[FFmpeg-devel] [PATCH 12/24] avcodec/mjpegenc: add support for non-YUVJ formats

[Rostislav Pehlivanov]

On 2 May 2018 at 19:16, wm4 <nfxjfg at googlemail.com> wrote:

> On Wed, 2 May 2018 19:14:21 +0100
> Rostislav Pehlivanov <atomnuker at gmail.com> wrote:
>
> > On 2 May 2018 at 19:04, Marton Balint <cus at passwd.hu> wrote:
> >
> > >
> > >
> > > On Tue, 1 May 2018, Rostislav Pehlivanov wrote:
> > >
> > > On 1 May 2018 at 23:22, Paul B Mahol <onemda at gmail.com> wrote:
> > >>
> > >> On 5/2/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > >>> > Hi
> > >>> >
> > >>> > On Tue, May 01, 2018 at 09:40:01PM +0200, Paul B Mahol wrote:
> > >>> >> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> > >>> >> ---
> > >>> >>  libavcodec/mjpegenc.c      | 5 ++++-
> > >>> >>  libavcodec/mpegvideo_enc.c | 3 +--
> > >>> >>  tests/lavf-regression.sh   | 2 +-
> > >>> >>  3 files changed, 6 insertions(+), 4 deletions(-)
> > >>> >
> > >>> > This doesnt work
> > >>>
> > >>> It does work, if you want full range set full range as option.
> > >>> Check visually colors.
> > >>> This happens because rgb is still marked incorrectly as limited
> range,
> > >>> so limited is picked instead.
> > >>>
> > >>>
> > >> Shouldn't this be part of the patchset?
> > >>
> > >
> > > I thought that color_range only matters for YUV formats, for RGB it is
> > > ignored. If it was decided to support limited RGB, then please update
> the
> > > docs of AVCOL_RANGE_JPEG/MPEG. Otherwise the color_range of an RGB
> format
> > > should not matter.
> > >
> > > On the other hand, if we decide to support limited RGB, then maybe a
> new
> > > member in color_range is better, this way we are able to specify more
> > > easily that we support limited YUV and full range RGB. (like ffplay
> > > typically does).
> > >
> >
> > Limited range RGB does NOT exist in the computer world, and I don't give
> a
> > fuck if broadcasting uses it. I've fought hard to keep it from getting
> into
> > AV1.
> > So no, we will not be supporting limited range RGB.
>
> You're very wrong. GPUs and HDMI (basically trash fire consumer
> garbage) sometimes seem to require you to feed limited RGB.
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Maybe if you took a second to read what I wrote. HDMI sometimes requires
limited range rgb because its derived from broadcasting junk where they had
technical limitations they weren't smart enough to overcome. GPUs can
generate or convert RGB to limited range only for transmission, through the
use of gamma LUTs I believe.

Either way, limited range RGB does NOT exist in computers, as in, not
inside codecs, nor is there anything supporting such, and we will certainly
not start doing it.