The Interlace/scanlines Issue.

[Radek]

the lcd tweaker helps for me, however it won't erase all of the scanlines, I guess that the tweaker needs a bit more tuning...

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Correct me if I'm wrong but the LCD tweaker is meant to fix the flickering issue. This isn't the same thing as the scanline problem. We need to keep these problems seperate. I don't think they are even related.

I'm quite sure that they ARE related. I don't have flickering to start with, I only have scanlines, however with the LCD Tweaker I also get flickering if the timing is wrong! But on the best Setting I found out for now, I get really small scanlines without any flickering and they are only visible at a certain angle...

I don't think scanlines are a problem of the screen, since scanlines shouldn't appear on any LCD screen in the first place...

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Yes! The lcd matrix is itself free of any "scanlines". This what we are talking about is certainly a refresh issue. I think it's due using interlacing (not updating the whole screen at one but with two passes - one for odd lines, second for even) as those artifacts aren't unsimiliar for such case.

At what rate gp2x's lcd runs? 60Hz? If so with interlacing only half of lines (odd or even) are displayed so whole screen is refreshed only at 30Hz! So it will flicker and some objects (especially the moving ones) will show that "scanline" distortion.

MMSP2 chipset supports the progressive refresh modes so it should not use interlacing for lcd. It looks like another "dumb" mistake in the firmware.

 

[Eolair]

I'm quite sure that they ARE related. I don't have flickering to start with, I only have scanlines, however with the LCD Tweaker I also get flickering if the timing is wrong! But on the best Setting I found out for now, I get really small scanlines without any flickering and they are only visible at a certain angle...

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I'm still not sure they are related. Yes, the flickering is timing related. That can be fixed by changing the timing values. But if the scanlines are caused by interlacing then two update passes are used to refresh the whole screen. Changing the LCD timing won't change the fact that the screen is updated with two passes, right? So it will still be interlaced.

You may decrease the visibility of the scanlines by changing the contrast/brightness of the screen, but the scanlines will still be there (even if you can't see them clearly).

Btw, what setting do you use to decrease the scanlines? If you're using "-" values for the timing prescaler then you'll get a brighter screen and the visibility of the scanlines will decrease.

Yes! The lcd matrix is itself free of any "scanlines". This what we are talking about is certainly a refresh issue. I think it's due using interlacing (not updating the whole screen at one but with two passes - one for odd lines, second for even) as those artifacts aren't unsimiliar for such case.

At what rate gp2x's lcd runs? 60Hz? If so with interlacing only half of lines (odd or even) are displayed so whole screen is refreshed only at 30Hz! So it will flicker and some objects (especially the moving ones) will show that "scanline" distortion.

MMSP2 chipset supports the progressive refresh modes so it should not use interlacing for lcd. It looks like another "dumb" mistake in the firmware.

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Yeah, I think it's unlikely that the LCD itself is the problem. The scanlines looks to be a refreshing issue.

But, that doesn't mean that it can't be hardware related though, does it? There are other things like the LCD driver chip that can affect the output quality of the screen. And just because the hardware supports something doesn't mean it can handle it in conjunction every other hardware that you throw at it. Components that work fine alone may work piss poor together. Even if they individually have the specified requirements/performance.

I really hope it's a software issue though. I hope all this is just caused by GPH being unskilled at making software rather than hardware. There certainly seems to be lots of proof in that direction...

 

[Aninhumer]

I think these problems are a bit hit & miss, no one seems to have the same problem.

I noticed scanlines on my unit but they seemed to oscillate, sometimes they are obvious then seconds later they are just not there. This is most noticeable on the logo screen (I think this is due to the actual image rather than the software)

Intrestingly when I was looking at the Test picture on my dad's LCD monitor it looked terrible! I had to look away after a few seconds :blink: , but on the gp2x it was fine (image viewer not LCD tweaker) there were hardly any scanlines.

I'm still waiting for a reply from gp2x.co.uk about replacing (or re-flashing) my unit, I corrupted it in 24 hours

 

[deadlychicken22]

so what everyone is trying to say is that the screen isnt that good really and we are stuck with these problems.

Get over it...no firmware is going to solve it, the only thing that would solve it is better screens but it looks like weve been lumped with the cheapest carp they could find.

Its not the end of the world but sometimes the scanlines on mine seem really bad but i can live with it.

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did you actually read this thread? It sounds to me like you're pissed because you decided to sell your gp2x and now you find out that the problems that you thought were hardware related were actually software related.

 

[Jarska333]

Cheapest carp? The GP32 BLU+ has the same LCD, and it's damn good. Either it's a hardware fault in some LCD-controller or something, or soft/firmware.

I hope the latter, but if it is the former, I'll simply opt for refund. A new unit, to be precice.

 

[TomVS]

Got an answer from evildragon about the scanline issue.

I must say this man truly offers excellent service. Not even my gp2x was here in 2 days, he also takes time to answer mails in detail.

So if you look for a place to buy a gp2x HIGHLY RECOMMENDED...

Anyway here is a piece of his mail to me.
(I hope you don´t mind that I share this information Evildragon !?!?)


Q : I have ONE BIG problem with my gp2x. The SCANLINES are really horrible. I am a gp32 owner and browse the gp32x-forum daily so I knew about it but, and here comes my question : Is this really a SOFTWARE (firmware) related problem ? If yes no problem I will patiently wait for the next firmware. If not, I find it a serious problem.


A : Well, no one can REALLY know for sure, but as the scanlines CAN be affected
using software (as it's a timing issue), it should definately be possible.
Also, the LCD is the same one used in the GP32 BLU+, and there are no scanlines
there, so....

Q: I tried the software solution... cpu/screen-tweaker but I do not seem to find a good solution. I browsed the gp32x forum for settings but did not find an acceptable setting.


A: Well, usually, it gets better when you use UPLL.
First, toggle the LCD Clock using B (should show UPLL on the bottom instead
of FPLL)
Change the values with Vol+ and Vol-, I usually find it gets better with lower
UPLL values (-3 worked fine for me).

 

[Eolair]

Yes, EvilDragon is a great chap!

As for using the LCD tweaker I think I'll quote myself:

Lowering UPLL to -2/-3 or FPLL to -12/-14 is only hiding the interlace problem by increasing the brightness of the screen.  You'll get too much brightness, low contrast and the real problem is still there. Even if you can't see it.

See my post here for an explanation.

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I wish GPH had at least one brain cell to spare on this problem. As it is I think we'll just have to be more paitent. Hopefully our excellent devs can find an answer once HH is closer to being usable.

 

[Jarska333]

Control for brightness would be nice...

 

[Eolair]

Yeah, I think a brightness control would work just as well as changing the FPLL/UPLL values. Anyone feel like coding us one?