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

Don Moir donmoir at comcast.net
Thu Jul 19 21:16:34 CEST 2012

----- Original Message ----- 
From: "Michael Bradshaw" <mbradshaw at sorensonmedia.com>
To: "This list is about using libavcodec, libavformat, libavutil,libavdevice 
and libavfilter." <libav-user at ffmpeg.org>
Sent: Thursday, July 19, 2012 1:13 PM
Subject: Re: [Libav-user] Why does av_seek_frame() not seek to a keyframe?

> On Thu, Jul 19, 2012 at 12:18 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> 
> wrote:
>> Michael Bradshaw <mbradshaw at ...> writes:
>>> But when I seek, the first packet returned out of the demuxer is
>>> not a keyframe packet, and I have to read several (~45ish) packets
>>> until I encounter a keyframe.
>> Could you provide a sample that does not seek to a keyframe with
>> ffmpeg -ss x -i input out.png
>> (I tested this yesterday on random mpeg2video samples and afaict,
>> it did work.)
> Sure, here's a link to a sample video I'm testing with (sorry, it's
> 785 MB): 
> https://doc-04-50-docs.googleusercontent.com/docs/securesc/ha0ro937gcuc7l7deffksulhg5h7mbp1/t0csnri6mmjsd3mqbnb8qdv7b1tiq1e8/1342713600000/11977383638970716307/*/0BxWx_dIBnyRoZDNDeDVud3NNcEE?e=download

I did some visual inspection seeking here and there with my own app and the 
above file does not seem to be a problem. When I get a chance I will look at 
the numbers to check the accuracy. Just doing the visual inspection may not 
be enough. 

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