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Discussion Starter · #1 ·
I have beed reading some posts with 2.35:1 setup solutions. If I deside to go for 1920x816P72Hz on my NEC XG1352 Moome DVI, what will happend??


To get full pic with bluray i need to set it up for 2.35:1 with powerdvd, will this remove the black bars?Or do I need to do some other tricks, like zooming will powerdvd "see" this resolution?? Will powerdvd actually CUT the black bars or will it make some scaling compensation???


If i play 1.78 materiel will I then just get black bars in each side?? ( I dont mind this, because the hight of the cinema is locking me to keep max. 64" screen hight)


I dont wont to switch resolution all the time both on HTPC and on CRT so as I can figure out i dont have 1:1 mapping after this AT ALL times? When I play bluray with 1.78:1 or HDTV, all signals are scaled big time?? right. Is this a good idea?? Will picture quality remains perfect allthough the HTPC is scaling like hell. I practially never watch any 1.78:1 1080p/i materiel in the cinema but maybe I will in the future (recorded HDTV from my Beyondtv4 Server) then this will be a bad idea, 1080 downscaled to 816??? Then i need to make a new input setting and switch between diff. setting to get 1:1 and black bars in each side....
 

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Hi, I am not nearly as knowledgeable as some more experienced members here (not to mention Pros
), but I hope I still can answer some of your questions.

Since I don't use HTPC (even being IT pro
), I will limit my comments to other aspects of HT. Remember, those are only my OPINIONS, so take them as such...:

Any time you deal with multiple resolutions/aspect ratios in HT, you HAVE to compromise somewhere. Since you say you watch mostly 2.35:1 movies, just like me, I think you should optimize your set-up for that particular resolution/aspect ratio. That would mean settings where size of screen, and your viewing distance would be ideal for 2.35:1 movies. From viewer's point of view, it then really doesn't matter, if you project 1080x1920, or 817x1920 - SIZE of actual image will be identical (and if you have decent mask around screen, black bars will simply disappear in case of 1080x1920). Advantage of using 817x1920 is lower bandwidth, meaning less stress on the PJ and usually sharper image.

I don't know what exactly you mean by "1:1 mapping", since the term is usually reserved for digital displays, but in either case there is NO scaling, so it's irrelevant.

On to 16x9: Again, assuming you have 2.35:1 screen, you have 2 options:

1. you can use software to scale 1080 to 817, so it will fit on your screen height-wise, or

2. you can set-up another memory in PJ to project 1080p so it fits screen's height.

Option 1 may give you some scaling artifacts, option 2 will obviously result in PJ not resolving all 1080 lines (remember, it IS optimized distance-, raster- etc. wise for 817 lines!), resulting most likely in image being little soft due to overlapping scan lines.

In both cases you will have black bars on the sides of image.

Personally, I resolved the issue going third route: Instead doing CIH set-up, I selected "almost" CIA
(Constant Image Area) option.

My screen is ~114"x54" with masking to 114"x48.5" for 2.35:1, and 54"x96" for 16x9. This way I have nicely resolved both resolutions (I use Lumagen HDP to do 817x1920 "active area scanning" and 48fps refresh).

You can see the screen at the link:

http://www.kbconsulting.com/ampro.html


- scroll down to the end.

Masks are made from aluminum flashing (used for roof construction), covered with "Fidelio" velvet (glue) and held in place by magnets. Long - top and bottom masks are stiffened by glues L-shaped aluminum rods.

When not in use, masks are held below and on the sides of the screen (steel plates to stick the magnets to).


By the way, since blu-ray is 1080x1920 either 24p or 60i, you don't have to have 817x1920 set-up. Conventional 1080x1920 WILL get you full picture (with black bars on top and bottom).


Hope it helps you
 

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Discussion Starter · #3 ·
thx a lot good answer. Still some understanding problems...

Why all this masking with a CRT projector when showing black bars. The black bars on a blyray projected with a CRT is totally black as i can see??


The conclusion in your answer is that there are no benefits of going 21:9 because of the res on a bluray disc. I am having height problems in my HT so I will be able to mount a much (much) bigger screen (104 to 150") if I go 1920x817 21:9 instead of 1920x1080 16:9.


The HTPC will then zoom the bluray movie to 21:9 and project the movie scaled to the right relation between hight and weith, meaning scaled picture by HTPC CPU/GPU and not "1:1 mapping" I know it is a digital expression, but it can be used here i think because we are going away for the original FullHD resolution.


Klaus, Denmark
 

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Well, simple thing first
:

black bars are indeed black, but they are projected onto white screen, and of course there is plenty of light in adjacent areas, hence they are NEVER really black... masking with good quality velvet makes whole image pop-up tremendously. It's really THAT big a difference!

As for 2.35:1 projection: I think you are making it unintentionally too complicated
!

