I needed a somewhat special Humanoid animation for my rig (precise walk and turn), which looked natural. I also needed to add a couple of "extra" coordinated items/bones.
It seemed theoretically possible to import FBX from a couple "Raw Mocap" clips into Blender, splice and edit, and re-export the result as a new FBX. It's a little tedious and finicky, but seems to be headed toward a good result. Easier than starting from scratch.
Is this something which is commonly done? Is there a better workflow for it?
If you feel comfortable working within Blender then I'd say stick with that, otherwise you could also look into using something like this: https://assetstore.unity.com/packages/tools/animation/umotion-community-animation-editor-95986. Editing animations can either be a quick process or a tedious process depending on what you're trying to achieve. It sounds like in your case you'd actually have to modify the animations quite a bit.
I'm not sure what you're trying to achieve, but if you're just blending between a walking/turning state you could use blend trees for that. This is a lesson that covers the process a bit more https://cgcookie.com/lesson/directional-2d-blend-trees. You can use blend trees to smoothly transition from various animation states for movement. I've used it to have a player run in any direction smoothly with just a few generic running animations.
Thanks jgonzalez . UMotion looks extremely interesting - hadn't heard of it. With the Pro version I probably could do everything I'm attempting completely inside Unity. Probably a more streamlined process, although I am more familiar with Blender. In my case I was a little lucky, because I could just splice together ranges of standard clips and get pretty close.
I tried ranging/chaining standard clips and fiddling with transitions (the normal way in a Controller), and I can get in the neighborhood, but not as precisely or smoothly as I like. The required motions are really tight.
I've used add/sync layers somewhat in the past for adjustment. I completed the blend tree training but haven't tried constructing anything that way yet.