• Adobe After Effects

  Addition to Audio volume to scale(layer) expression?

  Posted by Robin Hamilton on June 29, 2007 at 4:44 pm

  I have a character animation and for a quasi lip sync. I am using an expression that scales a layer (mouth), according to the volume of an audio track.

  I have one question though. Does anyone know of an expression that would turn the opacity of another layer from 0 to 100 (eg. a closed mouth layer) when the audio reaches a minimum volume (user set db value)? As well as a max volume.

  Markofcain replied 18 years, 10 months ago 3 Members · 2 Replies
• 2 Replies

• 

  Roland R. kahlenberg

  June 30, 2007 at 10:21 am

  Lots of similar Qs been posted here. Best to perform a Search using the word “Interpolation”

  Cheers
  Roland Kahlenberg
  https://www.broadcastGEMs.com – Adobe After Effects project files
  https://www.myspace.com/rorkrgbspace
• 

  Markofcain

  June 30, 2007 at 10:44 am

  Set up the comp by:

  1) Convert the Audio to key frames
  2) select the layer you want to toggle on and off
  3) open the opacity — “T” Key
  4) Alt click the stopwatch (PC assumed here)
  5) drag the pick whip to the audio slider

  AE will generate an expression for you like:
  thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”)

  We want to change this so that we can modify the value before it gets passed to the opacity. What we need to do is:
  1) assign a variable to the audio levels
  2) assign a variable to the opacity level
  3) set a lower limit value below which the opacity is zero and above which the opacity is set to 100.

  So now the expression looks like this:

  signal_value = thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”);
  if (signal_value < 25 ) { opacity_value = 0; } else { opacity_value = 100; }; opacity_value; The logic is intuitively obvious to the most casual observer -- but I will walk you through just in case: The conditional statement of the expression constantly checks the value of the variable "signal_value." If the value of variable "signal_value" is less than 25, then the expression path flows to the statement immediately below where the variable opacity_value is set to zero. If, however, the value of the variable "signal_value" is 25 or greater, then the expression path jumps to the statement immediately below the "else" where the variable opacity_value is set to 100. Finally, the last line "returns" or announces the opacity_value to the layer. HTH Mark Cain Sarasota, FL USA

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