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Discussion Starter · #1 ·
When i try 1080i, I get only 5 seconds of video (and part is wrapped around the bottom of the screen vertically) and then a blue "loss of signal" screen.


I have to use 720p to get a picture.


Am i missing anything from OTA broadcasts by not using 1080i?


Why can't I get this to work when others can do 1080i from their DVD players?


thx,

jaymer...
 

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Are you using RGB or YUV output from your accessDTV to your LT-150?


I've got the exact same setup going at home using YUV betwen the accessDTV and the projector. (made a custom cable without the H/V lines)


It's been a while since I tried RGB, but I don't think that I was able to get 1080i working and had to fallback to 720P.


(PS: DVD players don't output 1080i. You'll only get 480i or 480p out of a DVD player)


DB.
 

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Discussion Starter · #3 ·
hi,

i dont know what a YUV cable is - i'm using the RGB cable that came with the LT150, although I'm going to make a longer RGB cable using the shielded cat 5 method.


can you point me to info about this cable you made?


jaymer...
 

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Discussion Starter · #4 ·
Otaku, i found this post of yours:
Quote:
- 1080i does work with the LT-150, but it can be fussy about the signal at times. (some PBS shows in 1080i just don't sync, period)


- 720p and 480i always seem to work, or at least I've never had a signal in these formats that didn't work.


- 1080i, when it works, looks a lot better than 720p. (most likely due to the native panel res (1024x576) being a closer match to the signal res (1920x1080))


- If you doing HD component from the accessDTV, then you have to make sure that the sync pins (13/14) are not connected. I ended up building a custom Cat5/VGA cable to do this for my setup.


i don't understand completely... point 1 says 1080i doesn't work, then point 3 says when it works, blah blah blah.


and then you say in point 3 that the native resolution of the panel is (1024x576), but its 1024x768.


and i don't understand "If you doing HD component from the accessDTV"...


1) you mean coming from the RGB plug, you can do component into the LT150?

2) by cutting the 2 pins, do i have a YUV cable now?

3) can i just use a regular VGA cable and cut the two pins on one end.


thx

jaymer...

 

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Discussion Starter · #5 ·
I took a standard VGA extension cable and snipped pins 13 & 14 and placed it inline with the supplied VGA cable that came with the 150.


What I got was a fuzzy, warped screen that seemed to have sync problems.


So, if I cut the sync lines, how is the projector supposed to display correctly? Is there something in Powerstrip I'm supposed to do?


Jaymer...
 

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Ok, blah, blah, blah indeed. Once more, here are my personal experiences making HD work with my LT-150. No guarentees implied or otherwise, YMMV.


Using RGB with a normal VGA Cable:

- 480p and 720p work fine for me.

- 1080i doesn't work most of the time. Sometimes I can coax it into working by powering down the projector and/or plugging and unplugging the cable, but I haven't found any consistent behavior.


Using YUV with a modified VGA Cable (pins 13/14 removed from both ends)

- 480p, 720p, and 1080i work fine for me.

- This is the format that I refer to as "HD Component".

- The projector will take a few seconds to notice that the signal is YUV when switching from another input. The image will be green and stretched before it re-syncs and switches to YUV.


Native Panel Resolution:

Ok, so the panel is 1024x768 in 4x3 mode. When you project a 16x9 image on it though. it only uses the middle 576 lines of the panel. Hence, my description of the native 16x9 resolution of the projector being 1024x576.


A couple of other notes:

- The LT-150 is spec'd to accept 480p, 720p. amd 1080i, although this may be referring to YUV only.

- There may be different firmware across various production runs of the LT-150. I don't think this matters, but mine is one of the early build units (November 99).
 

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When a projector is spec'd for HDTV, all it means of course is that you will get a picture displayed from a video signal in one of the common modes 480p, 720p, or 1080i. In the case of a digital projector, I don't believe any common ones can display 1080i without scaling to either the native panel resolution (for a 16X9 panel) or more commonly to the center 16X9 section of a 4X3 panel. Someday of course 1920X1080 resolution, 16X9 panels will be common and cheap, but today only a few high-end CRT projectors and a few very expensive large-venue projectors can do proper justice to HDTV.


In the case of the NEC LT150, one difference between the RGBHV and the Component Video options of the HD15 connector interface is that you can drive the RGBHV interface at 1024X768 native resolution and bypass the scaler. The scaler circuitry is of course always engaged with the Component Video option, and the result is the different behavior described above. I'm also not surprised that the machine can't scale some 1080i signals - likely they were either broadcast just marginally within specification, or perhaps even just outside spec.


Gary

 

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Otaku-


YUV is a new one for me too. I assume you mean component Y Pb Pr?


