AC4 Codec Mapping

[optimiz]

Hello, is it too early to include mapping for Dolby AC4 in the Matroska specification? The core elements were defined in 2014 and subsequently standardized with the European Telecommunications Standards Institute (TS 103 190) and adopted for DVB (TS 101 154) in 2015. Please advise, thank you.

Bitstream syntax and frame documentation...

ETSI Digital Audio Compression (AC-4) Standard Part 1 v1.2.1 (2015-06)

• http://www.etsi.org/deliver/etsi_ts/103100_103199/10319001/01.02.01_60/ts_10319001v010201p.pdf

ETSI Digital Audio Compression (AC-4) Standard Part 2 v1.1.1 (2015-09)

• http://www.etsi.org/deliver/etsi_ts/103100_103199/10319002/01.01.01_60/ts_10319002v010101p.pdf

Digital Video Broadcasting (DVB) Specification for the use of Video and Audio Coding in Broadcasting Applications v2.2.1 (2015-06)

• http://www.etsi.org/deliver/etsi_ts/101100_101199/101154/02.02.01_60/ts_101154v020201p.pdf

[dericed]

I suggest referencing the proposal on the CELLAR list serv. For support for an AC4 Mapping, the codec spec document at https://github.com/Matroska-Org/matroska-specification/blob/master/codec_specs.md would need adjustment., to clarify what private data to store, make the id official, and describe it.

[mbunkus]

I appreciate you getting the ball rolling. I so second @dericed in that the discussion should probably be had on the mailing list for improved visibility. A good starting place would be the mapping for MP4 (I assume that it exists already).

[optimiz]

Will do, @dericed, thanks. Yes, @mbunkus, the mapping for MP4 and 3GPP is in Annex E of the ETSI Digital Audio Compression (AC-4) Standard Part 1 v1.2.1 linked above, under the heading "AC-4 Bitstream Storage in the ISO Base Media File Format", as registered with Apple's MP4 Registration Authority. I'll be sure to include this info to the mailing list.

FYI - The specific "code point" registration link is...
MP4 Registration ETSI AC-4