Why are widescreen movies and HDTV both 16:9?

[sneaux]

Am I crazy or are hdtv and widescreen movies different aspect ratios even though they are both called 16:9. When I recieve HDTV like episodes of Lost on my normal tv there are small black bars on the tops and bottoms of my screen and when they air letter box movies the black bars are much bigger. On 16:9 HDTVS letterbox movies have black bars. On the back of widescreen dvd cases they say the aspect ratio is 2.35:1 but when I rip it my editing progs like dvdlab say it is 16:9.
Also, why are 4:3 dvd aspect ratios different than computer monitor and television 4:3 aspect ratios. 800 divided by 600 is 1.33 and 720 divided by 480 is 1.5 and 16 divided by 9 is 1.77. When I am capturing an avi from tv should I capture in 600 by 800 or 720 by 480 if I am planning to put it onto a dvd? How can both 16:9 and 4:3 dvds both be 720 by 480 when there appears to be less horizontal lines in 16:9? What does anamorphic mean and where do babies come from!?

[manono]

Hi-

Lots of questions. I'll answer a few. You're confusing the DAR (Display Aspect Ratio) with the aspect ratio of the movie itself. There are 2 DARs in common usage, 16:9 and 4:3. They tell the DVD Player how to resize the image. The movie aspect ratio can be many things. For example, your HDTV Lost episodes, while 16:9, have an aspect ratio of 1.78:1, and show with small black bars on your TV set. Other movies from DVD, while 16:9, will display with more black bars, because the movie is 2.35:1, much narrower than your HDTV Lost episodes. In those cases, that 2.35:1 movie will also have some amount of black bars encoded onto the DVD, while your player adds more for output to a standard 4:3 TV set.

All NTSC DVDs are 720x480, but the DAR tells how it will be resized. It doesn't play as 720x480 on the TV set. If you were to look at that 720x480 16:9 DVD, you'll see that the image is stretched vertically, but when resized, it looks normal again.

A 16:9 NTSC DVD gets resized to 854x480 (480x16/9=853.333), and a 4:3 DVD gets resized to 640x480 (480x4/3=640).

I don't capture, but I guess that capturing at 720x480 will be much better, as then it doesn't have to be resized again before encoding. Maybe this will help to explain things:

http://www.doom9.org/aspectratios.htm