• Adobe After Effects Expressions

  Audio to Keyframe fade out

  Posted by James Hepher on August 29, 2016 at 2:13 pm

  Hi there,

  I’m trying to hold and fade out on flashing solid.

  It’s opacity value is creating using an audio to keyframe object.

  Any advice would be grateful.

  Many thanks,

  J

  James Hepher replied 9 years, 8 months ago 2 Members · 2 Replies
• 2 Replies

• 

  David Conklin

  August 29, 2016 at 5:23 pm

  Try something like this:

  //This gets the audio from the audio Amplitude layer that 'Convert Audio to Keyframes' made
var aud = thisComp.layer("Audio Amplitude")("Effects")("Both Channels")("Slider");

  // This gets the value of the Opacity property BEFORE you applied the expression. Basically returns the value you'd see when
  // you click the 'opacity' value box to enter a value. It then divides that by 100 to give you a range 0-1 instead of 0-100.
  var offset = value/100;

  // Now, we multiply the audio data by our offset.
aud*offset

  What this does, is that it allows you to keyframe your opacity from 0-100, and have that compound on top of the data that’s being created by the Audio to Keyframes. So, just paste this expression onto opacity, set a keyframe at 100 for when you want the fade out to begin, and a keyframe at 0 when you want the fade to be complete. This works because when your opacity is 100, we divide it by 100 and get a value of 1. The audio data multiplied by 1 is just the audio data. When our opacity is 0, we multiply the audio value by 0 and get 0. When our opacity is 50, we divide that by 100 to get 0.5, and 0.5 times our audio data is half of the value.

  I hope that makes sense. Give it a try and let me know if it doesn’t work!

  David Conklin
  mographcode.tumblr.com
• 

  James Hepher

  August 30, 2016 at 10:31 am

  It doesn’t seem to be doing what I need.

  I think I need to create some sort of linear ramp from 100-0.

  So when the opacity is 100 it automatically trigger a ramp that fades out for a set duration.

  Any ideas?

  Cheers,

  J

Reply to this Discussion! Login or Sign Up