QMediaDevices Class Reference

The QMediaDevices class provides information about available multimedia input and output devices. More...

#include <qmediadevices.h>

Inheritance diagram for QMediaDevices:

Collaboration diagram for QMediaDevices:

Signals
void	audioInputsChanged ()
void	audioOutputsChanged ()
void	videoInputsChanged ()
Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.
void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	QMediaDevices (QObject *parent=nullptr)
	~QMediaDevices ()
Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.
virtual	~QObject ()
	Destroys the object, deleting all its child objects.
virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.
virtual bool	eventFilter (QObject *watched, QEvent *event)
	Filters events if this object has been installed as an event filter for the watched object.
QString	objectName () const
Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.
void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QBindable< QString >	bindableObjectName ()
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false.
bool	isWindowType () const
	Returns true if the object is a window; otherwise returns false.
bool	isQuickItemType () const
	Returns true if the object is a QQuickItem; otherwise returns false.
bool	signalsBlocked () const noexcept
	Returns true if signals are blocked; otherwise returns false.
bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).
QThread *	thread () const
	Returns the thread in which the object lives.
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children.
int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.
int	startTimer (std::chrono::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
void	killTimer (int id)
	Kills the timer with timer identifier, id.
template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.
template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.
template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
const QObjectList &	children () const
	Returns a list of child objects.
void	setParent (QObject *parent)
	Makes the object a child of parent.
void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.
void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=nullptr, const QObject *receiver=nullptr, const char *member=nullptr) const
bool	disconnect (const QObject *receiver, const char *member=nullptr) const
void	dumpObjectTree () const
	Dumps a tree of children to the debug output.
void	dumpObjectInfo () const
	Dumps information about signal connections, etc.
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.
bool	setProperty (const char *name, QVariant &&value)
QVariant	property (const char *name) const
	Returns the value of the object's name property.
QList< QByteArray >	dynamicPropertyNames () const
QBindingStorage *	bindingStorage ()
const QBindingStorage *	bindingStorage () const
QObject *	parent () const
	Returns a pointer to the parent object.
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false.

Static Public Member Functions
static QList< QAudioDevice >	audioInputs ()
static QList< QAudioDevice >	audioOutputs ()
static QList< QCameraDevice >	videoInputs ()
static QAudioDevice	defaultAudioInput ()
static QAudioDevice	defaultAudioOutput ()
static QCameraDevice	defaultVideoInput ()
Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe
static QMetaObject::Connection	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType *context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	\threadsafe
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.
template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object *receiver, Func2 slot)
template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const QObject *receiver, void **zero)

Protected Member Functions
void	connectNotify (const QMetaMethod &signal) override
Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.
int	senderSignalIndex () const
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.
bool	isSignalConnected (const QMetaMethod &signal) const
virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.
virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.
virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	disconnectNotify (const QMetaMethod &signal)
	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Properties
QList< QAudioDevice >	audioInputs
	\qmltype MediaDevices
QList< QAudioDevice >	audioOutputs
	\qmlproperty list<audioDevice> QtMultimedia::MediaDevices::audioOutputs Contains a list of available audio output devices on the system.
QList< QCameraDevice >	videoInputs
	\qmlproperty list<cameraDevice> QtMultimedia::MediaDevices::videoInputs Contains a list of cameras on the system.
QAudioDevice	defaultAudioInput
	\qmlproperty audioDevice QtMultimedia::MediaDevices::defaultAudioInput Returns the default audio input device.
QAudioDevice	defaultAudioOutput
	\qmlproperty audioDevice QtMultimedia::MediaDevices::defaultAudioOutput Returns the default audio output device.
QCameraDevice	defaultVideoInput
	\qmlproperty cameraDevice QtMultimedia::MediaDevices::defaultVideoInput Returns the default camera on the system.
Properties inherited from QObject
QString	objectName
	the name of this object

Friends
class	QMediaDevicesPrivate

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe
Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

The QMediaDevices class provides information about available multimedia input and output devices.

\inmodule QtMultimedia

The QMediaDevices class provides information about the available multimedia devices and the system defaults. It monitors the following three groups: \list

• Audio input devices (Microphones)
• Audio output devices (Speakers, Headsets)
• Video input devices (Cameras) \endlist

QMediaDevices provides a separate list for each device group. If it detects that a new device has been connected to the system or an attached device has been disconnected from the system, it will update the corresponding device list and emit a signal notifying about the change.

