1080i vs. 720P - AVS Forum
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post #1 of 91 Old 11-05-2007, 06:28 PM - Thread Starter
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Which is better? Sending 1080i to a 1080P projector and having the projector just deinterlace the signal, and letting the xbox do the 720p to 1080i scaling, or sending the 720P to the projector and letting it scale to 1080P?

If it matters the projector is a Panasonic ae2000
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post #2 of 91 Old 11-05-2007, 06:42 PM
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That's a tough question that could be argued in either direction. Probably best you try both and then decide based on what your eyes tell you.

I'd go for 720p from the xbox scaled to 1080p by your projector. Why? Because you have a choice as to whether you de-interlace or not. However, you have no choice about scaling. You only get to choose where the scaling is done.
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post #3 of 91 Old 11-06-2007, 05:52 AM
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Unless you know a game is 1080p native, it makes a whole lot more sense to send it a 720p signal. If you scale to 1080i, you're essentially losing the 60 frames per second (if the game supports that.)

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post #4 of 91 Old 11-06-2007, 07:09 AM
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Why not try both and see which looks better?
It doesn't cost anything to experiment with settings. :-)
Or, you could try going with 1080p; your projector supports them and so does the 360.
Depending on your XBOX, you can go with HDMI, component, or VGA; all should work.
See which one looks better in your setup.

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post #5 of 91 Old 11-06-2007, 08:21 AM
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Better to send it 720p, if it won't accept 1080p over component.
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post #6 of 91 Old 11-06-2007, 08:34 AM
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Quote:
Originally Posted by NoThru22 View Post

Unless you know a game is 1080p native, it makes a whole lot more sense to send it a 720p signal.

Not just 1080p native. In any game that renders at anything over 720p but with no more than 30fps, 1080i is the obvious choice as it avoids unnecessary downscaling.
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post #7 of 91 Old 11-06-2007, 08:37 AM - Thread Starter
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Quote:
Originally Posted by chrisherbert View Post

Better to send it 720p, if it won't accept 1080p over component.

Even for games?
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post #8 of 91 Old 11-06-2007, 08:39 AM
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720p all the way I will keep it simple on how I explain it to people.

1080i=540 lines of resolution
720p=720 lines of resolution

More lines of resolution=better picture.

The choice is yours.
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post #9 of 91 Old 11-06-2007, 08:43 AM
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Nonsense. 1080i is 1080 lines of resolution per frame, that is why it is called 1080i.
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post #10 of 91 Old 11-06-2007, 08:53 AM
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Quote:
Originally Posted by kylebisme View Post

Nonsense. 1080i is 1080 lines of resolution per frame, that is why it is called 1080i.

...but only 540 per field, which is important when you're dealing with 60 fps.
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post #11 of 91 Old 11-06-2007, 08:54 AM
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Quote:
Originally Posted by kylebisme View Post

Not just 1080p native. In any game that renders at anything over 720p but with no more than 30fps, 1080i is the obvious choice as it avoids unnecessary downscaling.

There are only a handful of games that render at anything about 720p. 720p really is the best choice for games.

Ideally you should sent it 1080p, though. You may also want to look into using VGA cables.
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post #12 of 91 Old 11-06-2007, 09:41 AM
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Quote:
Originally Posted by chrisherbert View Post

...but only 540 per field, which is important when you're dealing with 60 fps.

Exactly, which is why I previously stated that 1080i is better for "any game that renders at anything over 720p but with no more than 30fps".

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Originally Posted by chrisherbert View Post

There are only a handful of games that render at anything about 720p.

And not many that render over 30fps either, which is why the choice often makes little to no difference either way.
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post #13 of 91 Old 11-06-2007, 09:50 AM
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Quote:
Originally Posted by kylebisme View Post

Nonsense. 1080i is 1080 lines of resolution per frame, that is why it is called 1080i.

Uhh no the I means interlaced so it cuts it in half.
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post #14 of 91 Old 11-06-2007, 09:53 AM
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The "i" means interlaced, but interlaced isn't as simple as "cuts it in half".
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post #15 of 91 Old 11-06-2007, 10:27 AM
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Quote:
Originally Posted by kylebisme View Post

Exactly, which is why I previously stated that 1080i is better for "any game that renders at anything over 720p but with no more than 30fps".


And not many that render over 30fps either, which is why the choice often makes little to no difference either way.

Many more run at 60fps (at least in spurts) than run in 1080p.

The best solution, in my opinion, is to connect the Xbox to the projector by VGA. Then you are probably not going to get any overscan, edge enhancement, etc, that you may have when you use component.
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post #16 of 91 Old 11-06-2007, 10:29 AM
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Quote:
Originally Posted by kylebisme View Post

The "i" means interlaced, but interlaced isn't as simple as "cuts it in half".

Ok whatever is 1080i the same as 1080p I mean christ it must mean both are getting 1080 lines of resolution continously throughout the picture.


Ignorance is bliss to some, but whatever..Fact is 1080i is not as many lines of resolution as 720p...I guess 1080i is on the same level as 1080p then to you right?


