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

Michael Niedermayer michaelni at gmx.at
Sat Apr 2 16:32:00 CEST 2011

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
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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