Adding a moving mosaic filter to a video

EHG_newguy · Post by **EHG_newguy** » Fri Jan 16, 2009 10:31 pm

Yes, I've searched. No joy.

I have videos of vehicles and I want to obscure their licence plates. I can easily obscure an unmoving fixed portion of the screen by overlaying a cropped, chroma-keyed and mosaic obscured copy onto the original. Is there a trick to applying a moving "window" to the video or do I have to do as I fear and chop the video up into many small portions and blur out the plate on just a few frames at a time?

I'm using Videostudio pro 12.

Accolades · Post by **Accolades** » Fri Jan 16, 2009 11:00 pm

Black Lab · Post by **Black Lab** » Fri Jan 16, 2009 11:15 pm

The "moving window" is called moving paths, and VS does not have it despite yearly pleas for it to be added. You will have to do it frame by frame. Have fun.

EHG_newguy · Post by **EHG_newguy** » Fri Jan 16, 2009 11:35 pm

Moving paths.....thanks. At least I know the proper term now. I guess I'd better clear my agenda for the next few days......

Post by **Ron P.** » Sat Jan 17, 2009 12:25 am

Have you had a look at Steve's tutorial called Number Plate Blur? It's not a real simple solution, but really not that difficult or time consuming..

EHG_newguy · Post by **EHG_newguy** » Sat Jan 17, 2009 2:07 am

I stumbled upon a rather quick & easy method and I thought I'd share it here.

1. Place the video that you wish to blur/obscure on both the video and overlay tracks. Make sure they're time aligned to start simultaneously.

2. Adjust the slider to point at the frame just before the image you want to blur/pixellate comes into frame, then right click the overlay track and select "cut clip".

3. Use the same method to point at the frame just after the image completely leaves the frame & cut the overlay clip again as outlined above.

4. Place a cropping overlay filter onto the clipped overlay track. Use the size & crosshair adjustments to properly align it over the image you want to obscure at the beginning and start of the shortened clip. Videostudio will automatically move and interpolate the mask in the time between the start and endpoints. DON'T select the "Stationary" check box for the cropping filter. Adjust chroma key as necessary.

5. Drag a mosaic (or whatever) overlay filter onto the same clipped overlay track and adjust as necessary.

6. If you're lucky, the pixellated box will perfectly track whatever it is you're trying to obscure. If not, chop the overlay track into smaller pieces and readjust the cropped filter as necessary.

I originally tried to chop a track into equal sized small pieces, then added the filters to each. Pain in the butt. Much easier to do it this way as any track you clip that already has filters applied doesn't need them reapplied afterward.