[Libav-user] Best way to provide avcodec_decode_video2 with h264 data?

Alex Cohn alexcohn at netvision.net.il
Sun Oct 28 20:04:24 CET 2012

On Thu, Oct 25, 2012 at 12:14 AM, Tim Pitman <tapitman11 at gmail.com> wrote:
> Yeah I finally got the decoder working on a frame to frame basis and
> got rid of the constant errors, at least as long as the stream is
> good.
> I'm confused what you mean by "The encoder expects NAL units". I'm
> piping raw video data (via ffmpeg using yuv4mpegpipe format) into x264
> which seems to work.
> Two questions for you?
> 1) Is live555 suitable for lossy physical layer transmissions or only
> for situations with a working UDP or TCP network?
> 2) Sometimes the video gets so corrupted over the wireless channel
> that the decoder seems to get stuck printing a constant series of
> errors and doesn't recover, even if the channel improves. Do you know
> of a way to restart or flush the decoder some way, or another way to
> get around this?
> Thanks,
> Tim

One typical case for decoder not being able to recover is when
statistically no key frames (which are naturally much bigger than the
average P-frames) can arrive correctly. We were experiencing this
effect even when on the average UDP packet loss was reasonable.

We ended with kind of custom FCC which improves the situation in
general, but especially for I-frames.


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