• Adobe After Effects Expressions

  Random Time/Frame

  Posted by Jeremy Wick on May 21, 2012 at 4:49 pm

  I created some .mov files in Photoshop, at 12 fps, using a basic rotoscoping technique. I like the wiggly effect, but to save time, I only animated 1 second of each asset and I am planning on looping these in After Effects with the loopOut expression.

  To make it look less like it is repeating every second, I am trying to figure out an easy way to randomly generate the time on each frame.

  For example: new frame 1 = original frame 3, new frame 2 = original frame 9, new frame 3 = original 1 …and so on.

  I would use random() but I want to avoid having the same frame twice in a row because it makes it look choppy.

  Dan Ebberts replied 13 years, 12 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Dan Ebberts

  May 22, 2012 at 1:09 am

  I think this will guarantee you don’t get the same frame twice in a row:

  
numFrames = 90;
seedRandom(index,true);
f = timeToFrames(time);

  fr = Math.floor(random(numFrames));
for ( i = 1; i <= f; i++)
fr = (fr + Math.floor(random(1,numFrames)))%numFrames;
framesToTime(fr)


  Dan

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