Qt Multimedia QML API

Overview

The Qt Multimedia module gives developers a simplified way to use audio and video playback, and access camera functionality. The Multimedia QML API provides a QML friendly interface to these features.

Types

Audio

Audio is an easy way to add audio playback to a Qt Quick scene. Qt Multimedia provides properties for control, methods (functions) and signals.

The code extract below shows the creation and use of an Audio instance.

 Item {
     width: 640
     height: 360

     Audio {
         id: playMusic
         source: "music.wav"
     }

     MouseArea {
         id: playArea
         anchors.fill: parent
         onPressed:  { playMusic.play() }
     }
 }

The snippet above shows how the inclusion of playMusic enables audio features on the type that contains it. So that when the parent's MouseArea is clicked the play() method of Audio is run. Other typical audio control methods are available such as pause() and stop().

Much of the getting / setting of Audio parameters is done through properties. These include

The set of signals available allow the developer to create custom behavior when the following events occur,

Camera

Camera enables still image and video capture using QML. It has a number of properties that help setting it up.

The details of using a Camera are described in further depth in the Camera Overview and in the corresponding reference documentation.

Video

Adding video playback, with sound, to a Qt Quick scene is also easy. The process is very similar to that of Audio above, in fact Video shares many of the property names, methods and signals. Here is the equivalent sample code to implement video playback in a scene

 Video {
     id: video
     width : 800
     height : 600
     source: "video.avi"

     MouseArea {
         anchors.fill: parent
         onClicked: {
             video.play()
         }
     }

     focus: true
     Keys.onSpacePressed: video.paused = !video.paused
     Keys.onLeftPressed: video.position -= 5000
     Keys.onRightPressed: video.position += 5000
 }

There are similar features like play() with new features specific to video.

In the above sample when the parent of MouseArea is clicked, an area of 800x600 pixels with an id of 'video', the source "video.avi" will play in that area. Notice also that signals for the Keys have been defined so that a spacebar will toggle the pause button; the left arrow will move the current position in the video to 5 seconds previously; and the right arrow will advance the current position in the video by 5 seconds.

Most of the differences will obviously be about video control and information. There are many properties associated with Video, most of them deal with meta-data, control of the video media and aspects of presentation.

SoundEffect

SoundEffect provides a way to play short sound effects, like in video games. Multiple sound effect instances can be played simultaneously. You should use Audio for music playback.

 Item {
     width: 640
     height: 360

     SoundEffect {
         id: effect
         source: "test.wav"
     }
     MouseArea {
         id: playArea
         anchors.fill: parent
         onPressed:  { effect.play() }
     }
 }

In the above sample the sound effect will be played when the MouseArea is clicked.

For a complete description of this type, see SoundEffect

Multimedia QML Types