For argument's sake let's forget "scaling", software etc.

You set-up 2,35:1 screen at the distance from PJ (or rather the other way around, I guess) so full raster, full image width (all 1920 pixels from blu-ray disk) from your player fits on the screen perfectly left to right.

At this point, if you put BR disk with 2.35:1 movie on it, you WILL HAVE 2.335:1 image projected on 2.35:1 screen, right?

Like I said before, black bars are really irrelevant, they will be off the screen (ideally on the velvet mask), and totally invisible.

Now, if your software can do what Lumagen scalers can - what's called Active Area Scanning, it (the software) will create 817x1920 pixel image (NO SCALING!), sort of cutting off black bars, and sending to the PJ only actual image info. Benefit is lover bandwidth resulting in sharper image.

Real trick starts when you try to decide what to do with regular 16x9 image
... Well, not really - if your screen is fixed 2.35:1, then of course you have to fit it height-wise, which obviously will create unused screen area on the sides... I think (if I understand your post correctly) that's probably your best option - getting you the biggest (widest) screen possible?

Now whether you use HTPC software (again - Lumagen has preprogrammed, switchable image aspect ratios), or different settings on PJ (or combination of both), you will be loosing some quality, there is no way around it...

One way or the other, find way to mask sides of the screen (for 16x9 projection), it's well worth the effort!


Good luck,


Kris


Kris
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by k.berger /forum/post/15583713


Well, simple thing first
:

black bars are indeed black, but they are projected onto white screen, and of course there is plenty of light in adjacent areas, hence they are NEVER really black... masking with good quality velvet makes whole image pop-up tremendously. It's really THAT big a difference!

As for 2.35:1 projection: I think you are making it unintentionally too complicated
!

For argument's sake let's forget "scaling", software etc.

You set-up 2,35:1 screen at the distance from PJ (or rather the other way around, I guess) so full raster, full image width (all 1920 pixels from blu-ray disk) from your player fits on the screen perfectly left to right.

At this point, if you put BR disk with 2.35:1 movie on it, you WILL HAVE 2.335:1 image projected on 2.35:1 screen, right?

Like I said before, black bars are really irrelevant, they will be off the screen (ideally on the velvet mask), and totally invisible.

Now, if your software can do what Lumagen scalers can - what's called Active Area Scanning, it (the software) will create 817x1920 pixel image (NO SCALING!), sort of cutting off black bars, and sending to the PJ only actual image info. Benefit is lover bandwidth resulting in sharper image.

Real trick starts when you try to decide what to do with regular 16x9 image
... Well, not really - if your screen is fixed 2.35:1, then of course you have to fit it height-wise, which obviously will create unused screen area on the sides... I think (if I understand your post correctly) that's probably your best option - getting you the biggest (widest) screen possible?

Now whether you use HTPC software (again - Lumagen has preprogrammed, switchable image aspect ratios), or different settings on PJ (or combination of both), you will be loosing some quality, there is no way around it...

One way or the other, find way to mask sides of the screen (for 16x9 projection), it's well worth the effort!


Good luck,


Kris


Kris

Now that gave a perfect understanding view. THX, now i have a perfect exclusion for making motorized 16:9 masking....
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by MikeEby /forum/post/15583789


I just posted a little application I wrote that might help you. It will allow you to stretch the software player to fill the screen.

http://www.avsforum.com/avs-vb/showthread.php?t=1109871


Mike

OUTSTANDING FEATURE, It explain all my worries, I will go for the 2.35:1 screen for sure.


Off tropic: Do you have a link to a recommeded acoustic transperant screen or screen materiel
 

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Quote:
Originally Posted by Klaus /forum/post/15584575


Now that gave a perfect understanding view. THX, now i have a perfect exclusion for making motorized 16:9 masking....
Glad to help!... Not that at this stage of addiction you need a lot of it...
!

Just to put it in perspective, I finally figured out how to utilize for HT another room i our house... Here we go again - just finished (about 4 months ago) THIS installation...

Hope it all works for you - it's a LOT of FUN!


Kris
 

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Quote:
Originally Posted by MikeEby /forum/post/15583789


I just posted a little application I wrote that might help you. It will allow you to stretch the software player to fill the screen.

http://www.avsforum.com/avs-vb/showthread.php?t=1109871


Mike

Mike - IT IS PRETTY NEAT! Not that I need it for anything - but it always amazes me how much knowledge, experience and ingenuity our little community possesses... W can pretty much solve any problem!

I am really proud to be small part of it,


Kris
 

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Here is another older post from Craig Rounds a professional Calibrator.

Want to Optimize your HTPC or Scaler for use with CRT?


For my marquee I had to do a small modification to 3 resistors on the VDM to get it to squeeze the 817p out of my Lumagen HDQ, but the improvement in the picture vs 1080p was easily seen. Anyone who watches 2.35 scope movies from Blu Ray predominantly should use 800/817p.


