An ugly example of writing to fifo file.

QtMultimedia2fifo.py

from PySide2 import QtMultimedia,QtWidgets
from PySide2.QtCore import QTimer,QFile,QIODevice

import sys
import os
import numpy as np

SAMPLE_RATE = 44100 # [Hz]
SAMPLE_SIZE = 16 # [bit]
CHANNEL_COUNT = 2
BUFFER_SIZE = 5000 

info = QtMultimedia.QAudioDeviceInfo.defaultInputDevice()
format = info.preferredFormat()
format.setChannelCount(CHANNEL_COUNT)
format.setSampleSize(SAMPLE_SIZE)
format.setSampleRate(SAMPLE_RATE)


app = QtWidgets.QApplication(sys.argv)

audio_input = QtMultimedia.QAudioInput(format, app)
audio_input.setBufferSize(BUFFER_SIZE)


path = "/tmp/my_program.fifo"
if not os.path.exists(path):
    os.mkfifo(path)

_file = QFile(path)
_file.open(QIODevice.WriteOnly)  

source = audio_input.start(_file)


print('exec')

import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)
app.exec_()