Jaymer-


I've had the same problem as Otaku displaying 1080i from the access card. It rarely works. I'm curious to see if the cable experiment works though. Even if it does, I'm concerned that removing pins 13 and 14 will adversely affect other source material like DVD playback from the HTPC. (Otaku, perhaps you can confirm or deny any such problem).


I've been content watching 720p, but wouldn't mind comparing it to 1080i. I guess in theory 1080i could (and perhaps should) look better because of the reduced scaling required; then again, I've had no real scaling complaints watching 720p on the LT150.


Kirk
 

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Again I'm not surprised ... scaled 720p (or any progressive scan video mode) would be totally free of interlaced video artifacts. There are other scaler artifacts but the most visible have always been the combing, the "Venician blinds", and similar interlacing artifacts.


Maybe someday we'll have the equivalent of DScaler for HDTV scaling of 1080i - and powerfull PCs that could keep up with the bitrate, and 1080p displays - sounds like another upgrade, I can see it coming, there's the first pang from the wallet...


Gary
 

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Discussion Starter · #10 ·
ok, good replies, but i'm trying to figure out HOW, now that I've cut pins 13 & 14 (only on one end) on a VGA extension cable, to get a functional picture.


The screens all twisted, just like when you have a PC set to a high resultion then you hook up some older monitor that can't handle the res/refresh. You can kinda see the screen, enough to operate the PC a tiny bit.


While in this bad mode, I changed from 1024x786 to the 3 lower sizes: 1024x576, 800x600 & 640x480


IN all cases, the resolution was changed, but I still had distorted screen. I verified I was at 60hz. I couldn't run Powerstrip because i'm at a loss of what to do when i CAN read the screen, much less being able to make out only about one inch high band of wavy text.


So, i throetically have the cable that Otaku used, with the exception that its not a custom cable and pins 13&14 are still plugged into the LT150, they just dont make it to the HTPC because of my "snipped" VGA extension cable. I guess this is equivalent to a YUV cable.


jaymer...




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Jaymer...

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AccessDTV (antenna on digital input, Tivo on analog)

HTPC, P3 933 (still having DVD playing probs)

NEC LT150 (awesome)

Homemade Blackout cloth screen (from Joann's Fabrics, $6 per yard)
 

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Otaku,


Good info. See much differences betwee the 1080i and 720p picture? On my LCD monitor (17"), I can't really tell the difference, but I can't try it on my LP350 as it won't accept 1080i happily.


jaymer,


I don't think that otaku was using the cable for the VGA graphics card output, but rather only the accessDTV card configured as Y-Pb-Pr, and the LT150 set to Component. If the component mode is present in the LT150, it would work, but you'd have to switch video cables between the two outputs without using the pass-thru cable.


Kei Clark
 

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jaymer,


Powerstrip won't affect anything the AccessDTV outputs because it is switching the VGA card off in order to get full-screen signal from the HDTV card.


Your LT150's panels are not programmed to run in 1080i mode (I ran into difficulties with my InFocus LP350 also), although my Princeton desktop LCD monitor accepts this signal. in order to run in the 720p mode, you normally have to set these display to maintain aspect ratio so that it will do proper 16:9. I believe most dedicated HT projectors can accept 1080i, but I can't really confirm that.


Kei Clark

Digital Connection
 

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Discussion Starter · #13 ·
Kei,

there's such limited info on this AccessDTV card thats its hard to figure all this out.


1) so, some people dont use the passthru cable?

what benefit would this have?


2) "to configure AccessDTV for Y-Pb-Pr", you mean by the output settings you can access by right clicking on the video window or by using setup?


but how do you "set the LT150 for component"?



3) Kei, I'm running on Win2k, and have sporadic wierd problems with the ADTV card.

a) tuning analog signal from my Tivo sometimes results in solid green screen

b) running for a while and trying to tune fringe channels will "piss off" the ADTV program and I can't close it (ie. no clicks respond to minimize, change to channel, etc.) - examination by the Task Manager reveals CPU @ 100%, and even after "Ending" the accessdtv task, it doesn't exit and CPU stays high - only a reboot will clean this up.

c) when trying to tune channels, sometimes I type in the channel # and it still won't tune that channel. But if I Up/Down channel to it, it will tune in.


Is this normal problems for this under win2k?

Will I have better results under another OS?

I'm 3 days over my 30 days (based on when my CC was charged) and I just started using the ADTV card this week - basically, a week delayed because the networks pushed stuff back a week cause of 9/11 stuff. I'm not convinced this card is a reliable option for me.


Jaymer...



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Jaymer...

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AccessDTV (antenna on digital input, Tivo on analog)

HTPC, P3 933 (still having DVD playing probs)

NEC LT150 (awesome)

Homemade Blackout cloth screen (from Joann's Fabrics, $6 per yard)
 

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