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

[Michael Koch]

Am 15.09.2022 um 11:26 schrieb 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.

This seems to work with VLC player:

ffmpeg -f lavfi -i color=0x19be0f:s=400x576 -colorspace bt709 -crf 0 
-vcodec libx264 -t 5 -y out1.mp4
ffmpeg -f lavfi -i color=0x19be0f:s=400x578 -colorspace bt709 -crf 0 
-vcodec libx264 -t 5 -y out2.mp4