def __init__(self, callbacks, control_channel):
self._control_channel = control_channel<EOL>self._control_fd = control_channel.fileno()<EOL>self._callbacks = callbacks<EOL>self._process = None<EOL>self._cmd = [self._find_path()]<EOL>
Constructor

        Will attempt to find the player binary on construction and fail if it
        is not found. Subclasses should append any additional arguments to
        _cmd.