audio - Generating sine wave sound in Python

Question

I need to generate a sine wave sound in Python, and I need to be able to control frequency, duration, and relative volume. By 'generate' I mean that I want it to play though the speakers immediately, not save to a file.

What is the easiest way to do this?

Answer 1

import pyaudio
import numpy as np

p = pyaudio.PyAudio()

volume = 0.5     # range [0.0, 1.0]
fs = 44100       # sampling rate, Hz, must be integer
duration = 1.0   # in seconds, may be float
f = 440.0        # sine frequency, Hz, may be float

# generate samples, note conversion to float32 array
samples = (np.sin(2*np.pi*np.arange(fs*duration)*f/fs)).astype(np.float32)

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

# play. May repeat with different volume values (if done interactively) 
stream.write(volume*samples)

stream.stop_stream()
stream.close()

p.terminate()

Answer 2

ivan-onys gave an excellent answer, but there is a little addition to it: this script will produce 4 times shorter sound than expected because Pyaudio write method needs string data of float32, but when you pass numpy array to this method, it converts whole array as entity to a string, therefore you have to convert data in numpy array to the byte sequence yourself like this:

samples = (np.sin(2*np.pi*np.arange(fs*duration)*f/fs)).astype(np.float32).tobytes()

and you have to change this line as well:

stream.write(samples)

Answer 3

One of the more consistent andeasy to install ways to deal with sound in Python is the Pygame multimedia libraries.

I'd recomend using it - there is the pygame.sndarray submodule that allows you to manipulate numbers in a data vector that become a high-level sound object that can be playerd in the pygame.mixer module.

The documentation in the pygame.org site should be enough for using the sndarray module.

Answer 4

Today for Python 3.5+ the best way is to install the packages recommended by the developer.

http://people.csail.mit.edu/hubert/pyaudio/

For Debian do

sudo apt-get install python3-all-dev portaudio19-dev

before trying to install pyaudio

Answer 5

I the bregman lab toolbox you have a set of functions that does exactly what you want. This python module is a little bit buggy but you can adapt this code to get your own functions

Answer 6

The script from ivan_onys produces a signal that is four times shorter than intended. If a TypeError is returned when volume is a float, try adding .tobytes() to the following line instead.

stream.write((volume*samples).tobytes())

@mm_ float32 = 32 bits, and 8 bits = 1 byte, so float32 = 4 bytes. When samples are passed to stream.write as float32, byte count (duration) is divided by 4. Writing samples back .tobytes() corrects for quartering the sample count when writing to float32.