PyExifTool (active PyPI project) - A Python library to communicate with an instance of Phil Harvey's ExifTool command-line application. Runs one process with special -stay_open flag, and pipes data to/from. Much more efficient than running a subprocess for each command!
https://github.com/sylikc/pyexiftool/blob/master/README.rst (v0.1) ~
et.get_metadata(files)
~ (v0.5.3)et.execute_json(files)[0]