[FFmpeg-devel] [PATCH] Only output necessary NAL units in H.264 extradata in SDP

Luca Abeni lucabe72
Mon Apr 6 09:16:59 CEST 2009

Hi Michael,

Michael Niedermayer wrote:
>> So, now I am confused... Which NALs should go in "sprop-parameter-sets"?
>> (I am asking because I intended to commit the patch, but after reading
>> your comment I want to be sure).
>> When I originally read the RFC, I somehow got the impression that all
>> the NALs contained in the extradata are allowed to be in
>> sprop-parameter-sets. Now, re-reading the RFC I see that it mentions
>> "sequence and picture parameter set NAL units", which I assume to be SPS
>> and PPS... Is this wrong?
> the RFC is poorly worded

No doubts about this ;-)

> the MUST NOT requirement pretty much says you cant put SPS&PPS in there.

Uh... I think I know what the RFC means: the key words here are "in any
capability exchange procedure". I think the RFC wants to say that
sprop-parameter-sets can be used during decoding, but must not be used
to check (for example) if a client can handle a stream (other fields are
supposed to be used for this).
Note that I am not trying to defend the RFC's wording... I am just trying
to see if we can find an interpretation that makes sense and allows us to
decide which NALs to put in sprop-parameter-sets.


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