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I'm looking at putting in a D-ILA projector, and am considering the screen type to use. I anticipate using this with an HTPC to view (in descending order of frequency):
  1. Widescreen DVD's (1.78 or wider)
  2. 4:3 DVD's (kids shows, etc)
  3. Regular TV (4:3)
  4. HDTV
  5. Computer games[/list=a]


    I suspect over time HDTV will move up this list, but as you can see 4:3 ratio material still makes up a fair amount of viewing. I would guess potentially 25% of viewing would be 4:3, at least for now.


    Due to the room configuration, and the fact that the bulk of viewing will be at a 16:9 ratio or wider, I'm going to go with a 16:9 screen. I can't afford a Panamorph / ISCO lens immediately to optimize the 4:3 D-ILA to the 16:9 screen, but may get one some day. This means for 16:9 material I'll only be using 768 lines of vertical resolution (right?).


    For the 4:3 material, I assume I should shrink (zoom out?) the image to fit the 4:3 rectangle horozontally in the center of the 16:9 screen, to use the full resolution. I believe my throw distance will allow this. I now have two questions:
    • Can these two zoom levels easily/automatically be alternated between with something like DILARD so I don't have to manually adjust the zoom each time I alternate between 4:3 and 16:9 material? I don't mind doing scripting on a computer.
    • I'm considering a Stewart Vertical ElectriScreen ElectriMask (I need a drop down screen, again due to room configuration) to be able to have the screen itself alternate aspect ratios. Is this overkill, since at the 4:3 ratio the projector wouldn't be illuminating the masked portions of the screen anyway, right?[/list=a]


      Finally, I guess a general question is will this kind of alternating work, and does anyone else do this sort of thing? Thanks for any tips!


      ------------------

      - Dan Butterfield


      [This message has been edited by danjb (edited 06-24-2001).]


      [This message has been edited by danjb (edited 06-24-2001).]
 

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I have kindof the same question. Barring the ability to zoom in/out for 4:3 material, can I show 4:3 material in just the upper/middle 1024x768 pixels?


I know, seems like major a waste of pixels but I'm still trying to figure out my optimum HTPC, kid friendly, WAF configuration.


Thanks.


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Tom L.
my-wannabe-home-theater
 

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Hi Dan,


Good question. It really comes down to this choice:


"To Zoom or Not To Zoom"


on 4:3 material. The answer isn't as straight-forward as it would first appear!


The first thing to consider is if the question even applies. It's a fairly tight tolerance in the throw distance to allow you to zoom the 4:3 image into the center of the 16:9 screen (with bars on the left and right), so the first thing is to determine if you can pull it off. The Projection Throw Calculator can help you figure this out.


If your room will allow such a throw, and you have a computer connected to the projector, Dilard can help with the zoom. There is a Directive called "Zoom To...", which allows you to specify the amount of zoom to go to (from 1 to 10,000). There is no easy way to figure out the "zoom number" except through trial and error. You will probably want one for 4:3 and another for 16:9 material.


After you have the "Zoom To..." Directives set, you will be able to push a button to go to either zoom pre-set.


So you know what is happening, Dilard is doing all of the work here, and the projector does not have "zoom presets". Dilard gets the zoom to a known state (full tele), and then boosts it's priority thread, starts a multimedia (high resolution) timer and begins the zoom. When 1 to 10,000 milliseconds have elapsed, Dilard stops the zoom at the specified position.


Your second option is to go with a "non-zoom" system where 4:3 is centered (horizontally) in the middle of the 16:9 screen. This is what I use.


Since my 4:3 sources are lower quality than my 16:9 sources, they are given fewer (not more) pixels to display the picture. I also don't give the extra brightness present to the lower-quality 4:3 material because the 16:9 material begins to get jealous.


Anyway, you can pillar-box 4:3 material on a 16:9 by modifying the 4:3 image memories (with the Dilard Image Geometry Wizard) so that instead of using the full D-ILA panel, they use the top-center 1024x768 pixels.


In other words, they use the 768 vertical pixels from the normal 16:9 picture in a 4:3 format, which makes 1024x768. Yes, there is a fair amount of waste there (basically turning the SXGA projector in XGA for 4:3 material), but I like this system for it's simplicity and convenience.


Adding a Panamorph or an Isco changes all of these choices, of course.


Mark
 

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I do the same as Mark, centering the 1024x768 4x3 inside the 16x9 screen. I do this with the Stewart Electrimask, with panels that come down on the sides for 4x3.


- Dave
 

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Another newbie question about aspect ratios. I want to do the same, use a 16x9 screen, but I have just received a JVC G15 and a CI scaler. My sources will initially be HDTV satellite and DVD. For non-HTDV TV, can I use 1024 x 768 in the center of the screen without zooming, or do I need to zoom if I change from a 16 x 9 source to a 4 x 3 source. Is this done in the CI or in the G15?


An HTPC is in my future, but I'll probably still use the CI for non-DVD sources.


Thanks,


Jim


[This message has been edited by jperry (edited 09-24-2001).]
 
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