Athanasios
 

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One thing that I don't get is how the 1920x800 thing work.

Does it scale it down to 800 or does it actually crop the picture ?

Any special settings/codecs for this crop function (htpc) ?
 

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Discussion Starter · #13 ·
Well...If you "zoom" with a software player/ HTPC (or hardware player) to 2:35:1 and set resolution to 1920x800, then the black bars is out of the picture/ raster usage and the projected image will now fit a 2.35:1 screen. This is for CRT projectors for Digital pj you also have to zoom the black bars out of the picture and you will get "long faces" like when stretch from 4:3 to 16:9 then get an anamorphic lense to "scale" the full screen 16:9 (1920x1080) back to 2.35:1. The AR will then be right again. Understandable???
 

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I got a CRT PJ



Ok, let me try to explain my question.


You set the resolution to 1920x800.

Then in your favourite player (mine is ZP) you zoom the picture to cover the 2.35/2.40 AR of your screen.


But if we go back one step, you actually scale the picture down to 800, then you zoom out those 800 to cover a larger area, wouldn't that degrade the picture ?

Since the scaled down picture would include the black bars, but you zoom those out.

Or will the "complete" image be intact and the image is just squeezed down in the first step.
 

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The correct resolution is 1920x804, which is as close as you can get to the actual 2.39:1 aspect ratio (1920x803.3).
 

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Quote:
Originally Posted by Fredrik /forum/post/15616528


I got a CRT PJ



Ok, let me try to explain my question.


You set the resolution to 1920x800.

Then in your favourite player (mine is ZP) you zoom the picture to cover the 2.35/2.40 AR of your screen.


But if we go back one step, you actually scale the picture down to 800, then you zoom out those 800 to cover a larger area, wouldn't that degrade the picture ?

Since the scaled down picture would include the black bars, but you zoom those out.

Or will the "complete" image be intact and the image is just squeezed down in the first step.

Ok let me try to explain. When setitng it to 800 for 2.4 aspect the scaler or the HTPC will only output the 800 lines of resolution that the "active image"

is on, the black bars get cropped out so to say. On on my Marquee when displaying the 800x1920 the image is tall like mentioned above, so with the PJ hight adjustment I squeeze the image down to the correct geometry so circles are circles and not tall ovals. So it still is 800p but the PJ squeeze's

scanned area to the correct aspect ratio, its still scanning 800 lines of the active image, the black bars are not scanned so they are not using up bandwidth.Now you can run a higher scan rate like 72hz with no degrading of the image, like going [email protected] would. This is how its done with a VP but a HTPC would work the same. So you dont down scale 1080p because in a scope movie on a blu ray the only area being used by the 1080p is actually 800p. However for a 1.78 movie all 1080p lines are being used.




Athanasios
 

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Quote:
Originally Posted by Mark_A_W /forum/post/15616633


The correct resolution is 1920x804, which is as close as you can get to the actual 2.39:1 aspect ratio (1920x803.3).

2.40:1 is what you want to use as it is a nice even clean 800p, no decimals, lots of films hit right at 2.40:1, some are in between which means you lose a small sliver at the top and bottom when doing 2.40:1 and that exact screen size


doing anything else but 2.40:1 will have some slight scaling on the scaler end, which you do not want


2.35:1 = 817.021276595744

2.39:1 = 803.347280334728

2.40:1 = 800



-Gary
 

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Quote:
Originally Posted by Gary Murrell /forum/post/15618508


2.40:1 is what you want to use as it is a nice even clean 800p, no decimals, lots of films hit right at 2.40:1, some are in between which means you lose a small sliver at the top and bottom when doing 2.40:1 and that exact screen size


doing anything else but 2.40:1 will have some slight scaling on the scaler end, which you do not want


2.35:1 = 817.021276595744

2.39:1 = 803.347280334728

2.40:1 = 800



-Gary

Gary,


Why would 800p be better than 817p?


You meantion some slight scaling on the scaler end but can you explain why this is so.


I run 817 so you've got me curious now.
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by acave_uk /forum/post/15622066


Gary,


Why would 800p be better than 817p?


You meantion some slight scaling on the scaler end but can you explain why this is so.


I run 817 so you've got me curious now.

I read that most movies was actually in 2.4:1 even they where marked 2.35:1!!
 

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Quote:
Originally Posted by acave_uk /forum/post/15622066


Gary,


Why would 800p be better than 817p?


You meantion some slight scaling on the scaler end but can you explain why this is so.


I run 817 so you've got me curious now.

its because there is no exact 817p, it is what I listed above, so the slight rounding off results in scaling and uneven numbers


800p/2.40:1 is exact and as Klaus says many a movie labeled 2.35:1 is 2.40:1 actually


-Gary
 
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