[FFmpeg-devel] [PATCH] Enable PAFF decoding

Michael Niedermayer michaelni
Fri Oct 12 03:26:16 CEST 2007

On Fri, Oct 12, 2007 at 11:12:40AM +1000, Neil Brown wrote:
> On Friday October 12, michaelni at gmx.at wrote:
> > the bugs just no (partially?) cancel each other out
> Fair enough.  I must admit that I find it very hard to follow the
> intended logic of that code and was focussed on producing the desired
> outcome.
> > 
> > 
> > > 
> > > It still leaves the first (presented) frame badly decoded though.
> > > There is a "double-vision" effect, as though the second field is being
> > > decoded with reference to the first (decoded) frame instead of the
> > > first field in the same frame.... does that make sense?
> > 
> > no, the first (IDR) frame should be decoded correctly, the "next" B frames
> > are prior to IDR in display order and cannot and should not be displayed 
> Perplexed...
> If those B frames "cannot and should not be displayed", why would they
> be put in the data stream at all, and why does the reference decoder
> decode them correctly?

ive not looked at the stream at all, but from what you posted these b frames
have timestamps which lay prior to the first IDR picture if that is the case
the sane solution is to drop them
it is possible to decode some SEI messages which will tell you what can be
decoded and what not, but i dont think i will accept such mess in svn
no half sane encoder generates b frames which only refer to future frames


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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