Moving image mask - peephole, James Bond effect?

kcwdad · Post by **kcwdad** » Sun Nov 19, 2006 3:29 am

Having trouble figuring out how to make an image matte move without seeing the frame of the matte (MSP8).

What I want: screen to be always black except small portion of video exposed only within a shape I created in my image matte, and I want this exposed shape to move across the video playing underneath, exposing different portions of the video as it moves across the screen. I never want to see the entire frame of video, just the shape exposing different parts of it as the shape moves, like a moving peephole into the video. Been a while since I've seen a Bond movie, but I think this is what the bullet hole does during the intros--moves around the black screen showing you different portions of the video underneath.

What I've tried

1) Black/white matte image is in timeline at V2 with video I want exposed underneath at V1. I've tried overlay options for color key (bmp) and I've tried alpha channel (TIF from CG Infinity). Then I apply moving path to overlay image on V2. The problems here are a) the entire matt image moves left to right, including the black frame, and b) the entire video is exposed until frame moves to cover it. It looks fine if remove the moving path (frame is black except shape of matte), but of course this is just because the image I used has a black background.

Here's the result in approach one, in middle of moving path. I don't want to see the video at the right, should all be black except the portion showing through the shape.

[img][img]http://img168.imageshack.us/img168/6184/logomaskprobzo7.th.jpg[/img][/img]

2) Video I want exposed is on V1, I select "image matte" as overlay option. I can get it to work as static matte, but can't find a way to apply a moving path to the matte itself. What I can do is apply moving path to the video (which now has overlay matte) but of course this moves the entire video underneath.

3) Black/white image on V1 with overlay option "video matte", then selecting the video I want exposed as the video matte. I don't see why this should work, but it was something to try.

It sure seems this should be possible, what am I missing?[/img]

Note I have successfully employed one ugly workaround, which is to make the mask image far larger than the video frame size (but keeping the white alpha/color key shape small) but this limits the moving path effects and is far more tedious for all the things I want to do (not just move left to right but also 3D moving path effects like flips, twirls, etc.)

Thanks in advance for any help!

Devil · Post by **Devil** » Sun Nov 19, 2006 9:46 am

Guess this is a job for VideoPaint.

If you have an earlier version of MSP, this was included. If not, you will need VideoGraphics Lab http://www.ulead.com/vgl/runme.htm "Create special effects such as ... video mattes"

sjj1805 · Post by **sjj1805** » Sun Nov 19, 2006 1:54 pm

Why not do it the way I did with the circles in this one:
Circles Project

andrewc · Post by **andrewc** » Sun Nov 19, 2006 6:47 pm

Dou you mean like this:

http://www.aimcosoftware.co.uk/video/mask.wmv

kcwdad · Post by **kcwdad** » Mon Nov 20, 2006 1:38 am

Thanks all. The movie above is actually how far I've got already, per image I posted. If you lost the white rectangle floating around and only had the circle, that would be what I'm trying to acheive.

The moving colored clip circles is a pretty nice trick, not sure how they would become image masks?

andrewc · Post by **andrewc** » Mon Nov 20, 2006 2:37 am

The white rectangle is only to show where the V2 Video is, you said that you wanted to apply flips and twirls and I assumed to the finished video.

It was done the same way you did it, with an image twice the size of the video frame so you can move it where you want without exposing V1 .

You described it as 'ugly' but that is how it must be done.

The overlay was created in a seperate timeline, then added to the main timeline and a 2D path applied to it.

If you meant flips and twirls to the matte only, then you will need to use a different method.

Method 1 - Path for whole video once masked

Timeline1:
V2 Image Matte >Overlay>Path
V1 Video to expose

Main Timeline:
V1 New Timeline >Path

Method 2 - Path on mask

Timeline1:
V2 Mask >Path
V1 Background colour same as non-transparent part of mask

Main Timeline:
V2 Timeline1 >Overlay
V1 Video to expose

I use b/w masks and grey key as it gives softe edge on antialiased masks without needing to use Alpha

If you are using V7 then you will need to create an intermediate video instead of using a seperate timeline.

kcwdad · Post by **kcwdad** » Mon Nov 20, 2006 3:59 am

FLash/clink-clink (sound of light appearing above my head and scales falling from my eyes).

Method #2 is what I wanted, and it did the trick. I had to read it a few times to realize this calls for nested timelines, and creating a video matte first and not trying to make an image matte do all the gymnastics.

Thanks for not only solving this problem, but also opening my eyes to the practical use of nested timelines, and for that matter, multi-step, multi-dimension effects.

Now I have the transparency growing via moving path from 1 pixel to entire screen, then bouncing around... Can't do that with oversized matte image background.

Thank you!!!