AVS Forum banner

Status
Not open for further replies.
1 - 10 of 10 Posts

·
Registered
Joined
·
212 Posts
Discussion Starter #1
I got my Z2 back in December and after testing it for a while I wasn't able to use it again until last night - don't hate me those who are waiting for one... it wasn't be choice - was doing some extended travelling ;) I finally got it back up and am projecting onto a piece of gatorboard... hooked up the Dish 6000 to it last night and all I can say is WOW!! The picture was flawless!! I've been reading all the tweaking and VB threads while I was on the road and I really couldn't remember if mine displayed those flaws as well... I must have got a nicely calibrated unit because I don't really see any VB and no red push - everything seems dead on.


Anyway, I was constantly switching between 1080i and 720p last night on the 6000 and I simply could not detect a difference in picture quality betweeen the 2 - the image looked identical on both! I saw a huge difference between passing 480i to the Z2 and letting it deinterlace it as opposed to passing it a 480p signal (much better to let the DVD player pass the 480p signal) but I am assuming that with high def the source is so good that the difference is really undetectable.


However, I noticed one thing that I find rather strange - when the Dish 6000 passes a 720p signal, the Z2 locks onto "full through" mode and cannot be changed. This doesn't affect the size of the broadcast image, but the 6000's menu screens are rather small (they have the large black border all around that full through mode produces).... when passing 1080i, the broadcast image looks identical to 720p, but the Z2 locks onto "full" mode so the 6000s menus screen are a lot larger. I suppose this isn't really a big deal but I do find it kind of odd - anyone have any thoughts on this?


LB
 

·
Registered
Joined
·
212 Posts
Discussion Starter #2
I should add that I don't detect any difference in picture quality on regular 480i material either... which is surprising considering if it is 480i the Dish 6000 will upconvert to 720p or 1080i and then pass it out to the Z2 which will then downconvert to 720p if it receives a 1080i signal... you would think it'd be much better to pass 720p then but I really don't see any difference in quality...


LB
 

·
Registered
Joined
·
3,161 Posts
Lord British, I have started leaving my 6000 in 1080i all the time. With my 2HD I can't really see any difference either and it's such a pain to go through the menu to switch resolution on the 6000 it was just easier to leave it alone.


I also have an issue with the screen changing position between 720p and 1080i and having a green stripe down the right hand side in 720p. Adjusting the screen position in 720p would just throw everything else off so I got it the way I want it in 1080i and just leave it alone.


Speaking of scaling 480i, I tape HD shows downconverted from my 6000 to a JVC 30K and play back via component input at 480i and the picture is stunning. I really need a HD tuner card for my PC so I can timeshift and record HD to my JVC.
 

·
Registered
Joined
·
1,156 Posts
If you cant detect a difference between the 2 I would say stick to whichever you like best (in this case 1080i because of the menus). Theoretically 720p should provide you with the best image as that is the native resolution of the Z2 but as you mentioned you cannot see any difference.


The reason it goes to "Full Through" mode when running in 720p is because it is a 1:1 pixel mapping. For example lets say you were watching some SD material (not upconverted). If you set it to "Normal" mode the image would fill the height of your screen but obviously have black bars on the sides. If you were to switch to "normal through" mode then the picture would decrease in size because it is displaying the SD signal in a 1:1 pixel mapping (cant remember the exact resolution) so natrually the entire panel is not being used. When in 1080i mode the Z2 cannot do 1:1 pixel mapping so it is set to "Full" mode so the scaler on the Z2 can scale it to 720p. I suspect that the guide is in a 4:3 format so when you enter the guide using 1080i it will stretch to the width and height of the screen because it is in "Full" mode whereas with 720p it will be displayed in a 1:1 mapping (i.e. not stretched at all).


I tend to not make sense and can be really unclear so let me know if you understand what I said or not :).
 

·
Registered
Joined
·
33 Posts
You shouldn't see much difference as there is no additional content in the source.


Think about it, take your 480i and scale it to 1920 x 1080, or better yet go for 16,000 x 9,000 (assuming the x1 could accept the input signal) and then feed it in to your x1, that should be even better, right?. No, it won't be, as there is no additional content.


Your x1 has a native matrix of 800x600 pixels, so it can't fully resolve a 720p signal. It can resolve a 480p or 1080i/540p. A 720p will look better because it can use more of the content since it can display up to 600 lines, but it will have to throw some of it away since it gets 720 lines of video but can only output 600 lines. That is of course done with a scaler, some are better than others. And don't just throw away 120 lines from the bottom of the screen, you use complex methods to try and represent the 720 lines of source using only the 600 that are available to display it. Same thing would happen if you had a native 320x200 pixel projector, it couldn't fully resolve a 480i/240p signal, some of the information would be lost, and could only use about 1/4 of the data from a 720p signal.


