• Adobe After Effects

  Audio Amplitude Expression Question

  Posted by Christine P. on June 7, 2005 at 5:15 pm

  I am using an expression to link the opacity of one layer to the Audio Amplitude layer. My problem is that since the range of my audio layer is so minimal, the opacity change is not visible to the eye. Is there a way to set the minimum and maximum range so that my minimum value of the audio layer becomes 0% opacity and the maximum becomes 100% opacity.

  I appreciate any help you may be able to give!

  Thanks,
  Christine

  Quentin Block replied 14 years, 10 months ago 3 Members · 3 Replies
• 3 Replies

• 

  Dan Ebberts

  June 7, 2005 at 5:58 pm

  Something like this should do it:

  minAudio = 0;
  maxAudio = 15;
  minOpacity = 0;
  maxOpacity = 100;

  audio = thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”);
  linear(audio,minAudio,maxAudio,minOpacity,maxOpacity)

  Adjust the parameters to fit your situation.

  Dan
• 

  Christine P.

  June 7, 2005 at 6:05 pm

  Thanks so much for your help! I tweaked the numbers to fit my parameters and it’s working wonderfully.
• 

  Quentin Block

  June 25, 2011 at 4:56 pm

  Took me hours to figure this out as I’m expression-illiterate, but I kept getting an error when I used the above expression.

  I had to change the word ‘audio’ in the last (just inside the parentheses) line to ‘opacity’.
  Then it worked great!!!

  minAudio = 0;
  maxAudio = 25;
  minOpacity = 0;
  maxOpacity = 100;

  thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”)
  linear(opacity,minAudio,maxAudio,minOpacity,maxOpacity)

  Thanks for the start and hope this helps the next person that needs this expression!
  QB

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