My previous post you quoted was in order to keep it simple.
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post #17 of 91 Old 11-06-2007, 10:30 AM
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i would do vga to the projector and get a full 1080p..
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post #18 of 91 Old 11-06-2007, 12:01 PM
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Quote:
Originally Posted by PatrickB101 View Post

i would do vga to the projector and get a full 1080p..

Agreed.

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post #19 of 91 Old 11-06-2007, 12:08 PM
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Quote:
Originally Posted by spinksjinx View Post

Ok whatever is 1080i the same as 1080p I mean christ it must mean both are getting 1080 lines of resolution continously throughout the picture.


Ignorance is bliss to some, but whatever..Fact is 1080i is not as many lines of resolution as 720p...I guess 1080i is on the same level as 1080p then to you right?


My previous post you quoted was in order to keep it simple.

Is it your ignorance that's bliss to you? 1080i is a larger picture, with more pixels than 720p. It's far more than just a split 540 lines of resolution. There is a reason that 540p wasn't considered high definition.

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post #20 of 91 Old 11-06-2007, 01:13 PM
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Quote:
Originally Posted by spinksjinx View Post

Ok whatever is 1080i the same as 1080p I mean christ it must mean both are getting 1080 lines of resolution continously throughout the picture.


Ignorance is bliss to some, but whatever..Fact is 1080i is not as many lines of resolution as 720p...I guess 1080i is on the same level as 1080p then to you right?


My previous post you quoted was in order to keep it simple.

If you went by your flawed argument, that 1080i is 1920x540 and 720p is 1280x720 then you're talking 1,036,800 pixels versus 921,600 pixels. So even with the fact that don't understand how 1080i works, your argument still loses. The real drawbacks to 1080i are interlacing errors and lower actual framerates. It still contains 1920x1080 of information that your eye perceives.

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post #21 of 91 Old 11-06-2007, 03:41 PM
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Simple rule of thumb: feed the display native resolution whenever its possible. Its a 1080p display that, so...
Fallback: go with whatever looks good to you.
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post #22 of 91 Old 11-06-2007, 03:50 PM
 
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720p or 1080p. 1080i should almost never be spit out of an xbox 360, unless you have an old CRT HDTV. Why add latency and artifacting issue by making your fixed pixel display deinterlace stuff?

"If you went by your flawed argument, that 1080i is 1920x540 and 720p is 1280x720 then you're talking 1,036,800 pixels versus 921,600 pixels"
"It still contains 1920x1080 of information that your eye perceives."

Speaking of flawed arguements...
Pixel count is not the only important thing in an image. Regarding straight pixel count: The human eye is far more sensitive to vertical information that it is to horizontal. In your example of 1920x540 vs 1280x720, the 720p image will look sharper due to the higher vertical resolution, even though the 540p image has a larger pixel count.

720p vs 180i out of an Xbox 360. Here is the truth.

Most 360 games render at 1280x720 at a target of 30fps, but being vsynced, they will vary between 60, 30, 20, 15, 12, 10, 6, 5, 4 3, 2, and 1 frame per second. In the case that the game is rendering 1280x720 at 60fps (and 20, 12, 4fps) and the 360 is set to 1080i, the output image will contain 1280x540 pixels of information. Horizontal information is not added, but vertical information is lost. Deinterlaing that will drop the framerate to essentially 30fps, and will recover most of those vertical 720 pixels, but will also carry with it the standard deinterlacing artifacts.

It really is just silly to introduce interlacing into the picture path of a progressive image going to a fixed pixel display.

Movies are completely different. If you are using the HD-DVD add on or playing upscaled DVDs over VGA/HDMI, then 1080i is a valid option as the signal contains the full information required to easily rebuild the full 1920x1080@24fps of the source. I can not stress enough that this is absolutely not the case with games.
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post #23 of 91 Old 11-06-2007, 04:01 PM
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Quote:
Originally Posted by spinksjinx View Post

720p all the way I will keep it simple on how I explain it to people.

1080i=540 lines of resolution
720p=720 lines of resolution

More lines of resolution=better picture.

The choice is yours.

Hmm... I like your thinking. Yes, let's keep it simple.

1080i/p .= 2,073,600 pixels per frame (1920 x 1080)
1080i . . = 1,036,800 pixels per field (1920 x 540)
720p . . . . = 921,600 pixels per frame (1280 x 720)

More pixels of resolution = better picture.

Wait!?! So what was the answer?

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post #24 of 91 Old 11-06-2007, 04:54 PM
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The following should be required reading by everyone on the internet:
http://ozymandias.com/archive/2006/1...Rendering.aspx

No game is rendered at 1920x540.

There needs to be a bot on every forum on the internet to instantly IP ban anyone that mentions 540. It's really quite annoying to keep hearing about it.

