TV-out - continuous rising horizontal bars

[Crafty35a]

I am using component out to my 1080i HDTV from my X1900XT. On the TV, I see continuous horizontal bars that slowly move up the screen. The bars are just a slightly darker color than the rest of the image, but it is very distracting.

Since I also had this problem with my X850XT, I'm guessing this is an issue with either the refresh rate, or my TV. What refresh rate should I choose for the TV? I have tried 30(interlaced), and 60 with the same results.

Any ideas?

 

[Lord Evermore]

Unless your TV supports higher than 60Hz, you may have to live with it. You are probably seeing the results of the low refresh rate. I see the same thing on my standard definition TV using S-Video. For some reason, using TV-out from the video card makes it visible, but I don't see it at all when watching cable directly or playing DVDs. I know what it is because I had the same problem with my old 14 inch monitor that didn't support anything higher than 70Hz.

The reason the dark bar seems to be moving up I think has something to do with the exact timing that our eyes have, compared to the timing of the refresh. As the screen dims between refreshes, the area that it has managed to refresh within the rate that our eyes can perceive changes slowly. I suppose it might be technically possible to measure each person's eyes to find out the exact rate where the refresh occurs exactly at the rate our eyes can pick up, but it's easier to just ramp up the refresh rates tremendously, so that the amount that it dims is so small we can't perceive it before the next refresh.

 

[LittleNemoNES]

I believe TV out is always vsync'ed @ 59.99999999 so it shoulndn't somehow not be working. Something weird is up.

 

[Crafty35a]

Interesting. I will try some higher refresh rates tonight and see if that makes a difference. The problem occured with my X850XT previously, and with RCA video input as well (Currently using component). The TV is certainly not a very great one, but cable and DVD both work fine with component inputs, so I don't think it is a problem with the TV.

 

[Peter]

Well, the timing for HDTV output is EXACTLY predefined for any given resolution. Trying to change the refresh rate on the host computer will probably do zip.

What you see there is interference, probably with the VGA signal on the other head.

 

[ElFenix]

how is the cable?

 

[Auric]

Could be a ground loop. Discon TV I/O cables starting with cable/sat/ant in to see if it clears.

 

[M0RPH]

I've always had this same thing on my TV-out. I have an ATI X800 connected to RCA on the TV. I always figured it was my cheapo cables (I have the adapter cable that came with video card, then an RCA extension adapter and another RCA cable). But I keep hearing about others getting the same thing, so it may just be a limitation of TV-out on video cards in general. I'm not going to stress it because I plan to get an LCD TV with a DVI connection soon enough.

 

[Raduque]

I've got this also on my home-made svide to composite adapter I built. I think it's computer-specific, because it doesn't happen when using the svid out on my laptop with this adapter and TV. It's either a ground loop, like Auric said, or an impedance mismatch in my case.