QMediaDevices monitors the system defaults for each device group. It will notify about any changes done through the system settings. For example, if the user selects a new default audio output in the system settings, QMediaDevices will update the default audio output accordingly and emit a signal. If the system does not provide a default for a camera or an audio input, QMediaDevices will select the first device from the list as the default device.

While using the default input and output devices is often sufficient for playing back or recording multimedia, there is often a need to explicitly select the device to be used.

QMediaDevices is a singleton object and all getters are thread-safe.

Definition at line 18 of file qmediadevices.h.

Constructor & Destructor Documentation

QMediaDevices()

QMediaDevices::QMediaDevices

(

QObject *

parent = nullptr

)

Definition at line 248 of file qmediadevices.cpp.

References QPlatformMediaDevices::audioInputsChanged(), audioInputsChanged(), QPlatformMediaDevices::audioOutputsChanged(), audioOutputsChanged(), QObject::connect(), QPlatformMediaDevices::instance(), QPlatformMediaDevices::videoInputsChanged(), and videoInputsChanged().

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~QMediaDevices()

QMediaDevices::~QMediaDevices ( )

default

Member Function Documentation

audioInputs()

static QList< QAudioDevice > QMediaDevices::audioInputs ( )

static

audioInputsChanged

void QMediaDevices::audioInputsChanged ( )

signal

Referenced by QMediaDevices().

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audioOutputs()

static QList< QAudioDevice > QMediaDevices::audioOutputs ( )

static

audioOutputsChanged

void QMediaDevices::audioOutputsChanged ( )

signal

Referenced by QMediaDevices().

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connectNotify()

void QMediaDevices::connectNotify ( const QMetaMethod &  signal )

overrideprotectedvirtual

Since

5.0

This virtual function is called when something has been connected to signal in this object.

If you want to compare signal with a specific signal, you can use QMetaMethod::fromSignal() as follows:

if (signal == QMetaMethod::fromSignal(&MyObject::valueChanged)) {
    // signal is valueChanged
}

Warning

This function violates the object-oriented principle of modularity. However, it might be useful when you need to perform expensive initialization only if something is connected to a signal.

This function is called from the thread which performs the connection, which may be a different thread from the thread in which this object lives. This function may also be called with a QObject internal mutex locked. It is therefore not allowed to re-enter any QObject functions, including isSignalConnected(), from your reimplementation. If you lock a mutex in your reimplementation, make sure that you don't call QObject functions with that mutex held in other places or it will result in a deadlock.

See also

connect(), disconnectNotify()

Reimplemented from QObject.

Definition at line 265 of file qmediadevices.cpp.

References QObject::connectNotify(), QMetaMethod::fromSignal(), QPlatformMediaDevices::initVideoDevicesConnection(), QPlatformMediaDevices::instance(), signal, and videoInputsChanged().

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defaultAudioInput()

static QAudioDevice QMediaDevices::defaultAudioInput ( )

static

defaultAudioOutput()

static QAudioDevice QMediaDevices::defaultAudioOutput ( )

static

defaultVideoInput()

static QCameraDevice QMediaDevices::defaultVideoInput ( )

static

videoInputs()

static QList< QCameraDevice > QMediaDevices::videoInputs ( )

static

videoInputsChanged

void QMediaDevices::videoInputsChanged ( )

signal

Referenced by QMediaDevices(), and connectNotify().

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Friends And Related Symbol Documentation

QMediaDevicesPrivate

friend class QMediaDevicesPrivate

friend

Definition at line 49 of file qmediadevices.h.

Property Documentation

audioInputs

QList< QAudioDevice > QMediaDevices::audioInputs

read

\qmltype MediaDevices

Since

6.2 \instantiates QMediaDevices

MediaDevices provides information about available multimedia input and output devices. \inqmlmodule QtMultimedia

The MediaDevices type provides information about the available multimedia devices and the system defaults. It monitors the following three groups: \list

• Audio input devices (Microphones)
• Audio output devices (Speakers, Headsets)
• Video input devices (Cameras) \endlist

MediaDevices provides a separate list for each device group. If it detects that a new device has been connected to the system or an attached device has been disconnected from the system, it will update the corresponding device list and emit a signal notifying about the change.

MediaDevices monitors the system defaults for each device group. It will notify about any changes done through the system settings. For example, if the user selects a new default audio output in the system settings, MediaDevices will update the default audio output accordingly and emit a signal. If the system does not provide a default for a camera or an audio input, MediaDevices will select the first device from the list as the default device.

