qt6-changes.qdoc

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
    \page qtmultimedia-changes-qt6.html
    \title Changes to Qt Multimedia
    \ingroup changes-qt-5-to-6
    \brief 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.
 
 
\section1 New features in Qt 6
 
There are a number of new features in Qt Multimedia:
\list
    \li QMediaCaptureSession class is the central object for media capture.
    \li QMediaRecorder class is now a class limited to recording audio and video.
    It handles encoding of data produced in a capture session.
    \li Using QMediaFormat and QMediaRecorder, setting up the desired encoding
    when recording has changed significantly.
    \li You can now also monitor the audio recorded by a capture session.
    \li Support for selection of audio, video and subtitle tracks when playing
    back media files has been added.
    \li QAudioDecoder is now supported on all platforms.
\endlist
 
 
\section1 Removed features
 
\table 70%
    \header
        \li Removed feature
        \li Notes or suggested alternative
    \row
        \li Playlist in QMediaPlayer
        \li QMediaPlayer does not do any playlist handling anymore in Qt 6.
    \row
        \li QMediaPlayList
        \li This class has been removed from the API. It does however still exist
        as part of the \l{Media Player Example}.
    \row
        \li QAudioProbe and QVideoProbe
        \li The audio and video probing API has been removed.
    \row
        \li QAudioRecorder
        \li Use the QMediaCaptureSession or CaptureSession QML type.
    \row
        \li \l{Audio QML type}
        \li Use MediaPlayer QML type.
    \row
        \li QMediaObject and QMediaBindableInterface
        \li These classes have been removed in favor of a more direct API for
        setting up connections between objects using, for example, setVideoOutput
        and QMediaCaptureSession.
    \row
        \li QCameraViewFinderSettings
        \li This class has been removed. Use QCameraFormat to define the
        resolution and frame rate the camera should be using.
    \row
        \li QMediaContent
        \li The class has been removed. Use QUrl for individual media files instead.
    \row
        \li QSound
        \li Use QSoundEffect instead.
    \row
        \li QVideoFilterRunnable
        \li Use \l{shader effects} in QML instead or access the QVideoFrame's
        content in C++.
    \row
        \li Public back-end API
        \li 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.
    \row
        \li Back-end plugins
        \li 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 \l gstreamer on
        Linux, WMF on Windows, AVFoundation on macOS and iOS and the Android
        multimedia APIs on Android.
\endtable
 
\section1 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.
 
\table 70%
    \header
        \li Changed feature
        \li Notes
    \row
        \li Handling of Camera resolutions and frame rates
        \li Handling of these has been simplified and a new QCameraFormat class
        helps with selecting the correct resolution and frame rate for the camera.
    \row
        \li Video output handling on the C++ side has changed significantly.
        \li QAbstractVideoSurface has been replaced by the QVideoSink class, and
        generic rendering support has been enhanced to cover all \l{pixel format}s
        supported by Qt Multimedia.
    \row
        \li Metadata types
        \li 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.
    \row
        \li QMediaFormat
        \li 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.
    \row
        \li QCameraImageCapture renamed QImageCapture
        \li None
    \row
        \li Audio inputs and outputs
        \li 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.
    \row
        \li Capturing video
        \li 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.
\endtable
 
*/