[Sumover-dev] Identifying I-frames and P-frames in mpeg4 packets

[Andrew Ford]

Hi,

I've been messing with the VPMedia code a bit, trying to get mpeg4 reception
to work, and comparing its code with decoder-mpeg4 in vic. I'm wondering
what the proper way to identify the beginning/end of frames is - is it
determined by the marker field in the RTP packet header? I had a couple
other issues:

-in the packets, (in the actual payload, after throwing out the header) it
looks like the first two bytes are always zero. Should these be passed to
libavcodec's decoder?
-from what I can tell in decoder-mpeg4.cpp, it looks like the sequence
0x000001b0 at the beginning of the payload means that that's the beginning
of an I-frame. Is there a similar sequence for a P-frame? Is that even
necessary to specifically identify P-frames if the marker bit is being
properly set?

Any help would be greatly appreciated.
Thanks,
--Andrew
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