A native 1024 x 768 projector can resolve 720p, since it has 768 display lines to do so, and will give you a better picture. The horizontal pixel count is a similar situation, but projection systems in the past including most rear projection big screen TV's and the typical 27" direct view TV's are CRT based, they can display a seemingly infinite number of 'pixels' horizontally as the electron gun scans across the phosphor of the CRT tube from the left to the right, but then it must 'retrace' and start again on the next line below. So the number of lines that can be displayed from the top to bottom are much more limiting to the picture quality than the ones from side to side, and the terminology has followed this. Of course there is a limit to how many 'pixels' it can really resolve from the left to the right side on a CRT, but the most limiting factor was the number of lines from the top to the bottom. On a digital projector like the x1 the horizontal resolution is fixed by the dlp matrix, in this case 800 pixels.


The dish 6000 will scale all of the output to either 720p or 1080i/540p. I add the 540p because your display device isn't a CRT and it can't really interlace the display. On a CRT, you can scan or 'light up' the phosphor on the CRT every other line on every other refresh of the tube, and the phosphor stays lit long enough that it appears that all 1080 lines were displayed during each refresh, even thought he speed of the electron gun is running 1/2 that speed. The digital projector displays every line on every refresh.


Now not every channel you watch has the same original content. Some channels are native HD and are originated at 720p or 1080i/540p and will look much better than a 480i or 480p source. If you currently don't get any HD channels, then you need to... just to exploit your equipment's capabilities and see what a good picture looks like. You will need the 8psk plug in module to recieve hd from the sattelite, they sent me one when I signed up for one year of hd-net programming. I also got the 8vsb card to pick up local digital tv, a lot of which is hd, but you need to have channels being broadcast in your area for that to work. The dish 6000 receiver doesn't tell you what the format/quality of source is, even on hd channels, both from the sattelite or digital tv, but sometimes you can go on the web and find out what format a certiain broadcast is.


720p has more content than 1080i/540p, which has more than 480p, which is more than 480i. A standard vhs tape is about 320x240, s-vhs players are a bit higher, i think around 400x320, about halve way between standard tape and a dvd, but only when you record your own s-vhs data onto the tape. Playing a standard vhs tape in an svhs player can't add more content to the source. Though you do get s-video output to the projector which is superior to composite video from a standard player, even for the same vhs tape.


Ideally you would output everything in it's native source format and let the x1 scale it to its 800x600 pixel display, even the 720p material. Also since the x1 has faroudja DCDi processing. Then everything is scaled only once to 800x600 for display, which is best because each time a signal is scaled, it looses some of it's content. But you can't do that, since the dish 6000 will always output at the selected resolution of either 720p or 1080i.


Think of it this way, get 1000 scalers all lined up in a row, daisy chained one to another, then feed in your 480i, then output 720p, then with the next scaler down convert it back to 480i, then back out at 720p, till it comes out of the 1000th processor, and what you will see in the end will look like mud on the side of the road (ignoring the 2 minute lip sync delay...). Conversions are lossy, never additive. Upscaling adds sharpness, not content.


A 480i feed scaled to 1280x1024 will look sharper than when the same 480i feed is scaled to 800x600, much more so at a close distance, less significant at a farther distance, and at an infinite distance (50 feet) would appear identical.


A 720p feed scaled to 1280x1024 (will look sharper) and have more detail than when the same 720p feed is scaled to 800x600, because there is more content that can be resolved on the 1280x1024 matrix.


Of course one up on that would be to get a high end Faroudja or similar scaler set to output 800x600, which would be a better scaler than the projector has in it, and then the projector wouldn't have to scale at all. But that would cost several times over what the projector did and is not really feasible.


So the best would be to set the dish 6000 to 720p output mode. This would provide additional data to the projector for hd source material that is in 720p format. Of course you won't know that unless you find out somehow what format a specific channel and program is being transmitted, but by doing that you will be sending the most possible information from the original source to your projector all the time, and hence, the projector has the most information available to work with to scale it onto its 800x600 matrix, although that second scaling operation performed by the projector will be lossy.


I don't think much of the hd material on sattelite is 720p, becuase the bandwidth is quite a bit higher than 1080i/540p. So you will only be sending addional content to the projector on rare occasions. Also as you mentioned, at 720p, the on screen menu's are smaller than they are in 1080i format. Actually the menu is the same size in 'pixels', but since there are so many more pixels sent out in 720p mode, the menu appears as a much smaller portion of the whole. I would guess the menu is about 400 pixels high, so it fills about 400/540p=.75 or 3/4 of the screen height in 1080i mode, but 400/720p=.55 or just over 1/2 the height of the screen in 720p mode. Personally, I like the larger menu, but that's the way it works until they decide to display a truly larger menu in 720p mode so that it will appear relatively the same size as it does in 1080i mode.


