Example: Blocking Mode Audio I/O — PyAudio 0.2.7 documentation

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# Example: Blocking Mode Audio I/O

    """PyAudio Example: Play a wave file."""

    import pyaudio
    import wave
    import sys

    CHUNK = 1024

    if len(sys.argv) < 2:
        print("Plays a wave file.\n\nUsage: %s filename.wav" % sys.argv[0])
        sys.exit(-1)

    wf = wave.open(sys.argv[1], 'rb')

    # instantiate PyAudio (1)
    p = pyaudio.PyAudio()

    # open stream (2)
    stream = p.open(format=p.get_format_from_width(wf.getsampwidth()),
                    channels=wf.getnchannels(),
                    rate=wf.getframerate(),
                    output=True)

    # read data
    data = wf.readframes(CHUNK)

    # play stream (3)
    while data != '':
        stream.write(data)
        data = wf.readframes(CHUNK)

    # stop stream (4)
    stream.stop_stream()
    stream.close()

    # close PyAudio (5)
    p.terminate()

To use PyAudio, first instantiate PyAudio using `pyaudio.PyAudio()` (1), which sets up the portaudio system.

To record or play audio, open a stream on the desired device with the desired audio parameters using `pyaudio.PyAudio.open()` (2). This sets up a `pyaudio.Stream` to play or record audio.

Play audio by writing audio data to the stream using `pyaudio.Stream.write()`, or read audio data from the stream using `pyaudio.Stream.read()`. (3)

Note that in “blocking mode”, each `pyaudio.Stream.write()` or `pyaudio.Stream.read()` blocks until all the given/requested frames have been played/recorded. Alternatively, to generate audio data on the fly or immediately process recorded audio data, use the “callback mode” outlined below.

Use `pyaudio.Stream.stop_stream()` to pause playing/recording, and `pyaudio.Stream.close()` to terminate the stream. (4)

Finally, terminate the portaudio session using `pyaudio.PyAudio.terminate()` (5)

# Example: Callback Mode Audio I/O

    """PyAudio Example: Play a wave file (callback version)."""

    import pyaudio
    import wave
    import time
    import sys

    if len(sys.argv) < 2:
        print("Plays a wave file.\n\nUsage: %s filename.wav" % sys.argv[0])
        sys.exit(-1)

    wf = wave.open(sys.argv[1], 'rb')

    # instantiate PyAudio (1)
    p = pyaudio.PyAudio()

    # define callback (2)
    def callback(in_data, frame_count, time_info, status):
        data = wf.readframes(frame_count)
        return (data, pyaudio.paContinue)

    # open stream using callback (3)
    stream = p.open(format=p.get_format_from_width(wf.getsampwidth()),
                    channels=wf.getnchannels(),
                    rate=wf.getframerate(),
                    output=True,
                    stream_callback=callback)

    # start the stream (4)
    stream.start_stream()

    # wait for stream to finish (5)
    while stream.is_active():
        time.sleep(0.1)

    # stop stream (6)
    stream.stop_stream()
    stream.close()
    wf.close()

    # close PyAudio (7)
    p.terminate()

In callback mode, PyAudio will call a specified callback function (2) whenever it needs new audio data (to play) and/or when there is new (recorded) audio data available. Note that PyAudio calls the callback function in a separate thread. The function has the following signature `callback(<input_data>, <frame_count>, <time_info>, <status_flag>)` and must return a tuple containing `frame_count` frames of audio data and a flag signifying whether there are more frames to play/record.

Start processing the audio stream using `pyaudio.Stream.start_stream()` (4), which will call the callback function repeatedly until that function returns `pyaudio.paComplete`.

To keep the stream active, the main thread must not terminate, e.g., by sleeping (5).

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