def save_utterance(output_file, waveform, fs, start, end, overlap=0.1):
    """
    waveform: [#channel, audio_len]
    start, end, overlap: seconds
    """
    start = int((start - overlap) * fs)
    end = int((end + overlap) * fs)
    utterance = waveform[:, start:end]
    save_audio(output_file, utterance, fs)
waveform: [#channel, audio_len]
start, end, overlap: seconds
preprocessors/csd.py