The Qt Multimedia module in Qt 5 combines (and replaces) two older modules, namely the Qt Multimedia module from Qt 4.x, and Qt Multimedia Kit module from Qt Mobility. Existing code that uses Qt Multimedia from Qt 4 can be ported with minimal effort, but porting code that uses Qt Multimedia Kit may be a more involved process. The changed features section highlights changes relevant to porting.
Also, note that widget-based classes, such as QVideoWidget, are now in a separate module called Qt Multimedia Widgets.
There are a number of new features in Qt Multimedia:
A number of classes or features previously offered in Qt Multimedia or Qt Multimedia Kit have been removed.
| Removed feature | Notes |
|---|---|
| QMediaImageViewer | This class (and related controls and services) were removed since their functionality was not suitable for many applications |
A number of classes previously offered in Qt Multimedia or Qt Multimedia Kit have changed in ways that may affect previously written code. This table highlights such changes.
| Changed feature | Notes |
|---|---|
qmake project file changes |
Previously, to use Qt Multimedia Kit, the qmake project file must contain
CONFIG += mobility MOBILITY += multimedia Now, you only need to write QT += multimedia Or, if you want to use the widget classes, QT += multimedia multimediawidgets |
| Namespaces |
The QtMultimediaKit namespace has been renamed to QMultimedia. This affects a few enumerations, namely SupportEstimate, EncodingQuality,
EncodingMode and AvailabilityStatus. Searching and replacing QtMultimediaKit with QMultimedia will greatly aid porting efforts. Metadata have been split off into their
own namespace, QMediaMetaData.
|
| Metadata types | In Qt Multimedia Kit, pre-defined metadata keys were enumerations in the QtMultimediaKit namespace. These pre-defined keys have been changed to string literals in the QMediaMetaData
namespace, for consistency with extended keys. |
| Metadata accessor methods |
In Qt Multimedia Kit, there were two different families of methods to access metadata. Functions such as QMediaObject::metaData() operated on pre-defined metadata using enumerated keys, while functions such
as QMediaObject::extendedMetaData() operated on extended metadata using string keys. Qt 5 combines both families into one (e.g. QMediaObject::metaData()), which
can operate on both pre-defined and extended metadata, using string keys.
|
| Qt Metatype registration | Qt 5 registers many more classes and types with the meta-object system than before. If you have previously applied Q_DECLARE_METATYPE macros to any Qt Multimedia class, you will probably need to remove them. |
| QSoundEffect availability | The SoundEffect QML type was publicly accessible in Qt Multimeda Kit, and now the C++ version is officially public too. If your code contains the previously undocumented QSoundEffect, you may need to update it. |
| Camera controls | A large number of the camera controls (QCameraImageProcessingControl, QCameraFocusControl, etc.) have been updated to address a number of design flaws. In particular, a number of discrete accessor methods have been collapsed into parametrized methods, and the ranges or data types of some parameters have been adjusted. |
