I'd like some help in understanding just what a ture 1080p projector is, espically in the fixed pixel display technology.
Im not new to the HDTV thing, and I have a technical background, and this is partly why Im having some trouble understanding just what a 1080p fixed pixel system acutally is.
First, let me tell you what I know, and what Iv observed.
480i = Ok, 480i is the nomral number of visible lines of picture that is drawn onto our nomral TV screens in SD. What the American standard of TV knon as NTSC allows for 525 lines, only 480 of them acutally get used for viewable video. The rest are used for synch, cc, and some other stuff.
Every SD DVD out there is nativly encoded in the 480i format. When use use the yellow video out, or the S-Video out, your ARE using 480i format.
Every TV show on over-the-air-analog. analog cable, non-hd-digital cable, and non-hd-sat also decode and output 480i. And from what I can tell, on any CRT TUBE tv up to about 32 inchs, the picutre will be just spiffy.
When we start to get into larger screen tv sets, or projectors of any type, we start to notice all the problems with 480i analog video, and even digital video too, such as digital cable or satalite tv (in SD).
Problems on the anlaog side are pretty much due to noise on the line. At 32 inch CRT TUBE sets (which in my opnion give FAR better PQ then any other technology out there due to the non-pixel technology, and the killer black level and killer contrast ratio) you proabaly wont take notice of analog PQ issues, but above that size you surely will.
Problems on the digital side are mostly due to compression---most digital cable and satalite providers scale the video donw from its nomral rate of 720x480i into 480x480i, plus they cap the number of colors that can be sent---analog over-the-air has turelly INFINITY number of colors, but digital cable and satalite providers of SD video limit it down to only thousands of colors. Again, on a 32inch CRT Tube TV set, you proabaly wont even take notice of these problems, the PQ will look as good as anything you ever watch on that TV.
Big Screen TVs bring out the ture probelm of 480i. Besides the analog noise problems, and the digital compression and lack of color problems, the "i" of 480i means interlace video scanning...
Lines of video---480 of them, are darwn onto your CRT TUBE starting at line 2 then 4 then 6---all the way down to the bottom of the screen---every other line is left blank--or black.
Then the scan beam fly's back up to the top corner and then lines 1 3 5 7 and so on are drawn.
On 32inch CRT Tube or smaller TV sets, the physical distance of the top of the screen to the bottom is small enough that the time it takes to draw one sceen is short enough that to the nomral human eye ball, we see a full, solid picture, but on bigger screens, since there is more surface area to cover, since we get to view a bigger surface area, our eyes can more accuratly pick up the problems in the display.
On a big screen tv, running at 480i (big screen tv's up to the mid 1990's), you CAN see the black lines between each draw of the odd vs the even screen scan. These black lines are known as scan lines.
The very best picture quality you can get in SD to one of these older big screen TVs would proabaly be a good DVD hooked up to its SVideo port. DVD quality is superb 480i quality--generally speaking.
The result will be a nice picutre with very visible scan lines.
The only reason you dont see scanlines today on modern large screen tv sets is because modern sets have a built in scaler that upconverts that 480i signal into something higher.
Progressivs Scan 480p
This is kinda tricky to explain. I think all of us know that the only real difference between 480i and 480p is that in progressve scanning, then lines are drawn all in one pass, 1 2 3 4 5 6....all the way up to 480.
As far as I know, this jump from 480i to 480p has no effect on the resoultion. On DVD's its still 720x480 pixels.
What makes this tricky is that in order to view 480p, you will need something better then your SD tv, you will need an HDTV. The thing is, EVERY HDTV out there has a built-in-scaler to convert 480i to something higher then 480i. The main reason to do this is, most HDTV sets are bigger then 32 inch, and thus would show scan lines on 480i sources, and thus have built in scalers.
This is interesting, since you need an HDTV to use a progressive scan dvd player, and every HDTV out there has a built in scaler, then why are there progressive scan dvd players?
The answer to that question quality. If you have a higher quality scaler in your dvd player the the one built into your HDTV, then you will benifit from that higher end DVD player.
Keep this in mind for later in this post----THERE ARE NO NATIVE 480P DVD's.
The only other technical difference(other then 2 4 6 8 vs 1 2 3 4 5 6 7 8) as I understand it beween 480i an 480p, is the scan rate needs to be doubled in oder to draw all of that info in one pass. By upping the scan rate you also increase the amount of info per unit of time that can be deliverd. This is known as bandwidth.
On a dialup internet you could only get so much info per unit of time, when you got broadband internet, you could get alot more info in the same about of time.
When you increase your video bandwidth, good things happen to the picture quality.
Keep this in mind for later in this post--- THERE IS NOT MUCH DIFFERENCE BEWEEN 480i and 480p.
(considering that all 480i gets converted in your tv set to something higher anyways).
720p is the progressive 720line HDTV standard. 720p vs 480p is not that much of a jump is it? But why then is 720p HDTV look SOOOOOOOOOOOO much better then 480p DVD's?
