[FFmpeg-devel] xvYCC Conversion to Wide Gamut RGB with FFmpeg

Michael Niedermayer michaelni at gmx.at
Sat Apr 2 16:33:21 CEST 2011


On Sat, Apr 02, 2011 at 04:32:00PM +0200, Michael Niedermayer wrote:
> On Fri, Apr 01, 2011 at 09:28:16PM -0700, Thomas Worth wrote:
> > On Fri, Apr 1, 2011 at 8:45 PM, Kieran Kunhya <kieran at kunhya.com> wrote:
> > >> Are you sure Canon DLSRs use xvYCC? I thought this was a
> > >> Sony thing.
> > >> If you want to check you can download our tool, 5DtoRGB,
> > >> and convert a
> > >> clip using "none" as the decoding matrix. This will show
> > >> you raw pixel
> > >> values for Y, Cb, and Cr copied straight from the H.264
> > >> file prior to
> > >> being decoded. I don't know if Canon use values outside
> > >> 16-240 for
> > >> chroma, but it's possible. Some tests with a color chart
> > >> and jacking
> > >> up the saturation in a Picture Style may help determine
> > >> this.
> > >
> > > There's an SEI if I remember rightly that has all this information. The H.264 full_range_flag is usually incorrect.
> > 
> > Does the full_range_flag setting affect the actual decoding of the
> > stream? In other words, will pixel values be different off the decoder
> > if this is 1 vs 0? I'm just talking about the decoder, not any chroma
> > reconstructing or matrix decoding.
> 
> ffmpegs h264 decoder returns whats stored thus theres no change in the
> returned YUV values from that flag but the decoder might choose to
                                             ^^^^^^
i meant of course player

> interpret them differently
> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> It is dangerous to be right in matters on which the established authorities
> are wrong. -- Voltaire



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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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