mocha Pro is a great rotoscoping and masking tool for video. It has won awards (even Oscars were involved) and it offers a complete environment for rotoscoping and compositing artists to work their magic. But it lacks a direct integration with Final Cut Pro X or even the latest version of Motion. CoreMelt solved that problem by embedding the mocha tracking engine in their SliceX product.
CoreMelt's SliceX originally was a keyframe based tracker. This meant that with every move of the shape you're trying to rotoscope or turn into a mask, you needed to create a keyframe. Powerful, but tedious. SliceX "powered by mocha" now makes SliceX the best since — heh — sliced bread. You get the tracking power from mocha with the SliceX preset shapes. You also get the ability to create shapes in freeform manner, just like what you're used to in mocha Pro.
SliceX is a Final Cut Pro X plug-in. It lives in the Inspector with some five preset compositing effects, including one adjustment layer. The presets include Shape Mask, Object Remover, Blur Shape Mask, Color Correct Shape Mask, Depth of Field Shape Mask and Vignette Shape Mask. The adjustment layer comes in three versions: a blank one, a Shape Mask Border and a Vignette Shape Adjustment.
The first thing you'll have to do to make SliceX work well is turn off background rendering. Otherwise you risk background rendering to start while SliceX is still working.
Also best is to turn off stabilisation. Finally, playback should be set to "Use Original" or "Optimized Media" for best results.
I was already more or less familiar with mocha Pro's tracking workflow, so I used my knowledge with SliceX. That turned out to be a good idea as SliceX almost one-on-one works the same as mocha Pro. You first select the best frame in a clip, e.g. showing the plane to track as cleanly as possible. Then you draw your shape and track backwards and forwards.
You even get the same control over the tracking engine as in mocha Pro. That means you can set the tracker to "Perspective" or "Translate/Scale/Rotate" and to a quality of medium or high. The similarities end there, as mocha Pro enables you to export rotoscoping/tracking data as well as mask shapes to a plethora of third party applications. SliceX obviously doesn't export to anything and only works with shapes.
Having said that, SliceX does support the same freeform drawing modes as mocha Pro (Bezier and X-spline) and allows you to use the tracked shapes of the Blank Adjustment Layer for any effect, not just for its own preset effects like blurring or removing objects. Of course, lens correction and some of the other high-end capabilities you'll find in mocha Pro aren't available in SliceX — I guess it wouldn't make much sense to have these in the Final Cut Pro X environment, either.
In short, working with SliceX is as much fun as with mocha Pro. SliceX has the added benefit of providing instant gratification when you want to blur areas, colour correct a shape on the move, create a vignette, or even add an accurate and highly customisable "bokeh" effect.
In use, SliceX is really simple, which is not to say it's not time-intensive to create a well-defined and accurately tracked mask. Just as with mocha Pro, in the end it's how much time and effort you put into the compositing or rotoscoping that determines whether you'll end up with an effect that looks natural.
One thing is clear, though: if you want the power of the mocha planar tracker, the familiarity of the Final Cut Pro X interface and some powerful effects as well as customisation controls, SliceX is a killer app and it's inexpensive too at €115.75.