[mythtv-users] Interlaced vs. noninterlaced: getting perfect output smoothness

[Sasha Z]

As far as I can understand it, there are two ways of getting perfect
video output on SDTV using an svideo input. One is using an interlaced
mode with a 59.94-ish Hz refresh, and the other is with a progressive
mode with a 29.97-ish Hz refresh but with bob 2x deinterlacing.

So I've spent the last few hours trying to tweak my output, and here's
where I've gotten:

1) Interlaced modes have better picture quality, but I can't seem to
get the refresh quite right, so there's some jitter where frame
drawing doesn't line up to the refresh, and I spent about 1.5 hrs just
hand putzing with the modeline to try and get the pixel clock just
right. I got close, but never quite there. Bottom crawlers (tickers,
news, etc) are my standard for smoothness, and I want flawless
playback.

2) The noninterlaced mode with bob2x has an annoying verticle jitter
of something just under one pixel. I know you'll tell me I can't shift
an image less than one pixel, but it seems to be happening. On some
parts of a line, the next line will appear in the proper place.
Elsewhere, it'll spill over into the next line and appear to jitter.
The OSD and the video both seem to jitter at the same rate. From a
long distance this isn't too bad, but it gives me a headache after a
while. It is almost as smooth as butter, with very rare pauses, so I
assume the refresh rate is closer to correct.

I'm using an FX5200 via svideo to an NTSC SDTV RCA 25" display. I'm
trying to clear a progressive HDTV purchase, but am not having much
luck.

For X options, I've turned on renderaccel, hardware cursor, and have
opengl timing (apparently) working ok.

Any thoughts on final tuning? Is there a good way to adjust the clock
real time, and not have to edit the xorg.conf and restart the x server
all the time?