Should I let my TV upconvert resolution?

[roxy99]

I have a Hitachi 46in 16:9 RPTV hooked up to DVI on a Geforce Ti4200 video card. I am set up in VRM9 mode and finally after weeks of tinkering got the color, contrast, brightness set optimally both on the Nvidia side and the TV side.

I am using only Standard definition satelite on S-Video in. I realize that the input source on SDTV can only be 480i. The Nvidia drivers allow me to set the follwowing resolutions: 1920 x 1080i : 1280 x 720p : 850 x 480i/p.

The TV recognizes all of these signals. My preference gravitated to the max resolution of 1080i, however doing so limited my TV from being able to use is expanded mode of 4x3 source material. Basically the 4:3 expansion stretches the screen to eliminate black side bars and thus not damage the TV by uneven burnin. SageTV's Fill mode makes everyone appear with squished faces and short and fat.

I decided to set my Nvidia resolution to a low 850x480i and now my TV 4:3 expand mode works.

Is there any advantage to force the HTPC to scale 1080i on a SD signal? My TV automatically upconverts a 480p signal to 1080i, so I suppose its a question of what upscales better- Nvidia or the TV? My take on it is that 480i is the input and it doesn't matter how many times you upscale, it will still have 480i lines of resolution.

I can't seem to see any difference in PQ. Should I?

[blade]

It depends on how good the scaling in your TV is compared to your Sage box. My HTPC does a much better job of scaling that my TV does. Watching videos in Sage actually looks better than straight cable. I'm using SDTV analog cable.

I have a 57" Hitachi RPTV with a 6600GT connected via DVI and can tell a huge difference between sending 480i and 720p or 1080i to the TV. Personally I ended up using 720p and let my TV scale it to 1080i. The desktop is too small and fuzzy when running at 1080i which makes the computer useless for anything other than Sage. 480i just looks horrible and the desktop is too big. If I were never going to play games or use the desktop I'd probably be running at 1080i instead.

[roxy99]

Originally Posted by blade

It depends on how good the scaling in your TV is compared to your Sage box. My HTPC does a much better job of scaling that my TV does. Watching videos in Sage actually looks better than straight cable. I'm using SDTV analog cable.

I have a 57" Hitachi RPTV with a 6600GT connected via DVI and can tell a huge difference between sending 480i and 720p or 1080i to the TV. Personally I ended up using 720p and let my TV scale it to 1080i. The desktop is too small and fuzzy when running at 1080i which makes the computer useless for anything other than Sage. 480i just looks horrible and the desktop is too big. If I were never going to play games or use the desktop I'd probably be running at 1080i instead.

Blade,

Thanks for your input. It could also be your video card is better than mine. I'd like to do another experiment and try 1080i. Since we are both using Hitachi RPTV's and Nvidia video cards chances are I too should see a marked improvement. I just remember not being wowed when I had it set at 1080i. Maybe I was using the wrong vieo rendered, currently I have VMR9 enabled, although my video card is only a DX8 card so that could be the reason we have different results.

Is your video card set to enable Antialiasing?

The most important issue for me how are you able to fill your 16:9 screen without distortion? That is my only concern.
Does SageTV have a 4:3 extended mode similar to our Hitachi's?

[stanger89]

Odds are, youre best picture will come from setting your video card to the highest resolution (for a CRT like yours) your TV supports (you'd use native res on a digital LCD/DLP) and letting the PC do the deinterlacing/scaling.

Oh, and an SD source won't "wow" you, regardless of the resolution you display it at

[roxy99]

Originally Posted by stanger89

Odds are, youre best picture will come from setting your video card to the highest resolution (for a CRT like yours) your TV supports (you'd use native res on a digital LCD/DLP) and letting the PC do the deinterlacing/scaling.

Oh, and an SD source won't "wow" you, regardless of the resolution you display it at

So true. Funny thing is, SageTV or direct hookup of Satelite, I find my plaim old 27inch non-HDTV regular tube TV to give a crisper display for SDTV. For DVDs, the Hitachi RPTV is the clear winner.

Everyone seems to describe 480i as crap compared to 720p/1080i. I would'nt call it crap. On the other hand I was not overly impressed when I tried setting my PC to a resolution of 1080i. Basically I could'nt spot the difference that people seem to swear by. So I wonder if I am doing something wrong.

Since it is SDTV there won't be much of a wow factor. Perhaps since Blade is using a 57 inch display the increase PQ from 480p to 720p is more visible. Yet even on a coax video in, Blade has a much better PQ on 1080i.

