Video becomes blurry with track motion

Nat wrote on 4/9/2004, 7:06 AM

I am editing a TV program with Vegas and I noticed a strange problem.

I have the host for the show shot on a white background, I have to use a mask to hide the sides of the background. So basically, I have my first track which is the mask and the second track which is the talent. The last track is the background.

I use track motion on the mask track to move the whole picture, as soon as I move the image up or down, it becomes blurry. It will be sharp/blurry depending on the vertical position of the frame.

Our deadline comes pretty soon so if anyone has some tips or solution it would be greatly appreciated. Thanks.

Here are some example images :

Vegas Timeline
Good shot
Bad shot

Comments

TheHappyFriar wrote on 4/9/2004, 8:15 AM

I belive it's an interlace thing. And, if it is, there isn't much you can do (besides convert parts to progressive scan). Is it noticable on a TV (i assume it is cuz you're telling us about it, but just checking).

Sorry.

Former user wrote on 4/9/2004, 8:18 AM

Make sure you render using BEST.

Dave T2

farss wrote on 4/9/2004, 8:23 AM

I cannot really see the problem from the screen shots but I would expect that to happen. You only have a fixed number of lines of resolution. As you move the image up the original lines may or may not line up with the lines to be output. When they don't Vegas has to use interpolation to create the lines of the image and this softens the image.
You may be able to improve this process by using Supersampling. I've never used it myslef but I believe it upscales the iamge to a higher res prior to interpolation which should give better results but longer render times.

Nat wrote on 4/9/2004, 10:48 AM

Thanks guys,

As you said, this is probably a field/interlace issue, I will try to use supersampling but I still find it weird that the video blurs out depending on it's position on the screen....

TheHappyFriar wrote on 4/9/2004, 2:28 PM

If you move it up 2 pixels (lines, fields, whatever) at a time, you might not have this fuzzyness problem. It's worth a try.

J_Mac wrote on 4/9/2004, 4:40 PM

When looking at your good vs bad png's, I could not see any difference in the backgrounds, but the model face etc, was blurred. I recently had a similar issue but on a larger scale. Cheesehole suggested these settings and fixed my png problems.
'If you want to see your preview without the "ghost" you can change your project settings to:

Frame Rate: 59.94060
Deinterlace Method: Interpolate
Field Order: Progressive
(I'm assuming you started with the NTSC DV preset)

Then make sure your preview window is sets for Best (Full) and size it so it is displaying the full 720x480 image.

Then right click on the preview and make sure that Simulate Device Aspect Ratio is checked.

Now you can advance frame by frame in the project (ALT + ARROWS) and choose the best still. It will be composed of a single field of video, interpolated to create a full frame. You can save stills from the preview window by clicking the floppy diskette icon. Saving as PNG will preserve the most quality.'

One must assume that what you see ain't what you get. My post was referring to stills from the TL. Hope this may help you. John.

Nat wrote on 4/9/2004, 6:49 PM

Could this be because my image is "in between lines" depending on it's position on the screen ?