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Format

Dolby Digital AC-3

Summary

Name
Dolby Digital AC-3
Identifiers
  • MIME: audio/ac3
  • PUID: fmt/735
Format type
Audio
Description
AC-3 (backronymed to Audio Codec 3 or Advanced Codec 3) is the common version of Dolby Laboratories' Dolby Digital audio compression technology.
File extensions
ac3
Source
Digital Preservation Department / The National Archives

Internal signatures

Dolby Digital AC-3

Note
The file consists of repeated frames of audio data. Each frame begins with the 0x0B77 syncword. The size of the frame is determined by the nominal bit rate and sample rate as per Table 5.18 of the Digital Audio Compression Standard specification http://www.atsc.org/cms/standards/a_52-2010.pdf

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
0
Byte Sequence
0B77
Endianness
None

Changelog

  • Updated in V84

    Release date
    21 January 2016

    Dolby Digital AC-3: Added MIME.

  • Added in V82

    Release date
    27 March 2015

    Dolby Digital AC-3: Signature developed through PRONOM Research.

    Dolby Digital AC-3: Full entry added.