Video Frame Pixel Size

Sid_Phillips wrote on 5/25/2004, 5:50 AM
I am totally confused. When I create a project, the frame size is 720x480 according to the property sheet. The preview window is 360x240. But when I create graphics in Photoshop 7.0 at 720x480 the image is much smaller than the preview window, and renders with black all around the edges.

If I select the NTSC/DVD template in PS7 the graphic comes much closer to filling the frame, but it's still a couple of pixels short in the width. I could continue with the trial & error approach to solving this problem, but I am hoping that someone out there already knows the answer:

What are the correct pixel dimensions and resolution for a graphic to fit full-frame in Vegas? Thanks much!

Comments

logiquem wrote on 5/25/2004, 7:33 AM
655 x 480. This is clearly stated in the manual.
John_Cline wrote on 5/25/2004, 10:07 AM
You could also generate your graphics at 720x540 so Vegas won't have to stretch the image from 655 to 720. It is always better to scale down than scale up since you will be removing information rather than trying to create information that wasn't there to begin with.

John

Chienworks wrote on 5/25/2004, 11:17 AM
Wouldn't it be 720x528 ?
John_Cline wrote on 5/25/2004, 12:23 PM
720x480 is a 1.5:1 aspect ratio, but it's based on rectangular pixels. When it is displayed on a 1.333:1 (4:3) television, it appears correct. 720x540 is 4:3 or 1.3333:1 based on square pixels. 720x528 is 1.363636:1, which doesn't appear to fit the formula. I'm not exactly sure how Vegas arrived at the 655x480 dimension, that doesn't fit the formula either.

John
Chienworks wrote on 5/25/2004, 12:30 PM
That's because DV isn't 4:3 or 1.333333... . It's 1.363636...

DV pixels are 0.909090... . Multiply that by 720 and you get 654.545454..., which is where the number came from. So, 720 / 1.363636... = 528.

Try it and see. A 720x528 picture will fill the frame just about perfectly. 720x540 will fill it vertically but leave some empty space on the sides.
John_Cline wrote on 5/25/2004, 12:41 PM
You're right. I stand corrected.

John
rmack350 wrote on 5/25/2004, 10:53 PM
It's helpful to remember that 4:3 describes the visible picture area. The whole spec was designed for slow tube electronics that would gradually drop the raster voltage down to 0VDC at the end of a line and then gradually raise it up at the start of the next. Somewhere in the middle of that was a 4:3 subsection of the frame that would be suitable to show to viewers.

If you look at captures from VHS deck output you'll see those same soft edges in the left and right frame edges. VHS doesn't do too much better than a 1950s TV.

BTW, to get a 720x528 dimension just take a 655x480 image in photoshop and resize the horizontal to 720. The vertical will go to 528. Illustrates the point without having to do any math.

Rob Mack