[mythtv-users] How I got great quality TV-out on my nVidia MX4000

[Will Dormann]

Jeroen Brosens wrote:
> Therefore, using bob is paramount for a smooth video playback. All other
> deinterlacers as well as no deinterlacing (!) can't provide this.

Just a follow-up to this thread.

While the combination of settings I originally posted does give 
excellent results, I've recently discovered that that particular 
combination does not actually do Bob Deinterlacing.

I had a hunch that this was the case, as the non-XvMC settings @ 640x480 
+ Bob enabled did seem to produce a slightly smoother picture than XvMC 
@ "coryntsci" + Bob.  Although the smooth motion was excellent with the 
former, the OSD was ugly and the Bob didn't always seem to get the 
picture right, especially after a seek.   (Sometimes 1/2 the vertical 
resolution would appear to be lost)

The way I determined this was by zooming in significantly and pausing 
the video during a high motion scene.   This made the "mouse tooth" 
appearance of the interlacing effects quite evident.  If the Bob was 
actually taking place, none of the frames should have any interlacing at 
all.  (Since each frame is derived from a single field).   The 
mythfrontend log does indicate that the Bob is taking place:
  2005-03-08 19:20:41 XvMC will use bob deinterlacing
  2005-03-08 19:20:41 Using deinterlace method bobdeint
but visual analysis of the picture shows otherwise.  I'm not sure if 
this is some sort of problem with the drivers, resolution and/or 
rounding errors, or MythTV itself.

I think the combination of the low CPU usage of XvMC and the Vsync 
provided by OpenGL provides a very good looking picture.  However, if 
the Bob would actually take place, I think it might indeed be "optimal" 
as I had originally stated.


-- 
-WD