. This is therefore also known as the −3 dB bandwidth. Bandwidths for other response tolerances are sometimes quoted (−1 dB, −6 dB etc.).

A full-range audio amplifier will be essentially flat between 20 Hz to about 20 kHz (the range of normal human hearing.) In minimalist amplifier design, the amp's usable frequency response needs to extend considerably beyond this (one or more octaves either side) and typically a good minimalist amplifier will have −3 dB points <> 65 kHz. Professional touring amplifiers often have input and/or output filtering to sharply limit frequency response beyond 20 Hz-20 kHz; too much of the amplifier's potential output power would otherwise be wasted on infrasonic and ultrasonic frequencies, and the danger of AM radio interference would increase. Modern switching amplifiers need steep low pass filtering at the output to get rid of high frequency switching noise and harmonics.

Efficiency

Efficiency is a measure of how much of the input power is usefully applied to the amplifier's output. Class A amplifiers are very inefficient, in the range of 10–20% with a max efficiency of 25%. Class B amplifiers have a very high efficiency but are impractical because of high levels of distortion (See: Crossover distortion). In practical design, the result of a tradeoff is the class AB design. Modern Class AB amps are commonly between 35–55% efficient with a theoretical maximum of 78.5%. Commercially available Class D switching amplifiers have reported efficiencies as high as 97%. Amplifiers of Class C-F are usually known to be very high efficiency amplifiers. The efficiency of the amplifier limits the amount of total power output that is usefully available. Note that more efficient amplifiers run much cooler, and often do not need any cooling fans even in multi-kilowatt designs. The reason for this is that the loss of efficiency produces heat as a by-product of the energy lost during the conversion of power. In more efficient amplifiers there is less loss of energy so in turn less heat.

Linearity

An ideal amplifier would be a totally linear device, but real amplifiers are only linear within certain practical limits. When the signal drive to the amplifier is increased, the output also increases until a point is reached where some part of the amplifier becomes saturated and cannot produce any more output; this is called clipping, and results in distortion.
Some amplifiers are designed to handle this in a controlled way which causes a reduction in gain to take place instead of excessive distortion; the result is a compression effect, which (if the amplifier is an audio amplifier) will sound much less unpleasant to the ear. For these amplifiers, the 1 dB compression point is defined as the input power (or output power) where the gain is 1 dB less than the small signal gain.
Linearization is an emergent field, and there are many techniques, such as feedforward, predistortion, postdistortion, EER, LINC, CALLUM, cartesian feedback, etc., in order to avoid the undesired effects of the non-linearities.

Noise

This is a measure of how much noise is introduced in the amplification process. Noise is an undesirable but inevitable product of the electronic devices and components. It is measured in either decibels or the peak output voltage produced by the amplifier when no signal is applied.
[edit]Output dynamic range

Output dynamic range is the range, usually given in dB, between the smallest and largest useful output levels. The lowest useful level is limited by output noise, while the largest is limited most often by distortion. The ratio of these two is quoted as the amplifier dynamic range. More precisely, if S = maximal allowed signal power and N = noise power, the dynamic range DR is DR = (S + N ) /N.[1]

Slew rate

Slew rate is the maximum rate of change of output variable, usually quoted in volts per second (or microsecond). Many amplifiers are ultimately slew rate limited (typically by the impedance of a drive current having to overcome capacitive effects at some point in the circuit), which may limit the full power bandwidth to frequencies well below the amplifier's small-signal frequency response.

Rise time

The rise time, tr, of an amplifier is the time taken for the output to change from 10% to 90% of its final level when driven by a step input. For a Gaussian response system (or a simple RC roll off), the rise time is approximated by:
tr * BW = 0.35, where tr is rise time in seconds and BW is bandwidth in Hz.

Settling time and ringing

Time taken for output to settle to within a certain percentage of the final value (say 0.1%). This is usually specified for oscilloscope vertical amplifiers and high accuracy measurement systems. Ringing refers to an output that cycles above and below its final value, leading to a delay in reaching final value quantified by the settling time above.

Stability factor

Stability is a major concern in RF and microwave amplifiers. The degree of an amplifiers stability can be quantified by a so-called stability factor. There are several different stability factors, such as the Stern stability factor and the Linvil stability factor, which specify a condition that must be met for the absolute stability of an amplifier in terms of its two-port parameters.

Electronic amplifiers

There are many types of electronic amplifiers, commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers. Critical components include active devices, such as vacuum tubes or transistors. A brief introduction to the many types of electronic amplifier follows.

