Problem with Zoom and Pan/Zoom effects.

[deleted]

I suspect this problem is connected to the way VP calculates image position for these effects and I would like to know if it can be improved.

I use quite a lot of webcam clips that depict an object moving at a steady, regular pace across the field of view of the camera. (Close up images of the Moon, Sunspots etc.) The camera support is also steady.

In the resulting avi the object is seen moving smoothly in a straight line. For technical reasons the web camera is set to expose 5 images/sec so the apparent steady movement is actually a series of short movements. As the apparent movement is produced by the Earths rotation, it is ABSOLUTELY steady.

Reviewing the avi In VP frame by frame, the movement of the object is seen every 8 frames.

I want the object, in fact to remain stationary within a set rectangle.

i.e. I want to use the Zoom effect to outline the object in the first frame of the clip. Set a key frame and then using the same rectangle, outline the object in the last frame of the clip and set a second key frame. The hope now being that the sequence will play from start to finish with the object now appearing stationary.

This, however doesn't happen. The resulting sequence shows the object (actually the whole of the zoomed frame) moving forward and then backwards and then forward again and then backwards etc. It is in no sense a steady image which is what I would have expected.

I have also tried setting keyframes for every "new" frame of the avi manually adjusting the rectangle to cover the same area of the frame for each frame showing movement (every 8 frames).

The forwards/backwards motion occurs just as before.

Why is this effect not working correctly and can it be corrected please?

Nat

c_major_2

Hi Nat,

Have you tried matching the framerate of the preview and export to the shooting framerate? Preview/Export at different framerate might lead to the issue you've got.

Try preview or export at a multiplication of the shooting framerate such that every frame in the shooting footage are in the output (no drop or unaligned frames).

For example:

20fps: 1 2 3 4 5 6 7 8 9 10

30fps: 1 1 2 2 3 4 4 5 5 6 7 7 8 8 9 10

20fps: 1 2 3 4 5 6 7 8 9 10

40fps: 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10

As you can see, output 20 fps to 30 lead to uneven duplicated frames. Effect don't duplicate frame and show exact state of given time position.

[deleted]

Hi Sam

Thanks I'll give that a try. I thought it might be frame rate somehow. Unfortunately the webcam frame rate is not always steady as my old portable drops frames like mad but I'll play with it. Thanks again.

Later....

Your advice almost works but still some judder. I find I now that I can export the clip(s) and then stabilize them. After adjusting the borders the result looks fine. :-))

BTW is there any possibility we can have the "Ask me" option back for where to place Clips and Images?

Nat

c_major_2

Hi Nat,

Your advice almost works but still some judder.

I'll do some testing on this...Is that only happen on Zoom or Zoom&Pan effect? Or maybe you can shard the project files to me so I can try myself.

BTW is there any possibility we can have the "Ask me" option back for where to place Clips and Images?

There is a small downward arrow next to the Place buttons. You can click on the arrow to choose where you want to place.

[deleted]

Hi Sam

"There is a small downward arrow next to the Place buttons. You can click on the arrow to choose where you want to place."

:-)) Obvious! Always tend to right click the clip and use the top option. DOH! Old habits die hard.

With regards the frame matching, After looking at the webcam output carefully I have noted quite a few dropped frames resulting in the image appearing to jump a different amount and it's quite irregular so not correctable. Stabilizing gets around this.

I completed this project OK and have already shown it at my Astro club. As mentioned, I matched the frame rates and stabilized the result (which worked very well.)

Nat