As I said, most sattelite hd is 1080i and will probably remain that way because of the limited bandwidth available, so setting the output of the dish to 1080i will provide your x1 with all of the available data 'most of the time'. Probably often enough that you won't worry about it much. And you also get the larger on screen menu's. Most of the over the air hd digital tv is 1080i, although there is some 720p. You could check the stations in your area to see what you can get. But even when you do get a true 720p feed, you can only resolve an extra 60 lines of it over 540p, up to 600 pixels, so 120 lines of the 720p remain unresolved, which is more than 1/2 of it. So you may really not be able to see much difference between a 540p and 720p which is displayed as 600p on your x1. If you had a native vertical pixel count over 720 then you would certianly be able to see a difference in a 720p feed. Another way to look at it, "everything feed into your x1 is scaled to 600p".


So for your x1, I would set the dish 6000 to 1080i output until there is more 720p content available in hd. Or change it to 720p on the rare occasion that you can get your hands on a real 720p video feed.


If your projector was native 720 or more vertical pixels, like 1024x768, then I would leave the dish 6000 output set to 720p and put up with the smaller on screen menu as a trade off for occasional better picture quality when you get a real 720p feed.


If you had a front projection CRT that can sync on the 45khz signal, I would also stick with the 720p output. That's because the CRT will display all 720 lines all the time using the dish 6000 scaler to produce it, and even with a huge screen size you won't see any horizontal lines in the display. And of course there are never any horizontal pixels on a CRT, giving you a 'perfect' movie theater picture.


When DVD-HD comes along in a couple of years, if it's 1080i, then keep your x1, but I'm hoping it is at least 720p, then you will want to trade up to a higher resolution projector to enjoy all of the higher quality feed.


*** OOps, just noticed you had the Z2, which is 1280x1024, why was I thinking the x1? Probably because I was thinking of buying one.


OK, so your Z2 will look better when the feed is 720p instead of 1080i, because you can fully resolve 720p, so I would probably stick with that, and you will not need a new projector when HD-DVD comes out in a couple of years..... And when you see something that looks really really good, it's probably 720p instead of 1080i.
 

·
Registered
Joined
·
1,156 Posts
Ouch! Typed out all that in regard to the X1 when he has a Z2 :p.


The reason 720p would (theoretically) look better is because there are no D/A or A/D conversions along the way and there is no de-interlacing required.
 

·
Registered
Joined
·
33 Posts
Vlad_Dracule, thanks for the heads up on the X1/Z2 mistake, my bad...:eek:


Both the 1080i and 720p leave the dish 6000 as analog, either component or RGB, the 6000 doesn't have a DVI output. So the D/A conversion always occurs.


If you did match the video feed with the output, ie, 720p hd channel and output is set to 720p, or 1080i hd channel set to 1080i out, then the dish 6000 would not have to scale it, and that would be a good thing as I mentioned above, as scaling the feed twice is lossy. Then the Z2 could do the single scale on to the 1280x1024 LCD matrix producing the '1024p' for the projector.


However if it is 1080i, and you plug it into a CRT, you will be watching an interlaced display (540 * 2). When you view 1080i on a digital projector, it is de-interlaced, the LCD doesn't produce an interlaced display.
 

·
Registered
Joined
·
1,515 Posts
Lord British, don't worry. It's the 6000 receiver, and it's operating as it's supposed to. I have one with a CRT projector, which displays exactly what it's given -- no scaling. The menues on 720P are simply smaller.
 

·
Registered
Joined
·
212 Posts
Discussion Starter #9
Quote:
Originally posted by Marissadad
Lord British, I have started leaving my 6000 in 1080i all the time. With my 2HD I can't really see any difference either and it's such a pain to go through the menu to switch resolution on the 6000 it was just easier to leave it alone.


I also have an issue with the screen changing position between 720p and 1080i and having a green stripe down the right hand side in 720p. Adjusting the screen position in 720p would just throw everything else off so I got it the way I want it in 1080i and just leave it alone.
I had a greenish stripe too - just used the 6000's adjust function and moved the screen over a couple of notches... took care of it.

LB
 

·
Registered
Joined
·
212 Posts
Discussion Starter #10
Thanks for the replies everyone...


Though I don't really notice a difference in PQ, I have decided to leave the 6000 outputting 720p simply because if the content is in 720p (like Gladiator on ABC the other night) then it is passed out and absolutely no scaling is done... if it is 1080i or 480i, the 6000 scales it once and the Z2 doesn't touch it...


If you leave it on 1080i, then 480i content is first upconverted by the 6000 then downconverted by the Z2... 1080i content only has to go through one conversion, and that is by the Z2...


So it seems to me that the picture is somewhat "purer" when the 6000 is set to 720p as it goes through less conversions...


LB


BTW - Gladiator in 720p off of ABC with the Z2 was absolutely amazing!!
 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top