Display a GUI and play pure tones with PyQt5

qt_audio_example.py

from math import pi, sin
import struct, sys

from PyQt5.QtCore import QBuffer, QByteArray, QIODevice, Qt
from PyQt5.QtWidgets import (
    QApplication,
    QFormLayout,
    QLineEdit,
    QHBoxLayout,
    QPushButton,
    QSlider,
    QVBoxLayout,
    QWidget,
)
from PyQt5.QtMultimedia import QAudio, QAudioDeviceInfo, QAudioFormat, QAudioOutput


class Window(QWidget):
    def __init__(self, parent=None):

        QWidget.__init__(self, parent)

        format = QAudioFormat()
        format.setChannelCount(1)
        format.setSampleRate(22050)
        format.setSampleSize(16)
        format.setCodec("audio/pcm")
        format.setByteOrder(QAudioFormat.LittleEndian)
        format.setSampleType(QAudioFormat.SignedInt)
        self.output = QAudioOutput(format, self)

        self.frequency = 440
        self.volume = 0
        self.buffer = QBuffer()
        self.data = QByteArray()

        self.deviceLineEdit = QLineEdit()
        self.deviceLineEdit.setReadOnly(True)
        self.deviceLineEdit.setText(QAudioDeviceInfo.defaultOutputDevice().deviceName())

        self.pitchSlider = QSlider(Qt.Horizontal)
        self.pitchSlider.setMaximum(100)
        self.volumeSlider = QSlider(Qt.Horizontal)
        self.volumeSlider.setMaximum(32767)
        self.volumeSlider.setPageStep(1024)

        self.playButton = QPushButton(self.tr("&Play"))

        self.pitchSlider.valueChanged.connect(self.changeFrequency)
        self.volumeSlider.valueChanged.connect(self.changeVolume)
        self.playButton.clicked.connect(self.play)

        formLayout = QFormLayout()
        formLayout.addRow(self.tr("Device:"), self.deviceLineEdit)
        formLayout.addRow(self.tr("P&itch:"), self.pitchSlider)
        formLayout.addRow(self.tr("&Volume:"), self.volumeSlider)

        buttonLayout = QVBoxLayout()
        buttonLayout.addWidget(self.playButton)
        buttonLayout.addStretch()

        horizontalLayout = QHBoxLayout(self)
        horizontalLayout.addLayout(formLayout)
        horizontalLayout.addLayout(buttonLayout)

        self.play()
        self.createData()

    def changeFrequency(self, value):

        self.frequency = 440 + (value * 2)
        self.createData()

    def play(self):

        if self.output.state() == QAudio.ActiveState:
            self.output.stop()

        if self.buffer.isOpen():
            self.buffer.close()

        if self.output.error() == QAudio.UnderrunError:
            self.output.reset()

        self.buffer.setData(self.data)
        self.buffer.open(QIODevice.ReadOnly)
        self.buffer.seek(0)

        self.output.start(self.buffer)

    def changeVolume(self, value):

        self.volume = value
        self.createData()

    def createData(self):

        self.data.clear()
        for i in range(2 * 22050):
            t = i / 22050.0
            value = int(self.volume * sin(2 * pi * self.frequency * t))
            self.data.append(struct.pack("<h", value))


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())