The Basics
Mocha is an application all unto itself with its own manual,longer than this chapter (just click Guide on the Mocha
Welcome dialog). It’s not a bad read. Because it’s a new
feature, here’s a look at how best to get up and running.
First of all, Mocha is limited to a subset of footage formats
that you might use in an After Effects project. Cineon log
fi les are okay, but several other higher-than-8-bpc formats
seem to be off-limits, so you may need to render a special
version of your source clip to be compatible. (I suggest Animation
compressed QuickTime; it’s imperative to get the
frame rate correct and having it embedded in the source
fi le helps you avoid careless errors with image sequences.)
The wizard to set up a project results in the creation of
the Mocha project fi le before you get started—either in
a location you specify or adjacent to the shot. The most
crucial thing to get right in this three-page process is frame
rate (which is only an issue with an image sequence); the
difference between, for example, 23.976 and 24 frames per
second is crucial; a mismatch will result in a track that slips.
Once your shot appears in Mocha, the next step is to scrub
to a frame that clearly shows the planar area you wish to
track. The rules are entirely different than with a point
tracker: You don’t need to see the entire plane or any of
its boundaries; you’re just looking for coplanar details that
are most consistent through the shot. “Consistent” means
not obscured by foreground motion or light fl ares and
refl ections, although there are workarounds for both.
On that starting frame, you use one of two tools to draw
out a mask shape: Bézier splines or the less familiar but
preferable Mocha X-splines . Select either and tap a few
points—it doesn’t matter how many—around the target
details. It’s helpful if these points correspond
to some recognizable detail for fi ne-tuning later, but they
don’t have to. Close the shape by clicking back on the
fi rst point.
At this point, with an easy track, you can use the forward
and backward controls and watch Mocha work its magic.
If the track sticks to its target, the next step is to fi ne-tune
it. Assuming you’re exporting corner pin data, you must
at minimum enable Surface under the View Controls and
place the corners where you want them in the result.
If all is still well, you can now click Export Tracking Data
on the Track panel and copy or save After Effects CS4
Corner Pin Data. If you copy, you can then paste directly
into the target layer in After Effects at the fi rst frame of the
source; Mocha creates a keyframe on every frame .
If you instead choose to save a text fi le, you can then
copy and paste its data from an ordinary text editor.
