Pose/animation retargetting?

I would like to be able to load character poses and animations in BVH format and be able to re-target the animation to a rigged model loaded in Panda with a different bone sizes and hierarchy.

Where can I even start with this?

This is possible thanks to a 3D graphics editor using animation export, for example, through the Yabee blender or another editor, for example 3d max.

No, I need it in a 3d engine.

Engines such as Source have this feature.