Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Video Overview#
Video playback
Video Features#
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 QVideoWidget
, QGraphicsVideoItem
, or a custom class.
Here’s an example of using QVideoWidget
:
player = QMediaPlayer() player.setSource(QUrl("http://example.com/myclip1.mp4")) videoWidget = QVideoWidget() player.setVideoOutput(videoWidget) videoWidget.show() player.play()
And an example with QGraphicsVideoItem
:
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.
The 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 QMediaPlayer
and QCamera
.
Recording Video#
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.
Windows#
By default what is available on a MS Windows target depends on the version of Windows Media Player that was packaged with the OS. See the Windows Media Player documentation for official information.
Independent of Windows Media Player, there are of course numerous codec packs that could be installed. See the codec guide site for some examples.
Android#
See Android supported media formats for this information.
Linux#
On Linux this is about installing the correct GStreamer plugins.
Minimum Required GStreamer Plugins#
gstreamer1.0-plugins-base
gstreamer1.0-plugins-good
gstreamer1.0-plugins-pulseaudio
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 QMediaFormat
API.
Use
isSupported()
on aConversionMode
to query a specific format.Use
supportedFileFormats()
on a default constructedQMediaFormat
to get all the supported file formats.
Examples#
There are both C++ and QML examples available.
C++ Examples#
Camera-Example
Shows how to capture a still image or record video.
Media-Player-Example
Playing audio and video.
QML Examples#
QML-Media-Player-Example
Playing audio and video using Qt Quick.
QML-Video-Recorder
Recording audio and video using Qt Quick.
Reference Documentation#
C++ Classes#
The QMediaPlayer class allows the playing of a media files.
Used for getting the basic information of a capturable window.
The QMediaCaptureSession class allows capturing of audio and video content.
The QMediaRecorder class is used for encoding and recording a capture session.
This class is used for capturing a screen.
This class is used for capturing a window.
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.
QML Types#
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.
The CapturableWindow type is used getting basic of a window that is available for capturing via WindowCapture.
Allows capturing of audio and video content.
For encoding and recording media generated in a CaptureSession.
This type is used for capturing a screen.
This type is used for capturing a window.
A convenience type for showing a specified video.
Defines an item in a Playlist.
Render video or camera viewfinder.