Jan Jacob Hofman has implemented 2nd order ambisonic encoding and decoding in Csound. The implementation is extended with additional techniques for spatialisation and offers instruments for creation of a trajectory for the movement of 20 coexisting sources in 3d space combination of the soundfile with distance clues and creation of a sonic environment and spatialisation of the sound the reverberation and the early reflections using the Ambisonic equations.
Here is a direct link to the goodies.