Creative Communities of the World Forums

The peer to peer support community for media production professionals.

Activity Forums Adobe After Effects Expressions tracking speed to control frame rate

  • tracking speed to control frame rate

    Posted by Daniel Cantwell on April 25, 2019 at 2:59 pm

    Howdy Folks

    I was wondering does anybody have any experience controlling frame rate with the speed curve of tracking data. I am sure it should be possible to have a linear camera move rendered out at a high frame rate (provided the distance rendered is the same as a live action camera) and have the speed of a live action track control the frame rate to get the appropriate ease in and out. Any help with this would be greatly appreciated.

    Filip Vandueren replied 7 years ago 2 Members · 1 Reply
  • 1 Reply
  • Filip Vandueren

    May 1, 2019 at 2:44 pm

    It depends… if you’re tracking 2D data, the position of your track would indeed have a linear relationship to distance traveled. You can integrate and scale that by a value that is dependant on the actual amount of mpixels travelled. Easiest would be to tweak that value with a slider.
    Something like the attached expression would work (in theory !).
    Maybe checking the speed at every frame-duration wouldn’t be accurate enough, just change the fd = line and adjust scalingFactor accordingly…

    scalingFactor = effect("Slider Control")("Slider").value;
    trackingProp = thisComp.layer("2").transform.position;
    fd = thisComp.frameDuration;
    delta = 0;
    for (t=0; t<time; t+=fd) {
    delta += trackingProp.speedAtTime(t);
    }
    d=(delta/scalingFactor);

    valueAtTime(d);

We use anonymous cookies to give you the best experience we can.
Our Privacy policy | GDPR Policy