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Discussion Starter · #1 ·
Forgive me if this is a dumb newbie question, but has anyone gotten a 1920x1080 computer screen mode to display on a 1080i HDTV using either a 3rd party VGA-to-YPbPr transcoder, or a DVI-to-DVI(hdcp) cable?
 

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I think more often than not most people run with a ???? x 540 display to get their TV's to treat it like a 1080 feed. It really depends on your TV, the video card and how you are connected as to whether or not it works though I seem to remember one or two people running that resolution using either at transcoder or DVI set up.
 

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Discussion Starter · #3 ·
Thanks for my the reply, cowtown.
Quote:
I think more often than not most people run with a ???? x 540 display to get their TV's to treat it like a 1080 feed.
Do you think that's because they prefer the look of 540p, or because they're unable to do a true 1080 lines?


If you're translating a 540pixel-60Hz mode to 1080i, that doesn't seem like it would deliver the correct field offset to be considered a genuine 1080 line mode.


From what I've seen so far, it appears only the ATI component adapter and HD tuner cards with YPbPr output are capable of doing true 1080i. Perhaps I'm mistaken about this though.
 

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Powerstrip allows you to output 1080i, i figure this would be true 1080i :p


Cyphatic
 

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Discussion Starter · #6 ·
Quote:
Powerstrip allows you to output 1080i, i figure this would be true 1080i
Groovy. Has anyone gotten this to work with a VGA transcoder or DVI cable? Again, my apologies if these are dumb questions. Just tryin to understand how this stuff works.
 

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ADU,


There are very few systems capable of displaying a 1080p picture (1080*[email protected])... which is why people use the 540p trick on many direct view TVs or rear projection TVs


If you have a 9" CRT projector or a high end computer monitor (which will give you a small picture, 24" being about as big as it gets for high quality monitors), you could watch a 1080p desktop in its full glory...


With digital products such as LCD, or DLP displays or projectors, the best results are usually obtained with the native resulution of these products, and a progressive signal (720p is thus common for plasma displays...)
 

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Discussion Starter · #8 ·
Thanks, Eiffel.


I guess I shouldn't have put the P (for Progressive) in the title. What I'm really wondering is whether or not it's possible with a 3rd party VGA transcoder or DVI cable to pass a true 1080 line mode to an HDTV.


And if so, then why do most people seem to prefer 540p->1080i?
 

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Adu,


1080p should not be a problem over DVI, but the commercially available transcoders I know of won't work, as they will not go above 720p on their YPrPb (component) output
 

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Discussion Starter · #10 ·
OK. That's clear. One other teensy question...


If your HDTV isn't capable of syncing to 1080p or downconverting it to 1080i, then would you have to drop down to a lower progressive resolution like 720p, 540p, or 480p with the DVI cable as well?


Your help on this is much appreciated.
 

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Quote:
Originally posted by Eiffel
Adu,


1080p should not be a problem over DVI, but the commercially available transcoders I know of won't work, as they will not go above 720p on their YPrPb (component) output
The Radeon component dongle is advertised as 1080 capable.
 

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Discussion Starter · #12 ·
Quote:
The Radeon component dongle is advertised as 1080 capable.
Understood, Lava. What I'm tryin to get a handle on here are the capabilities of devices other than the Radeon adapter... namely 3rd party transcoders like the Keydigital KD-VTCA2, or Audio Authority A960, or using a direct DVI input. Sorry I'm doin such a clumsy job.


Here's my basic question though at this point:


If your HDTV isn't capable of syncing to 1080p or downconverting it to 1080i, then would you have to drop down to a lower progressive resolution like 720p, 540p, or 480p with the DVI cable as well? Or is it possible for a DVI cable to pass an interlaced signal like 1080i from a computer to an HDTV?
 

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I believe transcoders are capable of 1080i if your device will output 1080i. They have no means of stripping half the fields if your device is outputting 1080p, and I believe the real problem is that MANY device drivers do not support interlaced resolutions in WinXP. The radeon in conjunction with the HDTV dongle is one of the few exceptions because it enables resolutions otherwise unavailable. If anyone has successfully forced an interlaced resolution in XP, then I'll stand corrected, but I believe this is one of the key problems.
 

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LLF, Are you sure of this? Per ATI's literature, it is only 1080i capable:

Multiple component video modes available for use.

The HDTV Component Video Adapter will support:

480i (interlaced)

480p (progressive)

720p

1080i



----

ADU,


Most consumer grade HDTVs won't sync to 1080p... and they won't be able to downcovert such signal either. Typically they only accept a limited number of input signal formats: 1080i, 480i, 480p and, if you're lucky, 720p.


