could anyone record...

[VJ]

a small movie showing the banding-issue on a Parhelia ?

I know it is not possible to take screenshots or whatever, but there must be people out here that have a video-camera ?

For my upgrade, I really don't know which card to choose, judging by the features, the Parhelia still seems the card for me. However, I'd like to be able to see just what this banding issue is...

It still is unclear to me when it shows up; I know it is in 3D modes, but does it also occur lower resolutions ?

Jörg

[Wombat]

No, I don't think a movie of it could be recorded. With the beat frequencies of the monitor refresh vs. the camcorder capture, you wouldn't distinguish the banding from the recording effect.

[VJ]

Ok, thanks.... I was afraid something like that might be the case... (no-one has a highspeed camera ? )

Does it always occur, or just in certain resolutions/refresh rates ? Or only in some games ? Does every Parhelia suffer from it ?


Jörg

[DGhost]

Not every parhelia suffers from it. The higher the refresh rate (at least when forcing VSync), worse it gets. and if your Parhelia is affected, it pretty much happens in all games, and in some apps that use video overlays...

[VJ]

The cards that suffer from the banding, do they have refresh rates at which it doesn't occur (e.g. 85Hz or lower) ?

Does the resolution come into play (e.g. no banding at 640x480@100Hz, but banding at 1280x1024@100Hz) ?


Jörg

[Silak]

Originally posted by Wombat
No, I don't think a movie of it could be recorded. With the beat frequencies of the monitor refresh vs. the camcorder capture, you wouldn't distinguish the banding from the recording effect.

It could be, it's not too hard to sync your screen refresh-rate and the camera shutterspeed to make a nonbeating picture.

Ofcourse your camera has to support manual shutterspeed selection...

[Wombat]

Manual shutterspeed selection, not to mention trying to synch it with the screen refresh, and a ton of other things. Trust me, I've thought about it. I think one of the reasons Matrox is telling us to go **** ourselves is that they know how difficult it would be to collect evidence for an article or something.

[Admiral]

Can it be done by multiple screen captures saved (merged) as a multipage image (animated) ?

[VJ]

I doubt it: based on what I have read (collected) so far, it does not occur on the DVI-D interface. This means the problem must be in the RAMDACs. Grabbing a screenshot does not require the RAMDACs, so the problem won't be visible.
Besides: how would you time *when* to save it ?

Due to the nature of the problem, I think either a highspeed camera might work (but finding someone who has one + a Parhelia seems difficult), or perhaps a simple recording, but then edited frame per frame (as a real-time recording will have too much interference (different refreshrates et al).

Perhaps someone could simply make an animation (flash or animated gif) that shows just what the banding issue is. It is quite hard to understand for us not (yet ?) -Parhelia users...

Jörg

[Admiral]

Not owning one, my guess would be that it's pretty much like running in 60Hz (better or worst).

[Pace]

Is it possible for the Parhelia to drive one screen via DVI-D, and another "cloned" via analogue?

And so, anyone have a spare RAMDAC? (we're getting silly now)...I was thinking, we could set up some electronic equipment to compare a banded analogue output against the digital output.

[VJ]

I was thinking more along the lines of the interference you get (got ?) when you put 2 monitors next to each other: one had a horizontal line band going up, the other had an horizontal band going down...

However, I also though it could be like I have seen in some games, where a portion is not rendered correctly, and simply alternates between "rendered" and "solid black".

Could anyone with a Parhelia please enlighten us ?


Jörg

[Maggi]

Hi Guys,

I tried to simulate a screenshot (scaled it down from 3200x1200 in order to match the max filesize limit for attachments in this forum software), but be aware that the amount, position and movement of those bandings is not static, ie. it really depends on the actual situation and combination of circumstances, how noticable or strong the bandings occur on other systems.

Also note that I exaggarated the strength of banding, for making it more obvious and easier to spot for the non-trained eye.

Basically you can say that the banding manifests itself as wandering (moving, jumping, flickering) horizontal soft shadows, overlaying your whole desktop, stretched over both of my screens in either stretched or independant DH mode (couldn't be bothered to verify if it also occurs in clone mode or in TH setup, but in SH it's definately also there).

I hope this helps to clarify the situation a little and stops all misinforming rumours and guesses.

[edit]
just fixed a few typos
[/edit]

[VJ]

Great ! (well, euhm, not "great great" , but now I know what the problem looks like !). Thanks !!!

Could you comment on my earlier question wrt. the refreshrates and the resolutions ?


Jörg

[Maggi]

Originally posted by VJ
Could you comment on my earlier question wrt. the refreshrates and the resolutions ?


Jörg

I didn't really notice a connection between those factors yet, but I'm not exactly keen to do so either, because it would be quite a hassle to crosscheck between various resolutions, refresh rates and other DT settings, like GigaColor, 32bpp, 16bpp, SH, DH stretched/cloned/independant etc.

Maybe somebody else willing to do that ?