[Libav-user] RTP H263 demuxer

Pierluigi Cifani pcifani at oonair.com
Thu Aug 25 10:45:36 CEST 2011

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

pcifani at oonair.com

Passeig de Gràcia 67 1º
08008 Barcelona 
M.+34 673767404
T. +34 934875941

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20110825/bedfbb71/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 3572bb2.png
Type: image/png
Size: 1067 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20110825/bedfbb71/attachment.png>

More information about the Libav-user mailing list