How can I play a sine/square wave using Pygame?

Question

I'm trying to play a sine wave using Pygame's sndarray.make_sound function. However, when I use this array to play it:

np.sin(2 * np.pi * np.arange(44100) * 440 / 44100).astype(np.float32)

where 440 is the frequency and 44100 is the sample rate, a loud, jarring noise plays instead. This works using pyaudio.PyAudio(), however I need something that doesn't block execution. This happens with square waves, too, however there it just doesn't play anything. I'm using channels=1 for the mixer.pre_init and mixer.init functions.

How can I fix this? If it helps, I'm using a Mac. Thanks in advance!

Answer 1

You can load the numpy array directly to a pygame.mixer.Sound object and play it. The jarring sound occurs because you're probably sending 32bit float samples to the mixer when it's expecting 16bit integer samples. If you want to use an array of 32bit floats, you must set the size parameter of the mixer's init function to 32:

import pygame
import numpy as np

pygame.mixer.init(size=32)

buffer = np.sin(2 * np.pi * np.arange(44100) * 440 / 44100).astype(np.float32)
sound = pygame.mixer.Sound(buffer)

sound.play(0)
pygame.time.wait(int(sound.get_length() * 1000))