[Libav-user] Why does av_seek_frame() not seek to a keyframe?

[Hendrik Leppkes]

On Thu, Jul 19, 2012 at 8:31 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

>
> Isn't this necessary for some codecs / at least for H264? Wouldn't
> the API do exactly the same?
>

Sure, if you end up seeking to a non-keyframe, it should not decode garbage
frames.
The point here is that we would want to actually end up on a proper
keyframe.


>
> > But the idea is to ensure that you can decode as of time X,
> > which means you need to seek to the last keyframe *before*
> > time X, which is something that is not supported currently.
>
> I see.
> (But am I wrong to assume that this is not generally possible,
> assuming large GOPs?)
>
>
Even a large GOP has a start somewhere. Granted seeking might take a bit
longer because reading data backwards to find the keyframe is not as ideal
as going forward, but it should be possible.
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