How does an HD broadcast work? (1 Viewer)

[Barry_B_B]

My wife asked this question last night as we were watching Rosemary's Baby and I realized I didn't have a good answer. It's one of her favorite movies, and she kept commenting on how sharp and clean the picture was. Are the networks running standard video through an upconversion process, or is this an over-simplification? Since some offer 5.1 Dolby Digital, are they using DVD format?

 

[Ken Chan]

It depends. Sometimes, the movie is rescanned for HD. A rule of thumb is whether it is in widescreen, but you should be able to see the difference. The cable HD networks definitely do this -- it's part of their selling point. As for the broadcast networks, in decreasing frequency, it's roughly ABC, Fox, CBS, NBC, and well, The CW is barely a network. If they don't, then they upconvert it, just like they upconvert all their other SD content.

Everything is Dolby Digital, but that can also generated on the fly. If it's true 5.1 which uses all the channels, that also points to being a remaster.

As far as I know, they don't actually use the DVD format of the content. Even if that's not on a DVD per se, it wouldn't be quite as simple as playing the DVD content over the air.

 

[Ryan L. Bisasky]

i had a question regarding sound. whne you watch tv shows on dvd, on the 5.1 track, the dialogue usually sounds very flat while the sound effects sound crisp and clear, but when watching it in hd and 5.1 the dialogue sounds normal and not flat.

 

[ChristopherDAC]

A proper High Definition broadcast is prepared in the same general way as a standard TV broadcast, except using High Definition cameras (for live-talent programmes) or telecines (for film programmes), High Definition mixers and switchers, High Definition videotape, and so on. At one time, these were very difficult to build — the Sony HDV-1000 analog component High Definition recorder, using open-reel 1" tape at twice the speed of NTSC broadcast decks, is supposed to have been a nightmare to maintain and run — but the technology has gotten cheaper and easier to use. In fact, you can now buy a consumer-level HD camcorder using HDV (same tapes as DV), although it's quite expensive and not up to the quality level of broadcast equipment. The widespread adoption of the Serial Digital Interface in broadcasting plants also makes things easier, because the same equipment (mostly) can be used to handle SD and HD digital broadcasts. Also, Dolby Digital 5.1 audio was developed, in part, for High Definition : in fact, multichannel digital audio has been part of the concept for HD since the Japanese worked it out in the early '70s, and their analog HD broadcast system from the '80s provided 4.0 digital audio. Anything which has a 5.1 soundtrack (and many things do, today) can be encoded into DD5.1, either on the master tape or on-the-fly, for full Surround Sound transmission.

 

[Barry_B_B]

Very educational, nice to put a visible process to this; thanks!