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 = new QMediaPlayer; player->setSource(QUrl("http://example.com/myclip1.mp4")); videoWidget = new QVideoWidget; player->setVideoOutput(videoWidget); videoWidget->show(); player->play();
And an example with QGraphicsVideoItem:
player = new QMediaPlayer(this); QGraphicsVideoItem *item = new 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.
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.
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.
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 QMediaFormat API.
- Use QMediaFormat::isSupported() on a QMediaFormat::ConversionMode to query a specific format.
- Use QMediaFormat::supportedFileFormats() on a default constructed QMediaFormat to get all the supported file formats.
There are both C++ and QML examples available.
Shows how to capture a still image or record video. or video.
Playing audio and video.
Playing audio and video using Qt Quick.
Recording audio and video using Qt Quick.
Allows capturing of audio and video content
Allows the playing of a media files
Used for encoding and recording a capture session
Used for capturing a screen
Represents a frame of video data
Specifies the stream format of a video presentation surface
Represents a generic sink for video data
Widget which presents video produced by a media object
Allows capturing of audio and video content
Adds media playback to a scene
For encoding and recording media generated in a CaptureSession
Type is used for capturing a screen
A convenience type for showing a specified video
Render video or camera viewfinder
Describes a camera device
Describes a video format supported by a camera device
Provides meta-data for media files
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