I have been working on a set of tools to make the process of cleaning up motion capture data easier, faster, and more enjoyable. I'm using Houdini's newest tools called KineFX for this, which allows me to treat animation and skeletons as geometry. It allows me to build tools that can "model" an animation into place.
This tool allows the user to draw over an extracted motion path in an orthographic viewport. It is procedural and makes use of Python Viewer States. Each stroke's properties can be altered after creation, for example to blend the new curve smoothly with the old curve.
Changing the animation curve by drawing in an orthographic viewport.