After much research I’ve discovered how to remove the comb effect from recorded mythtv shows. This occurs when using the xbmcmythtv python scripts to stream recorded tv shows from your myth box to Xbox Media Center. Mythfrontend can do this easily, but there has always been interlacing artifacts if you use the python script. I believe this is caused mplayer not getting the switche it needs to know to de-interlace the video. The fix is rather simple.
Edit the following file on the xbox:
Add the following line:
Mplayer does have other options for de-interlacing but I found that lavcdeint was the only one that didn’t crash. These were the other options I tried:
This change hasn’t effected other non mythtv files as far as I can tell, but I will keep an eye on things to make sure there isn’t anything dodgy going on. For now though it’s looking pretty good!