[mythtv-users] TV out card suggestions

[Michael T. Dean]

Ben Rometsch wrote:

> I'd also be interested to know what the quality of the image is like 
> when compared to using the direct TV-Out from a standard video card...?

Read this thread 
http://www.gossamer-threads.com/lists/mythtv/users/50643 (updated for 
the new archive--the old link didn't work for it).

Basically, it discusses using a VGA to NTSC/PAL converter and the fact 
that many video cards use a very low quality converter for their 
on-board converter.  That coupled with the fact that the on-board 
converter has to perform other conversions (color, interlacing, timings, 
etc.) tend to cause the display quality to be lower than can be achieved 
by using a "good" converter fed a "proper" TV-like signal (i.e. for 
NTSC, 29.97Hz interlaced signal).  With a proper signal, the converter 
simply does a color conversion (RGB to Y/C NTSC).  However, the VGA 
signal cannot be output to a monitor, but provides very high quality TV 
output.  This would seem to explain why all TV output I've ever seen 
through a VGA to NTSC converter was very low quality--the converter was 
required to do far too many conversions because it wasn't driven with a 
proper signal.

The only thing that wasn't discussed was the definition of a "good" 
converter.

I'm building a converter based on the Analog Digital AD724 chip (which 
is available from http://www.arrow.com/ and http://www.newark.com/ ).  
The design I'm using is the one for the evaluation board ( 
http://www.analog.com/UploadedFiles/Evaluation_Boards/Tools/452661188AD724eb.pdf 
).  If you're not into buiding electronics, you can even buy a completed 
board ( search for AD724EB at http://www.arrow.com/ ).  The only problem 
is that it's about $172US.

Mike