Power amplifier

The term "power amplifier" is a relative term with respect to the amount of power delivered to the load and/or sourced by the supply circuit. In general a power amplifier is designated as the last amplifier in a transmission chain (the output stage) and is the amplifier stage that typically requires most attention to power efficiency. Efficiency considerations lead to various classes of power amplifier: see power amplifier classes.

Vacuum tube (valve) amplifiers

According to Symons, while semiconductor amplifiers have largely displaced valve amplifiers for low power applications, valve amplifiers are much more cost effective in high power applications such as "radar, countermeasures equipment, or communications equipment" (p. 56). Many microwave amplifiers are specially designed valves, such as the klystron, gyrotron, traveling wave tube, and crossed-field amplifier, and these microwave valves provide much greater single-device power output at microwave frequencies than solid-state devices.

Transistor amplifiersMain articles: transistor, bipolar junction transistor, Audio amplifier, and MOSFET
The essential role of this active element is to magnify an input signal to yield a significantly larger output signal. The amount of magnification (the "forward gain") is determined by the external circuit design as well as the active device.
Many common active devices in transistor amplifiers are bipolar junction transistors (BJTs) and metal oxide semiconductor field-effect transistors (MOSFETs).
Applications are numerous, some common examples are audio amplifiers in a home stereo or PA system, RF high power generation for semiconductor equipment, to RF and Microwave applications such as radio transmitters.
Transistor-based amplifier can be realized using various configurations: for example with a bipolar junction transistor we can realize common base, common collector or common emitter amplifier; using a MOSFET we can realize common gate, common source or common drain amplifier. Each configuration has different characteristic (gain, impedance...).

Transistor amplifiers

The essential role of this active element is to magnify an input signal to yield a significantly larger output signal. The amount of magnification (the "forward gain") is determined by the external circuit design as well as the active device.
Many common active devices in transistor amplifiers are bipolar junction transistors (BJTs) and metal oxide semiconductor field-effect transistors (MOSFETs).
Applications are numerous, some common examples are audio amplifiers in a home stereo or PA system, RF high power generation for semiconductor equipment, to RF and Microwave applications such as radio transmitters.
Transistor-based amplifier can be realized using various configurations: for example with a bipolar junction transistor we can realize common base, common collector or common emitter amplifier; using a MOSFET we can realize common gate, common source or common drain amplifier. Each configuration has different characteristic (gain, impedance...).

Operational amplifiers (op-amps)

An operational amplifier is a solid state integrated circuit amplifier which employs external feedback for control of its transfer function or gain.

Fully differential amplifiers (FDA)

A fully differential amplifier is a solid state integrated circuit amplifier which employs external feedback for control of its transfer function or gain. It is similar to the operational amplifier but it also has differential output pins.

Video amplifiers

These deal with video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc.. The specification of the bandwidth itself depends on what kind of filter is used and which point (-1 dB or -3 dB for example) the bandwidth is measured. Certain requirements for step response and overshoot are necessary in order for acceptable TV images to be presented.

Oscilloscope vertical amplifiers

These are used to deal with video signals to drive an oscilloscope display tube and can have bandwidths of about 500 MHz. The specifications on step response, rise time, overshoot and aberrations can make the design of these amplifiers extremely difficult. One of the pioneers in high bandwidth vertical amplifiers was the Tektronix company.

Distributed amplifiers

These use transmission lines to temporally split the signal and amplify each portion separately in order to achieve higher bandwidth than can be obtained from a single amplifying device. The outputs of each stage are combined in the output transmission line. This type of amplifier was commonly used on oscilloscopes as the final vertical amplifier. The transmission lines were often housed inside the display tube glass envelope.

Microwave amplifiers

Travelling wave tube (TWT) amplifiers

Used for high power amplification at low microwave frequencies. They typically can amplify across a broad spectrum of frequencies; however, they are usually not as tunable as klystrons.

KlystronsMain article: Klystron

Very similar to TWT amplifiers, but more powerful and with a specific frequency "sweet spot". They generally are also much heavier than TWT amplifiers, and are therefore ill-suited for light-weight mobile applications. Klystrons are tunable, offering selective output within their specified frequency range.

Audio and video

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Audio and video connector

Audio and video connectorFrom Wikipedia, the free encyclopedia RCA connectors are commonly used for home stereo and video equipment.

