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Random value every X frames offset?
Hello, I’m using a simple random expression every 13.7 frames (every beat of a song) but the expression begins 5 frames into the clip (instead of 13.7 frame, a beat), so the effect changes every half beat, I need it to change every beat. I’m pretty new to expressions and I’m wondering if there’s a way to offset the beginning of an expression if i’m not missing something. Thanks.
Composition fps = 23.976
Song bpm = 105period = 13.7; // frames
posterizeTime(1/(period*thisComp.frameDuration));
random(-50,50); -
6 Replies
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Try it this way:
period = 13.7; // frames
seed = Math.floor(time/(period*thisComp.frameDuration));
seedRandom(seed,true);
random(-50,50);Dan
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Hey, thanks for the quick response. The expression still applies every half beat but I thought I’d add that i’m using this expression on a trimmed adjustment layer that lasts 109 frames. I apologize in advance if the problem has been something obvious I haven’t noticed.
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Where does the first beat occur relative to the layer’s in point?
Dan
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This might work better:
period = 13.7; // frames
offset = 5; // first beat relative to in point
seed = Math.floor((timeToFrames(time-inPoint) – offset)/period);
seedRandom(seed,true);
random(-50,50);Dan
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The first beat lands on the layer’s in point so I think ideally the expression should wait for the first 13 frames and then apply the random.
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Hey, that worked. Just changed the offset to 13.7 and the effects are now vibing with the beat.
Thanks a lot Dan.
period = 13.7; // frames
offset = 13.7; // first beat relative to in point
seed = Math.floor((timeToFrames(time-inPoint) - offset)/period);
seedRandom(seed,true);
random(-50,50);
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