[MPlayer-users] Desaturate video output

[Vladimir Mosgalin]

Hi Paolo Bolzoni!

 On 2014.12.30 at 23:47:00 +0100, Paolo Bolzoni wrote next:

> I am using a nvidia (closed driver) in linux, I will check about this
> PC to TV levels conversion thingy. Thanks.
> 
> However the movie I noticed the problem was Teenage Ninja Mutant
> Turtles [2014] that is actually quite oversaturated also to begin
> with; still I think in the TV is even moreso.

Well, correcting badly mastered movie is one thing and I assumed that
your TV colors are generally fine (that is, you didn't set it to display
oversaturated picture in general). In that case, when the picture on TV
feels oversaturated only when displaying video from HDMI input connected
to PC, it's the problem of colorspace/levels conversion.

PC/TV levels aren't the only thing to check, type of output (RGB vs YUV
and pixel format in case of YUV) matters too (depending on TV and
settings).
Using any format other than RGB on HDMI output means extra conversions
(YUV->RGB in mplayer, RGB->YUV in video card, YUV->RGB in display. Not
that feeding RGB to display doesn't mean there isn't RGB->YUV->RGB
conversion taking place in there - sometimes there still is one - but
that's another problem). It's not that these conversions by themselves
change saturation, but in practice TVs are designed such way so their
settings such as brightness/contrast/gamma/CMS system might produce
different effects depending on whether input is RGB or YUV. That is,
unless TV is converting everything to same format. So you can see
different picture/colors with the same settings when you change input
color format because effect of settings was slightly different.

Some TVs are very strange beasts (you might consult avsforum.com if
you're seriously interested in getting good picture for the movies on
your TV), but in general for modern TVs setting input type to "PC" and
feeding it full range RGB reduces amounts of conversions and processing
side-effects and has the least chance to get incorrect colors.

There are lots of various tests to check if levels and pixel format are
set correctly, but I think that black level & white saturation tests
from http://www.lagom.nl/lcd-test/ and this test picture
http://madshi.net/madVR/ChromaRes.png (for checking that 4:4:4 RGB is
displayed properly) should be enough for simple cases.

-- 

Vladimir