My conventional wisdom has tended to think of upscaling like zooming whereby you are not really increasing the resolution, you are only magnifying the pixels of the source mpeg2 stream. The input is still SDTV whatever resolution its being scaled to.

My display is only 46 inches and so maybe its not as noticable compared to a 57 inch display. Or maybe I need new glasses

If Sage supported a stretch mode simalar to the non-linear stretch mode of my Hitachi, then I would set my PC to 1080i and let Sage stretch the 4:3 image to 16:9. I can't get used to squished faces produced by using the 'Fill' aspect mode of Sage.

Any suggestions on why I am not seeing as huge a difference in 480p mode vs 1080i

[stanger89]

Originally Posted by roxy99

So true. Funny thing is, SageTV or direct hookup of Satelite, I find my plaim old 27inch non-HDTV regular tube TV to give a crisper display for SDTV. For DVDs, the Hitachi RPTV is the clear winner.

Yup, "crispness" is inversely related to screen size and directly related to resolution DVDs can provide more resolution than SDTVs can display, hence they look better on an HD display.

Everyone seems to describe 480i as crap compared to 720p/1080i. I would'nt call it crap. On the other hand I was not overly impressed when I tried setting my PC to a resolution of 1080i. Basically I could'nt spot the difference that people seem to swear by. So I wonder if I am doing something wrong.

Hard to say, on my Mits, the scaling/deinterlacing sucks, such that when deinterlaced/scaled by my HTPC to 1080i everything was noticeable smoother (less jaggies).

My conventional wisdom has tended to think of upscaling like zooming whereby you are not really increasing the resolution, you are only magnifying the pixels of the source mpeg2 stream. The input is still SDTV whatever resolution its being scaled to.

Yes and no. No, you don't increase the resolution, but it's not as simple as just magnifying pixels either. The information is interpolated when scaling happens, such that the scaled image should look just like unscaled one. Let me explain better, or try at least (it gets into sampling theory ).

Say you have a big image (say 1920x1080), and you shrink it down (say 720x480). Say you scale it back up (to 1920x1080) using a "good" method. The only difference between the original image, and the upscaled one will be the loss of fine detail that the 720x480 version couldn't store. You wouldn't have a stair-stepy, blocky picture, you'd have a smooth picture without the fine detail.

The technical-ish explanation would be that the conversion from 1920x1080 to 720x480 would be like running the image through a lowpass filter, removing the high frequency information. The upscaling from 720x480 to 1920x1080 would restore the resolution lost, but not the high frequency information.

My display is only 46 inches and so maybe its not as noticable compared to a 57 inch display. Or maybe I need new glasses

Maybe it does a decent job scaling itself.

If Sage supported a stretch mode simalar to the non-linear stretch mode of my Hitachi, then I would set my PC to 1080i and let Sage stretch the 4:3 image to 16:9. I can't get used to squished faces produced by using the 'Fill' aspect mode of Sage.

You could use ffdshow to do the non-linear stretch.

Any suggestions on why I am not seeing as huge a difference in 480p mode vs 1080i

It won't be a huge difference, it would be a small one, and it will depend on if your TV was/is doing a bad job to start with or not.

[blade]

The difference may very well be in the video card, decoder being used, or some other setting. I guess it could even be the way your TV is calibrated. It could also be that I'm noticing things you aren't. I know some people notice things in their setup that honestly I can't spot.

If I use 480i the picture is very fuzzy and the colors look washed out. You mentioned switching between 480p and 1080i, I notice less difference between those two than when switching from 480i.

I can't tell much difference between 720p and 1080i. Both are much sharper and the colors look better. I'm sure there are people here that could tell the difference, but it all comes down to individual perception. I notice flaws, now that I've used and tweaked Sage, that I never noticed before. If you can't tell the difference and the PQ is acceptable to you don't worry about it. If you start to see the flaws it'll drive you nuts.

Your 480i content is going to be upscaled one way or another and you might as well use the best scaling available to you. The content isn't going to wow you, but the better the scaling the better the end result will be.

I absolutely hate non-linear stretching, so that isn't an issue for me. It distorts the image worse IMO than linear stretching. Try watching scenes with a lot of panning and you'll see what I mean. You can literally see the actor's body change shape as the camera pans. It looks like you're watching a reflection in a funhouse mirror.

Like I said before it just depends on the individual who's watching the show. We all have different opinions on what looks good or bad.

