[mythtv-users] Summery of my problems

Robert Johnston anaerin at gmail.com
Fri Jan 27 06:07:21 UTC 2006

On 1/26/06, Dylan R. Semler <dsemler at macalester.edu> wrote:
> Hello list, I've gotten everything with my myth system set-up marginally
> well, but I'm still having some annoying problems.  So here's what I'm
> running:
> Master backend (Dell 8200 circa 2002):
> Intel Pentium 4 (probably about 2 GHz)
> Nvidia GeForce2 MX
> Fedora Core 4 with kernel 2.6.14-1.1656_FC4
> mythtv rpms from atrpms
> pcHDTV-3000
> Frontend (laptop):
> Intel Centrino 1.6 GHz
> ATI mobility radeon 9700
> Fedora Core 4 with kernel 2.6.14-1.1656_FC4
> mythtv rpms from atrpms
> I've only really been working with LiveTV so far.  HD is able to stream
> pretty well to the frontend, but there are some problems.  In the first
> minute or so after I change a channel, there are a few pauses but
> eventually it smooths out (something I can live with).  However,
> whenever there is fast motion in the video, every other line gets
> slightly offset--I guess this is described as "combing."  How do I fix this?

Enable "DeInterlacing". The "Combing" is your (Progressive) laptop
display trying to show an interlaced signal. DeInterlacing corrects

> For analog, the picture quality is pretty bad (noisy) and there are
> about three or four horizontal lines at the top of the screen that have
> some random patterns of black and white streaks.  The picture quality is
> much better using tvtime and those lines do not appear.

Those lines are called the "VBI" (Vertical Blank Interrupt). They're
what gets sent as the TV's scanning electron beam travels from
bottom-right to top-left to start the next screenful. The "Random
Patterns" you see are (Most likely) the Timecode, and the Closed
Captioning data. You can adjust the "Overscan" parameters in Myth to
remove these.

As for the noise, make sure that Myth is tuning into the same
frequency (EXACTLY the same frequency) as TVTime is. It sounds like
Myth's off by a few Khz.

>  Also, the color
> balance is not quite right, but when I press F to 'rotate between
> Picture Adjustments (Colour, Hue, etc.)', nothing happens.  If I press
> 'G', I am able to make the adjustments for the recording.  Also, the
> backend logs indicate that its using v4l v1 rather than v4l v2:

IIRC, ATI cards don't support the XV picture controls. This is a
problem with their drivers.

> > Channel(/dev/video0)::SwitchToInput(in 0): Error -1 while setting
> > video mode (v2), "Invalid argument", trying v4l v1
> > 2006-01-26 22:52:21.234 Channel(/dev/video0)::SwitchToInput(in 0):
> > Setting video mode with v4l version 1 worked

Check the drivers you are using.

> Non-mythtv issue but maybe someone has a clue.  The master backend does
> not draw the desktop onto the entire monitor or tv (when using s-video
> out).  There is a black bar on the left side where the monitor and tv
> are scanning, but nothing is drawn (does that make any sense?).  I am
> currently running without any nvidia drivers, but the problem exists
> with a driver installed as well.  Any ideas?

Make sure you are using the NVidia driver (Just having it installed
does no good, it needs to be defined in your
Xorg.conf/XFree86Settings-4 file). Also check your ModeLines to make
sure you're using a proper modeline for your display (And make sure
you have the correct type of TV-Out defined. Outputting a PAL picture
to an NTSC TV will give black borders, as the picture sizes are

Hope this helps.
Robert "Anaerin" Johnston

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