QML Video Recorder▲
QML Recorder demonstrates a simple application that can record audio and video separate or together, using a microphone, a camera, or with screen capturing.
Running the Example▲
To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.
Overview▲
At its core, this is a QML application, see Getting Started Programming with Qt Quick. This documentation is focused on how this example uses the Qt Multimedia QML types.
The example uses the QML Camera and AudioInput types connected to a CaptureSession. A MediaRecorder object is then used to record the captured audio and video.
In addition to QtMultimedia, features of Qt Quick Windows, Controls, and Layouts are used to implement the graphic user interface and functionality. Playback won't be covered here, for that see the QML Media Player Example.
The example demonstrates the following:
-
Input devices can be selected.
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An input type switched off.
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Settings for capturing such as quality, codec choice, file format, and assigning metadata.
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Captured files are stored and can be played back.
Recording▲
The application implements recording.
captureSession▲
In main.qml, captureSession is declared like so:
CaptureSession {
id: captureSession
recorder: recorder
audioInput: controls.audioInput
camera: controls.camera
screenCapture: controls.screenCapture
videoOutput: videoOutput
}recorder▲
In main.qml, the MediaRecorder recorder handles recording media as well as capturing a thumbnail for the file and appending it to a ListModel, mediaList.
MediaRecorder {
id: recorder
onRecorderStateChanged:
(state) => {
if (state === MediaRecorder.StoppedState) {
root.contentOrientation = Qt.PrimaryOrientation
mediaList.append()
} else if (state === MediaRecorder.RecordingState && captureSession.camera) {
// lock orientation while recording and create a preview image
root.contentOrientation = root.screen.orientation;
videoOutput.grabToImage(function(res) { mediaList.mediaThumbnail = res.url })
}
}
onActualLocationChanged: (url) => { mediaList.mediaUrl = url }
onErrorOccurred: { recorderErrorText.text = recorder.errorString; recorderError.open(); }
}mediaList is declared in the Frame mediaListFrame
Frame {
id: mediaListFrame
height: 150
width: parent.width
anchors.bottom: controlsFrame.top
x: controls.capturesVisible ? 0 : parent.width
background: Rectangle {
anchors.fill: parent
color: "white"
opacity: 0.8
}
Behavior on x { NumberAnimation { duration: 200 } }
MediaList {
id: mediaList
anchors.fill: parent
playback: playbackcontrols▲
These are defined in Controls.qml and declared in main.qml.
Its root is a Row that contains the Columns inputControls, recordButton, optionButtons, each defined in their own .qml files.
Selecting a video source▲
Defined in VideoSourceSelect.qml, VideoSourceSlect is comprised of a Switch and a ComboBox and enables the user to select from available cameras.
Row {
id: root
height: Style.height
property Camera selectedCamera: cameraAvailable ? camera : null
property ScreenCapture selectedScreenCapture: screenAvailable ? screenCapture : null
property bool cameraAvailable: (comboBox.currentValue.type === 'camera') && cameraSwitch.checked
property bool screenAvailable: (comboBox.currentValue.type === 'screen') && cameraSwitch.checked
Component.onCompleted: {
videoSourceModel.populate()
comboBox.currentIndex = 0
}
Camera {
id: camera
active: cameraAvailable
}
ScreenCapture {
id: screenCapture
active: screenAvailable
}
MediaDevices { id: mediaDevices }
Switch {
id: cameraSwitch
anchors.verticalCenter: parent.verticalCenter
checked: true
}
ListModel {
id: videoSourceModel
property var cameras: mediaDevices.videoInputs
property var screens: Application.screens
function populate() {
videoSourceModel.clear()
for (var camera of cameras)
videoSourceModel.append({ text: camera.description, value:
{ type: 'camera', camera: camera } })
for (var screen of screens)
videoSourceModel.append({ text: screen.name,
value: { type: 'screen', screen: screen }})
}
}comboBox, declared in the above snippet, assigns the current video source.
ComboBox {
id: comboBox
width: Style.widthLong
height: Style.height
background: StyleRectangle { anchors.fill: parent }
model: videoSourceModel
displayText: typeof currentValue === 'undefined' ? "Unavailable" : currentText
font.pointSize: Style.fontSize
textRole: "text"
valueRole: "value"
onCurrentValueChanged: {
if (currentValue.type === 'screen')
screenCapture.screen = currentValue.screen
else if (currentValue.type === 'camera')
camera.cameraDevice = currentValue.cameraSelecting an audio input▲
Implemented in the same way as Selecting a video source and defined in AudioInputSelect.qml like so:
Row {
id: root
height: Style.height
property AudioInput selected: available ? audioInput : null
property bool available: (typeof comboBox.currentValue !== 'undefined') && audioSwitch.checked
Component.onCompleted: {
audioInputModel.populate()
comboBox.currentIndex = 0
}
MediaDevices { id: mediaDevices }
AudioInput { id: audioInput; muted: !audioSwitch.checked }
Switch {
id: audioSwitch;
height: Style.height;
checked: true
}
ListModel {
id: audioInputModel
property var audioInputs: mediaDevices.audioInputs
function populate() {
audioInputModel.clear()
for (var audioDevice of audioInputs)
audioInputModel.append({ text: audioDevice.description, value:
{ type: 'audioDevice', audioDevice: audioDevice } })
}
}
ComboBox {
id: comboBox
width: Style.widthLong
height: Style.height
background: StyleRectangle { anchors.fill: parent }
model: audioInputModel
textRole: "text"
font.pointSize: Style.fontSize
displayText: typeof currentValue === 'undefined' ? "unavailable" : currentText
valueRole: "value"