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Dolby Digital (AC-3) is Dolby's third generation audio coding algorithm. It is a perceptual coding algorithm developed to allow the use of lower data rates with a minimum of perceived degration of sound quality.
This coder has been designed to take maximum advantage of human auditory masking in that it divides the audio spectrum of each channel into narrow frequency bands of different sizes optimized with respect to the frequency selectivity of human hearing. This makes it possible to sharply filter coding noise so that it is forced to stay very close in frequency to the frequency components of the audio signal being coded. By reducing or eliminating coding noise wherever there are no audio signals to mask it, the sound quality of the original signal can be subjectively preserved. In this key respect, a coding system like AC-3 is essentially a form of very selective and powerful noise reduction.
In the consumer electronics industry the Dolby Digital soundtrack can be found on the latest generation of LaserDiscs (in space where one of the analog tracks used to be), can be found as the standard audio track on Digital Versatile Discs (DVD), is the standard audio format for High Definition Television (HDTV), and is being used for digital cable and satellite transmissions.
Related glossary terms
Related software tools
AC3Filter (Open source)
AC3Filter is an open source AC3 decoding filter that allows you to watch videos with AC3-encoded surround audio.
FFDSHOW (Open source)
FFDSHOW is a super-fast DirectShow decoding filter for decompressing DivX, XviD, WMV, MPEG-1 and MPEG-2 movies and supports subtitles as well. If you ever want to watch movies, get this!
Media Player Classic (Open source)
Media Player Classic is an extremely light-weight media player for Windows. It looks just like the good-old Media Player v6.4, but has lots of nice extra features.