Simple proof of concept to stream audio from main microphone and then extract its pitch and volume properties on the fly.

pitch_volume_detection_alsaaudio.py

# Only works with operating system that uses
# AlsaAudio as audio driver. Most Linux distros
# are using this (Debian, Ubuntu). Does not work
# any where else (MacOS or Windows).
#
# This is a class to stream audio data from
# computer microphone then extract the pitch
# and the volume from it. This is done using
# AlsaAudio and Aubio Python library. The
# AlsaAudio is used to turn on the computer
# microphone and then stream the data. While
# the Aubio is used to process the streamed
# data into its pitch detector object to get
# the pitch and the volume.
import alsaaudio as alsa
import aubio
# The NumPy library is used to convert data
# from AlsaAudio into format that Aubio understand.
import numpy as num
import sys

# Some constants for setting the PyAudio and the
# Aubio.
BUFFER_SIZE             = 2048
CHANNELS                = 1
FORMAT                  = alsa.PCM_FORMAT_FLOAT_LE
METHOD                  = "default"
SAMPLE_RATE             = 44100
TYPE                    = alsa.PCM_CAPTURE
HOP_SIZE                = BUFFER_SIZE//2
PERIOD_SIZE_IN_FRAME    = HOP_SIZE

def main(args):

    # Audio input from microphone. Determine the PCM
    # (pulse code modulation) device. The default type
    # is for play backing audio file. Hence, for this
    # case set the mode into alsa
    # (type=alsa.PCM_CAPTURE) instead of the default
    # one that for voice capturing. The microphone that
    # will be used to stream the voice is the microphone
    # that is set in the alsamixer (Linux default driver
    # and sound manager). Hence, this AlsaAudio library
    # is only for Linux operating system.
    # Here is the main recorder object.
    mic = alsa.PCM(type=TYPE)
    # The other properties that I do not know
    # what it does :D :D :D :D :D.
    mic.setchannels(CHANNELS)
    mic.setformat(FORMAT)
    mic.setperiodsize(PERIOD_SIZE_IN_FRAME)
    mic.setrate(SAMPLE_RATE)

    # Finally create the main pitch detection object.
    # This object is from Aubio library.
    pDetection = aubio.pitch(METHOD, BUFFER_SIZE,
        HOP_SIZE, SAMPLE_RATE)
    # Set the output unit. This can be "cent",
    # "midi", "Hz".
    pDetection.set_unit("Hz")
    # Ignore frames under this level.
    pDetection.set_silence(-40)

    # Starting the infinite loop!
    while True:

        # Keep reading data from the audio input.
        length, data = mic.read()
        # Convert data from the microphone of
        # AlsaAudio library into Aubio format samples.
        samples = num.fromstring(data,
            dtype=aubio.float_type)
        # Pitch of the current frame.
        pitch = pDetection(samples)[0]
        # Compute the energy (volume) of the
        # current frame.
        volume = num.sum(samples**2)/len(samples)
        # Format the volume output so that at most
        # it has six decimal numbers.
        volume = "{:.6f}".format(volume)

        # Finally print the pitch and the volume.
        print(str(pitch) + " " + str(volume))

if __name__ == "__main__": main(sys.argv)