You don't have to use fill mode to stretch 4*3 to fit the 16*9 screen. I have my 4*3 aspect ratio setup to stretch 4*3 content to fit the screen to my taste and I have 16*9 setup to stretch the letterboxed shows. I use source for my imported videos which are usually in 16*9 or some other common DVD aspect.

There are 4 aspect ratios and each can be modified to make the picture fit the screen better. None of mine are "correct" so I'm not the best person to give advice about setting up aspect ratios. Mine are set where they fill the most screen while still looking good to me. They definetly don't maintain the correct aspect.

[blade]

Originally Posted by stanger89

Hard to say, on my Mits, the scaling/deinterlacing sucks, such that when deinterlaced/scaled by my HTPC to 1080i everything was noticeable smoother (less jaggies).

I have a Hitachi and a Mits. Both 57" and my Hitachi has much worse deinterlacing/scaling than the Mits. The jaggies are awful on both, but the Hitachi is much worse. Without a doubt my HTPC does a better job than either of the sets. Part of the "huge difference" I see may come from my hatred of jaggies.

[roxy99]

Originally Posted by blade

The difference may very well be in the video card, decoder being used, or some other setting. I guess it could even be the way your TV is calibrated. It could also be that I'm noticing things you aren't. I know some people notice things in their setup that honestly I can't spot.

If I use 480i the picture is very fuzzy and the colors look washed out. You mentioned switching between 480p and 1080i, I notice less difference between those two than when switching from 480i.

I can't tell much difference between 720p and 1080i. Both are much sharper and the colors look better. I'm sure there are people here that could tell the difference, but it all comes down to individual perception. I notice flaws, now that I've used and tweaked Sage, that I never noticed before. If you can't tell the difference and the PQ is acceptable to you don't worry about it. If you start to see the flaws it'll drive you nuts.

Your 480i content is going to be upscaled one way or another and you might as well use the best scaling available to you. The content isn't going to wow you, but the better the scaling the better the end result will be.

I absolutely hate non-linear stretching, so that isn't an issue for me. It distorts the image worse IMO than linear stretching. Try watching scenes with a lot of panning and you'll see what I mean. You can literally see the actor's body change shape as the camera pans. It looks like you're watching a reflection in a funhouse mirror.

Like I said before it just depends on the individual who's watching the show. We all have different opinions on what looks good or bad.

You don't have to use fill mode to stretch 4*3 to fit the 16*9 screen. I have my 4*3 aspect ratio setup to stretch 4*3 content to fit the screen to my taste and I have 16*9 setup to stretch the letterboxed shows. I use source for my imported videos which are usually in 16*9 or some other common DVD aspect.

There are 4 aspect ratios and each can be modified to make the picture fit the screen better. None of mine are "correct" so I'm not the best person to give advice about setting up aspect ratios. Mine are set where they fill the most screen while still looking good to me. They definetly don't maintain the correct aspect.

You are correct about the edge distortion caused by non-linear stretch.

I will give 1080i another try. I realize that that the aspect ratio modes of Sage permit for a linear stretch. Or mayme ffdshow as Stranger was saying.
I also hate the jaggies.

BTW, I think resolution wise this is the ranking from lowest to highest:
480i
480p
540p = 1080i
720p
1080p

So 480p is actually only one step lower than 1080i (which is the equivalent to 540p). That explains your noticing a larger PQ decline in 480i. Whereas your 720p is actually superior in resolution to the 1080i.

I think I will try 720p. I'll have to start over again with overscan correction but at least I should'nt have to tough my brightness/contrast levels.


Stranger,

I think I understand from your explanation of scaling why it works. Good explanation, thanks.

[roxy99]

Just for kicks I went ahead and set my pc back to 720p, and you know what,
now that I know what to look for I can see that there are noticably fewer jaggies in 720p vs 480p mode I was using previously.

To have the best possible de-interlacing, should I use the Sage Mpep2 decoder or the default. The Sage Mpg2 decoder allows Dscaler de-interlacing and I don't know what is better.

[stanger89]

Depends on what "Default" is.

[roxy99]

Originally Posted by stanger89

Depends on what "Default" is.

Well I don't know. Sage lists it as 'default' . Is there somewhere in my Windows control panel I can find out what default is? Under video codecs I suppose.

All I can say is 'default' doesn't stutter whereas the Sage decoder (probably software decoder) stutters.

[blade]

You can check it using this.

