Qt
Internal/Contributor docs for the Qt SDK. <b>Note:</b> These are NOT official API docs; those are found <a href='https://doc.qt.io/'>here</a>.
Loading...
Searching...
No Matches
Signals | Public Member Functions | Static Public Member Functions | Protected Member Functions | Properties | Friends | List of all members
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.
 
bool moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
 Changes the thread affinity for this object and its children and returns true on success.
 
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::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
 
void killTimer (int id)
 Kills the timer with timer identifier, id.
 
void killTimer (Qt::TimerId id)
 
template<typename T >
T findChild (QAnyStringView aName, 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 (QAnyStringView 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 >
T findChild (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.
 
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 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
 Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
 
 
 
 \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.

The QMediaDevices::audioInputs and QMediaDevices::audioOutputs functions can be used to enumerate all microphones and speakers/headsets on the system. This example first gets a list of all connected microphones, and then prints their identifier, description, and if it is the default device or not.

Similarly, the QMediaDevices::videoInputs will return a list of all connected cameras. In this example we list all connected cameras and their identifier, description, and if it is the default camera or not.

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 261 of file qmediadevices.cpp.

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

+ Here is the call graph for this function:

◆ ~QMediaDevices()

QMediaDevices::~QMediaDevices ( )
default

Member Function Documentation

◆ audioInputs()

static QList< QAudioDevice > QMediaDevices::audioInputs ( )
static

◆ audioInputsChanged

void QMediaDevices::audioInputsChanged ( )
signal

Referenced by QMediaDevices().

+ Here is the caller graph for this function:

◆ audioOutputs()

static QList< QAudioDevice > QMediaDevices::audioOutputs ( )
static

◆ audioOutputsChanged

void QMediaDevices::audioOutputsChanged ( )
signal

Referenced by QMediaDevices().

+ Here is the caller graph for this function:

◆ 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 278 of file qmediadevices.cpp.

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

+ Here is the call graph for this function:

◆ 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().

+ Here is the caller graph for this function:

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 21 of file qmediadevices.h.

Referenced by main().

◆ 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 22 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 24 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 25 of file qmediadevices.h.

Referenced by QAudioEnginePrivate::QAudioEnginePrivate(), QAudioOutput::QAudioOutput(), QDarwinAudioSink::QDarwinAudioSink(), openSlDebugInfo(), QSoundEffectPrivate::sampleReady(), 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 26 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 23 of file qmediadevices.h.

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

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