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Matroska File Format with Advanced Audio Codec (AAC) Audio Encoding

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Matroska File Format with Advanced Audio Codec (AAC) Audio Encoding
Description

Matroska file containing an Advanced Audio Codec (AAC) audio essence.

Supported encodings are declared via the unique Codec ID in the Matroska Codec Mappings. AAC have a number of profiles defined via MPEG2 Part 7 and MPEG4. This description focuses on the three default MPEG2 profiles.

Low Complexity (LC)

  • Codec ID: A_AAC/MPEG2/LC
  • Codec Name: Low Complexity
  • Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped from ADTS headers and normal Matroska frame based muxing scheme is applied. AAC audio always uses wFormatTag 0xFF.
  • Initialization: None

MPEG2 Main Profile

  • Codec ID: A_AAC/MPEG2/MAIN
  • Codec Name: MPEG2 Main Profile
  • Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped from ADTS headers and normal Matroska frame based muxing scheme is applied. AAC audio always uses wFormatTag 0xFF.
  • Initialization: None

Scalable Sampling Rate

  • Codec ID: A_AAC/MPEG2/SSR
  • Codec Name: Scalable Sampling Rate
  • Description: Channel number and sample rate have to be read from the corresponding audio element. Audio stream is stripped from ADTS headers and normal Matroska frame based muxing scheme is applied. AAC audio always uses wFormatTag 0xFF.
  • Initialization: None
Production phase Generally used for final-state, end-user delivery.
Relationship to other formats
    Subtype of Matroska, Matroska Multimedia Container
    Contains AAC_MP2, Advanced Audio Coding (MPEG-2)

Local use Explanation of format description terms

LC experience or existing holdings No extensive experience.
LC preference None.

Sustainability factors Explanation of format description terms

Disclosure See Matroska and AAC_MP2.
    Documentation See Matroska and AAC_MP2.
Adoption Moderate levels of adoption in professional production.
    Licensing and patents None.
Transparency Relatively transparent; requires tools to write and read.
Self-documentation See Matroska.
External dependencies None.
Technical protection considerations None.

Quality and functionality factors Explanation of format description terms

Sound
Normal rendering Good support
Fidelity (high audio resolution) See AAC_MP2
Multiple channels See AAC_MP2

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension See related format.  See Matroska.
Internet Media Type See related format.  See Matroska.
Magic numbers See related format.  See Matroska.
Pronom PUID See related format.  See Matroska
Wikidata Title ID See related format.  See Matroska and AAC_MP2

Notes Explanation of format description terms

General  
History  

Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 04/08/2022

 
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