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Progressive Scan works with "X" tv how?


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8 replies to this topic

#1 of 9 Matthew Will

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Posted May 04 2003 - 11:47 AM

Alright I am having some difficulty understanding something about progressive scan. Here's an example of what I don't understand.

Say I hook up a DVD player with progressive scan to a Dell 3200MP projector. The projector has compatability with 480p, 480i, 720p and 1080i. So what does the projector project? Does it project in 480p or 720p?

I guess some questions are:
1. Do DVD players only send out progressive signals and then its the display device to bear that signal down into either 480p or 720p?
2. Does the display device do this automatically or can I set it to the signal I want.
3. Is it the DVD player that sends a 480p or 720p signal? In which case can only certain DVD players send in 720p or is there a setting on the DVD player to send a 720p signal?Matt

On a side note, which is better, 720p or 1080i?

#2 of 9 Wes Goff

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Posted May 04 2003 - 12:11 PM

dvd players produce 480 lines. you can set them to 480 progressive on interlaced. your projector will then play 480p. or 480i depending on the dvd players setting. you can get a line doubler and then it would upgrade to a higher resolution, but your projector will only display what it is given from the source. As for 720p or 1080i, well that question will open a huge can of worms and alot of different opions. (the same for fiber optic or dig. coax?)

#3 of 9 Matthew Will

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Posted May 04 2003 - 12:37 PM

Forgive me if I'm not completely understanding this but wouldn't doubling the lines effectively make it 960p? I know 3:2 pulldown deals with how many times certain frames are drawn but it just seems odd that 720 is 1.5, or 3:2 times, to 480. So then does 3:2 pulldown have to do anything about this?
Lol, then I have no clue where 1080 comes from. I am so lost right now. Matt

#4 of 9 Allan Jayne

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Posted May 04 2003 - 01:28 PM

SOme DVD players output 480i only, those that output 480p offer a manual choice between 480p and 480i.

Most display devices that accept 480i, 480p, 720p, etc. will autoselect which kind is coming in and fill the screen with it. Some display devices have more than one set of component video jacks, one set is for some scan rates, the other is for other scan rates.

Doubling 480p to 960p requires a different kind of doubler than doubling 480i to 480p. The latter process when done to the highest quality is referred to as de-interlacing rather than "just" doubling.

The 3-2 pulldown (repeating frames of 24 frame pre second film source) may be present in any of the scan rates 480i, 480p, 720p, and 1080i, and others too. All of the U.S. consumer video scan rates are about 60 frames per second if progressive or fields per second if interlaced so the 3-2 pattern is the same for all. The number of scan lines in each field or frame has nothin to do with 3-2 pulldown. I believe that 1080i was chosen for U.S. ATSC HDTV because it was already in use for Japanese HDTV. THe U.S. and Japanese 1080i video signals are transmitted over the air differnetly (digital vs. analog respectively) but when they get to the TV as component video they are the same (analog).

One thing often seen in poor quality de-interlacing is failure to preserve 3-2 pulldown when present in the interlaced input and instead even and odd fields that don't match get woven together for the progressive frames.

The process of converting the 480 scan lines of 480p to some other number (such as 720 for 720p or 540 for 1080i) is referred to as scaling. Scaling varies in quality from one scaler to another. Display devices that accept several scan rates usually have built in scalers. 480i should be de-interlaced before any (additionally needed) scaling is done. Otherwise it becomes treated as 240p and the quality is lower.

Video hints:
http://members.aol.c...ynejr/video.htm
.

#5 of 9 Dzung Pham

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Posted May 04 2003 - 05:27 PM

Quote:
Say I hook up a DVD player with progressive scan to a Dell 3200MP projector. The projector has compatability with 480p, 480i, 720p and 1080i. So what does the projector project? Does it project in 480p or 720p?

Actually, the answer to this question is none of the above. The Dell 3200, because it has a fixed resolution, will project at 1024x768 progressive no matter what you input into it. The differences that you get between different input formats will be a result of what the projector has to do to the input to transform it to 1024x768. If you input 480i, the projector will have to deinterlace and then scale to 1024x768. If you input 480p, the projector only needs to scale to 1024x768. Which is better? It depends on your dvd player. In most cases, the deinterlacer on your dvd player will probably perform better than the one built into the projector. This article might help explain the issues better. You'll also find a lot of good info on Allan Jayne's site above.

#6 of 9 Matthew Will

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Posted May 04 2003 - 05:43 PM

Are TV's not fixed resolutions as well?

From how I read it this sounds like it could very well be possible to get a picture using a 480p signal than a 1080i or 720p signal. I say this because perhaps 1024X768 is closer in scaling to 480p than it is to 1080i, although I am unsure of that. So if the projector needs to scale less to get to 480p then there is less signal "distortion." The signal is kept more original. Of course I am probably wrong in saying this. I assume the most clean signal would be 1024p or 768p. Either or, I am unsure.

But again, are TV's not fixed resolutions as well? I don't know what to ask or point out to you when I say this but perhaps you know where I'm going? Lol...wow...if you can understand where Im going and then explain it to me then you deserve a medal. Matt

#7 of 9 Dzung Pham

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Posted May 05 2003 - 03:41 AM

CRTs are not fixed resolution displays. For example, computer monitors that are not LCD panels, can display just about any resolution, even interlaced resolutions, without scaling the input. I believe some CRT-based HDTVs might scale to particular resolutions to avoid scanlines and optimize viewing but the tube itsef is not fixed resolution. Fixed resolution displays typically refer to LCD, plasma, DLP, or LCOS.

Ideally for the Dell, you would probably want to feed it a 1024x768p input and bypass the onboard scaler, which is not currently possible with any mainstream dvd player alone. You can generate such an input if you used an external video scaler or a home theater computer (HTPC). Another option is to get the Bravo D1 dvd player, which will allow you to input 720p through DVI. This should provide very nice results at a cheap price. There are many different possibilities though, and you will probably have to do some testing to see what will give you the result that you're happy with it.

#8 of 9 Matthew Will

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Posted May 05 2003 - 05:32 AM

Would the Bravo D1 really be the optimum player for the Dell 3200MP?

On V Inc's website it has the following notes about the D1 -
Analog YPbPr video and digital DVI (Progressive or Interlaced) scalable up to 1920x1080i or 1280 x 720p resolutions**

Then is notes that-

** Copy-protected DVD playback limited to 480i, 576i or 480p on YPbPr

So does this mean DVD's that I buy will only play back as 480p? Matt

P.S. - I was very surprised to see a retail price of 199 on the D1.

#9 of 9 Dzung Pham

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Posted May 05 2003 - 05:53 AM

I can't say what would be optimal but there is a lot of talk about this player on the AVScience dvd hardware forum. It won't scale to higher resolutions on YPbPr (component outputs) but it will on DVI, which is what you would want to use on your projector anyway.