[Cin] xvYCC

[Andrew Randrianasulu]

ср, 4 сент. 2024 г., 20:31 Andrew Randrianasulu <randrianasulu at gmail.com>:

>
>
> ср, 4 сент. 2024 г., 20:26 Phyllis Smith <phylsmith2017 at gmail.com>:
>
>>
>> On Tue, Sep 3, 2024 at 3:41 PM Andrew Randrianasulu via Cin <
>> cin at lists.cinelerra-gg.org> wrote:
>>
>>> found via ffmpeg bugtracker referencing our bugtracker ;)
>>>
>>> https://trac.ffmpeg.org/ticket/6793
>>>
>>> Interesting. So the problem is with the Sony XAVC format (used by at
>> least FDR-AX100)? And since the ffmpeg bug report is still open, but it is
>> old, does that mean it is not fixed?  And it is not a CinGG bug, but an
>> ffmpeg bug?
>>
>
> As far as I understand this bug about specific timecode in this file. So,
> it reads ok (?) just not with all info.... I tried to use it for testing,
> assuming xvycc really should be compatible with yuv /bt709 signal paths
> assuming there was no clipper.
>
> It seems to.work in sense image looks ok, but it looks a bit differently
> if I add F_colorspace filter with xvycc transfer function.
>


10 days happen

I found article describing decoding a bit more

https://www.researchgate.net/publication/250999893_192_xvYCC_A_New_Standard_for_Video_Systems_using_Extended-Gamut_YCC_Color_Space

and there was half of iec-61966-2-4

https://cdn.standards.iteh.ai/samples/14431/9e5a80b3c1a54ad0866f818def33466c/IEC-61966-2-4-2006.pdf


describing xvycc conversion to cie xyz 1931 via RGB

It seems that decoder need to apply some 3-segment curve to get RGB values
outside of [0,1] and then those can be manipulated as usual?

"NOTE The possible range for non-linear R’G’B’ (709) calculated from, for
example, equation (11) will be between -1,1206 and 2,1305"

so, it seems to use really aggressive optico electrical transfer function
coefficients around zero , 4.5!





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