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

Andy Burns xorg.lists at burns.me.uk
Sun Jan 15 11:48:28 CET 2012

I have an ASUS P5E-VM HDMI motherboard which has GMA X3500 graphics
onboard, running Fedora 16, this is used as my mythTV frontend.

Previously the PC was connected directly to a Toshiba Regza 40ZF355DB
(which is an HDMI 1.3 device) and all was well including colour gamut
(RGB output with full 0..255 range)

I had calibrated the colours using the BBC HD Testcard W which uses
superblack (i.e < 16) and superwhite (ie. > 235) it was possible
during calibration to see the difference between black and superblack,
and between white and superwhite.

My setup now includes a Marantz NR1602 amp (which is an HDMI 1.4
device) this is connected between the PC and the TV, but has slightly
upset the apple cart :-(

Initially I noticed that the colours were different, blacks have
become grays, saturation seems higher, checked using the same

Previously I hadn't had to fiddle with xvYCC settings on the TV, I
have now tried this setting as on/off/auto and though it seems to
change the saturation,I still can't see the super black/white during
calibration, it seems the amp is "clipping" the RGB levels to the
16..235 studio range, which I gather is common behaviour for AV amps

OK, enough scene-setting, here are the xorg questions ...

Is there any xorg.conf setting to switch the HDMI output to YCbCr mode
instead of RGB mode?

Similarly is there any setting to indicate an xvYCC gamut, which might
persuade the amp not to clip the colours?

And finally, is there any support for DeepColour (30bpp or 36bpp)?

Searching around it seems I might need a newer chipset than X3500 for
some of the above, especially the DeepColour mode, I might treat the
PC to an ASUS P8H67-I motherboard and a sandybridge CPU if it would
help, any difference between HD2000/HD3000 as far as these options are

Any suggestions for HDMI connection via the amp would be welcome too ...

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