Actually 654.5454 wide, to be exact. Either 655x480 or 654x480 will work well enough.

Sorry I did not tell you I am in the USA and I am making an NTSC format video.
So will 640x480 still fit?

Yep.

Kelly (Chienworks) is right -- the correct pixel size should be 655 (or 654? 656?) pixels wide and 480 pixels high.

The root of the issue is that "4:3" DVD format isn't exactly 4:3 -- just very close to it. So simply multiplying 480 by 4/3 doesn't produce the correct answer. (The NTSC DVD format uses only 480 display lines instead of 486, and the output signal width is slightly wider than the standard broadcast signal?)

The easiest way to convince yourself of the "correct" answer for what you want to do is to save a snapshot image from Vegas (as a JPG or PNG) and see what pixel dimensions you get. Call up a std def NTSC project, find a frame of video that fills the screen, set preview to full/best, and click the "save snapshot" (flippy disk) button. Examine the JPG/PNG file that Vegas creates -- it will be in square pixels format -- and see what the dimensions are.

Ok I will do what you say but one thing did you meen 655x480 may work?

I will try this to.

No. What we mean is that 655x480 WILL work.

Yes, now that I'm home I can confirm that 655x480 is the right answer.

If you tell Vegas to save a snapshot of the current frame in an NTSC 4:3 DV (not widescreen) project, you will see that Vegas will save a square-pixel image that is 655 pixels wide by 480 pixels high.

So, if you want an exact image size for a square-pixel background slide in NTSC 4:3 DV project, 655x480 is what you want.

Kelly, would you please explain the theory or math behind how you get those numbers so I can better understand. Thanks. Cin

Cin, i'll start off by saying it's complete arbitrary; someone just picked those numbers rather than them having any deep essential meaning. Does that help at all?

Here's how they came about: when digital video was busy being born the engineers were trying to figure out the best ways of making it as compatible as possible with analog signals. It was decided by one group that 720 pixels across the scan line seemed an appropriate resolution. 720 could handle all the image detail that the TV signal could produce, it wasn't so low that it lacked detail, and it wasn't so high that digital electronic circuits at that time couldn't handle processing that much data. 480 was also chosen as the standard height of the frame for much of the same reasons (though 486 would have been more accurate, but 480 is a much nicer number to deal with).

Now, the problem with 720x480 is that it's a wider rectangle than the TV screen is (3:2 instead of 4:3). So in order to make it the same shape, the horizontal width of the pixels got squishied by a certain factor to make them fit. The visible part of the frame is only 704 pixels wide (the extra 8 on each side were reserved for control signals and moving the scan beam back to the other side of the screen) and a factor was needed to match those 704 to the width of the picture. Since the screen is 4:3, The width that would match 480 high is 640 wide. But to get 704 pixels to fit into a 640 space you need to adjust by a factor of 0.909090909 (divide 640 / 704 and that's the result you get)

Now, the actual digital physical frame is 720 wide, but it's 720 squishied narrow pixels. So, multiply 720 by 0.90909090... to get square pixels and you get 654.54545454...

Which brings up an interesting point. In fact, the really absolutely correct image size really is 640x480 with some blank black area on the sides. This is what would be most appropriate for an old analog TV in which the edges aren't visible. But no one watches anything on those old behemoths anymore. We watch everything on computer screens which do show all the edges, and people like to have those edges filled.

Now aren't you happy you asked? ;)

Thank you Kelly for the knowledgeable and detailed answer, but you are right in that I wished I had never asked! I just can't seem to figure out who invented this stuff in the first place, but more importantly, why someone hasn't fixed it yet.......Most things change and evolve over time, but it seems like some of this video stuff is still rooted in prehistoric times. Seems like there are plenty of smart people out there with 'a better way', and yet we still try and make do, or work around what's still out there. Thanks again for your time. I will save and reread your post a few more times and see if some of it will soak in a bit more. :)