Can Someone Explain HD vs. SD TV?

[Gregg.]

I understand that HD is High Definition, SD is Standard Definition. But I don't understand why, from a previous post, Cable TV providers have channel line ups in HD and SD? Shouldn't HD be all they need? If you have a standard definition television, is your viewing enjoyment less if you have to watch the HD signal? I still have a standard definition television and I simply tune it to the right channel on my Time Warner system.

TW provides its regular, over-the-air channels in two places. WCBS 2.1 NYC is on 2 and 1209, WNBC 4.1 NYC is on 4 and on 1204. But I don't think it has anything to do with HD. It's because they put all the over-the-air channels in the 1200s, including the subchannels and the must-carries (that they really would rather not carry but have to). Only the top .1 channels get carried in the single and double digit line up at the beginning of the dial.

A previous thread talks about out-of-market signals carried by some cable systems, including whether those stations are carried in SD and/or in HD. In some cases the out of market signal is carried in one format but not the other. Why? Do these operators carry some channels only in SD because it means less bandwidth, even though viewers with HD televisions will not get the full viewing experience?

Maybe I'm behind the times, but if you have a widescreen TV with an excellent picture, how does HD improve on that? Would the average person see that much improvement in HD vs. a good quality SD signal?

 

[KeithE4]

Maybe I'm behind the times, but if you have a widescreen TV with an excellent picture, how does HD improve on that? Would the average person see that much improvement in HD vs. a good quality SD signal?

SD = Standard Definition, aka 480i (480 viewable lines, interlaced scan), which is the rough equivalent to the old 525 line, 30 fps analog standard. 480i doesn't look very good on an HDTV -- in fact I think it looks as bad as an old VHS tape did on a CRT screen. Rather than the HD 16:9 aspect ratio, it uses the old 4:3 ratio and is a bit grainy.

HD = High Definition, which could be either 720p (720 lines, progressive, aka non-interlaced scan), 1080i (1080 lines, interlaced), or 1080p (1080 lines, progressive) depending on the media, station and/or network. 720p is available on all TVs, while 1080i & 1080p are also available on all but the cheapest models. Other than on my largest screen TV, I can't tell the difference between them. Getting old... eyes failing...

720p is roughly equivalent to a WXGA PC video standard (1360x768). 1080p or 1080i is the same as a 1920x1080 PC video standard.

1080p is used for Blu-Ray DVDs and some cable systems IIRC, but not on OTA broadcasts in the US.

 

[anotherguyTN]

From what I can see the main purpose for the SD channels is to provide a signal for older analog TV sets. I have 2 HD sets and 2 analog sets and in most cases the SD channels fit the analog screens better. Charter's tuners can be set to automatically change to the HD version of the old analog channel, and I guess other cable systems' tuners can do that as well. Going through the tuner the HD channels can actually come in on the analog sets, but they will be letterboxed or cut off on the sides, and when a show with a 3:4 display comes on it will look postage stamped with black bars on all sides. There are also some channels that are only available in SD.

 

[ansky212]

Maybe I'm behind the times, but if you have a widescreen TV with an excellent picture, how does HD improve on that? Would the average person see that much improvement in HD vs. a good quality SD signal?

Yes, you can easily notice a difference between HD and SD. Even the "best" SD channels are nowhere even close to the quality of HD.

 

[vchimpanzee]

It's not true that a new digital TV is HD. I'm correct about that, right?

 

[frankberry]

With the exception of TV sets with very small viewing areas, all flat panel TV sets are HD.

 

[pab]

Correct. Just because a TV is 16:9 doesn't mean it supports anything over 480 lines. Although newer ones will probably support at least 480p, which is easier on the eyes than 480i.

 

[newsmark]

>> If you have a standard definition television, is your viewing enjoyment less if you have to watch the HD signal?

Your standard definition, analog TV cannot receive an HD signal. It doesn't have the circutry needed to receive and display the digital signal--audio-or video. The only way to watch an "HD" channel on your SD TV is with some type of device that converts the digital channel to analog. Some cable boxes can do that, and in the process they either squeezing the picture down to fit and leave "letterbox" bars at the top and bottom of the picture, or they simply cut off the sides of the picture. Either way, the cable company is receiving the digital signal and retransmitting it as analog.

Many cable systems have stopped sending any analog signals, instead relying on cable boxes to convert the signal.

So, yes, the viewing enjoyment can be reduced, simply because your picture is smaller or portions of the picture are cut off.


>>Maybe I'm behind the times, but if you have a widescreen TV with an excellent picture, how does HD improve on that? Would the average person see that much improvement in HD vs. a good quality SD signal?

A widescreen TV with an excellent picture? In most cases, a widescreen TV is meant for HD. It usually CAN display an analog/SD signal, but most people find it doesn't look very good. Sometimes it actually looks worse than watching the same picture on an older analog set. A true HD signal will look much, much sharper.

(P.S. Someone mentioned that some cable channels are SD-only. That is true, but they're usually DIGITAL signals, which usually means they'll still look pretty good on an HD television set, even if there are blank spots, often called "wings," on the sides of the picture. And an analog TV still wouldn't see the signal without some type of converter.)

If you haven't noticed the difference, then perhaps the sharper picture is not something that's important to you. If the picture is good enough for you and you're happy with what you have, then enjoy it!

 

[KeithE4]

Correct. Just because a TV is 16:9 doesn't mean it supports anything over 480 lines. Although newer ones will probably support at least 480p, which is easier on the eyes than 480i.

720p and 1080i are supported, but converted down. So are 1080i broadcasts on sets that can only do 720p at best (including two of mine that are close to 6 years old now). And how many small-screen sets are anything less than 720p these days?

 

[KML0224]

Although delivered digitally, many TV station subchannels are presented in a 4:3 ratio with the pillar boxes (a.k.a. black bars) on either side of the picture. As an example:

WCCT-TV channel 20-2 of Waterbury is ThisTV
WTIC-TV channel 61-2 of Hartford is Antenna TV

Both stations are sent out as an SD 4:3 picture in 480i resolution. It's presented the same way on many cable systems, such as Comcast here. However, I presently use an antenna to receive them over-the-air for free.

Also, don't be fooled by somebody pitching a DIGITAL and/or HIGH DEFINITION antenna! Provided you're in a strong signal area, an old indoor antenna with rabbit ears may work. Keep in mind the the telescoping rods are better suited for VHF. In my case, that applies for WTNH-TV (ABC) channel 8 of New Haven. They use VHF channel 10 for their digital, yet the TV will still display "8-1", etc.

 

[Mediafrog+]

Yes, you can easily notice a difference between HD and SD. Even the "best" SD channels are nowhere even close to the quality of HD.

If you cannot tell the difference between SD and HD you should make an appointment with your ophthalmologist immediately. Probably shouldn't be driving, either.