[FFmpeg-devel] [PATCH] attachments support in matroska demuxer

[Michael Niedermayer]

On Mon, Jan 28, 2008 at 10:49:13AM +0100, Baptiste Coudurier wrote:
[...]
> Just remembered of SMPTE RP2025:
> 
> "This document was initiated by C24 in response to the need to store
> VC-1 coded bitstreams in file formats
> derived from the ISO Base Media File Format such as the MP4 file format
> and the 3GPP file format."
> "The purpose of this specification is to define the necessary structures
> for the integration of VC-1 coded
> bitstreams in a file format that is compliant with the ISO Base Media
> File Format. Examples of file formats that
> are derived from the ISO Base Media File Format include the MP4 file
> format and the 3GPP file format."
> 
> "6 VC1SampleEntry definition
> The box type of the VC1SampleEntry Box shall be 'vc-1'."
> 
> Now we got 2 differents codecs using stsd tag as a codec identifier.

Ive said it already, the stsd identifies the specification
It here identifies the specification about how to store vc-1, you even
quote this above:
"The purpose of this specification is to define the necessary structures
 for the integration of VC-1 coded
 bitstreams in a file format that is compliant with the ISO Base Media
 File Format"

And this is not vc-1 or avc1 but every derivation of the ISO Base Media
File Format ive seen. They each define their own stsd value to identify
the spec.

codec_tag is not the specification identifer!
If you want to we could add a spec_tag to export this information but
please stop misusing codec_tag for it!

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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