[FFmpeg-devel] [PATCH 1/2] avcodec: add photocd decoder

Steinar H. Gunderson steinar+ffmpeg at gunderson.no
Fri Dec 21 23:13:55 EET 2018


On Fri, Dec 21, 2018 at 05:07:45PM +0100, Paul B Mahol wrote:
> The colors that PhotoCD uses predates color space definitions.

Really? It looks fairly well-defined to me, though esoteric
(the gamma ramp is basically like sRGB but with a much bigger constant,
and the 8-bit Y'CbCr scaling seems unusual):

  https://en.wikipedia.org/wiki/Photo_CD#Encoding

FFmpeg doesn't have a good understanding of gamma (it rarely actually
converts between different gamma ramps), but that's not a problem with
PhotoCD per se. I can't find a good reason why FFmpeg could not be
extended with conversions from the PhotoCD color space to sRGB, at least
not if clipping out-of-gamut colors is acceptable.

/* Steinar */
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Homepage: https://www.sesse.net/


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