attack of the warble's

TeeJay wrote on 3/15/2006, 9:38 PM

Hi all,

I've been using Vegas for about 3 years now. Bought V5 back then, and now I'm using V6d. When I started, I was very much the amateur, but have progressed to churning out some pretty good stuff and have been upgrading my gear as I get better jobs. My work is generally output to PAL MPG2 (DVD)

So here's my problem. Whenever I use the Pan/Crop to zoom in on my clip, it turns all warbly. Of course, I can "iron" it out by using Super Sampling but the result is a general softening of the image. I want to retain it's original sharpness. I used to blame my camera, a Canon XM2, but have upgraded to a Sony DSR-PD170 and I'm still getting the problem.

What is causing it? A professional looking Output is definately not what I'm getting here. Is this a Vegas Anomaly, do users of other NLE's get this? It is driving me nuts and I have to sort it out as I am attracting (and striving for) better jobs, but it is things like this that is affecting the quality of my work.

Can anyone offer any suggestions here please?

Regards,

TeeJay

Comments

johnmeyer wrote on 3/15/2006, 10:11 PM

Whenever I use the Pan/Crop to zoom in on my clip, it turns all warbly.

If I am understanding what you are asking, the reason is simply that you have fewer pixels to display when you zoom. If you start with PAL DV video, you have 720 by 576 pixels in each frame. If you zoom in to the top left quarter of the frame, you only have 360 by 288 pixels, but to fill the screen, these must be duplicated and interpolated to get back to a full 720 by 576 pixels which is what is required to fill the screen. If you take it to an extreme and zoom in until you only have 6 pixels by 4 pixels, all you'll have on the screen are 24 very large dots.

So, unless you start with video (like HDV) or a still image that has MORE pixels than 720x576, you will always end up with a fuzzy picture.

In addition, if you turn OFF re-sampling, you will get all sorts of additional bad things happening, which is what you are reporting. The picture will tend to jump up and down and side to side. This happens becuase as you zoom in, each frame has fewer pixels than its predecessor. You actually have to draw a bunch of dots on a paper to see the problem, and the actual math gets complicated, but here's a simple example: If one frame is five pixels wide by 4 pixels high, and the next frame (because you've zoomed in) is only four pixels wide by 3 pixels high, then, since the number of pixels is odd in one frame and even in the other, the picture will appear to jump up or down because you can't align an even number of rows in one frame with the odd number of rows in the next. Re-sampling attempts to interpolate the missing rows and reduce that jumping.

So, use zooming VERY sparingly unless you have high-res material, and ALWAYS use resampling when Vegas is forced to change the resolution.

Laurence wrote on 3/15/2006, 10:56 PM

Are you talking about wavey vertical lines on motion? What do you mean by "warbly"?

farss wrote on 3/15/2006, 11:25 PM

Also rendering at Best will help a bit.
Bob.

TeeJay wrote on 3/16/2006, 3:42 AM

I always Render at Best, with a double pass. I always have Smart Resample set by default.

Sorry Laurence, I should have been more specific. It's wavey horizontal lines in motion. I understand what John is saying about the pixels, but this happens even if it is Cropped just a small amount, or even if I just flip the clip horizontally.

Laurence wrote on 3/16/2006, 7:20 AM

Here's your problem: you have the deinterlace method set to none. When you do that, Vegas assumes you are working with progressive video and resizes the frame as it should a progressive video frame, thereby resizing the interlace combing effect. This is the wavey lines in motion you are seeing. What you need to do is to select either deinterlace by interpolation or blending fields (it doesn't matter which) before resizing. I know what you're thinking: that you don't want to deinterlace. Don't worry. If you are resizing or zooming in on interlaced video it won't deinterlace. It will just resize the even and odd fields separately and fold them back together. You would think that Vegas would take it's identification of frames being interlaced from the project properties and that the deinterlace method wouldn't matter, but for some reason, the deinterlace method seems to set whatever flag the resizing algorythm is looking for to do a two field resize. I made the same mistake as well and it took me forever to figure it out. This also happens with 4:3 to 16:9 aspect ratio changes as done by Ultimate S.