Conversion Question

[YodaBJ21]

I'm new to HD...I have a Sony 57" widescreen TV
I have five channels in HD, PBS, ABC, NBC (Detroit affiliates that is), HBO and Showtime ... all through Comcast.

What physically happens to the signal for shows that aren't shown in true HDTV? The signal is better than my normal digital cable but yet falls short of true HDTV. These images are not recorded from true HDTV cameras, I assume, and are up converted somehow. What are the specifics to this? Also, these converted images are cropped left and right on my 16:9 TV because I assume they are in 4:3 format... Is a True HDTV signal (720p or 1080i) ALWAYS in widescreen mode? Are these images cropped t&b on a 4:3 HDTV?

Showtime and HBO show some movies that are in true HDTV and they look fantastic. I find myself watching movies only for the picture! But Showtime also shows some movies that are not in HDTV at all and some that are "up converted". The ones that aren't in HDTV at all seem to always be in 4:3 AR and is this process exactly the same as what happens on my local ABC, NBC channels? And what is the "up converted' format that Showtime shows, which seems to be PQ wise in between the non HDTV and true HDTV. (How is this process different than what happens on ABC,NBC?) Are movies that are shown in true HDTV always recorded using HDTV cameras?

Thanks for any help out there!

[BrianW]

That is one good post of questions.

I will attempt to answer a few of your points.

To start: The standard for true HDTV (720p or 1080i) calls for the aspect ratio to be 16:9. On a 4:3 set this image is not "cropped" (which would be removing some of the picture) but instead is "compressed" (again not really the right term but it describes it better) to fit in a 16:9 aspect window on you 4:3 set hench the black bars on the top and bottom.

Upconverting is basically just a method of adding additional lines to an image to get it to display at the higher resolutions. This is done by some amazing mathimatical calculations so can't really be explained much better. Upconverting wont improve the image quality much other then how sharp the image is. This is why non HD stuff looks ok but not fantastic.

And finally, yes, all HDTV stuff must be captured by high definition cameras. Some movies that where made before HDTV but are now being shown in HDTV were digitally remastered, probably from the original film. Movie studios have been using much higher resolution cameras for a long time now so the remastering process probably is just to remove artifacts and add dolby digital sound.

[YodaBJ21]

Super informative response, thank you!

I think I have it square now. On the listings for Showtime they basically have three options. One is non HDTV, one is WIDESCREEN OAR UPCONV and finally WIDESCREEN OAR HDTV. I think now that there is no difference between the first two other than aspect ratio. The HDTV upconverting is the same, which makes sense. (The mathematical process that you mentioned).

And I understand what you mean about compressed vs cropped - just bad symantics on my part. I realize that this is what is happening. But my main point being it really doesn't make much sense to get a 4:3 HDTV if the image always has bands when viewing true HDTV. Boy am I glad I got a widescreen (I bought quite uninformed).