[Matroska-devel] CodecSpecs

Moritz Bunkus moritz at bunkus.org
Sun Jan 9 18:33:20 CET 2011


Hey,

On Thu, 6 Jan 2011 00:01:45 +0100, "Santiago Jimeno" <sjimeno at ya.com>
wrote:

> AC3 and EAC3 in SymplyBlock (A3): follow ATSC a_52 - 2010
> specifications. My error is that I waited that audio code was in the
> first track of the cluster, but it doesn't always happen this way.

Yes.

> Quicktime in Private data: follows MP4 specifications of stsd atom.
> But QDMC from AudioSampleEntry with size (4 bytes) and format (4 char)
> before, and QDM2 from frma box (52 bytes later).

Sounds about right.

> DTS in SymplyBlock (A3): adds the whole header with included syncword
> (HD also).

True.

> New problem:  MLP and TrueHd
> MLP: includes complete Header in SymplyBlock. But it doesn't add more
> data than the content in TrackEntry.
> TrueHd:  impossible for my to find the relationship between the data
> of SymplyBlock and the specifications.

MLP and TrueHD are handled the same way. They contain the whole header
in the blocks.

> Does somebody have an audio sample of TrueHd?

http://www.bunkus.org/mtx-test-data/vob/vc1_truehd_eac3.evo contains
TrueHD and EAC3 audio tracks. If you don't know how to demux the TrueHD
track from it then merge with mkvmerge and extract the TrueHD track from
the resulting Matroska file with mkvextract.

Regards,
mosu




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