python - Reading realtime audio data into numpy array

Question

how can I read real-time audio into numpy array and use matplotlib to plot ?

Right Now I am recording audio on an wav file then using scikits.audiolab.wavread to read it into an array. Is there a way I could do this directly in realtime?

Answer 1

You can use PyAudio to record audio and use np.frombuffer to convert it into a numpy array.

import pyaudio
import numpy as np
from matplotlib import pyplot as plt

CHUNKSIZE = 1024 # fixed chunk size

# initialize portaudio
p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paInt16, channels=1, rate=44100, input=True, frames_per_buffer=CHUNKSIZE)

# do this as long as you want fresh samples
data = stream.read(CHUNKSIZE)
numpydata = np.frombuffer(data, dtype=np.int16)

# plot data
plt.plot(numpydata)
plt.show()

# close stream
stream.stop_stream()
stream.close()
p.terminate()

If you want to record stereo instead of mono, you have to set channels to 2. Then you get an array with interleaved channels. You can reshape it like this:

frame = np.frombuffer(data, dtype=numpy.int16)       # interleaved channels
frame = np.stack((frame[::2], frame[1::2]), axis=0)  # channels on separate axes