[Ffmpeg-devel] problem decoding frames when first frame is B

rkmr.em at gmail.com rkmr.em
Mon Apr 23 22:34:10 CEST 2007

On 4/23/07, Mathieu Monnier <manao at melix.net> wrote:
> >>>>> Open GOP makes some sense when
> >>>>> random access is impossible, such as broadcast, which is where it
> >>>>> is primarily found.  DVD uses closed
> Open gop always make sense.
> >>> So it is not possible to decode the first two frames?  Is this true
> >>> even with the latest svn version of ffmpeg?
> It can't be decoded if the broken link flag is set to 1 in the gop
> header. I wouldn't trust a broken link flag anyway, and I would bet
> anyway that they aren't decodable
> >> The first frame produced when the decoder is switched on must be
> >> possible to decode somehow.  If you jump into the stream at a later
> >> point you'll always have a couple of initial B-frames with one
> >> reference before your starting point.  Not even FFmpeg can invent this
> >> missing data.  The decoder copes with it just fine though, so there's
> >> no big deal.
> I think it rather seek to the following intra.
> > I am building a frame accurate video decoder using ffmpeg and I need to
> be
> > able to decode those frames.
> I don't think you can.

Do you know how hardware decoders would deal this issue?

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