qaudiooutput.cpp

Go to the documentation of this file.

// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qaudiooutput.h"
 
#include <QtMultimedia/private/qplatformaudiooutput_p.h>
#include <QtMultimedia/private/qplatformmediaintegration_p.h>
#include <QtMultimedia/qaudiodevice.h>
#include <QtMultimedia/qmediadevices.h>
 
/*!
    \qmltype AudioOutput
    \nativetype QAudioOutput
    \brief An audio output to be used for playback or monitoring of a capture session.
 
    \inqmlmodule QtMultimedia
    \ingroup multimedia_qml
    \ingroup multimedia_audio_qml
 
    \qml
    MediaPlayer {
        id: playMusic
        source: "music.wav"
        audioOutput: AudioOutput {
            volume: slider.value
        }
    }
    Slider {
        id: slider
        from: 0.
        to: 1.
    }
    \endqml
 
    You can use AudioOutput together with a \l{QtMultimedia::MediaPlayer}{MediaPlayer} to play audio
    content, or you can use it in conjunction with a
    \l{QtMultimedia::CaptureSession}{CaptureSession} to monitor the audio processed by the capture
    session.
 
    \sa VideoOutput, AudioInput
*/
 
/*!
    \class QAudioOutput
    \brief Represents an output channel for audio.
    \inmodule QtMultimedia
    \ingroup multimedia
    \ingroup multimedia_audio
    \since 6.0
 
    This class represents an output channel that can be used together with
    QMediaPlayer or QMediaCaptureSession. It enables the selection of the
    physical output device to be used, muting the channel, and changing the
    channel's volume.
 
    \note On WebAssembly platform, due to its asynchronous nature,
    QMediaDevices::audioOutputsChanged() signal is emitted when the list of
    audio outputs is ready. User permissions are required. Works only on secure https contexts.
 
    \sa QAudioInput
*/
QAudioOutput::QAudioOutput(QObject *parent)
    : QAudioOutput(QMediaDevices::defaultAudioOutput(), parent)
{
}
 
QAudioOutput::QAudioOutput(const QAudioDevice &device, QObject *parent)
    : QObject(parent)
{
    auto maybeAudioOutput = QPlatformMediaIntegration::instance()->createAudioOutput(this);
    if (maybeAudioOutput) {
        d = maybeAudioOutput.value();
        d->device = device.mode() == QAudioDevice::Output ? device : QMediaDevices::defaultAudioOutput();
        d->setAudioDevice(d->device);
    } else {
        d = new QPlatformAudioOutput(nullptr);
        qWarning() << "Failed to initialize QAudioOutput" << maybeAudioOutput.error();
    }
}
 
QAudioOutput::~QAudioOutput()
{
    setDisconnectFunction({});
    delete d;
}
 
/*!
    \qmlsignal void QtMultimedia::AudioOutput::volumeChanged()
 
    This signal is emitted when the \l{volume} property is changed.
*/
 
/*!
    \qmlproperty real QtMultimedia::AudioOutput::volume
 
    This property holds the volume of the audio output.
 
    The volume is scaled linearly from \c 0.0 (silence) to \c 1.0 (full volume).
    Values outside this range will be clamped: a value lower than 0.0 is set to
    0.0, a value higher than 1.0 will set to 1.0.
 
    The default volume is \c{1.0}.
 
    UI \l{volume controls} should usually be scaled non-linearly. For example,
    using a logarithmic scale will produce linear changes in perceived \l{loudness},
    which is what a user would normally expect from a volume control.
 
    See \l {QtAudio::convertVolume()}{QtMultimedia.convertVolume()}
    for more details.
*/
 
/*!
    \property QAudioOutput::volume
    \brief The current volume.
 
    The volume is scaled linearly, ranging from \c 0 (silence) to \c 1
    (full volume).
    \note values outside this range will be clamped.
 
    By default the volume is \c 1.
 
    UI volume controls should usually be scaled non-linearly. For example,
    using a logarithmic scale will produce linear changes in perceived loudness,
    which is what a user would normally expect from a volume control.
 
    \sa QtAudio::convertVolume()
*/
float QAudioOutput::volume() const
{
    return d->volume;
}
 
void QAudioOutput::setVolume(float volume)
{
    volume = qBound(0.f, volume, 1.f);
    if (d->volume == volume)
        return;
    d->volume = volume;
    d->setVolume(volume);
    Q_EMIT volumeChanged(volume);
}
 
/*!
    \qmlsignal void QtMultimedia::AudioOutput::mutedChanged()
 
    This signal is emitted when the \l{muted} property is changed.
*/
 
/*!
    \qmlproperty bool QtMultimedia::AudioOutput::muted
 
    This property holds whether the audio output is muted.
 
    Defaults to \c{false}.
*/
 
/*!
    \property QAudioOutput::muted
    \brief The muted state of the current media.
 
    The value will be \c true if the output is muted; otherwise \c{false}.
*/
bool QAudioOutput::isMuted() const
{
    return d->muted;
}
 
void QAudioOutput::setMuted(bool muted)
{
    if (d->muted == muted)
        return;
    d->muted = muted;
    d->setMuted(muted);
    Q_EMIT mutedChanged(muted);
}
 
/*!
    \qmlsignal void QtMultimedia::AudioOutput::deviceChanged()
 
    This signal is emitted when the \l{device} property is changed.
*/
 
/*!
    \qmlproperty audioDevice QtMultimedia::AudioOutput::device
 
    This property describes the audio device connected to this output.
 
    The device property represents the audio device this output is connected to.
    This property can be used to select an output device from the
    \l{QtMultimedia::MediaDevices::audioOutputs}{MediaDevices.audioOutputs} list.
*/
 
/*!
    \property QAudioOutput::device
    \brief The audio device connected to this output.
 
    The device property represents the audio device this output is connected to.
    This property can be used to select an output device from the
    \l{QMediaDevices::audioOutputs} list.
    You can select the system default audio output by setting this property to
    a default constructed QAudioDevice object.
*/
QAudioDevice QAudioOutput::device() const
{
    return d->device;
}
 
void QAudioOutput::setDevice(const QAudioDevice &device)
{
    auto dev = device;
    if (dev.isNull())
        dev = QMediaDevices::defaultAudioOutput();
    if (dev.mode() != QAudioDevice::Output)
        return;
    if (d->device == dev)
        return;
    d->device = dev;
    d->setAudioDevice(dev);
    Q_EMIT deviceChanged();
}
 
/*!
    \internal
*/
void QAudioOutput::setDisconnectFunction(std::function<void()> disconnectFunction)
{
    if (d->disconnectFunction) {
        auto df = d->disconnectFunction;
        d->disconnectFunction = {};
        df();
    }
    d->disconnectFunction = std::move(disconnectFunction);
}
 
#include "moc_qaudiooutput.cpp"