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## Copyright (C) 2021 Riverbank Computing Limited.
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from math import pi, sin
from struct import pack

from PyQt6.QtCore import QByteArray, QIODevice, Qt, QTimer, qWarning
from PyQt6.QtMultimedia import (QAudio, QAudioDevice, QAudioFormat, QAudioSink,
        QMediaDevices)
from PyQt6.QtWidgets import (QApplication, QComboBox, QHBoxLayout, QLabel,
        QMainWindow, QPushButton, QSlider, QVBoxLayout, QWidget)


class Generator(QIODevice):

    def __init__(self, format, durationUs, sampleRate):
        super().__init__()

        self.m_pos = 0
        self.m_buffer = QByteArray()

        if format.isValid():
            self.generateData(format, durationUs, sampleRate)

    def start(self):
        self.open(QIODevice.OpenModeFlag.ReadOnly)

    def stop(self):
        self.m_pos = 0
        self.close()

    def generateData(self, format, durationUs, sampleRate):
        packFormat = ''

        sampleFormat = format.sampleFormat()

        if sampleFormat is QAudioFormat.SampleFormat.UInt8:
            scaler = lambda x: ((1.0 + x) / 2 * 255)
            packFormat = 'B'
        elif sampleFormat is QAudioFormat.SampleFormat.Int16:
            scaler = lambda x: x * 32767
            packFormat = 'h'
        elif sampleFormat is QAudioFormat.SampleFormat.Int32:
            scaler = lambda x: x * 2147483647
            packFormat = 'i'
        elif sampleFormat is QAudioFormat.SampleFormat.Float:
            scaler = lambda x: x
            packFormat = 'f'

        assert(packFormat != '')

        channelBytes = format.bytesPerSample()
        sampleBytes = format.channelCount() * channelBytes
        length = format.bytesForDuration(durationUs)

        assert(length % sampleBytes == 0)

        self.m_buffer.clear()
        sampleIndex = 0
        factor = 2 * pi * sampleRate / format.sampleRate()

        while length != 0:
            x = sin((sampleIndex % format.sampleRate()) * factor)
            packed = pack(packFormat, int(scaler(x)))

            for _ in range(format.channelCount()):
                self.m_buffer.append(packed)
                length -= channelBytes

            sampleIndex += 1

    def readData(self, maxlen):
        data = QByteArray()
        total = 0

        while maxlen > total:
            chunk = min(self.m_buffer.size() - self.m_pos, maxlen - total)
            data.append(self.m_buffer.mid(self.m_pos, chunk))
            self.m_pos = (self.m_pos + chunk) % self.m_buffer.size()
            total += chunk

        return data.data()

    def writeData(self, data):
        return 0

    def bytesAvailable(self):
        return self.m_buffer.size() + super().bytesAvailable()


class AudioTest(QMainWindow):

    DurationSeconds = 1
    ToneSampleRateHz = 600

    def __init__(self):
        super().__init__()

        self.m_devices = QMediaDevices(self)
        self.m_pushTimer = QTimer(self)
        self.m_pullMode = True
        self.m_generator = None
        self.m_audioOutput = None

        self.initializeWindow()
        self.initializeAudio(self.m_devices.defaultAudioOutput())

    def initializeWindow(self):
        layout = QVBoxLayout()

        self.m_deviceBox = QComboBox(activated=self.deviceChanged)
        defaultDeviceInfo = self.m_devices.defaultAudioOutput()
        self.m_deviceBox.addItem(defaultDeviceInfo.description(),
                defaultDeviceInfo)

        for deviceInfo in self.m_devices.audioOutputs():
            if deviceInfo != defaultDeviceInfo:
                self.m_deviceBox.addItem(deviceInfo.description(), deviceInfo)

        layout.addWidget(self.m_deviceBox)

        self.m_modeButton = QPushButton(clicked=self.toggleMode)
        layout.addWidget(self.m_modeButton)

        self.m_suspendResumeButton = QPushButton(
                clicked=self.toggleSuspendResume)
        layout.addWidget(self.m_suspendResumeButton)

        volumeBox = QHBoxLayout()
        volumeLabel = QLabel("Volume:")
        self.m_volumeSlider = QSlider(Qt.Orientation.Horizontal, minimum=0,
                maximum=100, singleStep=10, valueChanged=self.volumeChanged)
        volumeBox.addWidget(volumeLabel)
        volumeBox.addWidget(self.m_volumeSlider)

        layout.addLayout(volumeBox)

        window = QWidget()
        window.setLayout(layout)

        self.setCentralWidget(window)

    def initializeAudio(self, deviceInfo):
        format = deviceInfo.preferredFormat()

        self.m_generator = Generator(format, self.DurationSeconds * 1000000,
                self.ToneSampleRateHz)

        self.m_audioOutput = QAudioSink(deviceInfo, format)

        self.m_generator.start()

        initialVolume = QAudio.convertVolume(self.m_audioOutput.volume(),
                QAudio.VolumeScale.LinearVolumeScale,
                QAudio.VolumeScale.LogarithmicVolumeScale)
        self.m_volumeSlider.setValue(int(initialVolume * 100))

        self.toggleMode()

    def deviceChanged(self, index):
        self.m_generator.stop()
        self.m_audioOutput.stop()

        try:
            # This will raise an exception if the are no connections.
            self.m_audioOutput.disconnect()
        except:
            pass

        self.initializeAudio(self.m_deviceBox.itemData(index))

    def volumeChanged(self, value):
        linearVolume = QAudio.convertVolume(value / 100.0,
                QAudio.VolumeScale.LinearVolumeScale,
                QAudio.VolumeScale.LogarithmicVolumeScale)

        self.m_audioOutput.setVolume(linearVolume)

    def toggleMode(self):
        self.m_pushTimer.stop()
        self.m_audioOutput.stop()
        self.toggleSuspendResume()

        if self.m_pullMode:
            self.m_modeButton.setText("Enable push mode")
            self.m_audioOutput.start(self.m_generator)
        else:
            self.m_modeButton.setText("Enable pull mode")
            io = self.m_audioOutput.start()

            try:
                # This will raise an exception if the are no connections.
                self.m_pushTimer.timeout.disconnect()
            except:
                pass

            self.m_pushTimer.timeout.connect(lambda: self.handlePushTimer(io))
            self.m_pushTimer.start(10)

        self.m_pullMode = not self.m_pullMode

    def handlePushTimer(self, io):
        if self.m_audioOutput.state() is QAudio.State.StoppedState:
            return

        buffer = self.m_generator.read(self.m_audioOutput.bytesFree())
        if buffer:
            io.write(buffer)

    def toggleSuspendResume(self):
        if self.m_audioOutput.state() in (QAudio.State.SuspendedState, QAudio.State.StoppedState):
            self.m_audioOutput.resume()
            self.m_suspendResumeButton.setText("Suspend playback")
        elif self.m_audioOutput.state() is QAudio.State.ActiveState:
            self.m_audioOutput.suspend()
            self.m_suspendResumeButton.setText("Resume playback")


if __name__ == '__main__':

    import sys

    app = QApplication(sys.argv)
    app.setApplicationName("Audio Output Test")

    audio = AudioTest()
    audio.show()

    sys.exit(app.exec())