[mlivesay]

Hi Guys,


I need to pick the brain of someone who owns the LT150 and is using it with a 16:9 screen (maybe one of you luck b-stards who picked it up for $1500 on Dell


Assume the following:


1024x768 Native Projector Res

16:9 screen

480p progessive video source (720x480)

Anamorphic 16:9 DVD Content

Standard lens (no Panny's)


So given the above, what resolution will the LT150 display converting an anamorphic 16:9 source on its 1024x768 4:3 panels?


I did some quick calcs, and assuming the projector would devote the full horizontal resolution of the panel to the image, it would scale the 720x480 source to a 1024x432 area within the panel. This assumes square pixels (which I think is more or less the case)


If this is how it handles things, then how is the 16:9 rectangle oriented within the 4:3 panel? Top or bottom justified, or centered?


Another question: Let's say the projector top justifies a 1024x432 16:9 image. So I set up my screen and projector orientations so that a 16:9 anamorphic source displays properly and fills my screen. Now what happens if I want to view 4:3 material but don't wan't it stretched and scaled to fit the 16:9 screen?


Ideally I'd want to have the 4:3 window centered in my 16:9 screen. But if I display the 4:3 source at the native res of the panels with the same screen/projector setup, then the 4:3 image will fill the width of the screen but about 330 scanlines will fall off the bottom of my 16:9 screen.


So I guess in order to avoid having to remount the projector when switching between 16:9 and 4:3 material, the projector would have to scale any 4:3 material within the 1024x423 16:9 rectangle mentioned above. This means scaling a 720x480 source to a 575x432 window centered in the 16:9 screen. 4:3 material could look pretty crappy unless the internal scaler of the LT150 is decent.


Another stupid question: What happens when you want to view letterboxed material? Can you treat it as 16:9 material and zoom it to fill the height of the screen?


If the LT150's scaler isn't up to handling all this stuff properly, than can something the QuadScan handle all these scaling gyrations?


Anyway, sure would appreciate any insight you can share. If the LT150 can handle a 16:9 setup in a reasonably efficent manner,then its a huge deal at under $2K.


Best,

Mike

 

[lmo]

I don't own an LT150 yet (have one on order), but this has been discussed before.


The projector displays 16:9 in the center. I think you're resolution calculations are off for 16:9 - you get more horizontal resolution than you're calculating.


If you get a Quadscan or other scaler (or HTPC)you can change where on the 4:3 panels the 16:9 image appears.


Finally, the LT150 has a "Native" mode which permits you to see a non-scaled image inside the panels, allowing you to view a 4:3 image inside the 16:9 screen. You don't take advantage of the entire resolution, however, but this might be fine for noncritical 4:3 viewing. (I'm probably going to buy a Quadscan or HTPC, so this can be taken care of by external aspect ratio control.).

 

[JackLT]



720/480 = 1024/x

720x=480*1024

x=682


Seems 720x480 would scale to 1024x682.


Since most films are not scaled at 1.5, rather at 1.78, 1.85 or 2.35 we get...


1.78:

1024/1.78 = 575 1024x575


1.85

1024/1.85 = 553 1024x553


2.35

1024/2.35 = 435 1024x435

 

[mlivesay]

Imo,


Thanks for the info. Yeah, I screwed up on my calculations. Assuming the projector scales to the full native width of its DLP panel, here's my (hopefully correct) formulas:


On a 16:9 display, H = 9/16W = 0.563W


So assuming a 1024 width and square pixels, we get:


H = 1024 * 0.563 = 576


So the res of the 16:9 rectangle within the 1024x768 4:3 DLP panel is 1024x576 (WxH). Using the same assumptions as before, a 4:3 source would then appear as a 768x576 window within the 1024x576 16:9 area.


Any LT150 owners with a 16:9 setup: Does the above seem to match what you see in actual operation?


Thanks again,

Mike

 

[lmo]

Again, not speaking from experience, that matches the resolutions that have been posted for 16:9 HTPC use, so I think that is accurate. Anyone who's tried it? (also, try searching some of the older threads from Grant Smyth, there's lots of info).

 

[TC]

It seems to me it would just be easier to have a 4:3 screen if the projector is native 4:3. I have the Sony 10HT and it is native 16:9, so thats the screen I'm using. If I were to use a 4:3 screen on my Sony then I would get all kinds of light spill on walls and speakers to the left and right sides of the screen.

 

[Frode]

I posted this in another thread, but thought I'd repeat it here. Native mode does _not_ work for 480p. It does work for 480i however. This means that if you're going to view 4:3 sources using 480p via component you'll have to either get a 4:3 screen, or move the projector closer to the screen since there is no zoom on the LT150.


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

/frode

 

[lmo]

Or use an external scaler, of course. I know the Quadscan Elite (@ $1200 street price) has a nice feature which will automatically scale to a 4:3 aspect inside a 16:9 screen for 4:3 projectors using 16:9 screens as a display.

 

[Signal]

Can the Panasonic RP-91 DVD player display 4:3 DVDs within a 16:9 screen at 480p connected to the LT150 via component video?

 

[arrow]

Quote:

Originally posted by Frode: Native mode does _not_ work for 480p. It does work for 480i however. This means that if you're going to view 4:3 sources using 480p via component you'll have to either get a 4:3 screen, or move the projector closer to the screen since there is no zoom on the LT150.

Or get a scaler that can move the image on the DMD.


When I tested native mode on the LT150, I noted that the image was placed at the bottom of the frame. Not good for 16:9 screen owners. ****Note: 8/14 After retesting the LT150, the 4:3 image is placed smack in the middle of the 16:9 screen. The bad news? Native mode is not available when viewing 480P through component*****


Though, as I posted in another thread, if you're using the panny, it seems that your projector will need to be tilted so the bottom of the image is even with the bottom of your screen. So, voila, 4:3 native will work. But, 16:9 non anamorphic material will still require a scalar to be placed properly.


My preference: I much prefer the largest 16:9 screen possible. And here's why: http://www.avsforum.com/ubb/Forum10/HTML/007345.html


--Les





[This message has been edited by arrow (edited 08-14-2001).]

 

[arrow]

Quote:

Originally posted by Signal: Can the Panasonic RP-91 DVD player display 4:3 DVDs within a 16:9 screen at 480p connected to the LT150 via component video?

According to Frode above, the answer would be no. You'll need an external scaler.


--Les

 

[Signal]

I looked at some previous threads and if I understand correctly, the RP-91 has a scaler that can preserve the original aspect ratio on displays that "lock in full" when receiving a progressive signal. The scaler can shrink 4:3 material and place black panels on either side. It can zoom non-anamorphic letterbox material to fill a 16:9 screen.

Unless I'm missing something, the RP-91's scaler should display the correct aspect ratio with the LT150 set to cinema (16:9) aspect ratio.
http://www.avsforum.com/ubb/Forum4/HTML/003361.html
http://www.avsforum.com/ubb/Forum4/HTML/002516.html


If native resolution places the image at the bottom of the 4:3 DMD panel regardless of whether the LT150's aspect ratio is set to normal or cinema, I guess I would still need a scaler for S-Video sources.