fmtest.py

#!/usr/bin/python3

import pyaudio
import numpy as np
import sys
import time
import math

p = pyaudio.PyAudio()

# samplerate
fs = 44100

# frequencies
f = 440.0
f2 = 44.0

# current angles
angle = 0
increment = 2 * math.pi / fs * f
angle2 = 0
increment2 = 2 * math.pi / fs * f2

# sample buffer
data = []

# called for each sample, creates a FM test signal
def sample():
    global angle, increment
    global angle2, increment2
    s = math.sin(angle)
    s2 = math.sin(angle2)
    angle = angle + increment
    angle2 = angle2 + increment2
    if angle > 2 * math.pi:
        angle = angle - 2 * math.pi
    if angle2 > 2 * math.pi:
        angle2 = angle2 - 2 * math.pi
    return s * s2 * 0.4

# called for each audio block, e.g. 1024 samples
def callback(in_data, frame_count, time_info, status):
    global data
    if len(data) == 0:
        data = np.zeros(frame_count).astype(np.float32)
    for i in range(frame_count):
        data[i] = sample()
    return (data, pyaudio.paContinue)

# for paFloat32 sample values must be in range [-1.0, 1.0]
stream = p.open(format=pyaudio.paFloat32,
                channels=1,
                rate=fs,
                output=True,
                stream_callback=callback)

stream.start_stream()
while stream.is_active():
    time.sleep(0.1)
stream.stop_stream()
stream.close()

p.terminate()