Audio connectors and video connectors are electrical connectors for carrying an audio signal or video signal, either in an analog or digital format. Analog A/V connectors often use Shielded cable to inhibit RF interference and noise.Contents [hide]1 Audio Only 1.1 Colour codes2 Video Only 2.1 Colour codes3 Multiple signals4 See also

Audio Only

Audio connectors are electrical connectors designed and used for audio frequencies. They can be analogue or digital. Common audio connectors include:Single-conductor connectors: Banana connectorsFive-way binding posts and banana plugs for loudspeakersFahnestock clips on early breadboard radio receivers.Multi-conductor connectors: DB25 is for multi-track recording and other multi-channel audio, analog or digitalDIN connectors and mini-DIN connectorsRCA connectors, also known as phono connectors or phono plugs, used for analog or digital audio or analog videoSpeakon connectors by Neutrik for loudspeakersTRS connector also known as tip-ring-sleeve plug, phone plug, jack plug, mini-jack, and mini-stereo. This includes the original 6.35mm (quarter inch) jack and the more recent 3.5mm (miniature or 1/8th inch) and 2.5mm (subminiature) jacks, both mono and stereo (balanced) versions.XLR connectors, also known as Cannon plugs, used for analog or digital balanced audio with a balanced lineDigital audio interfaces and interconnects: ADAT interface (DB25)AES/EBU interface, normally with XLR connectorsS/PDIF, either over electrical coaxial cable (with RCA jacks) or optical fiber (TOSLINK).

Colour codes

White RCA/TS analogue audio, left channel;also mono (RCA/TS), stereo (TRS only),or undefined/otherblack RCA/TS/TRSgrey RCA/TS/TRSred RCA/TS analogue audio, right channelorange RCA SPDIF digital audio. For computers:green TRS 3.5mm stereo output, front channelsblack TRS 3.5mm stereo output, rear channelsgrey TRS 3.5mm stereo output, side channelsgold TRS 3.5mm dual output, center and subwooferblue TRS 3.5mm stereo input, line levelpink TS 3.5mm mono microphone input.

There are exceptions to the above:Hosa cables use grey and orange for left and right analogue channels.RadioShack cables sometimes use grey and black for left and right.Older sound cards had non-standard colour codes until after PC99, prior to that there were no colours at all.

Video Only

Video connectors carry only video signals. Common video-only connectors include:Component video aka YPbPr (3 RCA or BNC; or D-Terminal)Composite video (1 RCA, Antenna socket, or BNC)DB13W3 ("13W3" computer video connector)DMS-59, single connector carrying two DVI and two VGAMusa, British connector used in broadcasting and telecommunicationsPAL connector, formerly common in EuropeS-Video (1 Mini-DIN)SDI - Broadcast grade digital interface over BNC cablesVGA connector A type of D-sub connector standard on most video cardsMini-VGA Found on some laptop computers5 BNC Connectors can also be used to carry the VGA signal as R, G, B, HSync, VSyncDigital Visual Interface (DVI) A hybrid analog/digital connector commonly found on PC graphics cards and LCD monitorsMini-DVI Found on some Apple laptopsEnhanced Graphics Adapter (EGA)RGBI interfaceRGB interface

Colour codes

Yellow RCA/BNC : composite video

red RCA/BNC : red or Pr/Cr chrominance

green RCA/BNC : green or luminance

blue RCA/BNC : blue or Pb/Cb chrominance

white BNC : horizontal sync

black BNC : vertical sync

Newer connectors are identified by their shape and not their colour.

Multiple signals

Some connectors can carry both audio and video signals simultaneously:DisplayPort digital connectorUnified Display Interface (UDI)F connectors are used with RF modulators for televisions without direct inputsHDMI is a new digital standardSCART, now the most common in EuropeTRS connectors with more than one ring, or Sony's hybrid RCA with a TRS pinCoaxial cable/RG-6/RG-59/Cable television (CATV)
Other composite connectors carry video, power, and USB:ADC, now-defunct Apple Display Connector

History

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1950s and 1960s

In the 1950s, home movies became popular in the United States and elsewhere as Kodak 8 mm film (Pathé 9.5 mm in France) and camera and projector equipment became affordable. Projected with a small, portable movie projector onto a portable screen, often without sound, this system became the first practical home theater. They were generally used to show home movies of family travels and celebrations but also doubled as a means of showing private stag films. Dedicated home cinemas were called screening rooms at the time and were outfitted with 16 mm or even 35 mm projectors for showing commercial films. These were found almost exclusively in the homes of the very wealthy, especially those in the movie industry.

Portable home cinemas improved over time with color film, Kodak Super 8 mm film film cartridges, and monaural sound but remained awkward and somewhat expensive. The rise of home video in the late 1970s almost completely killed the consumer market for 8 mm film cameras and projectors, as VCRs connected to ordinary televisions provided a simpler and more flexible substitute.

