'Open the file to read the PCM stream from the using
``item.path``.
:return: the audiofile instance
:rtype: :class:`audiotools.AudioFile`
:raises :exc:`ReplayGainError`: if the file is not found or the
file format is not supported'

def open_audio_file(self, item):

    try:
        audiofile = self._mod_audiotools.open(item.path)
    except IOError:
        raise ReplayGainError(u'File    {}    was    not    found'.format(item.path))
    except self._mod_audiotools.UnsupportedFile:
        raise ReplayGainError(u'Unsupported    file    type    {}'.format(item.format))
    return audiofile
