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# Link audio to opacity effect of an image in After Effects

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 Link audio to opacity effect of an image in After Effects on Feb 25, 2017 at 4:26:25 pm

I have 3 audio files from a podcast. 1 file from Steve, one from john, and the other is from me.

I have a composition with the three audio files and also 3 png images of our faces, one for each of our faces. Each image has an opacity keyframe set to 50% by default. Now i want to connect each audio track to the right image and animate as follows:

✖ When audio intensity of a track is more than x decibels then gradually animate the image that's linked to that track from 50% opacity to 100% opacity`. To give the
visual effect of who is currently talking
.

✖ When the sound intensity drops below the x decibels i have set before, then gradually animate the opacity back to 50%

How can i achieve that?

 Re: Link audio to opacity effect of an image in After Effectson Feb 25, 2017 at 6:05:43 pm

By hand. The problem: pauses in speech. AE can't tell through an expression whether a speaker is pausing for effect, taking a breath or is actually done talking for a while.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

 Re: Link audio to opacity effect of an image in After Effectson Apr 12, 2017 at 5:50:03 pmLast Edited By Dmitry Klingensmith on Apr 12, 2017 at 6:25:59 pm

What's you expression for your audio keyframes? You will need to use expressions for this.

First create 3 separate audio amplitudes of the 3 audio files.
Then press U on one of the audio amplitudes to bring up the keyframes.
Delete left and right track as its not needed, only both.
Alt click the stopwatch next to the both output, this will allow you to type an expression in.
The expression you would want to type in is this: Linear(value,x1,x2,y1,y2)
This will output a value for your opacity based on the Keyframe value of amplitude.
x1 = the lowest value of a keyframe (shown on the timeline) you want for the lowest value of opacity you want.
x2 = the highest value of a keyframe you want for the highest value of opacity you want.
y1 = the lowest value for the opacity you want for the x1 value keyframe
y2 = the Highest value for the opacity you want for the x1 value keyframe

example: linear(value, 0,50,50,100)

This says that at keyframe 0 of the amplitude of audio your opacity will be 50% and at keyframe 50 it will be 100%, and any keyframes in between will scale the opacity in a linear way. so say the keyframe value is 25, then your opacity output value will be 75%. You can also use easeOut and easeIn instead of linear if preferred for that type of opacity animation change.

Next alt click the stop watch on the opacity to bring up its expression.
Use the pickwhip tool to select the output both channel of your audio amplitude layer.
Now repeat this for each individual audio amplitude layer you have and pickwhip it to the corresponding image you want the opacity to change with.