1980s

The development of multi-channel audio systems and laserdisc in the 1980s added new dimensions for home cinema. The first known home cinema system was installed as a sales tool at Kirshmans furniture store in Metairie, Louisiana in 1974. They built a special sound room which incorporated the earliest quadraphonic audio systems and modified Sony trinitron televisions for projecting the image. Many systems were sold in the New Orleans area in the ensuing years before the first public demonstration of this integration occurred in 1982 at the Summer Consumer Electronics Show in Chicago, Illinois. Peter Tribeman of NAD (USA) organized and presented a demonstration made possible by the collaborative effort of NAD, Proton, ADS, Lucasfilm and Dolby Labs who contributed their technologies to demonstrate what a home cinema would "look and sound" like.
Over the course of three days, retailers, manufacturers, and members of the consumer electronics press were exposed to the first "home like" experience of combining a high quality video source with multi-channel surround sound. That one demonstration is credited with being the impetus for developing what is now a multi-billion dollar business.

1990s and 2000s

In the early to mid 90's, a typical Home Cinema would have a Laserdisc or S-VHS player fed to a large screen: rear projection for the more affordable setups, and LCD or CRT front projection in the more elaborate. In the late 1990s, the development of DVD, 5.1-channel audio, and high-quality video projectors that provide a cinema experience at a price that rivals a big-screen HDTVs sparked a new wave of home cinema interest. In the 2000s, developments such as High Definition video and newer HD display technologies enable people to enjoy a cinematic feeling in their own home at an affordable price.

Plasma display

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A display that produces an image by using a matrix of transparent electrodes, positioned in front of a gas- (plasma) filled cavity. The gas is contained in hundreds of thousands of tiny cells between the two plates, and when excited by the electrodes, acts like tiny fluorescent lights. Each pixel of the image comprises a red fluorescent light, a green one and a blue one. Just like a CRT television, the plasma display varies the intensities of the different lights to produce a full range of colours. Most plasma displays are not technically televisions, since they do not include a television tuner. They must be connected to a tuner, cable box or some other source such as a DVD or VCR. Plasma displays are popular because even large-screen models are only a few inches thick.

NVOD

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Near Video On Demand. A system typically used for subscription movies, whereby the same movie is continuously played on several channels, with the start time between each channel being staggered by 15 or 30 minutes, so that the consumer does not have too long a wait to catch the beginning.

MPEG-4

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Sometimes called the 'MP3 of the video world', MPEG-4 is designed for multimedia applications including web, handheld and wireless devices. It is based on object-based compression, whereby individual objects within a scene are tracked separately and compressed together to create an MPEG-4 file. This results in very efficient compression that is highly scalable, from low bit rates to high quality.

MPEG-2

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Developed by the Motion Pictures Experts Group (MPEG), MPEG-2 is a video compression algorithm that compresses the data required to represent a video picture by a factor of around 40. MPEG-2 is used by DVD-Video, digital broadcast satellite, and digital TV (including HDTV).

MP3

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MPEG Layer 3. The data required for an MP3-encoded audio track is 12 times less than that of the same track recorded at standard CD quality. Hence MP3 requires shorter download times if used to transfer music via the Internet for example, and less storage space, giving rise to a proliferation of solid-state MP3 players such as the Apple iPod and players in mobile phones. MP3 files can be stored on any digital recording medium. Provided they have MP3 decoding capabilities, CD and DVD players can read a CD that has been burned with MP3 tracks.

ISDN

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Integrated Services Digital Network. A communications network offered by BT for data transmission of 64kb/s per channel. ISDN has mostly been superseded by broadband/ADSL.

IR

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Infra-red. IR frequencies have electromagnetic wavelengths that are shorter than those of RF fields. IR is typically used for sending wireless control signals from television and hi-fi remote-controllers, some cordless computer keyboards and mice, and some wireless hi-fi headphones.

IEEE802.11

2008-07-03T01:06:00.002-07:00

A wireless transmission protocol. It exists in a number of versions (labelled a to g) that run at different frequencies in the spectrum 2.4GHz (g) to 5.7GHz (a), giving different possible data rates. Version b is currently in commercial use, predominately for wireless PC networks (WLAN).

IEEE1394

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A communications protocol that allows direct digital transfer of data from one device to another. IEEE1394 allows for example, digital video from a DV camcorder to be transferred to the hard disk of a personal computer, provided both camera and computer have each have an IEEE1394 connection. IEEE1394 is also at the heart of the HAVi home networking standard (see HAVi).

