write data to file.

        :Parameters:
            input : ndarray
                array containing data to write.
            nframes : int
                number of frames to write.

        Notes
        -----

        - One column is one channel (one row per channel after 0.9)
        - updates the write pointer.
        - if float are given when the file contains integer data, you should
          put normalized data (that is the range [-1..1] will be written as the
          maximum range allowed by the integer bitwidth).

def write_frames(self, input, nframes = -1):
        """write data to file.

        :Parameters:
            input : ndarray
                array containing data to write.
            nframes : int
                number of frames to write.

        Notes
        -----

        - One column is one channel (one row per channel after 0.9)
        - updates the write pointer.
        - if float are given when the file contains integer data, you should
          put normalized data (that is the range [-1..1] will be written as the
          maximum range allowed by the integer bitwidth)."""
        if nframes == -1:
            if input.ndim == 1:
                nframes = input.size
            elif input.ndim == 2:
                nframes = input.shape[0]
            else:
                raise ValueError("Input has to be rank 1 (mono) or rank 2 "\
                                 "(multi-channels)")
        return self._sndfile.write_frames(input[:nframes,...])