smoothing music sync

[Dan Ebberts]

Interesting problem. The expression in the tutorial was designed with the idea that the “hit” animation runs at normal comp speed, centered around each hit point marker in the audio layer. What you’re talking about here is something different.

You need it to speed up/slow down the hit animation depending on the time between markers in the audio layer. That’s possible to do, but there are some loose ends, like what speed does it run at before the first audio marker or after the last one? How does it know how long the animation is?

It would take a little work, but I think it’s doable.

Dan

[158slim]

Dan, thanks for the hints…I’m working with some ideas for setting up different variables to define the duration of the animation and then the distance between the two markers I’m trying to match that animation up with. In theory, I could then just interpolate the two duration periods, right?

Anyway, it helps to know that you think it is doable; and I think I’m on a better track than I was before. More hints – if you have any – would be very appreciated.

-slim

[Dan Ebberts]

Play around with this one – I think it’s pretty close to what you’re after. Set “dur” to the duration of your animation and “L” to your layer with the markers you want to sync to. You may need to change the behavior somewhat. Right now it will speed up if markers are too close together for it to run at normal speed, but if the markers are far apart the animation will run at normal speed (it doesn’t slow down to fit the space, but that’s a pretty easy mod).

dur = 1; // duration of animation
L = thisComp.layer("control");

hit = marker.key(1).time;
prev = 0;
if (L.marker.numKeys > 0){
  prev = L.marker.nearestKey(time).index;
    if (L.marker.key(prev).time > time) prev--;
}
next = 0; // assume no markers in future
if (L.marker.numKeys > 0){
  next = L.marker.nearestKey(time).index;
    if (L.marker.key(next).time <= time){
      next++;
      if (next > L.marker.numKeys) next = 0;
    }
}
if (prev == 0 && next == 0){
  0;
}else if (prev == 0 || next == 0){
  time - L.marker.key(Math.max(prev,next)).time + hit;
}else{
  t0 = L.marker.key(prev).time;
  t1 = L.marker.key(next).time;
  mid = t0 + (t1 - t0)*(dur - hit)/dur;
  if (time > mid){
    linear(time,mid,t1,0,hit);
  }else{
    linear(time,t0,mid,hit,dur);
  }
}

Dan

[158slim]

Wow! this works perfectly; and it does slow down when I spread out the markers. I was trying some other work-arounds but couldn’t get them to remap right. I was having a hard time following the exceptions through to the result I wanted. My brain was near exploding. I can’t thank you enough for the help.

-slim