2 Replies Latest reply on Nov 14, 2009 12:00 PM by Andy Bay

    Motion tile a video with an alpha channel

    Andy Bay Level 2



      I'm trying to use the motion tile effect to fill transparent edges that are the result of stabilization with the prodad mercalli plugin. The problem is however that because the stabilization hasn't been done using keyframe movement in AE, it sees the transparent edges as part of the frame and applies the motion tile so that the transparent areas stay intact. In other words the motion tile effect doesn't see that the image is moving around because only the alpha channel is changing.


      Is there any smart ways to solve this problem in AE so that I can apply the motion tile effect to get rid of the alpha transparency around the edges of the stabilized footage?


      Any help will be appreciated!

        • 1. Re: Motion tile a video with an alpha channel
          Mylenium Most Valuable Participant

          Separate the components by using multiple duplicates and the Shift Channel effect. Apply your Motion Tile in the required manner, then combine everything back together using Add blending mode and re-introducing the Alpha channel using Alpha Matte/ Stencil Alpha blending mode.



          • 2. Re: Motion tile a video with an alpha channel
            Andy Bay Level 2

            Hi and thank you for helping out!


            Unfortunately I didn't get this to work with shift channels. I'm not sure what you meant by separating the components? I put shift channels on the videoclip and told it to use alpha from the video of the alpha.


            Actually I'm a bit confused on why shift channels should help. The way I see it, the problem is that the "motion tile" effect is seeing the "whole" pixel dimension of the video that also includes the alpha channel and is applying itself to the whole frame instead of just the opaque area (the actual stabilized  video). Because of that the motion tile effect is tiling the whole frame, including the alpha of it which leaves transparent gaps between the two tiles.


            Maybe there was a miscommunication between us or should I just try the shift channels effect again? If that's the case, then could you explain what you mean by separating components?


            Thank you very much!