AW: [mythtv-users] Hardware for Best TV-Out?

Cory Papenfuss papenfuss at
Tue Oct 26 13:02:41 UTC 2004

 	Aside from VSYNC tearing necessitating deinterlacing, the system 
is brain-dead stupid.  There's no scaling, flicker filtering, 
deinterlacing (on the vid card), etc, etc.  The PVR-250 captures 
interlaced MPEG, and sends it out the VGA port interlaced.  When you say, 
"jitter," do you mean flicker?  I've never paid that much attention to 
ticker scrollers, but I'll look.  Keep in mind that there is no way to get 
rid of flicker on a 480i signal without essentially lowpass filtering the 
signal.  480i is 30Hz, so flicker is part of the deal.

 	The settings I use for X are a custom modeline to generate 480i 
timings.  The actual resolution could be lots of things, so long as:
1. There are a total of 525 pixels vertically.
2. The total time to draw a single horizonal scanline is 15.734kHz
3. The signal is interlaced.

 	Other than that, the sky's the limit.  Of course, trying to see 
any more than 480 vertical pixels will be off the screen at the 
top/bottom.  I have made NTSC modelines for 480x480, 640x480, 720x480, and 
1440x480... they're all fine.  Of course things that don't do aspect ratio 
correction look a bit skinny at 1440x480, but that's another issue.


* Cory Papenfuss							*
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University 			*

On Mon, 25 Oct 2004, Joe Votour wrote:

> Cory,
> With such a converter, are you able to pass what I
> call the "CNN test"?  That is, tune to CNN (or some
> other channel with a scrolling ticker), and the ticker
> is completely jitter free (as on a real TV)?
> Also, what kind of settings do you use for X?  Do you
> run at a "standard" mode of 640x480 or 800x600. or do
> you have to run at a different mode that might not
> play nicely with the MythTV GUI (for example on the
> PVR-350 output, which is 720x480, the GUI has to be
> resized, and overscan applied to the OSD, which has
> it's own set of problems).
> -- Joe

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