MediaSource播放视频，快进（直接点击进度条）的时候怎么知道range范围呢

Question

我通过MediaSource使用ajax加载视频数据播放，下面是关键代码

const mimeCodec = 'video/webm; codecs="vorbis,vp8"';
const mediaSource = new MediaSource();
this.video.src = URL.createObjectURL(mediaSource);
mediaSource.addEventListener('sourceopen', () => {
  this.sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  this.sourceBuffer.addEventListener('updateend', () => {
    if(!this.sourceBuffer.updating && mediaSource.readyState === 'open') {
      // mediaSource.endOfStream();
      this.video.play();
      const { currentTime, duration, buffered } = this.video;
      console.log({
        currentTime,
        duration,
        buffered,
      });
    }
  });
  fetch('/api/video', {
    headers: {
      Range: `bytes=0-512000`,
    },
  }).then(res => res.arrayBuffer())
    .then(buffer => {
      this.sourceBuffer.appendBuffer(buffer);
    });
});

问题：

1. 点击进度条怎么知道ajax请求头里面的Range应该传什么值呢
   

Answer 1

这么做的话 在fetch 里面 判断他的大小