The SoundStorm, used for the Xbox game console and certain nForce2 motherboards, used an early form of this technology.It will enhance any encyclopedic page you visit with the magic of the WIKI 2 technology.Originally named Dolby Stereo Digital until 1995, except for Dolby TrueHD, the audio compression is lossy, based on the modified discrete cosine transform (MDCT) algorithm.The first use of Dolby Digital was to provide digital sound in cinemas from 35 mm film prints; today, it is now also used for applications such as TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles.
The AC-3 format was released as the Dolby Digital standard in 1991. Dolby Digital was the earliest MDCT-based audio compression standard to be released, and was followed by other MDCT-based audio compression standards for home and portable usage, such as Sony s ATRAC (1992), the MP3 standard (1993) and AAC (1997). A charge-coupled device (CCD) scanner in the image projector picks up a scanned video image of this area, and a processor correlates the image area and extracts the digital data as an AC-3 bitstream. All film prints with Dolby Digital data also have Dolby Stereo analogue soundtracks using Dolby SR noise reduction and such prints are known as Dolby SR-D prints. ![]() Dolby Surround 7.1 Logo Code Track ToAlmost all current release cinema prints are of this type and may also include SDDS data and a timecode track to synchronize CD-ROMs carrying DTS soundtracks. However, for new projectors it made sense to use dual analoguedigital soundheads in the normal optical soundhead position under the projector head. To allow for the dual-soundhead arrangement the data is recorded 26 frames ahead of the picture. ![]() This delay can be adjusted in steps of the time between perforations, (approximately 10.4 ms). Dolby Surround 7.1 Logo Movie Theaters CurrentlyWhile the majority of movie theaters currently utilize Dolby Digital, virtually all films released today are mixed in Dolby Surround 7.1 and Dolby Atmos. The most elaborate mode in common use involves five channels for normal-range speakers ( 20 Hz 20,000 Hz ) (right, center, left, right surround, left surround) and one channel ( 20 Hz 120 Hz allotted audio) for the subwoofer driven low-frequency effects. Mono and stereo modes are also supported. Adaptive Transform Acoustic Coding 3 is a separate format developed by Sony.) 17. EX adds an extension to the standard 5.1 channel Dolby Digital codec in the form of matrixed rear channels, creating 6.1 or 7.1 channel output. The extra surround channel is matrix encoded onto the discrete left surround and right surround channels of the 5.1 mix, much like the front center channel on Dolby Pro Logic encoded stereo soundtracks. The result can be played without loss of information on standard 5.1 systems, or played in 6.1 or 7.1 on systems with Surround EX decoding and added speakers. Dolby Digital Surround EX has since been used for the Star Wars prequels on the DVD versions and also the remastered original Star Wars trilogy. A number of DVDs have a Dolby Digital Surround EX audio option. It converts any audio signals on a PC or game console into a 5.1-channel 16-bit48 kHz Dolby Digital format at 640 kbits and transports it via a single SPDIF cable. A similar technology known as DTS Connect is available from competitor DTS. An important benefit of this technology is that it enables the use of digital multichannel sound with consumer sound cards, which are otherwise limited to digital PCM stereo or analog multichannel sound because SPDIF over RCA, BNC, and TOSLINK can only support two-channel PCM, Dolby Digital multichannel audio, and DTS multichannel audio. HDMI was later introduced, and it can carry uncompressed multichannel PCM, lossless compressed multichannel audio, and lossy compressed digital audio. However, Dolby Digital Live is still useful with HDMI to allow transport of multichannel audio over HDMI to devices that are unable to handle uncompressed multichannel PCM.
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