Starts a playback

def play(self):
        """Starts a playback"""
        if self._proc.state() == QProcess.Running:
            if self.isPlaying is False:
                self._execute("pause")
                self._changePlayingState(True)
        elif self._filePath is not None:
            self._kill()
            self._run(self._filePath)
            self._changePlayingState(True)