explanation of DVI and how it relates to the parhelia

[Wombat]

The P is good for photo editing because we CAN see the difference between 8- and 10-bits per channel, especially in the green regions of the spectrum.

[simpy2]

I must admit that I cannot check that for myself on my old 8-bit/channel G550

[Wombat]

You don't need to check it that way. Check analysis of the human perception of the color spectrum, and you'll see that our eyes have been shown to have better accuracy in that range than 3x8-bits/channel can display. The running theory is so that our ancestors do a better job of percieving safe/unsafe edible plants.

[Greebe]

No. Dual channel uses twice the pins of single channel (even if there are unconnected ones on each channel).

He didn't explicitly says so, but I guess you're right in saying they must be using unused pins on the single channel -that might be (part of) a reason why there's the banding issue.

R

I was hoping you would come to the same conclusion that Wombat did.

Concerning the banding issue... if that were the case those (people) using DVI-D TFT monitors would see the banding issues which they do not.

Regardless of what pins are being used there is no more crosstalk between them and anyother pin on the connector.

Additionally there is virtually no difference between one connector and any other connector even if it's the 100 millionth one made. So that doesn't jive with say 50%(? unknown #) of users of Parhelia not having this banding issue.

[simpy2]

Thanks for the info, Wombat! I didn't know that.

[Kurt]

Originally posted by Greebe
<snip> Concerning the banding issue... if that were the case those (people) using DVI-D TFT monitors would see the banding issues which they do not.<snip>

Then you're limited to DualHead.

I was thinking there may be some crosstalk (on-chip or somewhere else) that could be eliminated by grounding the transmit wires (I'm getting a bit out of my league here, not being an electrical engineer ). Doing so wouldn't let them use only a single channel I guess (hence my previous post). But then I'm not sure where lies the crux of the problem... (who knows the ones who fixed the P core? )

[rylan]

Yeah, you don't see the banding when running through the tmds transmitter (DVI) because you're staying all digital to the display. The banding is most likely caused by a combination of crosstalk and noise/ripple on the amplifiers in the analog output stage of the board.

[Kurt]

Originally posted by rylan
Yeah, you don't see the banding when running through the tmds transmitter (DVI) because you're staying all digital to the display. The banding is most likely caused by a combination of crosstalk and noise/ripple on the amplifiers in the analog output stage of the board.

where would that happen? on the pcb or on-chip?

[Wombat]

The DACs themselves are on the P core. There's some filtering on the board after that. With TV/Triplehead, the third signal comes from one of the Chrontel chips.

Since the banding only seems to occur with certain chip functions engaged, it points towards a problem with the core, although an external solution may be possible.

The part that doesn't seem to fit is that people report banding in Surround Gaming setups.

[Kurt]

since the AGP 8x part seems to have been canned, I wonder why the ones who fixed the core don't let some info out...

if it really were a pcb problem I believe it would have been fixed, unless they more than really messed up their sales figures (can it be as bad as 6 months overstock?) and they're still sitting on the pcb rev that has the problem...don't think so...

[knirfie]

so does DVI-A have banding or not?

[rylan]

DVI-A is just analog through the dvi connector, since it has some analog pins. So yes, analog output appears to have the problem, while digital does not.
And yes, I would agree that the banding is probably internal to the core of the chip, but its hard to tell since I haven't really looked around at the board closely to see how they do the output state on the pcb. wombat, surround gaming uses analog output so I'd think it should show up there also.

[Greebe]

Where's that slap feature when you need it

[Wombat]

You misread me rylan. What I'm curious about is that the Parhelia has 2 DACs, and a Chrontel chip is used for the third display. From what others tell me, even that third display shows the banding. I'm curious as to how/why.

[Jon P. Inghram]