Qt Multimedia offers both high and low level C++ classes for playing and manipulating video data, and QML types for playback and recording. Some of the classes presented here overlap with what is presented in the Camera Overview and Audio Overview .
Video Implementation Details#
Playing Video in C++#
You can use the
QMediaPlayer class to decode a video file, and display it using
QGraphicsVideoItem , or a custom class.
Here’s an example of using
player = QMediaPlayer player.setSource(QUrl("http://example.com/myclip1.mp4")) videoWidget = QVideoWidget player.setVideoOutput(videoWidget) videoWidget.show() player.play()
And an example with
player = QMediaPlayer(self) item = QGraphicsVideoItem() player.setVideoOutput(item) graphicsView.scene().addItem(item) graphicsView.show() player.setSource(QUrl("http://example.com/myclip4.ogv")) player.play()
Playing Video in QML#
You can use VideoOutput to render content that is provided by either a MediaPlayer or a Camera . The VideoOutput is a visual component that can be embedded into a QQuickScene or Window , while all media decoding and playback control is handled by the MediaPlayer or CaptureSession . A Video element has been provided for convenience. It combines MediaPlayer , VideoOutput and AudioOutput elements in one item.
Working with Low Level Video Frames#
Qt Multimedia offers a number of low level classes to make handling video frames a bit easier. These classes are primarily used when writing code that processes video or camera frames (for example, detecting barcodes, or applying a fancy vignette effect), or needs to display video in a special way that is otherwise unsupported.
QVideoFrame class encapsulates a video frame and allows the contents to be mapped into system memory for manipulation or processing. Using your own
QVideoSink allows you to receive these frames from
The central class for any type of capturing or recording of audio and video is
QMediaCaptureSession (or the CaptureSession QML type). You can connect a
QCamera (Camera in QML) and a
QMediaRecorder ( MediaRecorder )to the session and then ask the media recorder to start recording.
Supported Media Formats#
What media formats are supported ultimately depends on the configuration of the target system.
Independent of Windows Media Player, there are of course numerous codec packs that could be installed. See the codec guide site for some examples.
See Android supported media formats for this information.
On Linux this is about installing the correct GStreamer plugins.
Minimum Required GStreamer Plugins#
For a Linux desktop target, it is strongly recommended to have
gstreamer1.0-libav for good codec coverage and
gstreamer1.0-vaapi to get hardware acceleration.
On embedded Linux, the required set of plugins could be somewhat different.
Determining Supported Media Formats at Runtime#
You can determine what formats are available on a target system at runtime using the static
ConversionModeto query a specific format.
supportedFileFormats()on a default constructed
QMediaFormatto get all the supported file formats.
There are both C++ and QML examples available.
The QMediaPlayer class allows the playing of a media files.
The QMediaCaptureSession class allows capturing of audio and video content.
The QMediaRecorder class is used for encoding and recording a capture session.
The QVideoFrame class represents a frame of video data.
The QVideoFrameFormat class specifies the stream format of a video presentation surface.
The QVideoSink class represents a generic sink for video data.
The QVideoWidget class provides a widget which presents video produced by a media object.
Describes a video format supported by a camera device.
Describes a camera device.
Adds media playback to a scene.
Provides meta-data for media files.
Allows capturing of audio and video content.
For encoding and recording media generated in a CaptureSession.
A convenience type for showing a specified video.
Defines an item in a Playlist.
Render video or camera viewfinder.