The AC3 (also known as AC-3) audio format is an audio
compression format commercially released in 1991 by Dolby
Laboratories. Better-known as Dolby Digital sound, the lossy algorithm
allows for some discarding of audio information for the sake of the most
efficient data-rate variable signal possible in digital delivery systems.
Some non-Dolby audio formats are AC3-compliant for home video
system compatibility.
Dolby Digital sound is commonly delivered in home video products with
audio channels ranging from 1.0 monaural, 2.0 stereo (with 2.0 mono
also being common), up to 7.1 channels of surround sound, at a encoded
at a 48kHz sample rate ranging from 8 to 32 bits per sample.
Most home video collectors will not hear the differences between a
compressed and uncompressed audio signal.
Dolby TrueHD, an uncompressed lossless audio format, is in use in
many of today’s standard Blu-ray Disc and UHD (4K) Blu-ray Disc
home video releases, with some parallel use of the Dolby Digital format
for compatibility with older home video systems.
More details on the AC3 standard audio format may be found on Wikipedia.
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