Qt Multimedia

Qt Multimedia is an add-on module that provides a rich set of QML types and C++ classes to handle multimedia content. It contains an easy to use API for playing back audio and video files and rendering those on screen, as well as a comprehensive API for recording audio and video from the system's cameras and microphones.

The functionality of this module is divided into the following submodules:

Getting started

If you are porting from Qt 5 to Qt 6 see Changes to Qt Multimedia.

If you are new to Qt Multimedia, the QML types can be imported into an application using the following statement in your .qml file.

import QtMultimedia

To link against the C++ libraries, add the following to your project's CMakeLists.txt file. Substitute my_project with the name of your project.

find_package(Qt6 REQUIRED COMPONENTS Multimedia)
target_link_libraries(my_project PRIVATE Qt6::Multimedia)

See Building Qt Multimedia from sources for guidance on building Qt Multimedia from sources.

Overviews and important topics

• Changes in Qt 6
• Multimedia Overview
• Audio Overview
• Spatial Audio Overview
• Video Overview
• Camera Overview
• Supported Media Formats

QML types

The following table outlines some important QML types.

C++ classes

The following table outlines some important C++ classes

For playback QMediaPlayer, QAudioOutput and QVideoOutput contain all the required functionality. The other classes are used for capturing audio and video content, where the QMediaCaptureSession is the central class managing the whole capture/recording process.

Licenses and attributions

The Qt Multimedia module is available under commercial licenses from The Qt Company. In addition, it is available under free software licenses. Since Qt 5.6, these free software licenses are GNU Lesser General Public License, version 3, or the GNU General Public License, version 2. See Qt Licensing for further details.

Furthermore, Qt Multimedia in Qt 6.5.8 may contain third-party modules under following permissive licenses:

Note that video compression standards, such as the H.264 media compression standard, may be covered by patents and can incur royalty fees. This can apply to any implementation, also if the implementation is provided as an operating system service, through a third party library, or through any of Qt Multimedia's backends. Such fees are not covered by the Qt licenses.

Target platform and backend notes

We aim to align the behavior on all the platforms but there are some issues to consider.

Backends

On most platforms, there are two different backends that can be used for Qt Multimedia.

FFmpeg as the default backend

In this release the FFmpeg framework is set as the default backend on Windows, macOS, Android, and Linux except Yocto distribution.

The version shipped with Qt binary packages is FFmpeg 6.1.1 and is tested by the maintainers.

Native backends

These are:

• gstreamer on Linux
• AVFoundation on macOS and iOS
• WMF Windows
• MediaCodec framework on Android

Backend support

Maintainers will strive to fix critical issues with the native backends but don't guarantee fixing minor issues and won't implement new features for the native backends. Furthermore, even some major issues with the gstreamer backend (on Linux) won't be fixed since gstreamer is difficult to debug and is further complicated as it is dependent on Linux distributions. The gstreamer based QMediaPlayer has known issues with seeking, which will only be fixed from Qt-6.8.1 onwards.

We aim to align the behavior on all the platforms, especially, with the FFmpeg backend. Despite this fact we still have platform-dependent issues with formats, codecs, advanced camera features, and screen capturing due to the Qt Multimedia API relying on target platform APIs. For example, with FFmpeg, there are specific problems with hardware acceleration on Linux targets with ARM architectures.

Backend-dependent limitations will be documented and their status maintained in the respective classes.

Changing backends

In the case of issues with the default FFmpeg backend, we suggest testing with a native backend. You can switch to native backends by setting the QT_MEDIA_BACKEND environment variable to windows, gstreamer (on Linux), darwin (on macOS and iOS), or android:

export QT_MEDIA_BACKEND=darwin

In order to force assign FFmpeg as the used backend, set the variable to ffmpeg:

export QT_MEDIA_BACKEND=ffmpeg

On the Qt Multimedia compilation stage the default media backend can be configured via cmake variable QT_DEFAULT_MEDIA_BACKEND.

Target platform notes

The following pages list issues for specific target platforms that are not related to the multimedia backend.

• Windows
• macOS and iOS
• WebAssembly

Permissions

Starting from Qt 6.6, the Qt Multimedia module uses new QPermission API to handle camera and microphone permissions. This means that Qt itself no longer queries for these permissions, so this needs to be done directly from the client application.

Please refer to the Application Permissions page for an example of how to integrate the new QPermission API into the application.

Reference and examples

• QML Types
• C++ Classes
• Examples