[MPlayer-dev-eng] [PATCH] VDPAU: add BT.709 support

[Lauri Mylläri]

On Sat, Oct 10, 2009 at 6:36 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Could you repeat why this is useful/correct/needed?

It is not always correct - the stream could specify a color space in
headers, the user might have scaled the video before vo or something
else.

Based on what I've read though it is my understanding that all HD
content should be assumed to be bt.709 unless otherwise specified. I
do agree with Reimar though that it is unreliable.

> If it is generally agreed on, 0 should probably be made default. (My original
> suggestion meant a patch that only accepted 1 or 2 and has 601 the default, so
> that 0 could be added later.)

I would be perfectly happy just having the option of specifying
"please guess, I think I know what I'm doing". :)

> I can't comment, also because I don't see any difference on my FW900. (Is a Flat
> Screen necessary to see a difference?)

Decent color reproduction should be enough, but the difference is
subtle. I've taken some screenshots to demonstrate, please see
http://img200.imageshack.us/i/shot1bt601.png/ and
http://img43.imageshack.us/i/shot1bt709.png/ for one example of the
difference in green and skin tones. Google Images finds another one at
http://members.cox.net/trbarry/BT709ToBT601.2.jpg

Using bt.601 for HD does make the image slightly unnatural on my
plasma (which has pretty accurate colors). I've had good results with
the guessing and find it useful. I won't argue that it's correct (or
even good enough to be set as default) but nice to have available.

--lauri