# Playing Media
The most basic case of multimedia integration in a QML application is for it to playback media. The QtMultimedia module supports this by providing a dedicated QML component: the MediaPlayer.
The MediaPlayer component is a non-visual item that connects a media source to one or several output channel(s). Depending on the nature of the media (i.e. audio, image or video) various output channel(s) can be configured.
# Playing audio
In the following example, the MediaPlayer plays a mp3 sample audio file from a remote URL in an empty window:
import QtQuick
import QtMultimedia
Window {
width: 1024
height: 768
visible: true
MediaPlayer {
id: player
source: "https://file-examples-com.github.io/uploads/2017/11/file_example_MP3_2MG.mp3"
audioOutput: AudioOutput {}
}
Component.onCompleted: {
player.play()
}
}In this example, the MediaPlayer defines two attributes:
source: it contains the URL of the media to play. It can either be embedded (qrc://), local (file://) or remote (https://).audioOutput: it contains an audio output channel,AudioOutput, connected to a physical output device. By default, it will use the default audio output device of the system.
As soon as the main component has been fully initialized, the player’s play function is called:
Component.onCompleted: {
player.play()
}# Playing a video
If you want to play visual media such as pictures or videos, you must also define a VideoOutput element to place the resulting image or video in the user interface.
In the following example, the MediaPlayer plays a mp4 sample video file from a remote URL and centers the video content in the window:
import QtQuick
import QtMultimedia
Window {
width: 1920
height: 1080
visible: true
MediaPlayer {
id: player
source: "https://file-examples-com.github.io/uploads/2017/04/file_example_MP4_1920_18MG.mp4"
audioOutput: AudioOutput {}
videoOutput: videoOutput
}
VideoOutput {
id: videoOutput
anchors.fill: parent
anchors.margins: 20
}
Component.onCompleted: {
player.play()
}
}In this example, the MediaPlayer defines a third attribute:
videoOutput: it contains the video output channel,VideoOutput, representing the visual space reserved to display the video in the user interface.
TIP
Please note that the VideoOutput component is a visual item. As such, it's essential that it is created within the visual components hierarchy and not within the MediaPlayer itself.
# Controlling the playback
The MediaPlayer component offers several useful properties. For instance, the duration and position properties can be used to build a progress bar. If the seekable property is true, it is even possible to update the position when the progress bar is tapped.
It's also possible to leverage AudioOutput and VideoOutput properties to customize the experience and provide, for instance, volume control.
The following example adds custom controls for the playback:
- a volume slider
- a play/pause button
- a progress slider
import QtQuick
import QtQuick.Controls
import QtMultimedia
Window {
id: root
width: 1920
height: 1080
visible: true
MediaPlayer {
id: player
source: Qt.resolvedUrl("sample-5s.mp4")
audioOutput: audioOutput
videoOutput: videoOutput
}
AudioOutput {
id: audioOutput
volume: volumeSlider.value
}
VideoOutput {
id: videoOutput
width: videoOutput.sourceRect.width
height: videoOutput.sourceRect.height
anchors.horizontalCenter: parent.horizontalCenter
}
Slider {
id: volumeSlider
anchors.top: parent.top
anchors.right: parent.right
anchors.margins: 20
orientation: Qt.Vertical
value: 0.5
}
Item {
height: 50
anchors.left: parent.left
anchors.right: parent.right
anchors.bottom: parent.bottom
anchors.margins: 20
Button {
anchors.horizontalCenter: parent.horizontalCenter
text: player.playbackState === MediaPlayer.PlayingState ? qsTr("Pause") : qsTr("Play")
onClicked: {
switch(player.playbackState) {
case MediaPlayer.PlayingState: player.pause(); break;
case MediaPlayer.PausedState: player.play(); break;
case MediaPlayer.StoppedState: player.play(); break;
}
}
}
Slider {
id: progressSlider
width: parent.width
anchors.bottom: parent.bottom
enabled: player.seekable
