[mythtv] Playback performance

[Matt Zimmerman]

On my test system (Athlon T-bird 1.4GHz), simple playback of recorded
material (480x480 mpeg4) using Deinterlace=0 seems to use about 25% of my
CPU.  Capture uses most of the remaining CPU, such that I am not able to
reliably do simultaneous record and playback of 640x480, only 480x480.
Obviously, I would prefer 640x480.

In contrast, playing back a 640x480 MPEG-4 AVI file using mplayer requires
less than 5% of my CPU (basically negligible).

Why is mythtv significantly more expensive?  What can be done to reduce the
CPU usage for playback so that I can run at 640x480?  Simple recording using
mpeg4 and ffmpegrec from NVrec requires less than 85% of my CPU, so it seems
like I should be closer to being able to run at 640x480 in mythtv.

-- 
 - mdz