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This message has been edited since posting. Last time this message was edited on 27. July 2004 @ 09:39

Prisoner, thanks for the link. It referred to this cable:



As you can see, this is only a cable. The price is only $15, which is much cheaper than the two devices that I found (the ones that I mentioned in my last post), but actually, I'm sure this cable is a scam. I'm sure that this cable won't work at all because it's so small and light (only 0.16 pounds) that there can't possibly be any components inside the D-sub plug or anywhere else. But with only wires and no components (no IC's, transistors, etc.), it would be impossible to convert from D-sub to component video.

Look at this website, which lists the pin assignment for each pin of the D-sub connector:

http://entertainment.howstuffworks.com/tv16.htm

Now look at this pin assignment for the S-video cable:

http://www.soundstage.com/video/columns/200009_db_svideo.htm

Now look at this analog waveform for the composite signal:

http://entertainment.howstuffworks.com/tv11.htm

(This is what's going through the middle pin, and the outer electrode is ground.)

Now you can see how the three different connectors (D-sub, S-video, and composite) each have completely different signals going through their pins.

For D-sub, you have the red, green, and blue signals, in addition to the horizontal sync and vertical sync signals.

For S-video, you just have luminance and chrominance. And to convert from RGB to luminance and chrominance, there are three linear equations:

Y = 0.30R + 0.59G + 0.11B
I = 0.60R - 0.28G - 0.32B
Q = 0.21R - 0.52G + 0.31B

So how could a simple cable do this with no circuitry at all?

In addition, for the Composite video connector, in the center pin, there is an analog waveform which is the luminance signal with a superimposed 3.579545 MHz sinewave subcarrier, which is phase-shifted to correspond to the color of the signal.

As you can see, each of these three connectors (D-sub, S-video, and Composite video) have completely different things going through their pins, so it's impossible to convert from one connector to another by just connecting certain pins of one connector to certain pins of the other connector, without any circuitry in between.

The only way you could have a simple cable converter like this would be if you wanted to convert from D-sub to component (Red, Green, and Blue), because D-sub already includes the RGB (actually Y, Pb, and Pr) signals.

Mark

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