CurtPalme.com Home Theater Forum

[gnnash]

I have a Runco DTV-1100 (Barco Data 1209s) which exhibits raster foldover when displaying 1080p. I bought a Lumagen HDQ in hopes of fixing this with custom timings, but I've unfortunately found that I need at least 2400 total horizontal pixels in order to fully display 1080p and keep the wraparound in the porches. When I do this on the Lumagen, it automatically reduces the vertical rate below my desired 59.94 Hz - I'm guessing there's some sort of a pixel clock limit. Anything above about 2300 total pixels causes a drop in vertical rate.

So, I have a dilemma. I want to keep 59.94 Hz, for obvious reasons. I tried 48 Hz, the flicker during bright scenes is unbearable. I'm actually surprised that 60 Hz doesn't bother me, it sure did back in the direct-view CRT days. So I think I need to downscale.

Does anyone run with non square pixels? If I reduced to about 1720 active horizontal pixels, I could blank out the foldover. Will the scaling effects of this be horrible? I might run out of width if I do this though.

Otherwise, I'm thinking of scaling to 960p, with square pixels. That should reduce my scanrate to a point where foldover isn't a problem. It seems to pop up past about 65 or 66 kHz scan rate. I tried 900p yesterday, since it would allow me to run at 72 Hz, but the high scanrate (about 68 kHz) caused some uncorrectable misconvergence on the left, and foldover on the right. I could eliminate the foldover with phase adjustments, but the misconvergence on the left was then too bad.

So I'm thinking 960p at 60 Hz may be my best bet. I watch a lot of laserdiscs too, so 960 is a nice number for those (although zooming widescreen laserdiscs will negate the simple quadrupling to 960).

Any suggestions? I wish there was just a simple fix to allow me to run the timings I need, but there just doesn't seem to be any.

[Nashou66]

Wait, are most of your movies 1.78 format or 2.4? if 2.4 then just use 800p@72 you will need the 24xx for the 1920. use that for BD and 960 for LD try the 960 at 72 as well I think it might work, i forgot its been a long time since i used that res on an HDQ.

I never noticed the droped rate on my HDQ.

Athanasios

[gnnash]

960 at 72Hz is definitely a no-go, at least for a 16:9 aspect. 900 at 72Hz already introduces the wraparound, it seems to be horizontal scanrate related. So if I went for 960, I'd have to go down to 60 Hz.

There is a definite bug in the HDQ software. I can make full 1080p work at 2400 with just a bit of the misconvergence on the left side, and 2450 with no issues at all. But... the HDQ is limiting vertical rate, despite showing 59.94 in the timings window! The projector shows 55 Hz as its inputted rate, despite the lumagen showing 59.94.

I can get around this by manually setting the pixel clock, but the pixel clock setting never restores properly when recalling the output mode, or cycling power on the HDQ. Once again, after switching to that mode, it displays the pixel clock that I selected, but outputs at a lower rate! There seems to be some limiting going on, but frustratingly, I can't pinpoint what the limit is, because the GUI won't display what it is truly outputting.

I sent Lumagen support an email about this yesterday morning, but haven't heard back yet.

[Nashou66]

It is an older unit and probably wont do anything. I have to play with this on my test Projector. Are you sure there is not a setting in the Barco like the marquee has for short or long retrace? I am not a barco guy so not sure if that might be it as well.

Athanasios

[gnnash]

The Barco Graphics 1209s has a low and high scanning mode, with its own discrete hardware for each, but unfortunately my projector is a clone of a Barco Data 1209s, which has only the low scanning mode, and a horizontal scan rate limit of 69 kHz. It seems to be that as I approach that limit, above 65 kHz or so, the issue occurs.

I guess my other option is to stay at 1080p and blank about 5% of the image on each side, to eliminate the visibility of the issues...

It would be interesting if you could test it out, 1080p with a total horizontal pixel count of 2450, seeing what happens to the actual vertical rate seen by the projector.

[stridsvognen]

I think you will get the best result if you go down to a resolution that you can display without problems.. I seen a Barco 808S with 1280x960P 60hz, that looked like it was ok.

[gjaky]

[gnnash]

Maybe I'm simply not being complicated enough hehe. Let me try a different approach:

How is this for a plan?

2.35:1 movies: 1920 x 817p, 72 Hz. This gives about 62 kHz scan rate, should be just fine.

1.85:1 movies: 1920 x 1038p, 60 Hz. About 65 kHz, but I should have some headroom for larger porches to eliminate my issues.

16:9 content: 1776 x 999p, 60 Hz. About 63 kHz. A slight downscale, but shouldn't be a huge detriment for what will largely be Blu-Ray menus, setup menus, and the occasional TV show.

4:3 Laserdisc movies (I have very few of these): 1280 x 960p, 60 Hz. A nice even quadrupling.

[Nashou66]

Id go 800p so its 2.4 aspect as most movies are that now and it is a nice easy number for the HDQ to scale.



Athanasios

[gnnash]

[gnnash]

Well, I setup all three resolutions, and watched a movie in 800p, and it looked great!

I may have to find another resolution for the 16:9 stuff though... my projector uses the same memory for it and the 1.85:1 resolution, so the size and phase are off on one or the other.

I fixed this by using a second memory bank for the 16:9 resolution, but it's (an admittedly small) pain to have to switch memories on both the projector and the scaler. Another thing that a universal remote would fix I suppose.

If I had to do it all over again, knowing what I know now, I would have made a 1.85:1 screen, and let the Lumagen downscale 16:9 content slightly at that resolution with bars on the side. I do have a lot of 1.85 movies kicking around, especially in my Laserdiscs.