[Libav-user] RTP H263 demuxer

[Pierluigi Cifani]

Hi Guys,

I've been trying to develop an RTP demuxer to pass to the FFMPEG (libavcodec) H263 packets in Mode-A.

However I can't seem to make the FFMPEG happy with the I-frames I am feeding it with. With fragmented frames (such as a large I-frame) I am rebuilding the whole frame following RFC 2190 and the "Marker" rules and passing it to the Libavcodec layer. However video looks buggy and it looks that I have to add some kind of header to the beginning of each frame before passing it to the Libavcodec layer. Errors like this are coming out all the time:

illegal dc 128 at 0 3
illegal ac vlc code at 0x3
Error at MB: 69
illegal ac vlc code at 4x15
Error at MB: 349
concealing 379 DC, 379 AC, 379 MV errors

I have previously built an H264 over RTP demuxer and I had to add 0x00 0x00 0x00 0x01 0x21 header to every fragment of I Frame in order for it to be decoded correctly. But I can't find anywhere documentation on how to do this with H263.

Maybe you could lend me a hand?

Cheers and thanks a lot


PIERLUIGI CIFANI
pcifani at oonair.com







Passeig de Gràcia 67 1º
08008 Barcelona 
M.+34 673767404
T. +34 934875941
http://www.oonair.com 
http://www.twitter.com/oonair

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