HD on a non-HDTV? It works, but why?

[Sulaco]

I started off with an HDTV and an HDTV cable box. I used a component video cable to connect them. I was not happy with HD so I returned the TV and got a non-HDTV instead. Now, I can watch all of the HDTV channels my local cable company broadcasts on my non-HDTV. I set the box to pass-through a 480i and then set my TV according to fullscreen or widescreen, depending on what is being broadcast. The video quality is better than standard digital cable and I get surround sound on most everything.

Is this normal? I don't know much about HD so I am not sure but it is nice to be able to watch a movie in a standard cable channel in better quality audio & video.

[Marco33]

I'm not sure why you would get the HD box and HD channels to play them through you NON HD tv.

[gshelley61]

A standard, interlaced TV with component YPbPr 480i inputs will display any 480i component video source, even your downscaled HD cable channels (which are being converted from either 1080i or 720p)

There's a dirty secret in the consumer electronics industry... many of the so-called "HDTV Ready" sets are not actually capable of displaying HD resolution - but they can accept a 720p or 1080i HD signal.

The vast majority of rear projection and direct view CRT "HDTV Ready" sets being sold don't have anywhere near 720 or 1080 horizontal lines. The lower priced plasma screens that you see are EDTV resolution, which is 853x480p (again, not HD), but they will accept a 720p or 1080i signal, downscale it and display the image.

Only the higher priced plasmas are actually at least 1280x720p native resolution, one of the two HDTV standards (some are 1366x768). LCD and DLP rear projection units are also 1280x720p. There are no 1920x1080i (the other HD standard) plasmas available yet, although some prototypes have been built.

As for 1920x1080 displays that can be purchased now, there are some multimedia computer monitors with that resolution or higher. There was a Toshiba LCos RPTV with 1920x1080p resolution, but it has been discontinued (it had problems).

Samsung will introduce a 1920x1080p DLP later this year. There are very expensive 9" CRT-based data projectors still being made with 2500x2000 native resolution (used for ultra high-end home theater). Finally, there are super-high resolution graphics and medical monitors with native resolution even higher than that.

My point is that the TV you are using may in fact be close in native resolution to many of the "HDTV Ready" models out there anyway.

[Sulaco]

Very interesting. But, not suprising. So, how do I determine the native resolution of my television and can I buy a seperate HD decoder to use with this set if the resolution is similar to lower end units available with decoders built-in?

[gshelley61]

You might be able to get the screen resolution specs of your TV by contacting the manufacturer. Otherwise, a SMPTE resolution test pattern (available on DVD test discs, check eBay) will show you approximately what you've got.

There are digital video scalers that can upconvert and downconvert practically any type of video signal, but they are very expensive. It's way less money to buy a new HDTV ready set. Wal Mart has just started selling Sanyo 4:3 and 16:9 HDTV ready sets with built in HDTV over-the-air tuners for less than $800... that is a great deal and they are supposed to be very good quality.

[iantri]

Err.. this whole thread is somewhat questionable in accuracy.

The vast majority of rear projection and direct view CRT "HDTV Ready" sets being sold don't have anywhere near 720 or 1080 horizontal lines. The lower priced plasma screens that you see are EDTV resolution, which is 853x480p (again, not HD), but they will accept a 720p or 1080i signal, downscale it and display the image.

That is a rather curious thing to say. Yes, EDTV sets are a bit of a scam, and some sets can only natively do 720p and downconvert 1080i to a bastard 720i mode, but the majority of HDTVs accept and properly display a 1080i signal. That doesn't neccessarily mean that the image quality will be high enough to see 1080 lines, but it WILL scan 1080 lines.

Very interesting. But, not suprising. So, how do I determine the native resolution of my television and can I buy a seperate HD decoder to use with this set if the resolution is similar to lower end units available with decoders built-in?

