[Xinlai Ni]

This does what you’ve described:

bucket = Math.floor(time / 5);
linear(time, bucket * 5 + 4, bucket * 5 + 5, bucket + 1, bucket + 2)

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

It depends on what particle system you are using. I think both CC and Particular only allow you to animate the speed at which particles are emitted, not the exact number of particles.
In case you mean that, for example, in Particular, you can use this expression in the Particles/sec property:
((timeToFrames() % 30) < 15) ? 100 : 0

It may be hard to see the effect until you adjust the particle life to 0.5s (on a 30fps frame rate).

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

What I mean is you can make speedModulatedFreq any function of the two variables cameraSpeed and baseFreq, not necessarily their product – as long as it monotonically increases when either or both of those increases.

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

opacities are not additive, if you will, transparencies are multiplicative:
Your set up has two black layers with opacity 50%, that’s the same as saying they both have transaparency of 50%, which means if you overlay them they have a transparency of 50%x50%=25%, which means 75% opacity.
The fact that transparencies are multiplicative can be justified by thinking of rays going through these layers, after the first layer, 50% of the original light passed through, and after the 2nd, 50% of the 50% passed through.
Hope this helps.

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

Are you using time remapping or shift of precomp layer on the timeline panel for the main comp?

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

Instead of using position.speed, you can use position.velocity which is a dim-3 array containing the velocity components of the x,y,z direction.

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

Here is a simple one:

cameraSpeed = thisComp.layer("Camera 1").position.speed;
baseFreq = thisComp.layer("Null 1").effect("Slider Control")(1);
speedModulatedFreq = cameraSpeed * baseFreq / 100;
wiggle(speedModulatedFreq, ampl)

It linearly multiply the base frequency as defined by your null control with the camera speed (divided by some constant just so the frequency is not crazily high).
But you can do anything with the speed and your base frequence – it does not have to be a linear function.

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

If you want PIP’s to maintain the constant size throughout the whole clip, it’s simple:
Add each conversation participant’s clip as a new layer in the main comp, scale it to the desired size (e.g., 1/3 comp width and 1/3 comp height), and move it to the correct position. Then shift the layer in the timeline panel to change its start time, that’s it, you don’t even need animation this way.
If you want sub picture’s size to change over time, you may add key frames to the scale property.

Xinlai Ni
Software Engineer, Google Inc.

[Xinlai Ni]

((timeToFrames() % 4) < 2) ? 100 : 0 Xinlai Ni Software Engineer, Google Inc.

[Xinlai Ni]

Have you tried switching to the custom views to see the relative positioning of your precomp camera and particular? Sounds like your particular is out of the sight from the camera. When you are in custom view (or even just top,left,right, etc views), select both camera and particular layer, even if there’s no particles generated, you should be able to see two set of gizmos representing these layers, then verify that the particular is in the visibility cone of that camera.

Xinlai Ni
Software Engineer, Google Inc.