mic_read.py

"""
mic_read.py
Created By Alexander Yared (akyared@gmail.com)

Microphone controller module for the Live Spectrogram project, a real time
spectrogram visualization tool

Dependencies: pyaudio, numpy and matplotlib
"""
############### Import Libraries ###############
import pyaudio
import numpy as np
import matplotlib.pyplot as plt

############### Constants ###############
# RATE = 44100 #sample rate
RATE = 8000
FORMAT = pyaudio.paInt16  # conversion format for PyAudio stream
CHANNELS = 1  # microphone audio channels
CHUNK_SIZE = 8192  # number of samples to take per read
SAMPLE_LENGTH = int(CHUNK_SIZE * 1000 / RATE)  # length of each sample in ms

############### Functions ###############
"""
open_mic:
creates a PyAudio object and initializes the mic stream
inputs: none
ouputs: stream, PyAudio object
"""


def open_mic():
    pa = pyaudio.PyAudio()
    stream = pa.open(
        format=FORMAT,
        channels=CHANNELS,
        rate=RATE,
        input=True,
        frames_per_buffer=CHUNK_SIZE,
    )
    return stream, pa


"""
get_data:
reads from the audio stream for a constant length of time, converts it to data
inputs: stream, PyAudio object
outputs: int16 data array
"""


def get_data(stream, pa):
    input_data = stream.read(CHUNK_SIZE)
    data = np.fromstring(input_data, np.int16)
    return data


############### Test Functions ###############
"""
make_10k:
creates a 10kHz test tone
"""


def make_10k():
    x = np.linspace(-2 * np.pi, 2 * np.pi, 21000)
    x = np.tile(x, int(SAMPLE_LENGTH / (4 * np.pi)))
    y = np.sin(2 * np.pi * 5000 * x)
    return x, y


"""
show_freq:
plots the test tone for a sanity check
"""


def show_freq():
    x, y = make_10k()
    plt.plot(x, y)
    plt.show()