Changes to Qt Multimedia¶
Migrate Qt Multimedia to Qt 6.
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:
QMediaCaptureSessionclass is the central object for media capture.
QMediaRecorderclass is now a class limited to recording audio and video. It handles encoding of data produced in a capture session.
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.
QAudioDecoderis now supported on all platforms.
Notes or suggested alternative
QMediaPlayerdoes not do any playlist handling anymore in Qt 6.
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.
QMediaCaptureSessionor CaptureSession 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
This class has been removed. Use
QCameraFormatto define the resolution and frame rate the camera should be using.
The class has been removed. Use
QUrlfor individual media files instead.
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.
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.
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.
Handling of Camera resolutions and frame rates
Handling of these has been simplified and a new
QCameraFormatclass 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
QVideoSinkclass, and generic rendering support has been enhanced to cover all pixel format s supported by Qt Multimedia.
QMediaMetaDatahas 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.
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
QMediaFormatclass. 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.
Audio inputs and outputs
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.
A capture session is by default not connected to a Camera. Connect it to a
QCameraobject (Camera item) to be able to capture video or still images.
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