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

[Paul B Mahol]

On 9/15/22, Michael Koch <astroelectronic at t-online.de> wrote:
> 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

mostly because of extra -colorspace flag supplied.

>
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