What is anamorphic NTSC and how do I know if my video file is or not?

[brassplyer]

Using Virtualdub, one of the options to check in the Thalen Deshaker filter is "Anamorphic NTSC (1.215)" as opposed to "Standard NTSC (0.912).

I've got some 16:9 DV shot with a Sony Digital8 Handycam. How do I know if it's anamorphic? I tried processing a file with both options, doesn't seem to make a difference. They both play as 16:9 in Windows Media Player, both look the same as far as I can tell.

Thanks for all input.

[jagabo]

I've got some 16:9 DV shot with a Sony Digital8 Handycam. How do I know if it's anamorphic?

If the video fills the 720x480 frame in VirtualDub and it looks squished from the sides it's anamorphic. If there are black bars top and bottom and looks a little too wide, it's not.

[brassplyer]

I've got some 16:9 DV shot with a Sony Digital8 Handycam. How do I know if it's anamorphic?

If the video fills the 720x480 frame in VirtualDub and it looks squished from the sides it's anamorphic. If there are black bars top and bottom and looks a little too wide, it's not.

There's more than one way to view a 720 x 480 video. When you say "If the video fills the 720x480 frame" - can you clarify? You mean when 16:9 is checked, unchecked, free adjust is selected?

[manono]

There's more than one way to view a 720 x 480 video.

Eh? Just open the 720x480 video, without any modification or box checking. Do people look too tall and thin? If so it's 16:9, aka anamorphic.

[jagabo]

There's more than one way to view a 720 x 480 video. When you say "If the video fills the 720x480 frame" - can you clarify? You mean when 16:9 is checked, unchecked, free adjust is selected?

Both 4:3 and 16:9 NTSC DVDs (and DV and many other formats) use a 720x480 frame. The difference comes down to Aspect Ratio flags in the video stream that tell the player whether the video should be viewed as 4:3 or 16:9 when it's played.

VirtualDub's default behavior is to ignore AR flags and display the frame pixel-for-pixel (720x480 square pixels resulting in a 3:2 display aspect ratio). This is important in a filtering program because you need to see the pixels exactly as they are, not a resized version of them. Otherwise you wouldn't be able to tell what is in the actual video vs what artifacts were introduced by resizing. Here's an example:



On the top is a portion of the Belle Nuit test image shown pixel-for-pixel. You can see that the vertical lines are 1, 2, or 3 pixels wide. On the bottom is the same test image show resized for a 16:9 DAR. Note how the thickness of the lines is distorted. If you only saw the bottom part of the image you wouldn't be able to tell what the source really looked like.

For 16:9 material in a 720x480 frame you have two possibilities: an "anamorphic" 16:9 DAR frame, or a 16:9 video letterboxed into a 4:3 DAR frame. In the former you will see the 16:9 video takes up the entire 720x480 frame. In the latter you will see letterbox bars at the top and bottom of the 720x480 frame.

Anamorphic 16:9 (half size, 360x240):


Letterboxed 4:3:

[brassplyer]

Okay, it would appear mine is anamorphic. So when using the Thalen Deshaker, what's the difference in checking Anamorphic NTSC 1.215 as opposed to standard NTSC .912? I've processed 16:9 video using standard numerous times because I wasn't aware of the anamorphic issue, and the processed video looks fine when rendered as a DVD.

[jagabo]

when using the Thalen Deshaker, what's the difference in checking Anamorphic NTSC 1.215 as opposed to standard NTSC .912?

The first is for 16:9, the secondn for 4:3. It probably works better with the correct setting.