[grooves12]

I'm not sure what leads you to beleive that 1080i and 540p are equal because they are NOT the same. 1080i has 1080 lines of distinct information... exactly the same as 1080p. The difference is just in the way they are displayed.

It is true however that some TV's with poor scalers will do a simple line doubling of 1080i therby downscaling it to 540p, but most will properly show the full 1080 lines of resoltion, and it should look better than 720p when shown properly.

[Rogue9]

I've got a 256MB GeForce 6600 outputting to my 51" Hitachi HDTV via DVI > HDMI cable. I'm outputting at 1280 X 720. 90% of my viewing is SDTV.

I am HIGHLY impressed with the picture quality from my HTPC, even on SD shows. The difference between it and the standard analog cable signal is like night and day.

As far as Aspect Ratios, I leave my TV set to 16:9, and I switch my AR around in Sage based on content. Most newer shows are letterboxed anyway, so I adjusted my 16:9 AR in Sage to something like 135% Vertical and 105% Horizontal (don't remember exactly, I'm at work). That removes the black bars from all 4 sides, for me. For older shows (non-letterboxed) I use a custom 4:3 AR. I have no idea what the numbers are, but I played around with the Horz & Vert zoom %'s until I was happy with the picture output (little to no distortion).

[roxy99]

Grooves12,
The info was something I read one time- I think in AVR forums. Basically 1080i is not the same as 1080p. My Hitachi does not support 1080p so I'd have to fiddle and see what's better 720p or 1080i. Who really knows- so many variables.

Edit: here is technical info for you: http://alvyray.com/DigitalTV/Naming_Proposal.htm

Rogue9,

I like your suggestion of a variable Horizontal and vert stretch to suit viewing conditions. I've also notice that allowing a little overscan is ok if you want to eliminate black bars. I've decided that 1" black bars is a minimal risk of burnin(even if it does occur a 1" zone of damaged phosphors will not be a big deal)

Out of curiosity what mpeg-2 video decoder do you use?

[stanger89]

Originally Posted by roxy99

Grooves12,
The info was something I read one time- I think in AVR forums. Basically 1080i is not the same as 1080p. My Hitachi does not support 1080p so I'd have to fiddle and see what's better 720p or 1080i. Who really knows- so many variables.

1080i may, or may not be equivalent to 1080p, it depends on a number of things.

In the general case of broadcast OTA, they aren't quite the same, because to generate the 1080i30 the original 1080p30 (or 1080p24) source is vertically filtered to reduce flicker/jitter, or in the case of video, it's sourced as 1080i30.

For PC output, 1080i has the same vertical resolution as 1080p (it's not vertically filtered), but since it's interlaced, it's tricky because you're only getting temporal resolution of 30fps. For a PC output, 1080i is roughly equivalent to 1080p30, much more so that than 540p.

The other thing is things like HD-DVD, which are 1080p24 sourced, and stored, without vertical filtering, but are output as 1080i30. It's possible to reconstruct the original 1080p24 from the 1080i30 stream, so in this case 1080i is exactly equal to 1080p.

[roxy99]

Originally Posted by stanger89

Depends on what "Default" is.

Stranger,
Having downloaded that application, upon running it all it tells me is that my mpeg-2 codecs are 3 Nero codecs and Cyberlink. I know that Cyberlink is an option in the Mpeg2 decoders of sagetv, so then what is default?

Cyberlink power DVD must have installed the mpeg2 codec so default must be that. Any way to know - the software doesn't say.

[stanger89]

"Default" in Sage is the "Preferred" decoder, Deccheck should tell you that. Of course given what you list you don't have any "good" decoders. You might want to try nVidia or Dscaler 5+Dscaler Deinterlacing (if Sage lets you do that).

[Rogue9]

Definately give the NVidia PureVideo Decoders a try. Thats what I'm using and I am very impressed. I use them for SDTV, HDTV, and DVD playback, and I'm very pleased with the results.

I'm not sure if they still offer it or not, but there used to be a trial version for the decoders at NVidia's site. If its still there, its definately worth a look.

Also, I'm using the SageMC STV, and set up a "custom" AR for 4:3 and 16:9. I don't remember if that option is available in the Normal STV or not. But I believe Nilem has an AR STV import utility that will allow you to do the same thing if your STV does not have the option of editing the zoom amount for each AR. You can also set it to select a specific AR for each channel, so that all shows on that channel will auto switch to a certain AR. Look for it in the customizations forum.