First, remeber that in 480i/p the acutal resoution is is 720x480, and thats if your on a DVD player, or over-the-air SDTV---Remember digital cable and satalite providers typicall dont even give us all of our already limiited bandwidth crushing it down to about 480x 480.
720p HDTV native res is 1280x720progressive. Look at the first number, 1280 dots of picture info per line vs 720 dots, or more typical 480 dots per line.
1280x720 is WAY better then 720x480 and WAY WAY WAY better then 480x480.
Again, just as before, more info beeing deliverd per unit of time means more video bandwidth. So its a safe bet to say that 720p HDTV has a higher bandwith then 480p, and a way higher bandwith then 480i.
Oh No! "i" ? "i" is BAD right? "p" is better right?
Well, 1080i is 1920x1080 pixels. 720p is 1280x720 pixels. If you do the math, this is what happens...
720p = 921600 pixels. or in other words not quite 1 megapixel of res.
1080i= 2073600 pixels. or in other words almost 2.1 meagpixel of res.
Again, more pixels per frame in the same amount of time means more bandwidth.
More bandwidth requires a higher scanning rate.
Remeber that doubling the scan rate of 480i to get to 480p was enough to ilimiate the scan lines, even on very large screens? Well the bandwidth scanning rate required to do 1080i is so high, that unless you uisng a MONSTER SCREEN size with a Ultra High Res projection system, you wont see scan lines at 1080i.
What's 1080p? Well, obviously its progrssivly scanned 1080i. It dose not have any higher resoution then 1080i---just as 480i and 480p have the same number of pixels, 1080i and 1080p have also the same number of pixels.
And since I already stated that the video bandwidth requirments to do 1080i are so high already as to not show any scan lines, then whats the point of 1080p?
Just as there are NO 480P NATIVE DVD's, at this time, the same is ture for 1080p content. While some HD-DVD players and Blu Ray Players and even some of the disks you can by for them say "1080p Beyond HDTV"---from what I have been reading, they only decode to 1080i, and use a built-in scaler to pump it to 1080p over its hdmi port.
Why pump to 1080p?
I could total understand pumping 480i to 480p - it gets rid of the visible scan lines (on big screen non-HDTVs made before the late 1990's).
Again since there are no scan lines visiable at 1080i, whats the point of 1080p?
I dont have a great answer to that question yet. For some (very very few people) might be lucky enough to have such a high-end video display, and a screen size so large that they CAN seen scan lines at 1080i---then this make sence for them. But I would guess you would need a screen size of at least 12 FEET wide or more, and if your doing that, your going to need a hell of lot of brightness to light that up, and if your talking high brightness, your proabaly not talking 1080i ture hd projection.
My question about 1080p
Sorry its taken me so long to get to the point, but I wanted you all to have a clear understanding of my knoledge on the subject....
Scan lines are only generated on devices that acutally SCAN. In other words, scanning means dropping pixels onto the display one-at-a-time using a "laser-beam like" technlogy. As far as I know, only CRT displays and CRT projectors do this.
LCD, LCOs, DLP, PLASMA, and even the new SXRD systems are all fixed pixel units, and are not scanning type displays.
When these type displays state that they can take signals such as 480i-1080p, the whole idea of "i" vs "p" makes no sence to me any more.
CRT technology type displays acutally have a physical part in them known as a "flyback transformer". It gets its name from the function of "flying back the electron beam to start its next scan down the tube surface."
In interlace scanning, the flyback zipps the beam back to line 1 after it completes drawing every other line, then it zipps it back again to line 2 to draw the next set of lines. In 2 pass's it will have completed the video frame.
In progressive scanning, the flyback zipps the beam back only after its has drawn all the video lines progressivly one after the other. In just 1 pass, it will have completed the video frame.
There is no flyback transformer in any fixed pixel display is there?
There is no beam drawing (scanning) pixels onto the screeen is there?
Thus there is NO DIFFERENCE BEWEEN 1080i and 1080p on a fixed pixel display, other then it should be able to accept video signal rates at double the 1080i bandwidth----HOWEVER, there is Z E R O P I C T U R E D I F F E R E N C E in quality beween 1080i and 1080p on these type display devices.....Right?
The only way to get higher quality out of 1080p equipment is if its based on CRT technology.
I have a very unique display system. I was luckly enouhg to find a great deal on ebay for a extreemly high end CRT/Hybrid system. The technology is known as ILA (not D-ila). It uses R G B CRT's that acutally drive analog LCD video plates with no pixels. The results are CRT resoution, without the brighness constraints of typical CRT projector systems. My current systme using a DVDO VP50 puhing 1080p over RGBHV at ture 1920x1080 progressive scan at just under 7000 lumens.
Whiile I dont have any ture 1080p content to feed it, ture 1080i stuff scaled to 1080p looks better to my eye then if I fed it natural 1080i.
screen shots at:http://bbs.flagnet.org
Sorry, I dont have any 1080p shots on the web site yet.