- Qt 6.12
- Qt Multimedia
- C++ Classes
- QtMultimedia
- QMediaDevices
- Qt 6.12.0 Reference Documentation

# QMediaDevices Class

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

Header: | `#include <QMediaDevices>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Multimedia)` `target_link_libraries(mytarget PRIVATE Qt6::Multimedia)`
qmake: | `QT += multimedia`
In QML: | MediaDevices
Inherits: | QObject

- List of all members, including inherited members

## Properties

audioInputs : QList<QAudioDevice> audioOutputs : QList<QAudioDevice> defaultAudioInput : QAudioDevice | defaultAudioOutput : QAudioDevice defaultVideoInput : QCameraDevice videoInputs : QList<QCameraDevice>

## Signals

void | audioInputsChanged()
void | audioOutputsChanged()
void | videoInputsChanged()

## Static Public Members

QList<QAudioDevice> | audioInputs()
QList<QAudioDevice> | audioOutputs()
QAudioDevice | defaultAudioInput()
QAudioDevice | defaultAudioOutput()
QCameraDevice | defaultVideoInput()
QList<QCameraDevice> | videoInputs()

## Detailed Description

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

- Audio input devices (Microphones)
- Audio output devices (Speakers, Headsets)
- Video input devices (Cameras)

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.

     const QList<QAudioDevice> audioDevices = QMediaDevices::audioInputs();
     for (const QAudioDevice &device : audioDevices)
     {
         out << "ID: " << device.id() << Qt::endl;
         out << "Description: " << device.description() << Qt::endl;
         out << "Is default: " << (device.isDefault() ? "Yes" : "No") << Qt::endl;
     }

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.

     const QList<QCameraDevice> videoDevices = QMediaDevices::videoInputs();
     for (const QCameraDevice &device : videoDevices)
     {
         out << "ID: " << device.id() << Qt::endl;
         out << "Description: " << device.description() << Qt::endl;
         out << "Is default: " << (device.isDefault() ? "Yes" : "No") << Qt::endl;
     }

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’ static methods are thread-safe and refer to an underlying singleton object.

Note: On WebAssembly platform, due to its asynchronous nature, the lists of devices will only be available after audioInputsChanged, audioOutputsChanded, or videoInputsChanged notifications.

## Property Documentation

### `[read-only]` audioInputs : QList<QAudioDevice>

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.

Access functions:

QList<QAudioDevice> | audioInputs()

Notifier signal:

void | audioInputsChanged()

### `[read-only]` audioOutputs : QList<QAudioDevice>

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.

Access functions:

QList<QAudioDevice> | audioOutputs()

Notifier signal:

void | audioOutputsChanged()

### `[read-only]` defaultAudioInput : QAudioDevice

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.

Access functions:

QAudioDevice | defaultAudioInput()

Notifier signal:

void | audioInputsChanged()

### `[read-only]` defaultAudioOutput : QAudioDevice

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.

Access functions:

QAudioDevice | defaultAudioOutput()

Notifier signal:

void | audioOutputsChanged()

### `[read-only]` defaultVideoInput : QCameraDevice

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.

Access functions:

QCameraDevice | defaultVideoInput()

Notifier signal:

void | videoInputsChanged()

See also videoInputs().

### `[read-only]` videoInputs : QList<QCameraDevice>

Returns a list of available cameras on the system.

Access functions:

QList<QCameraDevice> | videoInputs()

Notifier signal:

void | videoInputsChanged()