Confused about resolutions (567p, 720p) etc

[Dodgeyt]

Hi - I have an Infocus 5700 Projector which has a native resolution of 1024x576. I'm hooking it up to my PC via component (no other choice other than VGA)

I'm getting a touch confused about resolutions. I'm shortly about to start watching 720p content from my PC.

In my nvidia control panel., it knows I'm on component and offers me lots of resolutions. I've tried them all and they all work up to 1080i.

Considering I'm going to be watching 720p material, is my assumption that running the PJ at 720p (supported but clearly I'm a few pixels short) going to be the "best" bet.

I believe 720p is 1280x720 - it looks good enough. My panel is only 1024x576 - maybe I'm better off running at it's pure native resolution? - i.e. 1024x576?

This is where I get confused - I have read that 576p is 720x567 - so what happens with the rest of my pixels (1024 less 720)?

When I select the modes on my PC it doesn't talk about resolutions, merely "modes" - i.e. 675p, 720p etc.

My final assumtion is if I run 720p, the projector will handle the scaling to fit the pictures on the slightly smaller than 720p panel, and the 5700 has a very good scaler.

Am I on the right track?

The most confusing thing to me, is the 5700 is touted as being "native" to DVD - if that was the case, why is the chip not 720x576? (instead of the 1024x576 that it is)

oh - i'd add that in my control panel I have the res set to 1280x720 - confused even more. If i've set this res, why then do i have to select the "format" . i.e. 720p

[pRot3us]

576p will be 1024x576

A 16:9 screen has a ratio of 1.78:1

1280/720=1.78

1024/576=1.78

Selecting 1280x720 or choosing a 720p option on your PC are both the same thing.

I'd be inclined to run it at it's native res but its worth testing 720p as the projector may scale better than your graphics card.

[Dodgeyt]

Ahh = thanks for that. I get it now. The main source of my confusion seems to be that 576p is defined as a 4:3 standard - i.e. 720x576 - my Pj is "widescreen 576p" which , as you know, is 1024x576.

Rather annoyingly, when I tell my Nvidia card to use 576p - it outputs... you guessed it.... 720x576 - rather than 1024x576 - Guess I'll have to research custom resolutions - though saying that it does a fairly good job of scaling 1280x720 - just a hint of pixel smudging when you look at PC text.

[dovercat]

The 576x720 is from PAL DVD which was designed for crt not fixed pixel displays and has a native resolution of 576 lines by 720 samples per line.

With the PC I would use the sources native resolution 720x1280 and let the projector rescale it. Or have the PC rescale the source to the projectors native resolution 576x1024. It depends on which does a better job at scaling.

You may find the follow link informative as you are using a component (analogue) cable to fixed pixel display and trying to get the best resolution. It is for Dila projectors but applies to any fixed pixel display.
You will need to use a 720x1280 or 576x1024 test pattern depending which you have the pc output, a horizontal frequency sweep test pattern might do in a pinch as it will also show if pixel lock is out of phase.
REPOST: Calibrating DILA Tracking/Phase for Pixel Perfection - AVS Forum Archive

[nwgarratt]

720x576 is PAL DVD's. All video are stored on the DVD as 4:3 and the player then turns it into whatever ratio it has to be (16:9, 4:3 etc). Yours is already 16:9/1.78:1 so that is why it is 1024x576.

Everything that goes through the PJ regardless of what resolution it is, ends up as 1024x576.

[Dodgeyt]

Thanks guys - I feel I have a grasp on it all now.

I went back to VGA and selected 1280x1024 as recommended by Infocus and it went super sharp instantly - incomparable with component. Funny - I assumed component would "simplify things"

The scaler must be setup to handle this res well.

Now for the challenge of pixel mapping 1024x576 - search, search , search!

p..s the scaling from 1280x1024 is near perfect - same as 1024x768 - just my test cards show a very slight stretching on the horizontal plane.

[Dodgeyt]

Been playing around testing a 720p movie today and it's left me with one more question....

If I use my VGA input, at 1024x768 - the windows text is crystal clear. And the movie looks great too.

If I use my component input, the windows text looks aweful, but the movie looks exactly as good as the VGA input.

How can that be?

[Barcoing Mad]

VGA from the pc is the way to go - it's what is used to drive the display properly: the fact that your display is a pj as opposed to a panel is irrelevant. Use Powerstrip (software download) and that'll allow you to o/p at the pj's native res. PC's can be pretty good standard def scalers - I used to use DScaler with a video capture card for RGB scart inputs. 'ReClock' will also allow you to properly lock your refresh rate when playing back a DVD.

[binbag]

Originally Posted by Dodgeyt

Been playing around testing a 720p movie today and it's left me with one more question....

If I use my VGA input, at 1024x768 - the windows text is crystal clear. And the movie looks great too.

If I use my component input, the windows text looks aweful, but the movie looks exactly as good as the VGA input.

How can that be?

With component your PJ has 3 colour feeds with the timing (sync) signals mixed in. With VGA its getting RGB colour feeds as well as Horizontal and Vertical sync feeds.

VGA on the 5700 is as good as you'll see on an analogue feed; I actually preferred it to DVI when I had mine.

[Dodgeyt]

Thanks all - very helpfull.