how to convert wav to mp3 in live using python?

Question

I have code like what is shown below to get audio from microphone:

import pyaudio
p = pyaudio.PyAudio()
CHUNK = 1024
FORMAT = pyaudio.paInt16
CHANNELS = 2
RATE = 1024*10
RECORD_SECONDS = 10
stream = p.open(format=FORMAT,
                channels=CHANNELS,
                rate=RATE,
                input=True,
                frames_per_buffer=CHUNK)
for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)
    send_via_socket(data) # function to send each frame to remote system

This code is working fine. However each data frame has a size of 4kb. That means 40kb of internet data is needed to send 1 sec of audio data. It's only 6kb of data When I saved the 10 frames (1 second audio) to disc and convert it to mp3 using the pdub module. How can I convert each wav frame to mp3 before sending via socket? (I just need to reduce the size of the frame to save network usage). For example:

for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
    data = stream.read(CHUNK)  # data =4kb
    mp3_frame = wav_to_mp3(data) # mp3_frame should be 1kb or less
    send_via_socket(mp3_frame) # function to send each frame to remote system

Answer 1

try python-audiotools. I think it will help you stream the audio file that you want.

Answer 2

I was able to figure out a working approach using flask and ffmpeg...

import select
import subprocess

import numpy

from flask import Flask
from flask import Response

app = Flask(__name__)


def get_microphone_audio(num_samples):
    # TODO: Add the above microphone code. 
    audio = numpy.random.rand(num_samples).astype(numpy.float32) * 2 - 1
    assert audio.max() <= 1.0
    assert audio.min() >= -1.0
    assert audio.dtype == numpy.float32
    return audio


def response():
    pipe = subprocess.Popen(
        'ffmpeg -f f32le -acodec pcm_f32le -ar 24000 -ac 1 -i pipe: -f mp3 pipe:'
        .split(),
        stdin=subprocess.PIPE,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE)
    poll = select.poll()
    poll.register(pipe.stdout, select.POLLIN)
    while True:
        pipe.stdin.write(get_synthetic_audio(24000).tobytes())
        while poll.poll(0):
            yield pipe.stdout.readline()


@app.route('/stream.mp3', methods=['GET'])
def stream():
    return Response(
        response(),
        headers={
            # NOTE: Ensure stream is not cached.
            'Cache-Control': 'no-cache, no-store, must-revalidate',
            'Pragma': 'no-cache',
            'Expires': '0',
        },
        mimetype='audio/mpeg')


if __name__ == "__main__":
    app.run(host='0.0.0.0', port=8000, debug=True)

This solution allows for live streaming and is supported in Chrome, Firefox, and Safari.

This solution also worked for this similar question: How to stream MP3 chunks given a NumPy array in Python?