[Libav-user] "no picture" from decoding single h264 keyframe

[cyril poulet]

You can have a look at this tutorial, which explains how to make sure that
you get a whole image
http://blog.tomaka17.com/2012/03/libavcodeclibavformat-tutorial/


2014-04-03 20:01 GMT+02:00 Andrey Utkin <andrey.krieger.utkin at gmail.com>:

> 2014-04-03 12:33 GMT+03:00 cyril poulet <xenosender at gmail.com>:
> > I'm no expert, but it would not surprise me much if the flag indicated
> only
> > the beginning of the key frame, and not that it contains an entire key
> > frame...
> > Also, I'm not sure that you can really rely on it, the
> AVFrame->pict_type is
> > much more reliable
>
> You are right, looks AV_PKT_FLAG_KEY marks a "beginning of key frame".
> Some log excerpt is below for justification. You can see a large first
> AVPacket marked as key, and one small following AVPacket. The decoder
> returns actual picture (if I type) after decoding both of them.
> Thanks to all for sharing ideas, especially to Cyril.
>
> <30>Apr  3 20:50:23 : D(3/axis): read AVPacket: stream_index: 0, size:
> 15080, flags: 1, dts: -9223372036854775808, pts: -9223372036854775808
> <30>Apr  3 20:50:23 : D(3/axis): read AVPacket: stream_index: 0, size:
> 66, flags: 0, dts: -9223372036854775808, pts: 3560
> <30>Apr  3 20:50:23 : D(3/axis): read AVPacket: stream_index: 0, size:
> 10232, flags: 0, dts: 3560, pts: 7198
> ...
> <30>Apr  3 20:50:23 : D(3/axis): mo proc block decodes packet, size
> 15080, flags 1
> <30>Apr  3 20:50:23 : D(3/axis): [libav] debug no picture
> <30>Apr  3 20:50:23 : D(3/axis): no picture from decoding frame in mo proc
> <30>Apr  3 20:50:23 : D(3/axis): mo proc block decodes packet, size 66,
> flags 0
> <30>Apr  3 20:50:23 : D(3/axis): Decoded picture type: I (1)
> <30>Apr  3 20:50:23 : D(3/axis): mo proc block decodes packet, size
> 10232, flags 0
> <30>Apr  3 20:50:23 : D(3/axis): Decoded picture type: P (2)
>
> --
> Andrey Utkin
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