[gst-devel] addition of a buffer flag

Michael Smith msmith at xiph.org
Tue May 18 10:11:15 CEST 2004

On Thursday 13 May 2004 20:50, Wim Taymans wrote:
> > Play for 10 seconds, then disconnect identity and blah, and connect
> > identity to vorbisdec.  How does vorbisdec get the header packets?
> And how does oggdemux know what packets are codec data so that it can
> put these as blobs in the caps? Or is de codec responsible for updating
> the caps blob? Your identity example would still fail.. Maybe we can
> assume that as long as the granule pos in the ogg page header remains
> constant, we are dealing with headers?

One of the design goals (at one point) for ogg was that pages containing 
headers would always have granulepos 0. This is definately true (and 
required) for vorbis, but I don't know if it was ever written down as an 
_ogg_ requirement, so I'm not sure if other codecs follow this. A related 
requirement is that pages must never contain header AND data packets (it must 
be one or the other) - again, this is followed by vorbis but not neccesarily 
all other codecs.

It's a good way to identify "blob of data needed by the codec" if it works. We 
should probably think some more about this in the ongoing ogg-mux design 


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