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Bandwidth FAIL

post #1 of 17
Thread Starter 
I have a question that nobody seems to be able to answer anywhere else, but I'm confident that you guys won't let me down. As I understand it the HDTV switchover date was supposed to free bandwidth that corporations have already paid big bucks to use. If this is so however, why are there still two of every channel? I thought that on the switchover date the SDTV was being turned off completely to free up that space for other use. What happened?
post #2 of 17
The switchover had nothing to do with standard definition vs high definition television.
post #3 of 17
Thread Starter 
Both of these signals occupy bandwidth though... So, WTF? Explain.
post #4 of 17
Are you talking about the standard def and HD channels on cable or satellite? If so, the analog over the air DTV transition had nothing to do with that.

On the other hand, if you have a local TV station that broadcasts an SD subchannel alongside its primary HD programming, then you have a local channel that is throwing away bits. Nonetheless, this local station still is limiting itself to the 6 MHz chunk of spectrum that they were allotted after the DTV transition.

So tell me again what the details are on this bandwidth fail?
post #5 of 17
There was no "HDTV switchover date". There was a digital television transition, and it occurred on June 12, 2009. Full power analog stations are no longer on the air, the transition accomplished what it was supposed to: end analog over the air(not cable) broadcasting and replace it with a digital channel.

The SD/HD channels you speak of I assume are on a cable or satellite system. The 6/12 DTV transition had nothing to do with cable and satellite TV, as they are not broadcast over the air. Cable and satellite TV continue to operate the same as they did before, at the provider's discretion. Cable and satellite continue to carry both SD and HD channels because of equipment limitations. Cable TV has analog 'must carry' rules on local channels and both also have many customers with SDTV sets and SDTV equipment that would need to be replaced to carry HD only channels, like OTA broadcasting.
post #6 of 17
HDTV = Digital
SDTV = Analog
SDTV can ALSO = Digital
Digital does NOT = HDTV

The switchover turned off the Analog broadcasts. Everything is DIGITAL now, but, not every digital signal (broadcast) is HD...
post #7 of 17
Fail!
post #8 of 17
Quote:
Originally Posted by nickdawg View Post

The SD/HD channels you speak of I assume are on a cable or satellite system.

Probably, but there's a variety of broadcasters (including my local ABC affiliate WLOS) who simulcast a 480i subchannel of their main HD channel. I'd like to think there's a good reason for it. I doubt it, though. Hey, MPEG-2 encoders are blessed and holy and can make anything look nice no matter how little bandwidth you give it, right? Right?
post #9 of 17
Quote:
Originally Posted by ncxcstud View Post

HDTV = Digital
SDTV = Analog
SDTV can ALSO = Digital
Digital does NOT = HDTV

The switchover turned off the Analog broadcasts. Everything is DIGITAL now, but, not every digital signal (broadcast) is HD...

What he said, stations were required to go digital, not HD. They can pass HD/SD or a combo of both with their allotted digital space, that's up to them.
post #10 of 17
Quote:
Originally Posted by ncxcstud View Post

HDTV = Digital
SDTV = Analog
SDTV can ALSO = Digital
Digital does NOT = HDTV

The switchover turned off the Analog broadcasts. Everything is DIGITAL now, but, not every digital signal (broadcast) is HD...

Actually, I don't believe you are quite right. Def not completely wrong, but not quite right. The term SDTV refers to digital SD as it was to differentiate it from HDTV. I know you may say, well there is no difference, but if you were to try and buy pro equipment there would be no analog referred to as SDTV.
post #11 of 17
Hi there

> The term SDTV refers to digital SD as it was to differentiate it from HDTV.

I agree with you 100%.
But you will find many users on this forum (esp the HTPC section) who use "SD" and "SDTV" and "480i" to exclusively refer to analog, NTSC television signals, even though all three terms also apply to digital video. (E.G. "I'm looking for a SD tuner" or "I have an old SDTV.")

By popular mis-usage:
"SD" means "analog"
"you're" is now spelled "your"
"should've" is now spelled "should of"



Regards
post #12 of 17
While we're nitpicking there was analog HDTV.
post #13 of 17
Thread Starter 
Thanks Nickdawg for the detailed explanation. Semantics aside, this thread answered my question thoroughly.

Sadly, with duplicated stations though I have twice the nothing to watch on TV these days...
post #14 of 17
SD duplicates must be a local thing.

None of the local stations I receive with my OTA antenna run SD duplicates of their HD broadcasts.
post #15 of 17
Quote:
Originally Posted by arxaw View Post

SD duplicates must be a local thing.

None of the local stations I receive with my OTA antenna run SD duplicates of their HD broadcasts.

AIUI some stations simulcast a 480i SD feed on their main digital service so that they have control over the SD feed carried on cable networks. So rather than the cable company downconverting the 1080i/720p cable feed themselves (permanently letterboxing or permanently centre-cutting) the local station could provide a 4:3 optimised SD feed for those consumers receiving 4:3 SD analogue or digital cable feeds.
This is relevant particularly if the local station is able to use network AFDs (to dynamically ARC the 16:9 HD network feed between 4:3 centre cut and 16:9 letterbox on a show by show basis) and the cable co isn't ?
post #16 of 17
Quote:
Originally Posted by sneals2000 View Post

AIUI some stations simulcast a 480i SD feed on their main digital service so that they have control over the SD feed carried on cable networks.

That's a pretty cheesy reason to waste bandwidth on a subchannel. Are there really that many people with SD sets using analog cable without a box who care about aspect ratio?
post #17 of 17
Quote:
Originally Posted by arxaw View Post

SD duplicates must be a local thing.

None of the local stations I receive with my OTA antenna run SD duplicates of their HD broadcasts.

Initially, some stations did it to provide a cleaner digital SD feed to a cable company.
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