[Libav-user] Decoding specific formats?

Patrick Zielinski dzeesea at gmail.com
Thu Feb 23 01:16:38 CET 2012

Ok, firstly please bare with me, up until two weeks ago I didn't even know
what codec were and how encoding worked. Also, this code is ported within a
C++ framework so it might not comply with your usual coding standards.

Essentially here is the code that I have written which resembles closely to
the libav decoding example with minor tweaks due to deprecated functions. I
actually have a different version in our code, but it's mostly just working
with the buffer and the image data to add to our own structure.


I'd like to have either tips on how I could make this more robust, or what
steps I should take to extract each frame from different formats. I've
taken a look at ffmpeg.c, but not as much as I wanted.

On Wed, Feb 22, 2012 at 11:22 AM, Alex Cohn <alexcohn at netvision.net.il>wrote:

> On Tue, Feb 21, 2012 at 23:24, Patrick Zielinski <dzeesea at gmail.com>
> wrote:
> > Hello all, I have integrated decoding with libavformat and libavcodec a
> > basic decoder. It works for H264 encoded video's and also I converted one
> > into avi, it also works.
> >
> > But for some reason when I try other formats like .mkv I receive this
> > error:
> >
> > [h264 @ 05f32a80] no frame!
> >
> > I've encoded  the mkv's with x264 so I'm having a hard time understand
> how
> > it cannot find a frame, it occurs when I call
> >
> > avcodec_decode_video2(pCodecCtx, pFrame, &gotFrame, &packet);
> >
> >
> > What kind of details am I missing, because the different structs seem to
> > have correct data.
> You probably have metadata missing, e.g. SPS/PPS, if MKV container
> keeps this information not with the frames that you push into
> avcodec_decode_video2(). Please make sure that your mkv can be played
> by command-line ffmpeg. If this simple test succeeds, please make your
> initialization code available (e.g. via pastebin).
> BR,
> Alex
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