KnoppMyth on a 320G drive

[Tim Writer]

"D. Hugh Redelmeier" <hugh-pmF8o41NoarQT0dZR+AlfA at public.gmane.org> writes:

> | From: Tim Writer <tim-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org>
> 
> | Cable/connector quality, for example, can make a _big_ difference. I use a
> | regular (NTSC) TV with composite (RCA) input together with a (relatively
> | low end) nVidia card with TV-out. The nVidia card has only S-Video for
> | TV-out but comes with an S-Video to RCA converter. With this connector, my
> | picture was black and white. Replacing the nVidia connector with a high
> | quality S-Video to RCA cable gave me good quality colour (as good as can be
> | expected with NTSC).
> 
> Interesting.
> 
> I don't think that S-Video to RCA can be done with a simple cable.
> The signals on the wires don't match.  From Len's message:
> 
> Composite (RCA): Audio channels seperated, video signal still merged.
> 
> SVideo: Audio channels seperated, video seperated into luminance
> 	(brightness) and the chrominance (colour).  Color components
> 	still merged.
> 
> Any conversion would have to involve a more complicated circuit.
> 
> Can you tell us more about how you do the conversion?

There's not much to tell. Like I said, the converter supplied by nVidia
didn't work. A lot of googling suggested that others were having the same
problem (and not just with MythTV) and time and again the suggestion was to
use a high quality cable. To be honest, I was sceptical because I had
already tested the nVidia connector by feeding S-Video out (without the
nVidia connector) into a device with S-Video input, then feeding the same
output using the nVidia converter into the composite input of the same
device. In both cases, I had colour. The problem occurred only with my TV.
I bought the most expensive S-Video to RCA cable I could find at Future
Shop, not really expecting it to work, and was happily surprised when it
did.

> I have two video cards (in two different computers) hooked up to two
> TVs.  One is an nVidia 5200 and the other is an ATI 9250.  Both have
> S-Video connectors with converters to RCA.  The converters are *not*
> interchangeable.

Interesting.

> Standard S-Video connectors have 4 pins.
> 
> The ATI S-Video jack accepts 3 extra.  I would presume that the
> standard 4 pins carry S-Video and the extra 3 carry composite video.
> 
> The nVidia has the standard 4 pins.  I have no idea how the nVidia
> S-Video to Composite cable works.
> 
> In my unscientific testing, the nVidia's composite output was not so
> hot.

With the the nVidia converter? I assume the card doesn't have separate
composite output.

With the expensive cable, mine is fine, although there's a little
instability around the edges. My TV's fairly old (1995-ish) and I'm not
much of a videophile so I'm not too bothered by it. DVDs look fine.

> I cranked the saturation control down a lot and that improved
> things to the point of being watchable.  I have not done systematic
> testing so this should not be considered definitive.
> 
> On the other hand, TVout from the ATI wasn't a piece of cake.  I
> needed a non-standard patch to the ATI driver.
>   http://megahurts.dk/rune/tv_output.html
> Apparently this is too much of a hack for xorg to adopt.
> --
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-- 
tim writer <tim-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org>                                  starnix inc.
647.722.5301                                      toronto, ontario, canada
http://www.starnix.com              professional linux services & products
--
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