[FFmpeg-user] ffmpeg MP4/x264 output colours change when input source is different resolution (bug?)

[Dan]

> You are right that datascope shows no difference. But the issue is also
> reproducible with VLC player.

As well as VLC Player and FFplay, I've tried MediaPlayerClassic, Google Chrome,
Microsoft Edge and Vegas Pro, and the problem occurs with each of those. Could
there be a "takes two to tango" thing going on, where both the players and ffmpeg
are at fault due to miscommunication? It's somewhat hard to conceive they'd all
interpret the file incorrectly otherwise. Only one player I tried - Irfanview - interpreted
it correctly.

I can't get to test it with Firefox or Waterfox unfortunately. They think the file
is corrupt (output mp4 produced using the "-f lavfi -i color=0x19be0f:s=400x720" technique).
Maybe there's a way around that.

Also, showinfo produced an incorrect colour too. See: https://i.imgur.com/LF43udT.png

(I use: "ffplay.exe -vf showinfo 576.mp4" ).

In summary, I've love a workaround at least, or at least some reassurance that
Chrome et al. will come round to fix this, or that ffmpeg will communicate the file
better to them.

Dan