[mythtv-users] ATSC Unwatchable

[Keith Wait]

I just started using mythtv after a 3 year hiatus and built a new
computer to run it so that I can record HD.  I now have a Hauppage
HVR-1250 that is correctly identified by the kernel and all of the
/dev/dvb/adapter0/* devices are created.  I'm using a cheap-ish indoor
antenna that worked well plugged directly into the TV.

First, MythTV was able to scan for a few channels, but when I went to
watch live tv, the picture was just terrible.  It was very blocky,
most of the screen would be just one color with a little of the
picture's detail visible at any given moment.  The sound was either
only chirps or silent.

In troubleshooting, I was able to (from the command line) run scan and
create a channels.conf, again with a number of the channels that my
television on its own is able to receive.  When I run azap, it
definitely reports a status of FE_HAS_LOCK, gives a BER of 0 and gives
signal strengths in the E0-FF range (I assume this card reports 8-bit
signal strengths).

When I use mplayer to watch the same channels, (mplayer dvb://*) it
shows the same awful picture as mythtv.

I came across a posting or two on this list that mentioned this could
be due to multipath and recommended an attenuator.  I'm a little
disinclined to try that because I ran an experiment where I put the
computer just under the television, connected the antenna to the
computer, and got the lousy picture described above.  Then, without
changing anything else, I disconnected the antenna from the computer
and ran it to the TV.  It is able to get a clear picture on the same
channel that I attempted on the PC.

I've also tried a Windows 7 PC and, using Windows Media Center, I can
get excellent picture and sound using this same exact card and
antenna.

I've googled lots of different things trying to find some good steps
to overcome this problem, but haven't really come up with anything.

Thanks for any advice or suggestions of steps to take.