[FFmpeg-user] YUV->RGB Color Shift

[FFmichael]

Carl Eugen Hoyos wrote
> 
> rotoman <rotoman <at> gmail.com> writes:
> 
>> Carl Eugen Hoyos wrote
>> > 
>> > rotoman <rotoman <at> gmail.com> writes:
>> > 
>> >> I'm having the same problem. The reason is simple: the Prores 4444 is
>> RGB
>> >> and not YUV. FFmpeg assumes it's YUV and converts to RGB.
>> > 
>> > Please provide a sample.
>> 
>> Here is a sample Prores 4444 footage, with RGB encoding.
> 
> There is a misunderstanding, sorry!
> 
> You mean that the colour dynamics are wrong, is that correct?
> ("video level" or "MPEG vs JPEG" etc.)
> Red is red for you, but you think it is too red (or not red enough)?
> 
> There is a color_range option that should affect this conversion, some
> users
> reported it does not work correctly, a reproducible bug report would be
> nice.
> 
> You can try to force PIX_FMT_YUVJ444P in the decoder, if this is needed
> for all
> samples, consider sending a patch to ffmpeg-devel.
> 
> If the encoding is "RGB" instead of "YUV" (this is possible for example
> with
> H264 and JPEG2000), red, green and blue become completely different
> colours.
> 
> Carl Eugen
> 
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> 

Prores4444 can be EITHER RGB or Y'CbCr (usually incorrectly referred to as
YUV;-) This is dependent on the origination of the footage and the
editing/conversion software. (Historically speaking, 4:4:4 referred to
Y'CbCr only)

If FFmpeg really was decoding RGB as Y'CbCr you would notice things to be a
whole lot stranger than a simple color shift.

FFmichael


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