HTPC and "scan lines?"

[alphasux]

Pre: After searching through the posts here and google (and reading the stickies here).

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I'm an avid fan of my HTPC but one of my main annoyances are the two thick bars (or lines) that creep up the screen and when they reach the top they start over again. I'd say that if you meter them, there are two of them and they split the screen wherever they are.

They're not as noticeable when you're watching FS movies but since everything is going towards WS, they are REALLY annoying in the black bars above and below.

We call them "scan lines" although I'm not sure if that's the correct term. Does anyone know why this happens and a good solution to resolve it?

I'm right now using SVideo out from my video card which I figure would send a clean digital signal but I was recently told the Svideo is nothing better than a "better" analog signal.

Any thoughts?

-dan the newb.

[ObiKenobi]

Sounds like some sort of interference in the signal causing it. You might try getting better S-video cables to see if that helps at all.

I'm right now using SVideo out from my video card which I figure would send a clean digital signal but I was recently told the Svideo is nothing better than a "better" analog signal.

Composite, S-Video and Component are all analog connections. If you want a digital video signal you need a DVI connection.

[M7S]

When using TV-out from my brother's computer I notice those lines as well. When I still lived at my parents house I used my own computer for TV-out and with that I had no problems with black lines. I blame the graphic card since I'm using nvidia geforce 4 MX and my brother is using ati radeon 9600. We used the same S-video cable and the same TV so that's not the problem. And I was the one recommending ATI to my brother since I tought it would be better for TV-out :o :(

[alphasux]

So the current setup is actually like this

Computer (Geforce 4 MX420) -> Kenwood Receiver -> Television

That's for both video and audio..

I'm going to try tonight to directly hook up to the TV.

Then, next bet is to try a new cable I guess.. Then another video card.

(I've got another GF4-(although a 440) here that I can try)

[mpucoder]

Two things come to mind. Refresh rate and ground loops. The first should be easy enough to play with on the computer.
Ground loops are caused by using different outlets to power the computer and monitor/television. Even different outlets on the same circuit can have a difference in voltage on the ground (caused by current being drawn on the wire). When you connect components together the ground conductor in the cable now bridges these two different voltages. This can result in AC from the mains getting into the signal.
Try powering the computer and television (and anything else in between) from the same outlet. Use power cables if necessary. An alternative is an AC isolation transformer, if that turns out to be the cause.