One can fool such HDTVs into displaying a 540p signal (which looks like a 1080i signal for the TV's perspective), which is why this resolution is commonly used.


As you indicated, these resolution limitations apply regardless of the type of connection (HD15, 3 or 5 RCA connectors, DVI, etc.) or coloring scheme (RGB or YPrPb)... so yes, on has to drop to a lower resolution over DVI as well
 

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Discussion Starter · #15 ·
I think Lava meant just 1080i for the Radeon, Eiffel.


I'm sorry that 'P' in the title of this thread is causing such confusion, because my interest here is simply whether or not it's possible to get a true 1080 line mode from computer to HDTV (interlaced or otherwise) using techniques other than the ATI adapter.


From what's been said, it sounds as though the hardware is capable of transmitting 1080i, but many device drivers simply may not support this.


One thing I'm still unclear on (which is probably irrelevant at this point)...


Are DVI cables only capable of transmitting progressive signals? Or could they pass an interlaced signal like 1080i to an HDTV (provided you could coax a computer into producing it)?


Many thanks for all the replies helping to clarify some of this.
 

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I am using a 1920x1080i timing in Poerstrip with a Geforce4 ti4600 and a home-made video transcoder (RGBHV to Y-Pr-Pb) without issues. Not sure why everyone else is having troubles. I never have owned a commerically available transcoder though, nor an ATI video card.
 

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"There are very few systems capable of displaying a 1080p picture (1080*[email protected])... which is why people use the 540p trick on many direct view TVs or rear projection TVs"


Pretty much what I was going to say, though as systems and video cards get better you'll see more of them able to do that resolution fine.


As far as transcoders displaying 1080i it shouldn't matter, they should (from what I have read and understood) just pass through the display of whatever is being thrown out the VGA port on your video card through the component cables. It is more of an analog to analog "switch" than any magical device really.


It is important to note that while the ATI dongle does support 1080i it will limit you to 480p for copywrite protected source material. That is of course not mentioning any third party software that could be used to defeat the macrovision protection on said protected source material.


"Are DVI cables only capable of transmitting progressive signals? Or could they pass an interlaced signal like 1080i to an HDTV (provided you could coax a computer into producing it.)"


Like component cables, the DVI will pass whatever is given to it, progressive or interlaced.
 

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Discussion Starter · #18 ·
Quote:
Like component cables, the DVI will pass whatever is given to it, progressive or interlaced.
I see, cowtown.
Quote:
I am using a 1920x1080i timing in Poerstrip with a Geforce4 ti4600 and a home-made video transcoder (RGBHV to Y-Pr-Pb) without issues. Not sure why everyone else is having troubles.
debennett2,

I think you're the only one I've run across that's been able to do this. Like you, I wonder why others are having difficulty. Perhaps some other video cards simply dislike the 1920x1080i timing?
 

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Discussion Starter · #19 ·
Actually, I just looked at the Key Digital KD-VTCA2 specs again, and as Eiffel originally mentioned it appears to be limited to the following computer resolutions: 640x480, 1280x720, and 960x540 which is output as 1080i. 1920x1080i isn't listed as a supported computer resolution.


Their specs are a little confusing though, because in the fine print it also says this:


"In auto mode both units automatically adjusts for ANY incoming video scanning format. Output scanning format is always the SAME as input scanning format."


...which would seem to imply that if your computer source can do 1920x1080i, that the transcoder would pass it thru to an HDTV unchanged. (?)


However, based on the experience of users here on AVS, it would appear this doesn't work, or simply isn't preferred.
 

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Reply to ADU:

"I think you're the only one I've run across that's been able to do this. Like you, I wonder why others are having difficulty. Perhaps some other video cards simply dislike the 1920x1080i timing?"


I have gotten 1920 x 1080i timing output from my Radeon 9700 using the DVI output, into my Hitachi 57GWX20B RPTV's DVI input.


Granted there are still issues, I can't use video overlays correctly, and text looks pretty bad. For viewing anything other than native 1080i HDTV content I would recommend 960 x 540p, it is just simpler. But for native 1080i it is theoretically better.


There is a complete thread specifically about 1080i through DVI here:
http://www.avsforum.com/avs-vb/showt...hreadid=249862


And a "custom resolutions" thread here to get powerstrip timings:
http://www.avsforum.com/avs-vb/showt...hreadid=206854
 
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