Consider that you're basically looking at what's been an analog system since its inception. No pixels at all!

That signal is sampled in order to digitize it, and sampling could be done at any speed. As it happens, DV25 is done at a rate that creates 720x480 samples for an NTSC frame. The rate the standards body chose was important because it is usable for both NTSC and PAL.

Another thing to keep in mind is that 4:3 ratio is for the viewable signal. The complete image is not really 4:3. Remember that SD signals have analog roots in the days of vacuum tubes. TV performance varied, and the beginning and end of a line or frame needed slop space to go black before the cathode ray could be reset to the beginning of the next line.

And then there's the "non-square pixel" thing. People like to say that DV NTSC pixels are actually narrower than they are tall. It's a good way of visualizing it but underlying that is the sample rate again and this is why the Vegas preview screen has an option to correct the pixel aspect ratio.

Let's take an extreme and fanciful example of sample rate and pixel aspect ratio. Suppose that instead of taking 720x480 sample, you just took 2x480 samples. In other words, you took two samples per line. Assuming the picture stays the same size on screen (which it should), each sample would stretch across half its row. A very wide pixel, and all because you slowed down the sample rate. Hopefully this gives you an idea of why a pixel would be "non-square".

This is a pretty loose explanation and filled this statements that are probably not strictly accurate but I hope they give you a sense of what you're seeing in Vegas.

Rob Mack

OK. I understand 720X480 issue BUT if I render my video in this aspect ratio then part of the image is not visible on the standard TV screen. It looks like Vegas is "zooming in" into the picture itself and cuts the edges of the original image.

I was just wondering if there is any way to "fit" the ENTIRE image within the Safe Area of the Preview Window so when the file would finish rendering the entire original image would be viewable on the standard TV set and not just part of it (the center).

Any ideas how to do that?

Thanks for your help,

PSB

Well, the safe area is just a rough estimate of what will definitely appear on screen. TVs always masked part of the picture, and a TV could have it's horizontal and vertical adjustments skewed by a user, so it was never expected that a TV would show all of the frame. This is why, while the viewable TV image is 4:3, the actual image in the signal is wider.

Projection and flat screens are a "horse of another color", as they say. These usually show the entire image edge to edge.

The normal procedure is to render your 720x480 project to a 720x480 format and let the player deal with it. So if it were a DVD you'd render a 720x480 MPEG2 file and then the DVD player would output the picture just as it should.

If you want to make everything fit into your safe zone you could, perhaps, render your project to a new track and then use Track Motion or Event Pan/crop to size the image into that area. My guess is that you don't really want to do that, but that's the way I'd do it if that was what I wanted.

Rob Mack

Thanks Rob ! I understand what you are saying about "mask part of the picture". I have rendered the projects as .avi files and maybe by rendering those files as MPEG2 would make a difference. Yeah, when I think about my DVD player I think of the same scenario as with my projector. Actually I am projecting those films (avi) from my compter to my big screen projector and the projector is projecting whatever comes out of the computer (via s-video).

I have not used Track Motion feature yet. Don't know how to do it yet but I will try to figure this out. I have found some info regarding Event Pan/Crop feature and when you click on the presets it gives you "Standard TV 4:3" aspect ratio. But even if I would choose that the outcome is the same = cropped edges of the original image. Weird !!!

I think that Safe Area is set up for (what else) safty feature and by now I think it is not possible to adjust that.

OK, I'll try to do the MPEG2 and see what will come out.

Thanks for your help,

PSB

All televisons overscan, whether they are CRT-based, LCD, plasma or some sort of projector. They all cut off varying amounts of the picture. The Safe Title and Safe Action markers in Vegas are there to guarantee that the action or titles will show up on screen, no matter how much the TV overscans. This has been a fact of television since the beginning and people have learned to take this into account in order to frame their shots correctly.

It isn't going to make any difference whatsoever whether you render in AVI or MPEG2. Since you are feeding the projector with the output of the computer video card, there may be some adjustments you can make to the card to minimize the overscan effect. Exactly how critical is the outer 5% of the images in your video anyway?

John