Problem with video ratio

[federico]

Hi All,
I have a question regarding a video I’m using for a permanent public Art piece I’m installing in the School of Architecture at the University of New Mexico, in Albuquerque
For this project I’m using a Sanyo PLC-XF1000 projector, XGA (1024 x 768). The video source comes from a Oppo BDP-93 Blu-Ray DVD player that connects to the projector via a DVI cable. When we tried the projectors on the site we end having a much smaller projection that we needed, 21 feet high instead of the 30 feet high we need. If we change the resolution on the DVD player, we could get the 30 feet high image but the image was vertically stretched.
We transcode the Blu-ray dvd at 1920x1080 (H.264). when we had the resolution on the DVD player at 720p or “source direct” the image was fine but too small, when we put it at 480/576p it was the right height but distorted. When we changed the resolution on the projector itself we couldn’t get a taller image.
I’m always confused when it comes to aspect ratio on video, mostly when my final format is a DVD. Could someone tell me at what size I should transcode my DVD to get an undistorted large image based on the setting I have?
The problem is that the projector is in Albuquerque and I’m based in New York, so I can’t test the system prior going back to the site, and once there I won’t be able to make another Blu-Ray dvd disk. If needed I’ll take few copies of the Blu-ray DVD disk in different aspect ratio…just in case.
I’m attaching few images for reference.
You can check the project at
http://www.federicomuelas.com/blue_flower/
Thanks!!!
Federico

[DB83]

I'll start this one off in the hope that others with more knowledge of how projectors work will follow.

The projector appears to send out an anamorphic image. That is to say it squuezes the horizontal in proportion to the vertical according to the source.

Your maximum height is 768 but you are trying to fit 1020 pixels in to that. The width of 1920 is not in proportion to the maximum width of 1024 pixels.

So you must look for a setting on the projector that provides for a 'letter-boxing'. The height of the image is then adjusted in proportion much like a 16:9 dvd and you end up with black bars top and bottom.

[federico]

mmmh,
That may be the problem.
what a pity i don't have here neither the projector nor the DVD player to give it a try. so do you think i don't need to transcode the dvd or render the original video file in a different format?
thanks DB83!

[DB83]

I, nor I doubt anyone else, would dream of answering that without knowing the ORIGINAL source.

[4candles]

Your description makes it sound like the projector is a 4:3 device - when displaying your video with the correct aspect ratio, the image is letterboxed, meaning you only get 21 feet of height. I'm assuming your source video is 16:9.

Checking the specs of your projector, it does indeed appear to be 4:3.

To fill the full frame of the projector, you need to convert your source to 4:3 by cropping it when you re-encode.

[DB83]

Your description makes it sound like the projector is a 4:3 device - when displaying your video with the correct aspect ratio, the image is letterboxed, meaning you only get 21 feet of height. I'm assuming your source video is 16:9.

Checking the specs of your projector, it does indeed appear to be 4:3.

To fill the full frame of the projector, you need to convert your source to 4:3 by cropping it when you re-encode.

Absolute nonsense.

The specs clearly state that it will accept a 1080p source. That is backed up with the images posted. A projector does not alter the source. It merely PROJECTS what it receives.

The issue is with the player. It may already output correctly and the OP is confused. A 1920*1080 can never fill a 1024*768 without either cropping the horizontal or letter-boxing. The latter is the job of the player.

To such to re-encode to 4:3 will only do what the player should do in the first place - letter-box. A more correct term is 4:3 letter-box which is what any player should be able to output when it has a 16:9 (or equivalent) source to be displayed as 4:3.

You can author a dvd to display like that. I do not know about HD.

[4candles]

Absolute nonsense.

I'm not sure what you think is nonsense - is it the whole of my post (you quoted my whole post) or just some of it?