[mythtv-users] Re: TV-Out: AITech Scan Converter vs CX2587x

[martin]

On Thursday 11 September 2003 ph:34, Fred wrote:
> I just tried out a GeForce3 with the Conexant CX25871 Rev 1 (1:8A)
> connected to my high quality standard definition television (32" Sony
> WEGA XBR) using the S-Video connector.
>
> I'm not happy.
>
> I spent hours adjusting the overscan using nvtv (I now fully appreciate
> why it's labeled "alpha" software).  I got the screen image to just
> barely exceed the television borders (which is what I want).  That
> part's okay except for the upper left hand corner.  For some reason the
> top left scan line bends downward to the left so the top scan line in
> the upper left hand corner is always dark.  The other three corners are
> fine.  I tried nudging the overscan to move the corner up a tad but the
> overscan modes go in discrete steps and the next one up is more than I
> want.
>
> The second problem is two broad arcs of color.  When I'm looking at a
> white image, I see what looks like a pink circle about the diameter of
> my screen, without the top and bottom arcs.  The arcs are about an inch
> thick.
>
> The problems are subtle enough (and NTSC televisions bad enough) that
> I'm not surprised the Conexant chip is sold as a reasonable TV-out
> solution.  It's just not up to the requirements of my intended
> application, which is the sole video source for my TV.
>
> The TVTool people compared Philips, Chrontel, Conexant, and Brooktree TV
> encoder chips [1] and rated the CX25871 as the best.  For this reason
> I'm giving up on encoder chips and will look next at scan converters.
> I'm apprehensive about losing interlaced capability but the
> (proprietary) nVidia driver's messages made me think it doesn't allow
> interlaced output either.
>
> Fred
>
> [1] http://tvtool.info/english/tvchips_e.htm

Lots of cheap scan converters are only 16 bit color and will show banding, 
bleeding colors and very unreadable text, the good scan converters are 24 bit 
color and have a proper overscan mode that you can turn on and it will fill 
the screen no problem, you will also be able to read the text in the console.

Look for Scan-do and Extron, they very good I think the Scan-do has a better 
picture than my Extron though.

Good scan converters cost over a thousand dollars but you can get older models 
on ebay cheap, I picked up a Scan-do 1024 for $36 on ebay, but watch out, 
lots don't come with power supplies when you see them for cheap, the Scan-do 
can be hooked up to your computer power supply because it is +5 volts.

Martin