在QT/QML中播放视频播放列表

Question

我正在QML上制作一个简单的播放列表播放器。我正在使用folderlistModel读取文件夹。 我想依次运行每个视频。但是我的播放器只播放第一个视频，然后程序崩溃。我的错误是无效的属性名称在thong.qml中打开。我的源代码：

main.qml

Rectangle {
    id: root
    width: 1024
    height: 600
    color: "black"
    property bool onStart: true
    Thong {
        id: playlist
        mediaPlayer: player
        fm: FolderListModel {
            id: fm
            folder: "file:///home/pi/Documents/nhacmp4test"
            showDirs: false
            showDotAndDotDot: false
            nameFilters: ["*.wmv"]
            property bool ready: count > 0
            onReadyChanged: {if (player.status == MediaPlayer.NoMedia) {
                                playlist.setIndex(0);
                                player.play();
                            }}
        }
    }
    MediaPlayer { id: player }
    VideoOutput {
        anchors.fill: parent
        source: player
    }
}/*Thong.qml*/ Item{
id: a
property int index: 0
property MediaPlayer mediaPlayer
property FolderListModel fm
Component.onCompleted: {
    mainWindow.showNormal();
}    
function setIndex(i)
{
    index = i;
    console.log("setting index to: " + i);
    index %= fm.count;
    mediaPlayer.source = "file://" + fm.get(index,"filePath");
    console.log("setting source to: " + mediaPlayer.source);
}
function next()
{
    setIndex(index+1);        
}
Connections {
    target:  a.mediaPlayer
    onStopped: {
        if (a.mediaPlayer.status == MediaPlayer.EndOfMedia) {
            a.next();
            a.mediaPlayer.play();
            console.log("ok");
        }
    }       
}