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

[Michael Bradshaw]

On Thu, Jul 19, 2012 at 2:01 PM, Michael Bradshaw
<mbradshaw at sorensonmedia.com> wrote:
> [...]
> I guess we should define what would be considered "erroneous" seeking
> to make sure I'm on the same page as everyone, as it's possible I'm
> not. Would these be considered "problematic:"
>
> 1) Seek is performed, first packet out of av_read_frame() has .flags=0
> (meaning not a keyframe)
> 2) Seek is performed, avcodec_decode_video2() must be fed several
> packets (57 in my test with ffmpeg command line, with #55 being the
> only one with .flags=1 (keyframe)) before it gets a full frame out

Anyone have any answers on these two things? If the answer to the
above would be "yes" can anyone else verify that "ffmpeg -dump
-loglevel debug -ss 38 -i 704x480-m2v-ac3.mpg -vframes 1 out.jpg" does
not seek to a keyframe?

Thanks,

Michel