[VDPAU] How is the H264_HIGH_444_PREDICTIVE profile supposed to be used?

[Philip Langdale]

Now that the 355.11 driver is out and the feature is no longer 'beta',
I have to ask - how is anyone supposed to use the
H264_HIGH_444_PREDICTIVE profile? The driver doesn't claim support for
any 444 video surfaces, which would seem to be necessary to actually
use the profile. I tried passing a 420 surface, which didn't generate
any errors but just gave me garbage, as you might expect.

What am I missing?

Thanks?

--phil