:orphan:

audio_ex3
---------


Play an audio file and display spectrogram in realtime

.. raw:: html

  <video width="558" height="558" controls autoplay>
    <source src="../_static/examples/audio_ex3.mov" type="video/mp4">
    <source src="../_static/examples/audio_ex3.ogg" type="video/ogg">
  </video>

----

.. code-block:: python
    
    
    
    import os
    import wave
    import numpy as np
    import pyaudio
    import gr
    import gr3
    
    FS = 44100  # Sampling frequency
    SAMPLES = 2048
    
    wf = wave.open(os.path.join(os.path.dirname(os.path.realpath(__file__)),
                                'Monty_Python.wav'), 'rb')
    pa = pyaudio.PyAudio()
    stream = pa.open(
        format=pa.get_format_from_width(wf.getsampwidth()),
        channels=wf.getnchannels(),
        rate=wf.getframerate(),
        output=True
    )
    
    spectrum = np.zeros((256, 64), dtype=float)
    t = -63
    dt = float(SAMPLES) / FS
    df = FS / float(SAMPLES) / 2 / 2
    
    data = wf.readframes(SAMPLES)
    while data != '' and len(data) == SAMPLES * wf.getsampwidth():
        stream.write(data)
        amplitudes = np.frombuffer(data, dtype=np.short)
        power = abs(np.fft.fft(amplitudes / 32768.0))[:SAMPLES // 2]
    
        gr.clearws()
        spectrum[:, 63] = power[:256]
        spectrum = np.roll(spectrum, 1)
        gr.setcolormap(-113)
        gr.setviewport(0.05, 0.95, 0.1, 1)
        gr.setwindow(t * dt, (t + 63) * dt, 0, df)
        gr.setscale(gr.OPTION_FLIP_X)
        gr.setspace(0, 256, 30, 80)
        gr3.surface((t + np.arange(64)) * dt, np.linspace(0, df, 256), spectrum, 4)
        gr.setscale(0)
        gr.axes3d(0.2, 0.2, 0, (t + 63) * dt, 0, 0, 5, 5, 0, -0.01)
        gr.titles3d('t [s]', 'f [kHz]', '')
        gr.updatews()
    
        data = wf.readframes(SAMPLES)
        t += 1