Most of us on AVS don't even have interlaced TV's, so most of this is moot.
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post #25 of 91 Old 11-06-2007, 05:24 PM
 
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"No game is rendered at 1920x540"

Gran Turismo 4. It renders each field as an individual 540p frame. It does not render 1080p and throw away half the lines.
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post #26 of 91 Old 11-06-2007, 06:07 PM
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The 360 does not take into consideration what frame rate the game is running at. So if you run at 1080i, the 360 takes 60 1280x720 frames and scales them to 60 1920x540 fields. The maximum actual resolution that can get output over 1080i is 60 fields of 1280x540. Now your TV may be able to rebuild that into something approaching the original 1280x720 image, but then again, it may not. If you have a progressive fixed pixel display then you can get interlacing artifacts on top of a possible lower maximum resolution. Optimally if you have a progressive based display, send it 720p/1080p and if you have a interlaced based display send it 1080i.

The real wild card in all of this is how the TV actually handles the signals it receives. If the TV handles one signal type better then the other for whatever reason, you may prefer the opposite. In some cases manufacturer implementation may trump the optimal input (though you might make the argument that the TV doesn't handle the optimal signal correctly).
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post #27 of 91 Old 11-06-2007, 07:42 PM
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The bottom line is that a 1080 picture means 1080 pixels vertically. It is interlaced, as most of you know, meaning that it is sending one frame in even and then odd lines. This still is 1080 pixels, and is still one frame.

You don't call 480i picture 240p, do you?

I agree that the best way to find out is to experiment. If you hook your Xbox up via HDMI, it will get the optimal resolution from your display and just use it, unless you tell it otherwise. If you don't have HDMI available to you, as it was said, try the native resolution of your display.

If your display is 720p, then put your Xbox at that and be happy, hopefully.

Most games currently are made to play best at 720p, but there's no harm in fiddling around to see what looks best.
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post #28 of 91 Old 11-06-2007, 07:56 PM
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I'm an Online Editor and Post Production Technical Supervisor. I don't know where this 540 garbage first started but I really wish it would stop.
Please take the time to properly educate yourselves on this.
Please don't take my word on it, even though the vast majority of my job is dealing with 1080i content, do the leg work and understand "why 1080i = 540" is garbage.

To the OP: it depends. I don't know much about your Panny projector in terms of specs. But I would assume it might have a better scaler/deinterlacer than the 360. I would do the research yourself to find out for sure though. Let's assume your projector is better at this for now. If you are playing a game that is 720p (as most games are) I would leave the 360 set 720p. I believe the game resolutions are noted on the game cases but I could be wrong about that. If the game is 1080i set the 360 to 1080i. Simple as that. From my experience most front projectors have superior scalers/deinterlacers than most other display technologies. But I do know the Panny is a lower end front projector, so it could be a wash.

The internal scaler for games on the 360 is pretty good. SD DVD's not quite as good. So as some above have suggested, trying finding a cheap 360 VGA cable form amazon or ebay and give 1080p a shot. Above all do some direct a/b comparisons with a buddy and see which you like best. Overall though I think the end result from each method will have very subtle differences.
If you can get your hands on an HQV benchmark DVD, that would be a sure fire way to determine which is better in the SD DVD realm though.
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post #29 of 91 Old 11-06-2007, 08:54 PM
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Quote:


You don't call 480i picture 240p, do you?

Actually, barring a few genesis games, pretty much every game made was literally 240p up until the playstation era (the consoles never told the TV to draw anything but odd scanlines which can cause problems when you try and play your old consoles on some digital TVs). Just because the console transmitted the video on a format capable of 480 lines of resolution doesn't mean the games automatically transmitted 480 lines of unique information.

Quote:


Please don't take my word on it, even though the vast majority of my job is dealing with 1080i content, do the leg work and understand "why 1080i = 540" is garbage.

Converting from 720p 60fps is one of the situations where 1080i does equal 540p. In a situation where the source is 720p at 24fps or 30fps it is possible to preserve the original 720 lines of resolution over 2 or more fields. Unfortunately this is not possible with a 60fps source since you are limited to one field for every frame. Since you cannot use 2 fields to represent one frame, you are limited to 540 lines of resolution to represent each of the original 720 lines of resolution in the original frame. You effectively lose 180 lines of resolution when converting 720p 60fps to 1080i.

Now if you want to make the argument that the additional resolution not be noticeable while playing a game, then you might have a point. But technically, 720p 60fps conversion to 1080i causes 1080i to effectively become 540p.

To put it another way:
1280 x 720 x 24 frames/second = 22,118,400 pixels
1280 x 720 x 30 frames/second = 27,648,000 pixels
1280 x 720 x 60 frames/second = 55,296,000 pixels
1280 x 540 x 60 fields/second = 41,472,000 pixels

There are only 1280 horizontal pixels rendered in the original frame. As you can see 1080i should be capable of preserving 24/30 fps, but does not have enough pixels to preserve 60 fps. You lose 25% of your vertical resolution when converting to 1080i from 720p 60fps.
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post #30 of 91 Old 11-07-2007, 04:37 AM
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Quote:
Originally Posted by Quidam67 View Post

That's a tough question that could be argued in either direction. Probably best you try both and then decide based on what your eyes tell you.


My vote for best answer. You could read all the technical aspects of both but what it really boils down to (in my opinion) is what looks best to your eyes

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