While using the default input and output devices is often sufficient for playing back or recording multimedia, there is often a need to explicitly select the device to be used.

For example, the snippet below will ensure that the media player always uses the systems default audio output device for playback:

\qml MediaDevices { id: devices } MediaPlayer { ... audioOutput: AudioOutput { device: devices.defaultAudioOutput } } \endqml

See also

Camera, AudioInput, VideoOutput

\qmlproperty list<audioDevice> QtMultimedia::MediaDevices::audioInputs Contains a list of available audio input devices on the system.

Those devices are usually microphones. Devices can be either built-in, or connected through for example USB or Bluetooth.

Returns a list of available audio input devices on the system.

Those devices are usually microphones. Devices can be either built-in, or connected through for example USB or Bluetooth.

Definition at line 52 of file qmediadevices.h.

audioOutputs

QList< QAudioDevice > QMediaDevices::audioOutputs

read

\qmlproperty list<audioDevice> QtMultimedia::MediaDevices::audioOutputs Contains a list of available audio output devices on the system.

Those devices are usually loudspeakers or head sets. Devices can be either built-in, or connected through for example USB or Bluetooth.

Returns a list of available audio output devices on the system.

Those devices are usually loudspeakers or head sets. Devices can be either built-in, or connected through for example USB or Bluetooth.

Definition at line 52 of file qmediadevices.h.

Referenced by AudioDeviceInfo(), and QSoundEffect::supportedMimeTypes().

defaultAudioInput

QAudioDevice QMediaDevices::defaultAudioInput

read

\qmlproperty audioDevice QtMultimedia::MediaDevices::defaultAudioInput Returns the default audio input device.

The default device can change during the runtime of the application. The value of this property will automatically adjust itself to such changes.

Returns the default audio input device.

The default device can change during the runtime of the application. The audioInputsChanged() signal is emitted in this case.

Definition at line 52 of file qmediadevices.h.

Referenced by QAudioInput::QAudioInput(), QDarwinAudioSource::QDarwinAudioSource(), QAudioInput::setDevice(), and AudioInputExample::setup().

defaultAudioOutput

QAudioDevice QMediaDevices::defaultAudioOutput

read

\qmlproperty audioDevice QtMultimedia::MediaDevices::defaultAudioOutput Returns the default audio output device.

The default device can change during the runtime of the application. The value of this property will automatically adjust itself to such changes.

Returns the default audio output device.

The default device can change during the runtime of the application. The audioOutputsChanged() signal is emitted in this case.

Definition at line 52 of file qmediadevices.h.

Referenced by QAudioEnginePrivate::QAudioEnginePrivate(), QAudioOutput::QAudioOutput(), QDarwinAudioSink::QDarwinAudioSink(), openSlDebugInfo(), QAudioOutput::setDevice(), and AudioOutputExample::setup().

defaultVideoInput

QCameraDevice QMediaDevices::defaultVideoInput

read

\qmlproperty cameraDevice QtMultimedia::MediaDevices::defaultVideoInput Returns the default camera on the system.

Note

The returned object should be checked using isNull() before being used, in case there is no camera available.

The default device can change during the runtime of the application. The value of this property will automatically adjust itself to such changes.

Returns the default camera on the system.

Note

The returned object should be checked using isNull() before being used, in case there is no default camera or no cameras at all.

The default device can change during the runtime of the application. The videoInputsChanged() signal is emitted in that case.

See also

videoInputs()

Definition at line 52 of file qmediadevices.h.

Referenced by QQnxPlatformCamera::QQnxPlatformCamera(), QCameraPrivate::init(), and QCamera::setCameraDevice().

videoInputs

QList< QCameraDevice > QMediaDevices::videoInputs

read

\qmlproperty list<cameraDevice> QtMultimedia::MediaDevices::videoInputs Contains a list of cameras on the system.

Returns a list of available cameras on the system.

Definition at line 52 of file qmediadevices.h.

Referenced by QCamera::QCamera(), camera_listing(), camera_selection(), checkCameraAvailability(), QAndroidCamera::setCamera(), and QWasmCamera::setCamera().

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The documentation for this class was generated from the following files:

• qtmultimedia/src/multimedia/qmediadevices.h
• qtmultimedia/src/multimedia/qmediadevices.cpp