[FFmpeg-devel] H.263 packetizing into RTP

Luca Abeni lucabe72
Sun Apr 5 21:31:19 CEST 2009

Hi Michael,

On Fri, 2009-04-03 at 23:15 +0200, Michael Niedermayer wrote:
> > >    A Follow-on Packet contains a number of bytes of coded H.263+ data
> > >    that do not start at a synchronization point.  That is, a Follow-on
> > >    Packet does not start with a Picture, GOB, Slice, EOS, or EOSBS
> > >    header, and it may or may not start at a macroblock boundary.
> > > 
> > > Splitting packets according to such boundaries would perhaps give better 
> > > handling of dropped packets, but isn't mandated.
> > 
> > Right. This is why I said that the patch is (IMHO) correct but
> > suboptimal.
> yes, also to clarify things as maintainer of the h263 decoder and error
> concealment code.
> the only thing that matters is
> that the code that splits at arbitrary byte boundaries tries to
> split at slice/gob boundaries when possible. That is it could try to put
> as many complete gobs/slices in a packet and only if it cannot put a 
> single complete one in there, put a partial one in there.

Ok; thanks for clarifying this (this is one of the aspects I was not
sure about). I'll not commit the patch until someone implements this
kind of frame splitting.

If someone can provide pointers and/or hints (I do not know much about
H.263 syntax... For example, can I identify slice/gob boundaries by
searching for 0x000001, or similar? Can ff_find_start_code() be used for
this purpose?) I'll work on this... Otherwise I'll wait for someone else
to do the job.


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