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?
Version with numpy:
import time
import numpy as np
import pyaudio
p = pyaudio.PyAudio()
volume = 0.5 # range [0.0, 1.0]
fs = 44100 # sampling rate, Hz, must be integer
duration = 5.0 # 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)
# per @yahweh comment explicitly convert to bytes sequence
output_bytes = (volume * samples).tobytes()
# 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)
start_time = time.time()
stream.write(output_bytes)
print("Played sound for {:.2f} seconds".format(time.time() - start_time))
stream.stop_stream()
stream.close()
p.terminate()
Version without numpy:
import array
import math
import time
import pyaudio
p = pyaudio.PyAudio()
volume = 0.5 # range [0.0, 1.0]
fs = 44100 # sampling rate, Hz, must be integer
duration = 5.0 # in seconds, may be float
f = 440.0 # sine frequency, Hz, may be float
# generate samples, note conversion to float32 array
num_samples = int(fs * duration)
samples = [volume * math.sin(2 * math.pi * k * f / fs) for k in range(0, num_samples)]
# per @yahweh comment explicitly convert to bytes sequence
output_bytes = array.array('f', samples).tobytes()
# 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)
start_time = time.time()
stream.write(output_bytes)
print("Played sound for {:.2f} seconds".format(time.time() - start_time))
stream.stop_stream()
stream.close()
p.terminate()
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)
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
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.
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.
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