Hub/Switch

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A device for connecting computers and peripherals to a router. A router connects a home network to outside networks or computers, while a hub or switch connects the computers and peripherals within the house, and appropriately disseminates the information they request. Routers and hubs/switches are traditionally separate units, but are more frequently being bundled in packages that include a built-in hub/switch, and sometimes a DSL modem also.

Home automation

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The automatic control of systems such as heating, lighting, entertainment, security and communications by a single user interface. Operation might be by remote control, wall-mounted keypad and/or personal computer, and may be manual or programmed.

HDCD

2008-07-03T01:03:00.002-07:00

High-Definition-Compatible Digital. An enhancement to standard audio CDs that effectively increases the 16-bit dynamic range to 20-bits. Originally developed by Pacific Microsonics, the technology is now owned by Microsoft. HDCDs are compatible with non-HDCD players, and standard CDs can be played on HDCD players.

HAVi

2008-07-03T01:03:00.001-07:00

Home Audio Video Interoperability. An initiative by some major consumer electronics companies to network consumer electronics hardware using an IEEE1394 connection. The network does not require a dedicated PC, and would allow communication with devices, such as heating, lighting and home appliances, operating on other networks.

FVD

2008-07-03T01:02:00.000-07:00

Forward Versatile Disc. An optical disc format for storing high definition video based on red laser technology, developed by Taiwan's Advanced Optical Storage Research Alliance (AOSRA) in conjunction with the Industrial Technology Research Institute (ITRI).

Front Projection

2008-07-03T01:01:00.002-07:00

Front Projection - when a projector, usually ceiling-mounted, projects the picture onto a white screen. Both the projector and the screen may be retractable when not in use.

EMI

2008-07-03T01:01:00.001-07:00

Electromagnetic interference. EMI is generated by the internal circuits of devices such as personal computers, wireless devices and CRT displays, and can cause interference and disruption of other electronic devices such as cordless telephones, home entertainment systems, computers, and certain medical devices. There are regulations governing EMI by electronic equipment in Europe, and problems can be minimised by grounding, filtering and shielding.

EIB

2008-07-03T01:00:00.000-07:00

European Installation Bus (a.k.a. Instabus). An embedded control protocol for digital communication between devices. It consists of a two-wire bus line that is installed along with normal electrical wiring. The Instabus functions like a telephone line over which appliances can be controlled, and links all appliances to a decentralised communication system.

DVD

2008-07-03T00:59:00.002-07:00

DVD-Audio - a Digital Versatile Disc that offers audio quality higher than standard compact disc. It supports 24-bit/192kHz stereo audio, and 24-bit/96kHz 5.1 channel PCM playback capability. DVD-Audio discs will play at their highest quality on DVD-Audio-compatible players. A DVD-Audio disc can also be played on a standard DVD player for multichannel sound, albeit at DVD-Video quality.

DVD-RAM

2008-07-03T00:59:00.001-07:00

DVD-RAM - a recordable DVD format that is claimed to have the best recording features, but which is not compatible with most DVD-ROM drives and DVD-Video players. It is more commonly used in applications where a removable hard disk might be used.

DVD+RW

2008-07-03T00:58:00.000-07:00

DVD+RW - DVD ReWriteable. DVD+RW as some different features to DVD-RW and is compatible with about 75% of all DVD players and most DVD-ROMs.

DVD-RW

2008-07-03T00:57:00.002-07:00

DVD-RW - DVD ReWriteable. It is compatible with about 75% of all DVD players and most DVD-ROMs. DVD-RW supports single-sided 4.7GB DVDs(called DVD-5) and double-sided 9.4GB DVDs(called DVD-10).

DVD+R

2008-07-03T00:57:00.001-07:00

DVD+R - DVD Recordable. DVD+R has some different features to DVD-R, and is compatible with about 86% of all DVD players and most DVD-ROMs.

DVD-R

2008-07-03T00:55:00.000-07:00

DVD-R - DVD Recordable. DVD-R is a non-rewriteable format and it is compatible with around 92% of all DVD players and most DVD-ROMs.

DVD

2008-07-03T00:53:00.001-07:00

DVD - Digital Versatile Disc (a.k.a. Digital Video Disc). An optical disc that has two sides and can store 4.7GB of data per side, i.e. enough for a 133-minute movie including several audio tracks in formats such as stereo, Dolby Digital or DTS, and advanced menu systems, subtitles and still pictures that can be played by many standalone DVD players and most computer DVD-ROMs. If the disc has two layers per side, then it can store up to 17GB of data. DVD uses MPEG-2 compression for video and audio.

