Trying to Understand Video Resolutions

[KyleMadrid]

Hi all, I'm new to all this stuff, but I'm very keen to learn. I do have a small amount of knowledge with videos in general, but it's very limited.

I have a whole lot of questions, but the first thing I would like to know is... why don't movies, whether they be on Bluray or DVD, take up the full screen? I have a full HD 1920x1080 monitor, but when I watch a Bluray movie on it, the movie is not shown in that resolution, and therefore has black parts at the top and bottom. I don't have a problem with this, I don't mind it at all, but I am just simply curious as to why movies are displayed like this? Also, I have a DVB-T tuner from which I watch football (soccer) matches live on my computer in HD, and they take up the full screen, and don't have any black parts like the movies do...

Can someone please explain to me why this is the case? Once again, I don't have a problem with this, I'm just curious.

Thanks in advance to anyone willing to help, any help will be greatly appreciated

[Baldrick]

It's because many movies are shot in 2.35:1 aspect ratio and that is wider than 16:9 monitors/tvs.

See http://en.wikipedia.org/wiki/Aspect_ratio_(image) and http://www.widescreen.org/aspect_ratios.shtml

[KyleMadrid]

Thanks, Baldrick. I will take a look.

[hello_hello]

The simple answer is that video uses all sorts of different dimensions (aspect ratios) but DVD and Bluray video only support two. 16:9 and 4:3. If the picture doesn't use one of those, any remaining area becomes black bars.

Often when widescreen movies are broadcast for TV, instead of using black bars, the picture is effectively enlarged to fill a 16:9 screen, or in the past, to fill a 4:3 screen. The process for doing so means some of the picture from the sides is lost. When "intelligently" removing much of the picture to make a wider aspect ratio video fill a 4:3 screen, the process is known as "pan and scan". http://en.wikipedia.org/wiki/Pan_and_scan
I guess if some of the picture from a wider aspect ratio ratio video is removed so it can fill a 16:9 screen, the pan and scan method is probably still used at times.

There's also other methods used to get the picture fill an entire screen, depending on the format in which it was shot. For example, http://en.wikipedia.org/wiki/Open_matte

[jagabo]

This:

It's because many movies are shot in 2.35:1 aspect ratio and that is wider than 16:9 monitors/tvs.

Before the advent of HDTV nothing was shot at 16:9. The closest common film aspect ratio was 1.85:1. Most "widescreen" movies are ~2.35:1.

[yoda313]

Most "widescreen" movies are ~2.35:1.

Yep but there are a few that are 2.4:1 and I think I've seen 2.5:1 which is quite unusual. The disaster movie 2012 is 2.4:1 for example - i just pulled my disc out to confirm. I can't remember off hand if 2.5:1 is real or not but I think I saw one that was "higher" than 2.4 I just can't recall off the top of my head right now.

[jagabo]

2001 A Space Odyssey was 2.20:1. Kubrick shot a lot of his other films at 1.66:1.

[Island_Dweller]

2.40:1 AR is commonly used, I think. Many of my bluray backups are done @ 1920x800.