Quote:
Originally Posted by Spuds
Ya I'm handy so what i'm trying to figure out is how many of the channels will be HD quality? I have a 55 tv and if its not HD the channels looks bad. So how do I figure what they are brodcasting?
Thanks for all your help.
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I have one quibble with
Electron. 480p is called Extended Definition TV (EDTV). He is correct that 480i is Standard Definition TV (SDTV). He is also correct that 16:9 720p and 16:9 1080i are both High Definition TV (HDTV). I am not aware of any broadcaster that transmits 16:9 1080p. If such broadcasts exist, then they are also HDTV.
Most broadcast stations multicast two or more sub channels. The primary sub-channel of most stations is HDTV. It broadcasts in 1080i or 720p and does not change. Most sub-channels transmit 480i. If it does, then it does not change unless the change is permanent. The rules here are not hard and fast. Some broadcast stations have no HDTV primary sub-channel. Others broadcast two nominally HD sub-channels. For example, one of the NBC stations of my childhood added CBS as a sub-channel during the digital sub-channel. Virtual 5.1 is NBC at 1080i. Virtual 5.2 is CBS at 720p.
Now here is where things get complicated. Your TV will tell you if a broadcast is 480i, 480p, 720p, or 1080i. However, just because a broadcast is 720p or 1080i does not mean that programming is high-definition quality. There are a lot of programs and commercials that were videotaped using analog equipment. It is not just vintage footage. A popular practice particularly with live feeds from Los Angeles to the East Coast is to do those at no better than SD quality even while maintaining the 16:9 widescreen aspect ratio. If any of that footage is broadcast on a 720p or 1080i sub-channel, then it will not be magically promoted to HD quality even though your TV will indicate 720p or 1080i.
The video quality of programming is determined by the source material. Quality cannot be higher than the source, but it can be lowered by the transmission flow.