DVD-Video. A means of distinguishing between DVD that is used primarily for audio (DVD-Audio) and DVD that is primarily used for video.

DTS

2008-07-03T00:52:00.000-07:00

DTS - a 5.1 digital surround sound system developed by Digital Theater Systems. It offers 5.1 channels of audio reproduction: front left, front right, front centre, surround left, surround right and a dedicated Low Frequency Effects (bass) channel, represented by the '.1.' DTS is used on CDs and DVDs, and is recommended for multichannel music playback. It uses less compression than Dolby Digital, and so requires more disc space.

DSLAM

2008-07-03T00:51:00.002-07:00

DSLAM - a multiplexing system that must be installed at the consumer's local telephone exchange in order to support ADSL and separate voice traffic and data traffic on the telephone line.

DSL

2008-07-03T00:51:00.001-07:00

DSL - Digital Subscriber Line. DSL uses existing copper wire telephone lines to provide high-speed (or broadband) data transfer. A common configuration of DSL is to support higher data rates downstream (towards the customer) and lower data rates upstream (towards the network). This arrangement is asymmetric (see ADSL). Another common configuration is symmetrical, having the same data rate in both directions.

DLP

2008-07-03T00:50:00.002-07:00

DLP - Digital Light Processing - a way to project and display video signals based on the Digital Micromirror Device (DMD) developed by Texas Instruments. The DMD stores image information and reflects light with thousands of 16x16-micron mirrors, and is designed to provide noise-free, precise image quality with digital gray scale and good colour reproduction. Close spacing of the micromirrors causes video images to be projected as seamless pictures with higher perceived resolution.

Dolby Pro-Logic

2008-07-03T00:50:00.001-07:00

Dolby Pro-Logic (a.k.a. Dolby Surround) - a surround sound system developed by Dolby Laboratories. It offers four channels of audio reproduction: front left, front right, front centre and a mono surround channel, usually delivered by two surround speakers located behind the listening position.

Dolby Digital

2008-07-03T00:49:00.002-07:00

Dolby Digital - a digital surround sound system developed by Dolby laboratories. It offers from 1 to 5.1 channels of audio reproduction: front left, front right, front centre, surround left, surround right and a dedicated Low Frequency Effects (bass) channel, represented by the '.1.' DVD players with Dolby Digital capability can provide a backward-compatible mixdown of the five main channels to four for Dolby Pro-Logic playback.

DiVX

2008-07-03T00:49:00.001-07:00

DiVX - A pay-per-view version of DVD. The disc costs less to buy than a normal DVD, but after a 48-hour viewing window has passed, the disc expires unless you pay more to extend the viewing window.

Disk

2008-07-03T00:48:00.002-07:00

Disk - the conventional spelling used for a Winchester hard disk, a non-optical magnetic medium.

Disc

2008-07-03T00:48:00.001-07:00

Disc - the conventional spelling used for an optical disc, such as a CD or DVD.

Digital Television

2008-07-03T00:47:00.002-07:00

Digital Television - (DTV) digital television theoretically offers better quality pictures than analogue because the digital signal is much less susceptible to interference. It uses MPEG-2 coding for video and audio, and once received, the digital signal is converted back to analogue via a set-top box (STB) or hardware within an integrated television set (iTV). DTV is available via satellite and cable through subscription, or free via terrestrial through a Freeview box. DTV offers the broadcaster the possibility of more channels, as well as interactive services.

DECT

2008-07-03T00:47:00.001-07:00

DECT- Digital European Cordless Telecommunication. DECT is a digital cordless system for communication within a local area, for example within a residence or a company.

CRT

2008-07-03T00:46:00.000-07:00

CRT - Cathode Ray Tube. The technology used in conventional television sets, where the picture is formed on a glass picture tube by an electron gun that excites phosphors on the back of the screen glass. CRT technology offers the most absolute levels of black as there is no light spill, and offers a large dynamic range, producing high peak in brightness over a short period. CRT technology is also used in projectors.

Coaxial Cable (a.k.a. coax)

2008-07-03T00:45:00.002-07:00

Coaxial Cable (a.k.a. coax) - a cable that has a single centre copper conductor surrounded by an insulating material that is covered with another conductive material, usually a braid or shield, and then wrapped in an overall jacket. Coaxial cable is typically used for video distribution of TV, satellite, video and CCTV images. Coaxial cables are designated by their overall impedance, but the naming process bears no relation to this. For example RG-58 cable has an impedance of 50 ohms, while RG-62 has an impedance of 93 ohms.

Broadband

2008-07-03T00:44:00.000-07:00

Broadband - generally defined as a connection that offers data rates of more than 128kb/s.

