[FFmpeg-devel] [PATCH] MPEG-TS demuxer: Report 4cc in codec_tag field instead of SMTPE RID

Reimar Döffinger Reimar.Doeffinger
Tue Sep 1 09:10:57 CEST 2009

On Mon, Aug 31, 2009 at 06:02:09PM -0700, Baptiste Coudurier wrote:
> On 08/31/2009 05:48 PM, M?ns Rullg?rd wrote:
> > Sorry, but you're wrong.  There is nowhere a requirement that the
> > format_identifier value correspond one-to-one with anything.
> I think the specs are pretty clear:
> "The registration descriptor of ITU-T Rec. H.222.0 | ISO/IEC 13818-1 is 
> provided by this text in order to enable users of this Specification to 
> unambiguously carry data when its format is not recognized by this 
> Specification. This provision will permit this Specification to carry 
> all types of data while providing for a method of unambiguous 
> identification of the characteristics of the underlying private data."
> I maintain that using the same registration descriptor for different 
> private data is against the specifications, since it goes against 
> providing unambiguous identification of the underlying private data.

I think M?ns meant to say that "private data" != "codec", and the
AC3+TrueHD combination mess with other data to differentiate them can
all together be considered the "private data" format.
Though I'd say that definitely is a case of going with the letter of the
spec instead of with the spirit...

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