Audio Example

This example shows the drawing of dynamic data (microphone input).

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audio.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

"""PySide6 port of the charts/audio example from Qt v5.x"""

import sys
from PySide6.QtCharts import QChart, QChartView, QLineSeries, QValueAxis
from PySide6.QtCore import QPointF, Slot
from PySide6.QtMultimedia import QAudioFormat, QAudioSource, QMediaDevices
from PySide6.QtWidgets import QApplication, QMainWindow, QMessageBox


SAMPLE_COUNT = 2000


RESOLUTION = 4


class MainWindow(QMainWindow):
    def __init__(self, device):
        super().__init__()

        self._series = QLineSeries()
        self._chart = QChart()
        self._chart.addSeries(self._series)
        self._axis_x = QValueAxis()
        self._axis_x.setRange(0, SAMPLE_COUNT)
        self._axis_x.setLabelFormat("%g")
        self._axis_x.setTitleText("Samples")
        self._axis_y = QValueAxis()
        self._axis_y.setRange(-1, 1)
        self._axis_y.setTitleText("Audio level")
        self._chart.setAxisX(self._axis_x, self._series)
        self._chart.setAxisY(self._axis_y, self._series)
        self._chart.legend().hide()
        name = device.description()
        self._chart.setTitle(f"Data from the microphone ({name})")

        format_audio = QAudioFormat()
        format_audio.setSampleRate(8000)
        format_audio.setChannelCount(1)
        format_audio.setSampleFormat(QAudioFormat.UInt8)

        self._audio_input = QAudioSource(device, format_audio, self)
        self._io_device = self._audio_input.start()
        self._io_device.readyRead.connect(self._readyRead)

        self._chart_view = QChartView(self._chart)
        self.setCentralWidget(self._chart_view)

        self._buffer = [QPointF(x, 0) for x in range(SAMPLE_COUNT)]
        self._series.append(self._buffer)

    def closeEvent(self, event):
        if self._audio_input is not None:
            self._audio_input.stop()
        event.accept()

    @Slot()
    def _readyRead(self):
        data = self._io_device.readAll()
        available_samples = data.size() // RESOLUTION
        start = 0
        if (available_samples < SAMPLE_COUNT):
            start = SAMPLE_COUNT - available_samples
            for s in range(start):
                self._buffer[s].setY(self._buffer[s + available_samples].y())

        data_index = 0
        for s in range(start, SAMPLE_COUNT):
            value = (ord(data[data_index]) - 128) / 128
            self._buffer[s].setY(value)
            data_index = data_index + RESOLUTION
        self._series.replace(self._buffer)


if __name__ == '__main__':
    app = QApplication(sys.argv)

    input_devices = QMediaDevices.audioInputs()
    if not input_devices:
        QMessageBox.warning(None, "audio", "There is no audio input device available.")
        sys.exit(-1)
    main_win = MainWindow(input_devices[0])
    main_win.setWindowTitle("audio")
    available_geometry = main_win.screen().availableGeometry()
    size = available_geometry.height() * 3 / 4
    main_win.resize(size, size)
    main_win.show()
    sys.exit(app.exec())