Changes to Qt Multimedia
Qt 6 is a result of the conscious effort to make the framework more efficient and easy to use.
We try to maintain binary and source compatibility for all the public APIs in each release. But some changes were inevitable in an effort to make Qt a better framework.
The module has been refactored significantly and has changed classification, from essential to add-on. The Qt Multimedia module in Qt 6 replaces the Qt Multimedia module from Qt 5.x. Existing code that uses Qt Multimedia from Qt 5 can be ported with limited effort.
New features in Qt 6
There are a number of new features in Qt Multimedia:
- QMediaCaptureSession class is the central object for media capture.
- QMediaRecorder class is now a class limited to recording audio and video. It handles encoding of data produced in a capture session.
- Using QMediaFormat and QMediaRecorder, setting up the desired encoding when recording has changed significantly.
- You can now also monitor the audio recorded by a capture session.
- Support for selection of audio, video and subtitle tracks when playing back media files has been added.
- QAudioDecoder is now supported on all platforms.
Removed features
| Removed feature | Notes or suggested alternative |
|---|---|
| Playlist in QMediaPlayer | QMediaPlayer does not do any playlist handling anymore in Qt 6. |
| QMediaPlayList | This class has been removed from the API. It does however still exist as part of the Media Player Example. |
| QAudioProbe and QVideoProbe | The audio and video probing API has been removed. |
| QAudioRecorder | Use the QMediaCaptureSession or CaptureSession QML type. |
| Audio QML type | Use MediaPlayer QML type. |
| QMediaObject and QMediaBindableInterface | These classes have been removed in favor of a more direct API for setting up connections between objects using, for example, setVideoOutput and QMediaCaptureSession. |
| QCameraViewFinderSettings | This class has been removed. Use QCameraFormat to define the resolution and frame rate the camera should be using. |
| QMediaContent | The class has been removed. Use QUrl for individual media files instead. |
| QSound | Use QSoundEffect instead. |
| QVideoFilterRunnable | Use shader effects in QML instead or access the QVideoFrame's content in C++. |
| Public back-end API | The back-end API of Qt Multimedia is private in Qt 6. This improves response time for supporting new multimedia use cases. Any classes that contain the words "Control" or "Abstract" in the class name in Qt 5 are now private in Qt 6. |
| Back-end plugins | Qt Multimedia in Qt 6 does not use a plugin infrastructure for its back ends anymore. This means that users no longer need to ship those back ends with their application. Instead, the back end being used is determined at compile time based on the underlying operating system. Qt uses gstreamer on Linux, WMF on Windows, AVFoundation on macOS and iOS and the Android multimedia APIs on Android. |
Changed features
A number of classes previously offered in Qt Multimedia have changed in ways that may affect previously written code. The following table highlights these changes.
| Changed feature | Notes |
|---|---|
| Handling of Camera resolutions and frame rates | Handling of these has been simplified and a new QCameraFormat class helps with selecting the correct resolution and frame rate for the camera. |
| Video output handling on the C++ side has changed significantly. | QAbstractVideoSurface has been replaced by the QVideoSink class, and generic rendering support has been enhanced to cover all pixel formats supported by Qt Multimedia. |
| Metadata types | QMediaMetaData has changed significantly: mainly moving from string based to enum based keys, and reducing the set of supported keys to the ones that can be supported on most platforms. |
| QMediaFormat | Handling of formats for encoded media and the settings for the media recorder have changed significantly. Qt 5 provides a string-based API, a separated file format, and audio and video codecs into three classes. However, Qt 6 unifies the formats in the QMediaFormat class. Additional settings are directly specified in QMediaRecorder. Setting up file formats and codecs is now implemented with enums and no longer uses strings. This puts some limitations on the set of codecs that can be used, but helps provide a consistent cross-platform API. |
| QCameraImageCapture renamed QImageCapture | None |
| Audio inputs and outputs | QMediaPlayer and QMediaCaptureSession (and the corresponding QML types MediaPlayer and CaptureSession) are not connected to any audio devices by default. Explicitly connect them to a QAudioInput/AudioInput or QAudioOutput/AudioOutput to capture or play back audio. |
| Capturing video | A capture session is by default not connected to a Camera. Connect it to a QCamera object (Camera item) to be able to capture video or still images. |
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