[mythtv-users] TV out card suggestions

John Kuhn kuhn at razorsys.com
Fri May 7 13:04:21 EDT 2004

I often wonder why hauuppage (or others) hasnt developed a Video card 
designed specificlly for TV usage.. setopboxes are all to common these 

an ideal card would have some sort of hardware based overscan control 
and superior conversion of the signal.. i cant imagine such a card would 
cost that much to manufacture


Michael T. Dean wrote:

> 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
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