[mythtv-users] Where to set hue/saturation

Joseph A. Caputo jcaputo1 at comcast.net
Wed Mar 10 09:59:37 EST 2004


On Wednesday 10 March 2004 07:32, Simon Lundell wrote:
> Hi!
>
> The picture from my mythtvbox is over saturated. (not considering the
> colors, the picture from my mythbox is _better_ than the actual
> TV-picture). Were is the the best place to change this setting?
>
> Capture? (using test_ioctl)
> Mythtv?
> X?
> TV?

Could be a little bit of everything, though I'd rule out your TV 
(assuming your regular TV-tuned picture looks OK).  There are 2 
variables here -- the captured picture, and the output picture.  First 
I'd get the output picture looking as good as I could.  I'd say an 
ideal setup would be to get 2 copies of a test-pattern VCD or DVD (1 
disc & 1 ripped file should work).  Play back the disc in a standalone 
DVD player & your Myth box (using mplayer or xine) at the same time (I 
hope you have an A/B switch).  Adjust the Xv output picture controls 
(xvattr is one program to do this; or you could use 'mythtv' to 
playback the file & use Myth's OSD controls to adjust the picture) 
until the pictures from the 2 sources match as well as possible.  Now 
you need to apply those Xv attribute settings to your Myth database so 
that Myth will use those settings for playback.

Now that your X output picture has been tuned, you can adjust your 
recorded picture.  This is done per-channel, but for the most part you 
should be able to tweak one channel and apply the same settings to the 
rest.  Just watch LiveTV and switch back & forth between TV-tuned tv & 
Myth LiveTV on the same channel, adjusting the V4L or ivtv picture (can 
be done via Myth w/the OSD; you don't need to use test_ioctl) settings 
until you get the best match.

Disclaimer:  I've never done this myself, but I've been meaning to for 
quite a while, as my Myth video looks slightly washed-out compared to 
direct TV-tuned picture.

It might be nice to provide a link somewhere on the Myth site to a 
(S)VCD image that can be burned for adjusting your picture... I'll see 
if I can find a good link (probably www.vcdhelp.com).

-JAC


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