A Question for HDTV owners.

[Smokey]

This question specifically regard progressive up conversion capability of HDTVs (thinking of buying one) for non HD channels.

Since I watch mostly Cable [non-HD] premium movie channels, was wondering if up converting these channels (480i) to progressive signal (480p) via TV's internal prograsive up-convertor improve the picture tremendously or not?

Thanks.

[Wireworm5]

My Panasonic HDTV crt 30" defaults to 480p when not in HD mode 1080i input.So yes its a better picture than my 32" Sony Trinitron. But it uses an aspect ratio to stretch the picture to fit the widescreen, but you can also watch in 4:3 if you want.

[edtyct]

Smokey, there's no hard and fast answer to this one. If you buy a microdisplay of any kind, the TV will convert every signal that you feed it to its native resolution, usually some variation of the basic 1280x720, for simulataneous display; you won't even have an option for 480p. Virtually, everyone complains about how an original 480i signal looks when deinterlaced and scaled on a reasonably big fixed-pixel display--that is, until they realize that upconvered SD is a small price to pay for HD, though some of the results are better than others.

If your HDTV is a CRT, the results should be better, just because the TV doesn't have to cater to the demands of fixed pixels; the deinterlacing can stay within the 480 domain. Nonetheless, deinterlacing will always face certain problems--line twitter and jagged edges on film and video material--and the quality of the signal along the cable will also carry noise and various artifacts. A smaller display can emerge from the muck and mire less dirty, just because it's harder to see anything that's smaller, but the drawback is that many people claim that the benefits of HD are visible only on a screen that measures at least 40" diagonally. This is not to imply that an HD picture will not look sharp otherwise; it certainly will. But because of limitations in what the eye can resolve, it will not easily distinguish between true 480p and 1080i on a screen with less real estate.

Back to your question, an HDTV cable box will give you the option of what to feed your TV in both HD and SD resolutions. In the CRT's case, the HD default should be 1080i and the SD default 480i if that's what looks best on the analog stations, or if the TV does a better job of deinterlacing it to 480p than the cable box. You would choose 480p if it looks better than 480i on the analog stations, and if your TV permits 480p to be displayed in 4:3 (some displays force 4:3 into an incorrigible 16:9).
On a microdisplay, the choice is usually 720p (except for the recent 1080p panels) and 480p, which will automatically be scaled to the display's native resolution.

Hope that helps.

Ed

[kexodusc]

This question specifically regard progressive up conversion capability of HDTVs (thinking of buying one) for non HD channels.

Since I watch mostly Cable [non-HD] premium movie channels, was wondering if up converting these channels (480i) to progressive signal (480p) via TV's internal prograsive up-convertor improve the picture tremendously or not?

Thanks.
Basically what ed said above...I've found the upconversion on digital SD channels to be either better or equal to 480i, never worse...and usually it's a bit better, though some of the over compressed digital stations don't benefit....the picture quality in my new HDTV is particularly better than during heavy movement scenes than it was on my smaller, 32" SDTV, this I believe can be directly credited to the upconversion.

The downside is my cable provider still sends relies on analog channels for the first 30 or so stations (which luckily for me are later repeated in digital SDTV or HDTV format for the most part, and I'm not missing the women's network or weather channel that much). For these analog stations, the upconversion seems to add further interference...it's basically digitizing an analog signal, then uncompressing it at the TV end...For these, I've selected my cable box to pass the analog stations at 480i to the tv, which helps some...for optimum quality, I've also used a splitter to deliver the analogue stations to the antenna in on the TV...It's a bit of a nuisance to have to change inputs on the TV to watch 2 the analog stations we don't receive in HDTV/digital yet, but oh well...my cable provider is scheduled to do a re-alignment by July to convert the remaining analogue stations to digital, decrease the compression on some stations, and offer a few more HDTV stations as well...can't wait.

I avoided buying a large screen tv for years, until finally my fiancee surprised me with a 51" HDTV a few weeks ago...so we ordered the HDTV service, and now I can't believe I made do with out...oddly enough, it's amazing how much bigger and more theater like programs sound now. If you are like I was, an audio enthusiast first, and more oriented in that aspect of home theater, you don't know what you're missing.

[Breezer88888]

Glad to see this upconversion question. And thanks to Ed & Kexo for all the descriptive help here.
My non-HD DishNetwork satellite box is limited to an S-Video output. I don't know if this puts out 480i, but it must be displayed in its native resolution (thru my new Sony Grand Wega, KDF55WF655). I just got the TV delivered last night, so I haven't had much time setting it up - or much sleep for that matter. I thought the TV would upconvert "all" signals to 768p, so I was up late running thru the menus of the TV and my progressive scan dvd player. (Pls send me a Private Message if you can help - thanks!)
Anyway, my question here elaborates on Smokey's original one above - even though I don't know about your cable box output. If the cable/sat box does not have component video output, will any good/mediocre upconverter provide much help to an SD's picture quality? Its doubtful to me. I'm thinking that I will need Dish's HD sat box that has component video output to upgrade the non-HD signals. I'm thrilled to finally have my big RP LCD, but what's the best approach to SD?

[edtyct]

Breezer, S-video owes its slight improvement over composite to its keeping the color and black/white information separate until the TV puts it back together. It is strictly an analog format unable to deliver any resolution higher than 480i, which is anathema to your big, beautiful digital TV. The Grand Wega will upconvert the signal as you say, but the poor signal that it has to use to interpolate pixels guarantees disappointing results. You need the Dish HD receiver for component at least, and either DVI or HDMI at best.

If, for some reason, you can't get it, but still want to improve your picture, you can try to find a used DVDO iScan Plus Pure Progressive Line Doubler on ebay. The Plus had two S-video inputs, but it output deinterlaced signals either via YPbPr (which you would use) or RGB from a 15-pin jack to three separate component cables. (I just sold one that I'd have been happy for you to use). It would send a higher-order 480p signal to the Grand Wega that would withstand upconversion much better. Do some research on the DVDO, and you'll see how good it was. Nonetheless, it would only be a stop-gap measure until you were able to get the HD satellite receiver, which would be necessary for true HD and ED (480p, eventually to be converted to 1268x768 on the GW). There wouldn't be any point in you spending money on a current video processor from iScan or anyone else if the HD receiver is in your future, as it should be (though the rare bird still inserts a separate high-quality video processor between tuner and TV to further improve the non-HD signals delivered to the display; these processors generally have an input that allows HD to pass through without interference).

If any of this isn't clear, just send me a message.

Ed

[Smokey]

Thanks Wireworm5, Ed, Kexodusc and Breezer88888 for all the good info.

My cable provider offer first 70 channels in analog, and these stations show alot of noise in them. So upgrading these channels probably will not yield a better picture.

But all premium stations which are digital show an excellent picture. So any benefits that may be had will be with these channels. The TV I was looking at will be 27-32 inch Tube TV, so will keep all of your responses in mind :)