[JerryR]

I'm planning on buying a Panasonic HDTV (PT-50LC13) and setting up an HTPC system connected to it running Myth. The tv has a DVI port through which I'd like to connect the PC for best picture quality. The chipset on the PC (SiS 315/301B) does not look like it can output at 1280 X 720 (the tv's native resolution). It can do close (1280 X 768, 1024 X 768, 1280 X 960, 1280 X 1024), but not 1280 X 720.


I've been unable to find any good documentation on what kind of input you can put into a DVI port, so I hope someone will be able to answer some basic questions that I've been unable to find answers to on my own:


Do HDTV DVI ports only accept the standard 480p/720p resolution feeds? Does it depend on the tv?


Can you damage the tv by sending improper resolution signals through its DVI port?


If the tv can handle other resolutions, which one is likely to give the best picture quality - 1280 X 768?


If the tv has to compress or stretch the signal to display it, will the DVI option still give the best PQ? Or would I get better PQ by going through the tv's VGA port, which the Panasonic site says can handle up to XGA resolution?


Just about all my HDTV knowledge is from fancy book lernin (i.e. surfing) over the last 3 weeks - I don't have much hands-on experience. I do have years of experience in the analog video realm though. It can be very difficult sometimes to find answers to what should be basic questions. I have read through all the faqs and other info I can find, but there's not a lot of hard DVI info that isn't on the cursory side or assumes you know a whole bunch more stuff and leaves out details.


Thanks.

 

[JerryR]

Bump.

 

[dfc106]

Quote:

Originally posted by JerryR Do HDTV DVI ports only accept the standard 480p/720p resolution feeds? Does it depend on the tv?

Depends on the TV. DVI itself has no restrictions on resolution, except that single link cables only support up to 1920x1080

Quote:

Can you damage the tv by sending improper resolution signals through its DVI port?

Probably not. The signal should just be rejected if its not supported. But its best to read your manual and stick to the resolutions you know are supported.

Quote:

If the tv can handle other resolutions, which one is likely to give the best picture quality - 1280 X 768?

Use Powerstrip to get your native resolution. Do a search here. You'll find lots of information on it.

 

[JerryR]

There are lots of specific questions answered about Powerstrip on the forum, but no help file or general information about what it can do over a DVI port. Can Powerstrip determine all the resolutions a DVI-connected device is capable of displaying?


In any case, since I don't have the tv yet, can someone on the forum who has a Panasonic PT-50LC13 run Powerstrip on it to find out the native resolution and what resolutions it supports? Or look at their manual and see if it talks about what resolutions it supports?


> But its best to read your manual and stick to the resolutions you know are supported.


Well sure, I'd like to do that, but as I said, the computer doesn't output at 720p.

 

[dfc106]

Powerstrip doesn't care what kind of cable you use to connect your PC to your monitor. Powerstrip just allows you to output whatever resolution you want, regardless of the resolution options you get from your video card drivers. The PT-50LC13 has a native resolution of 1280x720 (ie: 720p). So once you have everything connected, install Powerstrip and add the 1280x720 Standard HDTV resolution. That's it. You'll be outputing a perfect 1:1 pixel map to your TV and the TV's internal scaler won't be used at all.

 

[JerryR]

Dave,


Thanks for the reply. How can Powestrip set resolutions that the hardware doesn't support? Can you explain how this works?


Btw, I live in West Chester, work in Downingtown (Boot Road, one building down from the post office).


Edit: In this question, I'm talking about a digital signal. Can the tv accept both digital and analog signals through the DVI? A digital signal would still have better quality if it can, I assume.

 

[johnnyt]

I just bought the Panny and am looking forward to attaching a PC. However, I have the same ti4200 nvidia card mentioned so it looks like I'll be overscanning .


I have so many questions, but let's start with the basics: what cable will I need to make the PC to TV DVI connection? Do I just ask for a 'DVI cable'?

 

[JerryR]

johnnyt,


Can you tell me if it says anything in the manual about requirements, restrictions, or warnings about what kind of resolutions or signals the DVI port accepts?


As far as a cable, I think you need either a DVD-D or DVI-I cable, and I don't think it matters if it's single or dual. But you better confirmation from someone else, since I'm no expert.

 

[Newmie]

Quote:

Originally posted by johnnyt I have so many questions, but let's start with the basics: what cable will I need to make the PC to TV DVI connection? Do I just ask for a 'DVI cable'?

Your TV should have came with a DVI cable (atleast mine did) I should also come with a VGA cable too.


newmie

 

[dayvo]

One of the cool things about the 50LC13 is that it has a true VGA/XGA connector. If you have too much trouble getting DVI to work, try an analog RGB cable at 1280 x 720p (with powerstrip, if necessary) or 800x600 or ...

 

[JerryR]

That's true, I can always fall back on an analog signal. The 50LC13 specs say it can only accept up to XGA through the VGA port, which is 1024 X 768, so I would expect some picture conversion would have to go on if you started with a 720p signal.


The computer I want to use (Pundit) has no component out, but I could use a VGA to component converter to output 1280 X 720p into the component inputs on the Panasonic.


I'd still like to find out some more specifics about the DVI method though.

 

[johnnyt]

Has anyone here tried the VGA connection? How does the quality compare to that of the DVI? I'll find out in a few days when my set gets here, but I'd love to hear the experience of others...


Good to know the DVI/VGA cables are included! I already downloaded the manual off the Panny site HERE!


