Precomp is disappearing and Mocha tracking points aren't pasted

Very newbie with Boris Mocha.
I want to use Mocha to replace a computer mouse cursor by an object. Here, with screenshots, it’s how I try to proceed.

I then created a solid layer
Screenshot 2021-03-22 at 12.12.06

Next, I pre-composed that layer
Screenshot 2021-03-22 at 12.13.36

Following this tutorial :, I applied my Mocha tracking data to my newly created comp (Red Solid 1 Comp 1)

But Sadly, It doesn’t work :

What happened ? Please help!

PS: I use the latest version of AE and Boris Mocha to date, on my MBP Apple M1

Isolate the footage and cursor into their own precomp and make sure when you do that you check the checkbox for “Adjust composition duration to the time span of the selected layers.” It looks like it’s not lining up because the clip and insert don’t line up.

So make a bunch of isolating precomps or treat this like a single shot and render a trimmed version and drop that into your edit.

Please try that and let me know.


Thank you for your reply. I’ve done what you have recommended. But I’m still facing the same issue

Hi Brice,

I can see that the footage isn’t trimmed to the precomp (see how the footage starts to the left off the timeline), OR you are working inside of the precomp instead of on top of the precomp. Make sure you trim the timeline in the precomp and then apply Mocha to the precomp, not the raw footage.

Try that and let me know.


Thank you, I’ve done so. But now, I got a new kind of error : “Tracking layer ‘Layer 2’ terminated prematurely > One or more layers were not tracked properly,…”.

Please help

This isn’t a bug. This is an expected workflow when you run out of things to track. What you’ll need to do is do a manual track for the part where the mouse goes off screen.

No my mouse is not off-screen (it looked off-screen because the parameter block was hiding it).

Here is an another try, and I still get the same error.

Okay you can still either try manual tracking. Or you can switch to tracking translation only.

So there is a no workaround to make it work using Mocha ?

That is the workaround. You can try also turning the percentage of pixels down. Or you can use manual track. Or you can use translation only. I’m not sure why it’s not tracking that mouse. But it could be that there’s not a lot of texture to track, and it’s just solid white on solid black.