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Discussion Starter · #1 ·
Anyone out there noticing slight single pixel high horizontal noise bands on their IOMagic PC PVR cards? The noise is only apparent in the darkest areas of the image... (and only becomes readily apparent after gamma correcting thru descaler)


Any source fed into the IOmagic's s-jack picks up this noise... have swapped cables & verified the signal is good up till it gets to the card. This stuff doesn't look like typical external interference...


Any experience denoising an IOmagic card would be appreciated...
 

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Hi,


Are you talking about the noise moving up or down on dark area? It's little brighter than background. I saw same noise on RAGE THEATER too. I changed cable, PS, and CPU. I organized power cable inside. However, I'm still able to see it. So, I just gave up.


I also appreciate if somebody has the way to mod to reduce this noise. Thanks.


-- Kazushi
 

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If you are using a progressive display at a resolution not an even multiple of 240 lines (i.e., one frame of the 480i signal), then there is a scaling artifact called "line twitter" that can result when displaying 480i signals. In large areas of the screen of the same color, this is visible as single pixel wide horizontal lines one or two shades lighter or darker than the rest of that same area, moving or jittering up and down one pixel width (it sounds worse than it looks). To determine if this is your problem, temporarily switch to 640X480 resolution and see if the problem disappears. If it goes away, the problem you have is a scaler artifact, and you may want to address it a couple of ways. You could either use 640X480 or 720X480 or 720X720 display resolution (using one of the display memories on your monitor to return whatever mode you define to 4:3 aspect ratio). Your other option is to try another video board - some combinations of video boards and displays are less prone to this artifact than others.


For regular TV viewing, you might also try DScaler software in place of the I/O Magic stuff - but this of course is only for live TV, not PVR functions. My experience is that DScaler has less line twitter than most OEM TV tuner software.


I have a small amount of line twitter remaining when using DScaler in fullscreen and driving my XGA projector at native resolution. I can make it go away by displaying the signal in a 640X480 window on the screen - but I'd rather watch fullscreen TV.


Gary
 

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uncledeathmonkey,


Your problem is probably due to bandwidth issue on your motherboard.


You can try the following to clear up the issue.


1) Decrease your color depth to 16bit

2) Go to your motherboard's BIOS and increase your AGP aperture size to 128.

3) Decrease your Dscaler pixel width.


Hope this helps,


Obsidience
 

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Discussion Starter · #6 ·
Thanks for the responses guys...


Gary:

I am already using descaler 3.0.10A [build 2574]... the noise bands are visible even when running with a native video rez in a window (I'm pretty sure this isn't a scaling issue but thanks again)... oh yeah and none of the IOMagic software has been loaded on my machine.


obsidience:

I have messed with the pixel widths earlier and this seems to effect the noise but does not eliminate it... the agp apeture is already set to 256mb. I will try adjusting the bit depth, but if this eliminates the problem I am gonna be a bit disappointed... although if I understand correctly desktop bit depth does not effect the overlay bit depth..



A little system background... Soy.o Drago.n MoBo 512mb DDR 1.4GHZ TBird (no 4in1 applied - is this necessary under xp?), Radeo.n AIW 32mb DDR (3276 drivers), IOMagic PVR (no drivers), Audig.y (official new xp drivers), running XP pro.
 

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Discussion Starter · #8 ·
aha!

something I have not heard before...


it's a pricey silent fudin aluminum block 320w ps to go with my case...


(my ps looks a lot like the attached image, only with translucent plastic parts - why is there an attached image? well it was there...)
 

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Quote:
only with translucent plastic parts
How big of parts? Not much shielding in plastic. There is quite a bit of rf in switching power supplies. Maybe the ps is a harmonic of the video card and beating together.
 

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Then it probably isn't your problem. Sorry, I thought it might be someones idea to show what's inside the ps. Kind of like those "useers" that want the neon lightes and huge windows in the sides of their pc cases. Or worse yet 'Fruity colors" (as in raspberry and lemon). Yuck!
 

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Are you my Uncle?


to answer one of your questions:


No, you probably do not need 4-in-1's with XP. I use an Epox AMD 760/Via 686B motherboard, and I haven't installed anything for the motherboard, that wasn't included with Windows. I am still mulling over whether or not to install the AGP miniport driver, but everything looks fine right now.


Does your radeon 32mb ddr have a fan installed?
 

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Discussion Starter · #14 ·
I was hoping there was someone else out there running a similar box sans 4in1s. Thats good to hear.


Yes - my radeon does (unfortunately) have a fan. I started out with the ve (multi-headed) radeon - but the board was just plain bad under w2k (ati tech even suggested not using it) so I figured for $30 more why not get an aiw card.


Making the box silent is next on the list..
 

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Only thing I would be able to suggest you try is replacing the fan and heatsink on your radeon with a larger heatsink without a fan.


If you do a search here you could find posts about the subject. Or forums like overclockers.com, rage3d.com, or madonion.com, could have some info. Don't bother getting a new fan. Just try and find a big heatsink.


The fan could have something to do with this, its doubtful, but if you get rid of it your system will be much quieter anyways. I'm not sure but I think your video core is clocked at 183 MHZ or lower, and that is not something to worry about.
 

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Discussion Starter · #16 ·
The radeon's DAC (core) is running at 350mhz...


Ok - here's what the noise looks like...


Attached are sequential Descaler screen grabz [3] from clean digital source via the IOmagic's sjack - left side untouched - right side enhanced to better reveal the noise in question...


(I sure wish we could display attachments as inline images here)
 

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I was referring to the clock speed of the GPU, which isn't the DAC.


A Radeon 64DDR VIVO SE has a clock core speed of 198Mhz. An nVidia based GeForce 3 has a much higher clock rate, as does the new Radeon 8500. Most of the earlier Radeon models have a clock speed of below 183Mhz.
 

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exactly. Just replace it with something that represents an actual heatsink, and you will do better than what is on there from the factory. You could even underclock it if you had to. But if you do some research on this board, and others, you will see that it is not a scary issue. The huge glob of glue was no doubt easy to beat by cleaning it off and using some good quality thermal grease or paste.


I have heard that fans can introduce vibrations into the PCB which I don't know would cause noise or not, maybe just long term problems. But the fans on Radeons are wickedly loud and incredibly innefective. When I dismantled mine, the fins on the fan were plucked right off, and they sort of resembled fingernails. Now, what sort of air flow comes from waving a bunch of finger nails around in the air?:)
 

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Hi,


I got an image of horizontal noise annoying me. It's looks like different from uncledeathmonkey's noise, though.


I attached it to this post. It is taken from DVD player's waiting screen. It is taken from the right bottom area and magnified 6 times. It should be simply dark, but there are several horizontal area little brighter than the back. And these area are moving up or down.


I got this noise although I used most less noise machine (PS fan and coolPC fan only) in my house. So, I just gave up.


-- Kazushi
 
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