[mythtv-users] Channel Fine Tuning
atd7 at cornell.edu
Wed Jan 21 15:47:53 EST 2004
Quoting Curt Parker <dirt at dixie-net.com>:
> I have search the archives for "Channel" and "Tuning" but I can't seem
> to find what I am looking for in the 3000+ messages it returns.
> ivtv .1.9
> mythtv .13
> I have everything working fine. Recording, live tv, everything. The
> one problem I am having is with the color red on any channel. Red is
> giving me a blue ghost in both mtythtv and a cat capture from
> /dev/video0. For instance, if I tune in to CNN and the logo is at the
> bottom, the red CNN logo appears to have a blue shadow. Its like this
> on every channel. How do you go about fine tuning this, or is this an
> indication of some problem? I can post any other information that may
> help, I just didn't want to start with a bunch of information that is
> not needed.
Hmm. Well, it COULD be one of the following:
a) Hue/saturation/etc. values are incorrect. Try using ivtv's test_ioctl while
watching a direct capture to tweak these. A good example of a direct capture is:
cat /dev/video0 | xine -
b) Your frequency is off (the general definition of "fine tuning" is fixing
minor center frequency errors). You can use test_ioctl to get the current
center frequency for a given channel and then start tweaking that to see if it
Then you can change the finetune variable for a given channel in the channel
table of the mythconverg database to define an offset from the default center
freq of a channel.
For example, if the normal center frequency of a channel is 3188 (Note, this is
not in MHz, I believe the formula is n * 6.25/100 MHz.), and your optimum
reception is 3184, the value of the finetune variable would be -4.
See recent archives (within the past 3-4 days) for info on tweaking channel
settings directly within the database.
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