Video Asylum

Posted by Bruce from DC (B) on April 15, 2002 at 13:49:43

In Reply to: I am confused by the terminalogy. posted by ka on April 09, 2002 at 14:36:20:

There's probably an FAQ somewhere. "Digital TV" is just that: digital TV, like "digital audio" which includes MP3, CD's. SACD and so on. If you take the current interlaced scan analog television signal and make it digital, you've got digital tv. If you're watching DirecTV or The Dish Network, that's what you're seeing, along with a good deal of compression. If you'r watching "digital cable" that's what you're seeing.

"HDTV" usually refers to an image that uses 1080 lines of interlaced scanning or 480 lines of progressive scanning (as compared, I believe to the 440 lines of interlaced scanning that make up a standard broadcast TV signal in the U.S.) When HDTV was first developed (in Japan), it was analog. It was a big spectrum hog, because a lot more information is being sent.

I believe the US took the lead in developing a digital protocol for having digital HDTV and defined it as 1080 lines, interlaced. I believe (but am not positive) that part of HDTV spec is the 16 x 9 picture format, which more nearly resembles the shape of a modern motion picture screen. Standard TV is in 4 x 3 format.