[mythtv-users] Methods to avoid transcoding on slow frontend?

[Matthew Hager]

Hello all, I'm having a problem with stuttering HD playback on my mythtv 
system.

First off, I need to let you know that I'm running an ATSC tuner card 
(air2pc rev0.02) with a MX5200 AGP on a rig with a Pentium III 1.0Ghz CPU 
and 512MB of RAM.  Currently this is a combined FE/BE.  I'm splitting these 
very soon, which brings me to my main question.

I've had surprisingly good results using XvMC trying to playback the HD 
content recorded from the local PBS station.  Most of their stuff is 1080i, 
with some 720p content.  There are bubbly *blips* in the audio almost 
constantly, and the video gives a little stutter.  It was far more than I 
could have expected from a lowly 1.0Ghz proc.

I have need to re-use this hardware as a SD-only frontend with S-Video 
output.  I would like the capability to view LiveTV coming from the HD 
stations with this board, but I was unsure if there was any tweaking I 
could do with the "raw" MPEG2-TS stream itself to make it less intensive to 
play back.  Something akin to "real-time down sampling" if that makes any 
sense.  I don't know if anything like this exists.

My max resolution is only going to be 800x600 on the CRT.

Am I done before I begin due to the fact that the 1.0Ghz proc still needs 
to "touch" the full TS stream before it can try to "down sample it".

I realize that my situation is screaming for gratuitous amounts of 
transcoding to MPEG4 (which at 2200kbps works great with this proc), but I 
wanted to see if there was any way to avoid lengthy transcoding times for 
transient (ie not going to keep long term) items.  Plus the transcode 
option kinda nixes any possibility of Live HD programs?

Thanks,