videojs调整音频播放语速

参考：

​​https://stackoverflow.com/questions/19112255/change-the-video-playback-speed-using-video-js​​

以下代码相比stackoverflow添加了一个延时，否则无法正常播放，官方文档并没有相关过多说明，不理解具体原因

var player = videojs('example-video');
  player.ready(function() {
     var _this = this
     //速率
     var playbackRate = $("#playbackRate").val();
     var speed = parseFloat(playbackRate);           
         setTimeout(function() {
           _this.playbackRate(speed);
        },20);
   });
...
player.play();

$("#playbackRate").change(function(){
    var speed = $(this).val();
    $("#playbackRateLabel").text("x"+speed+"倍速");
});

<audio id=example-video preload="auto" class="video-js vjs-default-skin" type="audio/wav" hidden="hidden">
<input type="range" min="0.5" max="2" value="1" id="playbackRate" step="0.5"/><span id="playbackRateLabel">×1</span>

<script type="text/javascript" th:src="@{/js/jquery3.4.1.js}"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/video.js/7..0.0/video.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/video.js/7.6.0/lang/zh-CN.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/videojs-contrib-hls/5.15.0/videojs-contrib-hls.min.js"></script>
    <script src="https://cdn.bootcss.com/layer/2.3/layer.js"></script>
    <link href="https://cdn.bootcss.com/layer/2.3/skin/layer.css" rel="stylesheet">