The whole matter of TV resolution is misleading since analog televisions, by nature, do not have a fixed resolution. Your NTSC television has 525 scanlines. Horizontal resolution depends on the quality of the tube. It displays analog NTSC. That's all. An HD decoder box, as you've discovered, downconvert to 480i which is the only resolution possible for an NTSC television to display.

There are digital video scalers that can upconvert and downconvert practically any type of video signal, but they are very expensive.

What, exactly is the point of buying a digital video scaler when Sulaco is talking about viewing high definition content on his standard definition TV? It would be a great exercise in futility, since the only image the TV is capable of displaying is an interlaced, 525 line NTSC signal.[/quote]

[gshelley61]

That is a rather curious thing to say. Yes, EDTV sets are a bit of a scam, and some sets can only natively do 720p and downconvert 1080i to a bastard 720i mode, but the majority of HDTVs accept and properly display a 1080i signal. That doesn't neccessarily mean that the image quality will be high enough to see 1080 lines, but it WILL scan 1080 lines.

The whole matter of TV resolution is misleading since analog televisions, by nature, do not have a fixed resolution. Your NTSC television has 525 scanlines. Horizontal resolution depends on the quality of the tube. It displays analog NTSC. That's all. An HD decoder box, as you've discovered, downconvert to 480i which is the only resolution possible for an NTSC television to display.

What, exactly is the point of buying a digital video scaler when Sulaco is talking about viewing high definition content on his standard definition TV? It would be a great exercise in futility, since the only image the TV is capable of displaying is an interlaced, 525 line NTSC signal.

OK, first of all, I stand by my statement that most "HDTV Ready" sets sold today cannot properly display a 1080i or 720p image, regardless of how many lines they are capable of scanning. Have a close look at any color CRT and you will see a specific number of phosphor dots or segmented lines per square inch. That's the native resolution of the display, and they vary widely.

It might surprise you to find out that some NTSC televisions (especially the smaller inexpensive ones) do not have a native screen resolution (enough phosphorous dots) capable of displaying standard definition 640x480 images. The NTSC signal contains 525 scan lines (483 contain picture information). But not all TV's have a physical screen resolution high enough to display all 483 lines.

Even high resolution progressive CRT 's (like computer moniters) have a fixed native resolution. They are capable of displaying many resolution formats with varying scan rates, even those that exceed the native resolution of the monitor, but the visible image resolution will never exceed the physical screen resolution. Maximum quality and accuracy is achieved when the screen is fed a signal matching its native resolution.

Also, I happen to own a Samsung DLP HDTV (1280x720p is one of the two official HD standards). The 1080i downconversion to 720p is done with a built in Faroudja scaler (one of the best available), and is by no means some kind of "a bastard 720i mode".

[gshelley61]

OK, iantri -

I found an article from someone who knows a hell of a lot more than either of us about this... turns out we were both right and both wrong!

Here you go:

http://www.tvtechnology.com/features/Tech-Corner/f_technology_corner-04.07.04.shtml

[ktnwin]

Of course, you can always connect an HDTV receiver/tuner (cable/DirectTV) to a normal TV (non-HDTV) as long as you do not select Progressive. The picture is not as great as on an HDTV (with progressive) but still very decent.
As long as the receiver device as S-video (or composite video) OUT, you can connect to a non-HDTV using that.

[ViRaL1]

Is an HDTV signal really worth watching on an non-HDTV?

[SatStorm]

For the NTSC users yes. Normal TV Screens can show more than what an average NTSC transmission can offer.

[satviewer2000]

I don't know if this applies, but I have a HDTV satellite receiver which can output to HDTV or a standard definition TV.

I can watch all the HDTV channels on a regular TV as long as I output the signal thru the SVHS or RCA video output. The sat box simply down samples the HDTV signal to be viewable on a regular TV.

[flaninacupboard]

don't the HDTV decoders have component out? don't your non-HDTV's have component input? tv's here have had RGB (interlace component) SCART sockets for........ a decade? maybe more?