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Expression to use with audio keyframes and time remapping
I have manipulated the position of some keyframes using the graphic editor. The keyframes correspond the waveform of the music track. (Convert audio to keyframes, I don’t have Soundkeys nor can I afford it right now). Basically I have the top peaks of the waveform registering at a value of about 90 and everything else at zero. I works out to go with the beat quite nicely.
What I am trying to do needs a little bit of tweaking. I want the video to play fast during the peaks and at normal speed the rest of the time. I am using time remapping and this expression:
timeRemap+(thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”)*.01)
This makes the video play faster during the peaks but then jump back a bit off peak, the video continues to play all the way through (in other words it doesn’t just jump back and forth between the same couple of frames, b/c of the “timeRemap+” part).
I need to incorporate some kind of running total into the expression so that AE knows what has occurred in previous frames.
I am pretty new to AE, especially expressions. If someone could take the time to explain what I need to do I would greatly appreciate it. Also pictures showing how the expression(s) look(s) when entered would also be greatly beneficial.
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2 Replies
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Aharon Rabinowitz shows how to do something like this here.
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Todd Kopriva, Adobe Systems Incorporated
putting the ‘T’ back in ‘RTFM’ : After Effects Help on the Web
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This can be done, but you need to define exactly what you want to happen (and how long it lasts) at each beat. It will probably involve something similar to this beat counter:
https://www.motionscript.com/design-guide/audio-count.html
But the exact code depends on the desired behavior.
Dan
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