[Libav-user] Segfault on corrupted video

Tim Pitman tapitman11 at gmail.com
Tue Jun 26 21:28:28 CEST 2012

I'm experimenting with transmitting h264 over a lossy channel. On the
receiver side I have a very simple libav/opengl video player that
takes the stream and feeds it to avcodec_decode_video2 one NALU at a
time. There are lots of errors but mostly they just result in
artifacts, which is exactly what I want to happen. However, when the
channel is bad libav segfaults with:

mmco: unref short failure

I was wondering if anyone has a guess as to how I can avoid this
crashing. I don't care if the video looks horrible, I just want it to
keep going and recover when the channel improves again.

I have several ideas that I was going to try:
1) Make my video player NALU aware and checksum each NALU, throwing
out bad ones.
2) Make my video player frame-aware and throw out bad frames.

If I knew what it was about the NALU's that are crashing libav, I
would just get rid of those ones and be done with it.

I'm also planning to do some simple FEC, probably at the NALU level,
which will help as well.


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