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Experiment with catalyst 3.4 and interlaced output

Discussion in 'Desktop & Laptop Computers Forum' started by SeaneyC, Jun 3, 2003.

  1. SeaneyC

    SeaneyC
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    Please bear with me on this one, i'm a bit of a lurker round here, so excuse and thread posting faux pas. :)

    I've been using my HTPC with a NEC DP-1200E CRT projector for about 8 months now, running at 1024x576P@50hz. It has been driven mainly using a Radeon 9000, AMD XP2200+, 512mb DDR, and a pinnacle Rave PCTV card, running XP, Zoomplayer, WinDVD, and DScaler. Now that the new Catalyst drivers are out, (3.4) and once again offer full interlaced output support (interlaced overlay is fixed) i thought that i would tinker about, as i'm sure most CRT and HTPC owners do!

    This all came from my interest in the HD stuff coming out, just to see how good it really was, and downloaded some of the microsoft trailers onto my other PC. I was instantly impressed with how they looked on a 17" monitor, and would love to try them on the big screen.

    The problem i have is that my projector only supports scan up to 35Khz, which is not enough to run 720P, or 1080P. This is where the new catalyst drivers fuelled my interest, i could change to interlaced overlay, and run my projector at 2048x1152i@50hz, which although not ideal for 1080 line material, would still give me a quick taste of HD home cinema. I realised that changing to interlaced display would make it feel less "filmic", and render small fonts unreadable but was prepared to sacrifice this aspect just to test it out and see what it was like.

    Oddly enough, as i fired up the PC with the new interlaced resolution on it, i had a DVD in the drive, and i decided to give it a quick play in Zoomplayer, just to make sure the overlay was working in interlaced mode. All i can say is WOW! Granted, the overall image was less filmic than usual, but the extra detail gained was truely amazing. I was really impressed with this, and quickly exited DVD mode so i could watch some of the HD clips.

    I was stunned at the clarity of the picture, so much detail, and it just looked awesome. One of my flatmates was making dinner in the kitchen (joined to our front room) and said that the projector was looking "very good today, what had i done to it". (Being 22 and male he didn't actually say very good, but something quite similar) This reassured me that it wasn't just a placebo effect from all the tinkering i had done!

    Having now watched a few DVDs, and some scaled TV, i can safely say that i will definately NOT be going back to 576P for the forseeable future, and will probably only move back to progressive when i upgrade my projector. A huge side benefit i have noticed is that i now experience very little screen "bend" when large areas of white are on the screen. I've tried everything i can to minimise it, but i put it down to the fact that the PSU in my projector is simply underengineered. Nothing has reduced the bend as much as the interlacing has.

    The downsides to this exercise are that my FAF (Flat mate acceptance factor :D ) has gone way down, as they keep complaining that they can't read menus anymore (which you can't, it's near impossible), and that material does look less filmic. I personally don't mind the way it looks right now, and the detail gained certainly outweighs the "filmness" lost IMHO. Although i guess on the upside, the unreadable text will hopefully make them learn to use the pronto to control the PC instead of the mouse. :)

    If you have an HTPC, and a Radeon card, and a device that doesn't seem to support HD, i can thoroughly recommend having a tinker about with interlaced settings. This took a few hours, and this simple feature has put my projector upgrade back a year or more, and i will almost certainly now put the money towards a meaty sub.

    Any comments welcome, i'd like to hear what other people think of this little experiment.
     
  2. Paul Hayward

    Paul Hayward
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    Hi SeaneyC,

    I have a fixed panel 1280x720 DLP projector and currently I am running at 1080i. This actually produces a clearer and more 'filmic' look on my setup using mainly Pal discs with HTPC compared to the 720p alternative. BUT, I have been noticing jumping edges on vertical pans. Have you noticed this on your display? And I'm curious about why you chose the 2048x1152i at 50Hz. Is this more compatible with Pal? I could not get 1080i to work properly at 50Hz. If I could minimise the 'jumpy' pans and keep everything else the same I would be most happy with my picture. I will try your settings later on this week and your observations about the 'jumpy' pans would be most useful.

    Regards,

    Paul H
     
  3. SeaneyC

    SeaneyC
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    Hi Paul, i have very little experience with DLP devices, but from what i have read in the last 6 months, they should all be run from the HTPC at 1:1 pixel mapping, as to avoid the internal scaler. You say that you have been running a HTPC at 720P, but did you manage to get it to successfully map to the panel resolution? Otherwise your projector's internal scaler would still be doing some scaling, somewhat negating some of the benefits of a HTPC. I suspect the jumpy pans you describe could be due to the scaler of the projector not being bypassed.

    How are you driving the panel? DVI? VGA? Component transcoder?

    I chose 2048x1152 because:

    1152 is 2x576 (Native PAL DVD resolution)

    and 2048 is (1152/9)*16

    which gives me correct aspect ratio for the 16:9 screen, whilst using square pixels (not that you can see anything even close to pixels on my projector, which is not the greatest)

    The square pixels thing is not overly important, and i may fool about with 1800, or 2160 pixels wide, but i suspect this will make very little difference as my projector is not able to resolve anywhere near this resolution.

    To be quite honest, i've been pretty lucky with the jumpy pans business, since i got my CRT 8 months ago, i've never really experienced it (except for the time i updated my old soundblaster 5.1 drivers which screwed up XP totally) so i can't really offer much advice on how to cure it. My only suggesting is to try and stay as close to 50Hz as possible if you're doing PAL stuff, i guess we're quite lucky in that all DVDs, and all video/tv material comes in at 50Hz, and not 48hz or 60hz with 3:2 pulldown issues etc etc.
     

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