Blu-Ray Disc Format

2008-07-03T00:43:00.000-07:00

Blu-Ray Disc Format - a format developed by the 'Blu-Ray Disc Founders,' namely Hitachi, LG Electronics, Matsushita, Pioneer, Philips, Samsung, Sharp, Sony, and Thomson. This uses a new blue-violet laser technology that has a smaller laser beam width than a conventional laser beam and so can store more data on a standard 12cm optical disc. A single-layered Blu-Ray Disc can store up to 27GB, and a dual-layered double-sided Blu-Ray Disc can store up to 54GB.

Bandwidth

2008-07-03T00:42:00.000-07:00

Bandwidth - the band of frequencies occupied by transmitted modulated signals, but also used to refer to the capacity available in a communications network.

Balun

2008-07-03T00:40:00.000-07:00

Balun - a device that converts a balanced line signal to an unbalanced one, and vice versa. A balun is typically used for converting an unbalanced television antenna signal, with one conductor and an electrical earth, to a balanced signal with two conductors having equal currents that are opposite in phase.

AOD

2008-07-03T00:36:00.000-07:00

Advanced Optical Disc. Created by Toshiba in conjunction with NEC, the AOD format is a more recent development than the Blu-Ray Disc format, but is supported by the DVD Forum - a consortium that includes all nine members of the 'Blu-Ray Disc Founders' (see Blu-Ray Disc Format). The AOD format uses blue laser technology to store up to 15GB of data on a single-layered read-only 12cm optical disc. A dual-layered disc would hold 30GB, and a rewriteable version would hold 20GB. AOD is expected to offer long recording times by using MPEG-4 compression, which uses less data than MPEG-2.

ADSL

2008-07-03T00:31:00.000-07:00

ADSL - Asymmetric Digital Subscriber Line. ADSL uses existing copper wire telephone lines to provide high-speed (or broadband) data transfer. It is asymmetric because the downstream (towards the customer) data rates tend to be faster than upstream (towards the network) rates. In theory, ADSL supports up to 9Mb/s downstream and 640kb/s upstream, compared with ISDN that supports 128kb/s downstream and upstream. ADSL operates alongside the existing telephone service, and so supports Internet use as well as a normal telephone line for example.

AC3

2008-07-03T00:21:00.000-07:00

AC3 is the audio format utilized by ATSC and DigiCipher II.

AC3 is supported as an optional audio standard by DVB and DSS.

AC3 is also known as Dolby Digital.

The AC3 standard is being replaced with AAC (Advanced Audio Coding), although AC3 will continue to live on for many decades due to the number of systems and networks which currently utilize it.

To learn more about AC3, visit Dolby.

Advanced Audio Coding

2008-07-03T00:18:00.000-07:00

Advanced Audio Coding (AAC) is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at many bit rates.

AAC has been standardized by ISO and IEC, as part of the MPEG-2 & MPEG-4 specifications. The MPEG-2 standard contains several audio coding methods, including the MP3 coding scheme. AAC is able to include 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 15 low frequency enhancement (LFE, limited to 120 Hz) channels and up to 15 data streams. AAC is able to achieve indistinguishable audio quality at data rates of 320 kbit/s (64kbit/s/channel) for five channels. The quality is close to CD also at 96 kbit/s (48kbit/s/channel) for stereo.

AAC's best known use is as the default audio format of Apple's iPhone, iPod, iTunes, and the format used for all iTunes Store audio (with extensions for proprietary digital rights management).

AAC is also the standard audio format for Sony’s PlayStation 3, latest generation of Sony Walkman, Sony Ericsson Walkman Phone, Nintendo's Wii (with the Photo Channel 1.1 update installed for Wii consoles purchased before late 2007) and the MPEG-4 video standard. HE-AAC is part of digital radio standards like DAB+ and Digital Radio Mondiale.

High End Integrated Home Theater Systems

2008-07-03T00:06:00.000-07:00

While most audiophiles will usually spend lots of money on separate components, for people that want a complete set, there are extremely high quality integrated home theater systems. These systems usually cost more than $1,000 and deliver great sound and quality for large rooms. These systems can include high definition DVD players, top of the line surround speakers and a powerful receiver with enough power to give you an over the top home theater experience.

Mid Level Integrated Home Theater Systems

2008-07-03T00:05:00.000-07:00

Mid Level systems are usually priced from about $300 to $1,000. They usually produce a satisfactory home theater experience. They include a DVD player usually with progressive scan technology, 6 speakers including a subwoofer and a powerful amplifier with name brand digital signal processing such as Dolby DTS or THX Surround EX. These systems are for people that are not audiophiles, but would like to have a great sounding home theater system with most of the bells and whistles. Since these systems are integrated, set up is a breeze and can take only a few minutes.

