[Intel-gfx] HDMI colour space and depth questions (YCbCr, xvYCC, Deep Colour)

[Andy Burns]

Jesse Barnes <jbarnes at virtuousgeek.org> wrote:

> Andy Burns <xorg.lists at burns.me.uk> wrote:
>
>> Is there any xorg.conf setting to switch the HDMI output to YCbCr mode
>> instead of RGB mode?
>
> No, we haven't exposed that yet.  On some chipsets it may mean
> configuring colorspace conversion in the pipe code.  Paulo has been
> looking at some of this...
>
>> Similarly is there any setting to indicate an xvYCC gamut, which might
>> persuade the amp not to clip the colours?
>
> There is a way to configure the gamut to be compressed (default) or
> expanded (up to 255).  But that's not exposed either.

OK, thanks for the info, I'll keep an eye on release notes for such
time when support might be added.  On the bright side, it defers my
hardware upgrade at least until IVB is released ...

>> And finally, is there any support for DeepColour (30bpp or 36bpp)?
>
> There is some 30 bit support in place, but not 36bpp, which is what
> HDMI sinks generally want.  Doing that properly involves doing gamut
> expansion, since most sources aren't 36bpp unless you have very
> specific kinds of source data (e.g. custom HD DVD movies or something).

No, I don't have any high colour material, but if a wider gamut had
been available, it would have been nice to have more colour resolution
too, to see whether interpolation could reduce banding etc ...

Thanks.