• Adobe After Effects

  Using alpha channel from .mov stock footage

  Posted by Matthew Angus on July 12, 2011 at 5:40 am

  Hi there

  I am trying to incorparate a stock footage .mov of a Vault that opens and will reveal the content to my video. The file I have downloaded (for reference) is https://www.istockphoto.com/stock-video-4816262-vaulted-door-hd-video.php

  I have tried to interpret the relevant .mov file in the project, but it doesn’t allow me to select any of the options under alpha. The alpha channel is at the end of this clip, but I’m not sure the best way to use this. Ideally as the door opens it will show the start of my video.

  Any help would be great.

  Cheers

  Matt

  Matthew Angus replied 15 years ago 2 Members · 2 Replies
• 2 Replies

• 

  Walter Soyka

  July 12, 2011 at 12:37 pm

  [Matthew Angus] “I have tried to interpret the relevant .mov file in the project, but it doesn’t allow me to select any of the options under alpha. The alpha channel is at the end of this clip”

  It’s not a real alpha channel — it’s the fill followed by a luma matte.

  You will need to split the layer [link] in the middle, at the point where the black & white footage begins.

  Next, slide the B&W luma matte over to the left on the timeline so it’s directly above the fill, then set the fill layer’s track matte menu to Luma Matte [link].

  Walter Soyka
  Principal & Designer at Keen Live
  Motion Graphics, Widescreen Events, Presentation Design, and Consulting
  RenderBreak Blog – What I’m thinking when my workstation’s thinking
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• 

  Matthew Angus

  July 13, 2011 at 1:50 am

  Thanks Walter, for getting back.

  You wouldn’t believe it..but this is axactly what I tried about 5min after posting my original enquiry and got the exact result I was after!

  It’s amazing a bit of time away from AE does to clear your brain !

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