Budget Level Integrated Home Theater Systems

2008-07-03T00:04:00.000-07:00

You can easily find many budget level home theater systems at prices less than $100. These systems include a DVD player, 5 speakers and an amplifier that has a form of digital signal processing. Many of these systems also come with a subwoofer. While you should not expect anything earth shattering from these super low budget systems, they are great for people that live in very small dorms or apartments and are usually very easy to set up.

Integrated Home Theater System

2008-07-03T00:00:00.000-07:00

Integrated home theater systems are great for budget conscious consumers, non technical home theater consumers and for people that want to purchase an out of the box home theater solution. Most integrated home theater systems come complete with a DVD player, surround sound receiver, 5 surround speakers and 1 subwoofer. For the most part, you will still have to purchase your TV set on your own or use an existing TV set.

Integrated home theater systems are extremely easy to set up and can fit almost any type of budget. For instance, there are usually 3 separate levels for integrated home theater systems; budget, mid level and high end integrated home theater systems.

What is Home Entertainment?

2008-07-02T23:48:00.000-07:00

Most people characterize home entertainment as both audio and video components that can play a variety of media in a comfortable and convenient home setting. Some people might say that a home theater system is synonymous with home entertainment. A home theater system is where both audio and video work together to produce a cinema experience in the comfort of your own home.

Most home theater systems have two components; an audio component and a video component. In a home theater system, both of these components work together in concert with one another to produce a cinema experience.

Home theaters usually come in either individual components or in prepackaged integrated home theater systems. If you are buying separate components, you will probably need to choose a large widescreen TV set, DVD player, a receiver with digital surround sound processing and surround sound speakers.

When choosing a TV, you will probably want to go with a widescreen, HDTV set. These TV sets offer the highest quality picture in a format (widescreen) that is the same as the format used in cinemas. The screen shape at most movie theaters has an aspect ratio of 16:9, the same aspect ratio that many widescreen HDTV sets use. This way you can watch a film the way the director intended it to be viewed.

Another important component needed for a home theater system is a DVD player. Today, you can view DVD's on a standard DVD player or on high definition players such as HD-DVD or Blu-Ray DVD. While most consumers agree that the quality of movies on standard DVD is excellent, high definition DVD's although new to the market, promise even higher quality video and audio signals.

Now that you have a TV set and a way to play your favorite movie, you will need to focus on the audio components. You should first start with a receiver that can process digital surround sound. Practically all DVD's and some CD's have encoded data that specifically tells the receiver where the sound should be sent. For instance, most surround receivers have 5 types of speakers and the encoded data tells which of these speakers the sound should be sent to. There are many types of surround sound processing formats. Some of the more common formats are Dolby Pro Logic, DTS, Dolby EX and THX Surround EX.

Most of these surround sound formats are either 5.1 or 6.1. A 5.1 format means that there are five separate channels and 1 subwoofer. The 5 channels include one front right and one front left speaker, one center channel speaker and one set of rear speakers. A 6.1 requires the same speakers as a 5.1, except that you can also add a set of rear speakers that are in stereo, meaning one rear right speaker and one rear left speaker.

Hi-Fi & Home Cinema GLOSSARY

Digital television

Surround sound

Dolby Pro Logic

Digital cinema

Digital Theater System

Dolby

Central processing unit

CD-ROM

CinemaScope

Compact Disc

Broadband

Bluetooth

Blu-ray (2)

Blu-ray

Bass

Analog

Amplifier (2)

Amplifier

Audio and video

History

Plasma display

NVOD

MPEG-4

MPEG-2

MP3

ISDN

IR

IEEE802.11

IEEE1394

Hub/Switch

Home automation

HDCD

HAVi

FVD

Front Projection

EMI

EIB

DVD

DVD-RAM

DVD+RW

DVD-RW

DVD+R

DVD-R

DVD

DTS

DSLAM

DSL

DLP

Dolby Pro-Logic

Dolby Digital

DiVX

Disk

Disc

Digital Television

DECT

CRT

Coaxial Cable (a.k.a. coax)

Category

Broadband

Blu-Ray Disc Format

Bandwidth

Balun

AOD

ADSL

AC3

Advanced Audio Coding

High End Integrated Home Theater Systems

Mid Level Integrated Home Theater Systems

Budget Level Integrated Home Theater Systems

Integrated Home Theater System

What is Home Entertainment?