The original material were two video files in H264, and we started the process keying and rotoscoping the cat in After Effects, to get the cat as clean as possible.
In the second pass I had to create the loops for two different actions: the first one, the cat walking in and standing; and the second one, the cat walking in, sit in the floor and walking out. This pass involved an interesting mix of different techniques (re-timing, morph, masking…) mainly in After Effects.
The final step of the process we added a pair of 3D gadgets, a microphone and a pair of antlers (for the Christmas campaign).