I'm not sure I'm reading the manual correctly, but looks like the recommended settings are:


800x600 (56,60,72,75,85Hz) for PC signals

1280x720 (60Hz) for DTV signals


All the entries for 1024x728 have an asterisk by them, which indicates they are possibly unstable.


You can bet I'll be trying 1280x720 VGA and DVI. I'll let you know how it goes.

 

[JerryR]

johnnyt,


Thanks for that link to the manual! For some reason I couldn't find that on Panasonic's site. From the table on page 21, there are four resolutions in addition to the standard HDTV formats that it will accept through the DVI port - 640X400, 640X480, 800X600, and 1024X768, although as you mentioned, 1024X768 is an unknown. The manual is careful not to say how that will display, only that un-asterisked resolutions will give a "beautiful, stable picture". Probably means the tv will have to mess with the picture to make it fit.


So that leaves me with my question about how Powerstrip can set digital resolutions that its video hardware is not able to generate on its own, as dfc106 says. Anyone?

 

[dfc106]

Quote:

Originally posted by JerryR Dave, Thanks for the reply. How can Powestrip set resolutions that the hardware doesn't support? Can you explain how this works?

Well, I can't explain how Powerstrip works, but as I understand it the limitation is not in your hardware it's in your video card drivers (ie: software). Powerstrip is able to override the options the driver allows. Trust me, I've used it, it works.

Quote:

Btw, I live in West Chester, work in Downingtown (Boot Road, one building down from the post office).

Ha, small world. I moved from West Chester to Downingtown last year. I live just down the road from the post office. You're lucky I just finished the drywall in my theater. I might have had to recruit you.

Quote:

Edit: In this question, I'm talking about a digital signal. Can the tv accept both digital and analog signals through the DVI? A digital signal would still have better quality if it can, I assume.

It depends on the kind of DVI port on the TV. A DVI-I port takes either, a DVI-D takes only digital, a DVI-A only takes analog (don't know of anything that uses that). Same goes for cables. Yes, digital theoretically would have a better picture. Less D/A and A/D conversions. But personally, I've only been able to sync up my projector in 1280x720 using the DVI analog signal (still trying with the DVI digital signal) and the picture looks fan-freaking-tastic. Hard to believe it could get any better. Of course, that's what I thought when I first hooked it up to my old DVD player.

 

[dfc106]

Quote:

Originally posted by JerryR The manual is careful not to say how that will display, only that un-asterisked resolutions will give a "beautiful, stable picture". Probably means the tv will have to mess with the picture to make it fit.

Digital displays aren't like CRT. All digital displays (eg: LCD, DLP, etc) have 1 native resolution. In your case its 1280x720. Any other supported resolution will be scaled by the display to 1280x720. That's why 1:1 pixel mapping is so important. Let the PC do the scaling, and always output to the display in 1280x720 to get the best possible picture.

 

[JerryR]

>Well, I can't explain how Powerstrip works, but as I understand it the limitation is not in your hardware it's in your video card drivers (ie: software). Powerstrip is able to override the options the driver allows. Trust me, I've used it, it works.


Ok, then it doesn't sound like the Pundit will be able to output a digital signal at 720p. According to this page:

http://www.winischhofer.net/linuxsisvga.shtml


the hardware it uses (SiS 315 with 301B video bridge) is incapable of 1280 X 720 digital out.


Looking at the Panasonic manual, the pinout of the DVI port doesn't show any analog pins, so it must be DVI-D only. So what is my best option for optimal picture quality? It sounds like I have two choices. The manual has a mark by the 1280 X 720 resolution that indicates "signal that can be input with DIGITAL IN", but it doesn't say "only" digital in. So perhaps the panny can take that through the VGA port. The other is to get a VGA to component converter and go that way. Am I right in thinking those are the best two? Which is likely to be better?


johnnyt or dayvo (or anyone else with a PT50LC13), can you check whether the tv will display a 1280 X 720 signal well through the tv's VGA port?

 

[johnnyt]

Jerry,


I am in limbo waiting for the set to arrive. I plan to try both DVI and VGA @ 1280x720 @60Hz and will post the results.

 

[orogogus]

Quote:

Originally posted by dfc106 Digital displays aren't like CRT. All digital displays (eg: LCD, DLP, etc) have 1 native resolution. In your case its 1280x720. Any other supported resolution will be scaled by the display to 1280x720. That's why 1:1 pixel mapping is so important. Let the PC do the scaling, and always output to the display in 1280x720 to get the best possible picture.

Assumption here is that the PC is going to do a better job than the scaling electronics of the display, but being how this is the HTPC forum...

 

[JerryR]

johnnyt,


Excellent, I'll eagerly await your results. Any day now I'll be putting in an order on my set.

 

[johnnyt]

Well the Panny came yesterday (finally!). Today I hooked up the PC for the first time. As expected, got overscan on 1280x720 via both DVI and RGB (VGA). Both pictures looked crisp. DVI looked a bit better but RGB connection was quite good. I tried a bucnh of other resolutions, including some from Powerstrip that others have tried. None were close to looking as good.


Also of note was I checked out single version of RTCWolfenstein and looked fantastic - no cropping!. It puts it in 4:3 ratio, but you can change aspect to stretch it. I had it connected to optical audio to my Yamaha receiver /JBL speakers and the whole experience was very, very impressive.


My early conclusion is that I can live with overscan in windows, as mostly I'm doing e-mail, surfing, etc., for which I can use positioning to counteract overscan.


Will attempt to post some pics: