[FFmpeg-devel] [RFC]lavc/ffv1dec: Scale msb-packed output to full 16bit

[Ronald S. Bultje]

Hi,

On Thu, Nov 17, 2016 at 4:11 PM, Michael Niedermayer <michael at niedermayer.cc
> wrote:

> On Thu, Nov 17, 2016 at 09:13:55PM +0100, Carl Eugen Hoyos wrote:
> > 2016-11-17 14:49 GMT+01:00 Rostislav Pehlivanov <atomnuker at gmail.com>:
> > > On 16 November 2016 at 11:15, Carl Eugen Hoyos <cehoyos at ag.or.at>
> wrote:
> > >
> > >> Hi!
> > >>
> > >> Attached patch improves output for some ffv1 files imo.
> > >> Current slowdown for the existing decode-line timer is
> > >> 2%, I wonder if this can be improved through refactoring.
> > >>
> > >> Please comment, Carl Eugen
> > >>
> > >> _______________________________________________
> > >> ffmpeg-devel mailing list
> > >> ffmpeg-devel at ffmpeg.org
> > >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> > >>
> > >>
> > > So AFAIK the encoder pushes the values to the LSBs but the decoder
> didn't
> > > shift them back up?
> >
> > I don't think the encoder does any shifts here but I may misunderstand.
> >
> > > I think you should add a comment explaining that happens.
> >
> > Many (older) decoders have to do this and there is nowhere a
> > comment, I really believe that this is not particularly convoluted
> > code.
> >
> > > Also 2% on a decoder doesn't sound that great,
> >
> > It's 2% in a function of a decoder.
> >
> > > did you try using an if case for the entire loop for when the
> > > values need to be shifted?
> >
> > That is what I tried to suggest with "refactoring", I suspect
> > Michael wasn't too happy about the idea.
>
> can the whole "what to put in the lsb" question be avoided by adding
> gray10 support to ffv1dec ?
> if so this might be the best solution


I believe that would also resolve the issue, yes...

Ronald