How to use the av.container.open function in av

def load_audio(self, path):
        """This require an audio input longer than 2.24s."""
        fin = container.open(path)
        audio_frames = [frame for frame in fin.decode()]
        audios = list(map(lambda x: np.frombuffer(x.planes[0], self._format_dtypes[x.format.name],
                                                  x.samples), audio_frames))
        audio = np.concatenate(audios, axis=0)
        return nd.array(np.expand_dims(audio[:self._audio_length], axis=0))

def _load(path):
        fin = container.open(path)
        audio_frames = [frame for frame in fin.decode()]
        audios = list(map(lambda x: np.frombuffer(x.planes[0], format_dtypes[x.format.name],
                                                  x.samples), audio_frames))
        audio = np.concatenate(audios, axis=0)
        return nd.array(audio)