JWPlayer无法在多个来源上加载质量

Question

这是我的jwplayer实例设置。我正在尝试将播放列表从源切换到source2，但是问题是质量标签未加载到第一个源上。在第一个剪辑结束并加载并启动了source2之后，我可以看到“质量”选择器。

playerInstance.setup({
    width: "100%",
    height : "100%",
    playlist: [{
        image: posterURL,
        sources: sources,
    }],
    playbackRateControls: [0.5, 1, 1.5, 2]
});

var sources = [

{
    file: ur_intro_1080,
    type: "video/mp4",
    label: "1080p",
},
{
    file: url_intro_720,
    type: "video/mp4",
    label: "720p",
    "default": "true",
},
{
    file: url_intro_540,
    type: "video/mp4",
    label: "540p"
}
];

var sources2 = [

{
    file: url_clip_1080,
    type: "video/mp4",
    label: "1080p",
    tracks: [{
        file: "thumbURL",
        kind: "thumbnails"
    }]
},
{
    file: url_clip_720,
    type: "video/mp4",
    label: "720p",
    "default": "true",
    tracks: [{
        file: "thumbURL",
        kind: "thumbnails"
    }]
},
{
    file: url_clip_540,
    type: "video/mp4",
    title: movieTitle,
    label: "540p",
    tracks: [{
        file: "thumbURL",
        kind: "thumbnails"
    }]
}
];


playerInstance.on('complete', function(){
    playerInstance.load(sources2);
});

我尝试加载第二个源或仅放置一个播放列表数组，但问题仍然存在。我也检查过了，这不是CSS或皮肤问题。