[FFmpeg-devel] [PATCH v2 07/10] avfilter/vf_scale: preserve YUV range by default

[Niklas Haas]

On Tue, 31 Oct 2023 00:42:47 +0100 Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Sat, Oct 28, 2023 at 04:41:14PM +0200, Niklas Haas wrote:
> > From: Niklas Haas <git at haasn.dev>
> > 
> > YUV->YUV conversions should preserve input range, if the output range is
> > unspecified. Ensures full-range YUV input comes out as full-range YUV
> > output by default, even through YUV->YUV pixel format conversions.
> > ---
> >  libavfilter/vf_scale.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> 
> this seems to change the output of the following:
> ffmpeg -i 4493/AVCI100.mov -vframes 3 -bitexact file.nut
> did not investigate if this is a bug or bugfix
> 
> files are here: https://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket524/

Seems like it's a regression. mpeg4 does not support full range YUV, so
giving it full range YUV causes wrong levels to be saved.

I will drop this commit from this series and include it as part of the
filter negotiation series, since that one has the necessary
infrastructure to handle this more gracefully.