[xiph-rtp] Theora over RTP

[Ralph Giles]

On Wed, May 31, 2006 at 03:01:28PM +1000, Rhys Hawkins wrote:

> I've been looking at the draft spec:
> http://svn.xiph.org/trunk/theora/doc/draft-barbato-avt-rtp-theora-00.txt
> And libtheora 1.0_alpha3,

In case you're not aware, I just released alpha6 which has a number of 
bug fixes over alpha3 and some MMX asm optimizations.
 
>                           and have a query regarding implementing the
> encoding side of things. For each frame, I believe I do something
> like:
> 
>     theora_encode_YUVin(&state, &yuv);
>     result = theora_encode_packetout(&state, 0, &packet);
> 
>     wrap_packet_in_rtp(packet);

Yes, that's correct. As you say, wrap_packet_in_rtp() has to segment 
larger theora packets and can generate any number of RTP packets 
(including less than 1 if it's packing very short packets together).

I believe the length field is just for the chunk contained in a given 
RTP packet; where the theora packet spans several RTP packets, the 
decoder must use the fragment/continuation bits and the packet sequence 
numbers to infer whether it got all the data or not.

> Could someone please tell me the correct way to break apart the 
> ogg_packet if that is what is necessary? Or correct where I've gone
> wrong above.

Just chop it into pieces so the RTP packets you're sending fit in your 
MTU. Luca has written some example code you might find useful:

  http://downloads.xiph.org/releases/xiph-rtp/xiph-rtp-0.1.tar.gz
  http://svn.xiph.org/trunk/xiph-rtp/

Hope that helps, and let us know if you get it working!

 -r