Originally posted by Karnis
Try adjusting with a PC monitor & see what happens, maybe your set is losing sync for one reason or another.
Well, yes, it does look sort of like it is losing sync, but the question is why? As far as I can tell, nothing you do when attached to an RGB monitor via the VGA/DVI port will provide you with any clue as to what will happen using the YPbPr cable.
I forgot to mention, I'm using the Catalyst 3.5 drivers.
One thing I noticed. The first time I hit the horizontal narrow button in PowerStrip, the picture scrambles. But, if I continue to hit it, I see a fairly clean rectangle that gets narrower and narrower as the horizontal porches are increased. The content of this rectangle remains scrambled. If the timings were really getting screwed up, I would expect to either see garbage all over the screen or the TV switch to blue screen.
Here is some further explanation that I posted on the Entech forum. By the way, if anyone has succeeded in mucking with the 1000i/1080i resolutions on the AIW 9700 Pro using the YPbPr cable, I'd like to hear from you.
Let me expand a little on what I think I've learned about this beast. (Note my level of confidence.)
1776x1000i is one of the magic resolutions supported for the HDTV adapter. The magic resolutions 640x480p, 720x480p, 856x480, 1776x1000i or 1920x1080i don't result in a virtual screen. For any other resolution, you get a virtual screen scrolled in a window of the next smaller magic resolution. So, for example, if I tried to add a 1776x1002i resolution, the display would be set to 1776x1000 and the virtual screen could be scrolled up or down by 2 pixels. (There are probably other magic resolutions if you tell the driver your TV supports 720p. Mine doesn't and lying can have disastrous consequences.) I assume this is enforced by the driver, and PowerStrip can't seem to get around it.
If you use one of the 480p resolutions, without PowerStrip, you probably end up with a lot of overscan. But, using PowerStrip and the famed Karnis instructions, you can change the timing for the 480p resolution to 540p timing. This will eliminate vertical overscan. (Actually, it will probably result in vertical underscan.) You can then lock the scan rates and adjust the horizontal front and back porches to eliminate horizontal overscan. Thus, I end up with a complete set of 480p resolutions where I can see the whole desktop.
But, if I try to apply these same principles to the 1000i (and, I think 1080i) resolution, as soon as I touch the porches (or anything else, for that matter) the display is scrambled. I think that others have been able to accomplish this with the "dongles" that ATI sells for some of the other Radeon cards, but I'm not sure of that. (Any confirmations?) The dongles attach to the VGA or DVI port on the card (depending on which card you have). The AIW 9700 Pro comes with a YPbPr cable that plugs into the same video out port as the composite/S-Video cable.
In any case, I think there appears to be something subtly different that PowerStrip needs to do for the AIW 9700 Pro when it tries to change the timings for the 1000i/1080i HDTV resolutions. I'm at a loss to determine what that might be.