value: player.duration > 0 ? player.position / player.duration : 0
background: Rectangle {
implicitHeight: 8
color: "white"
radius: 3
Rectangle {
width: progressSlider.visualPosition * parent.width
height: parent.height
color: "#1D8BF8"
radius: 3
}
}
handle: Item {}
onMoved: function () {
player.position = player.duration * progressSlider.position
}
}
}
Component.onCompleted: {
player.play()
}
}# The volume slider
A vertical Slider component is added on the top right corner of the window, allowing the user to control the volume of the media:
Slider {
id: volumeSlider
anchors.top: parent.top
anchors.right: parent.right
anchors.margins: 20
orientation: Qt.Vertical
value: 0.5
}The volume attribute of the AudioOutput is then mapped to the value of the slider:
AudioOutput {
id: audioOutput
volume: volumeSlider.value
}# Play / Pause
A Button component reflects the playback state of the media and allows the user to control this state:
Button {
anchors.horizontalCenter: parent.horizontalCenter
text: player.playbackState === MediaPlayer.PlayingState ? qsTr("Pause") : qsTr("Play")
onClicked: {
switch(player.playbackState) {
case MediaPlayer.PlayingState: player.pause(); break;
case MediaPlayer.PausedState: player.play(); break;
case MediaPlayer.StoppedState: player.play(); break;
}
}
}Depending on the playback state, a different text will be displayed in the button. When clicked, the corresponding action will be triggered and will either play or pause the media.
TIP
The possible playback states are listed below:
MediaPlayer.PlayingState: The media is currently playing.MediaPlayer.PausedState: Playback of the media has been suspended.MediaPlayer.StoppedState: Playback of the media is yet to begin.
# Interactive progress slider
A Slider component is added to reflect the current progress of the playback. It also allows the user to control the current position of the playback.
Slider {
id: progressSlider
width: parent.width
anchors.bottom: parent.bottom
enabled: player.seekable
value: player.duration > 0 ? player.position / player.duration : 0
background: Rectangle {
implicitHeight: 8
color: "white"
radius: 3
Rectangle {
width: progressSlider.visualPosition * parent.width
height: parent.height
color: "#1D8BF8"
radius: 3
}
}
handle: Item {}
onMoved: function () {
player.position = player.duration * progressSlider.position
}
}A few things to note on this sample:
- This slider will only be enabled when the media is
seekable(line 5) - Its value will be set to the current media progress, i.e.
player.position / player.duration(line 6) - The media position will be (also) updated when the slider is moved by the user (lines 19-21)
# The media status
When using MediaPlayer to build a media player, it is good to monitor the status property of the player. Here is an enumeration of the possible statuses, ranging from MediaPlayer.Buffered to MediaPlayer.InvalidMedia. The possible values are summarized in the bullets below:
MediaPlayer.NoMedia. No media has been set. Playback is stopped.MediaPlayer.Loading. The media is currently being loaded.MediaPlayer.Loaded. The media has been loaded. Playback is stopped.MediaPlayer.Buffering. The media is buffering data.MediaPlayer.Stalled. The playback has been interrupted while the media is buffering data.MediaPlayer.Buffered. The media has been buffered, this means that the player can start playing the media.MediaPlayer.EndOfMedia. The end of the media has been reached. Playback is stopped.MediaPlayer.InvalidMedia. The media cannot be played. Playback is stopped.MediaPlayer.UnknownStatus. The status of the media is unknown.
As mentioned in the bullets above, the playback state can vary over time. Calling play, pause or stop alters the state, but the media in question can also have an effect. For example, the end can be reached, or it can be invalid, causing playback to stop.
TIP
It is also possible to let the MediaPlayer to loop a media item. The loops property controls how many times the source is to be played. Setting the property to MediaPlayer.Infinite causes endless looping. Great for continuous animations or a looping background song.
