[FFmpeg-user] Converting BT2020 HVEC Videos to H.264 without Color Washout

[Pedro Vivas Hernández]

Lurking. Important. Thank you.

On Thu, Mar 25, 2021 at 5:17 PM Pavel Koshevoy <pkoshevoy at gmail.com> wrote:

> On Thu, Mar 25, 2021 at 9:27 AM Craig L. <ffmpeg at trafficality.com> wrote:
>
> > I recently started finding certain videos were washing out upon H.264
> > conversion.
> >
> >
> > After doing some research I found that if I added -color_primaries
> > bt2020 to the command, the color would come out correctly, but ONLY if
> > the video was played in Quicktime.  When played in Chrome, it would look
> > washed out.
> >
> > Here is a link to a screengrab showing the video in quicktime on the
> > left and in Chrome on the right.  Same video.
> >
> >
> > *https://snipboard.io/N8nYv0.jpg* <https://snipboard.io/N8nYv0.jpg>
> >
> >
> >
> >
> > After much research I can't figure out how to handle this?
> >
> > What is the correct way to convert these videos that I suppose are 10
> > bit HDR  into H.264 so that they will play correctly in Chrome, etc.
> >
> >
> >
> > This is my current command:
> >
> > /usr/local/bin/ffmpeg  -i "156237-Video2.mov"   -filter_complex
> > "scale=480:270"  -color_trc smpte2084 -color_primaries bt2020 -c:v
> > libx264 -profile:v high -pix_fmt yuv420p -level 5.1 -preset ultrafast
> > -movflags faststart       -vsync 2  -c:a aac -b:a 128k     -y
> > 156237-Video2.mov-16-9-1616621202.mp4
> >
> >
> >
> >
> >
>
> For best possible player compatibility you really need to convert from
> HDR10 to SDR (bt709).
>
> To do that you need to use either colorspace or zscale ffmpeg filter.  The
> colorspace filter didn't support HLG the last time I checked, but that
> wouldn't matter if your source is HDR10, not HLG.
> Since you'd be converting from high dynamic range to standard dynamic range
> you would also need to use the tonemap filter.
>
> There is probably a LUT file somewhere that implements HDR10 -> BT709 color
> space conversion and tone mapping in one step, skipping zscale/tonemap.  If
> you had such LUT you could use it with lut3d filter.
>
> Pavel.
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