Python: realtime audio streaming with PyAudio (or something else)?

Question

Currently I'm using NumPy to generate the WAV file from a NumPy array. I wonder if it's possible to play the NumPy array in realtime before it's actually written to the hard drive. All examples I found using PyAudio rely on writing the NumPy array to a WAV file first, but I'd like to have a preview function that just spits out the NumPy array to the audio output.

Should be cross-platform, too. I'm using Python 3 (Anaconda distribution).

Answer 1

This has worked! Thanks for help!

def generate_sample(self, ob, preview):
    print("* Generating sample...")
    tone_out = array(ob, dtype=int16)

    if preview:
        print("* Previewing audio file...")

        bytestream = tone_out.tobytes()
        pya = pyaudio.PyAudio()
        stream = pya.open(format=pya.get_format_from_width(width=2), channels=1, rate=OUTPUT_SAMPLE_RATE, output=True)
        stream.write(bytestream)
        stream.stop_stream()
        stream.close()

        pya.terminate()
        print("* Preview completed!")
    else:
        write('sound.wav', SAMPLE_RATE, tone_out)
        print("* Wrote audio file!")

Seems so simple now, but when you don't know Python very well, it seems like hell.

Answer 2

This is really simple with python-sounddevice:

import sounddevice as sd
sd.play(myarray, 44100)

Answer 3

As you can see in the examples, pyaudio just reads data from the WAV file and writes that to the stream.

It is not necessary to write a WAV file first, you just need a stream of data in the right format.

I'm adding the example below in case the link ever goes dead (note that I didn't write this code):

"""PyAudio Example: Play a WAVE file."""

import pyaudio
import wave
import sys

CHUNK = 1024

if len(sys.argv) < 2:
    print("Plays a wave file.\n\nUsage: %s filename.wav" % sys.argv[0])
    sys.exit(-1)

wf = wave.open(sys.argv[1], 'rb')

p = pyaudio.PyAudio()

stream = p.open(format=p.get_format_from_width(wf.getsampwidth()),
                channels=wf.getnchannels(),
                rate=wf.getframerate(),
                output=True)

data = wf.readframes(CHUNK)

while data != '':
    stream.write(data)
    data = wf.readframes(CHUNK)

stream.stop_stream()
stream.close()

p.terminate()