这里有一个片段显示了实际的问题，但基本上，当标签在Chrome中处于后台时，requestVideoFrameCallback就会停止运行。

function startTest() {
    video = document.querySelector('video');
    canvas = document.querySelector('canvas');
    ctx = canvas.getContext('2d');

    let start_time = 1.0, paint_count = 0, raf_count = 0;
    let last_time = 0;
    var paintFrame = function(timestamp, metadata) {
      if (start_time == 1.0)
        start_time = timestamp;
      updateCanvas(ctx, video);
      last_counter = metadata.presentedFrames;

      var elapsed_frame = 0;
      var elapsed = (timestamp - start_time) / 1000.0;
      
      if(last_time == 0){
        console.log('init')
        elapsed_frame = 0
      }else{
         elapsed_frame = (new Date()).getTime() - last_time
      }
      last_time = (new Date()).getTime()
      
      var fps_text = document.querySelector('#fps');
      var presented = metadata.presentedFrames + 1;
      fps_text.innerText =
          'actual fps: ' + (++paint_count / elapsed).toFixed(3) + ', ideal fps: ' +
          (presented / elapsed).toFixed(3) + ', missed: ' +
          (presented - paint_count) + '/' + presented +
          '(' +  ((presented - paint_count)/presented*100.0).toFixed(1) + '%)';
      
      if(elapsed_frame > 100){
        console.log('Long clock-time', elapsed_frame, 'missed', (presented - paint_count));
      }
      
      video.requestVideoFrameCallback(paintFrame);
    };
    video.onplay = function(){
      v = video.requestVideoFrameCallback(paintFrame);
    };

    video.playbackRate = 1.0;

    video.src="https://tguilbert-google.github.io/vid/buck360p_vp9.webm"

  };

字符串
https://codepen.io/jerodvenemafm/pen/gOqqWmJ
以下是Chrome文档的参考：
https://developer.chrome.com/blog/background_tabs/的
并特别说明如果音频打开，这应该如何在后台运行：
https://bugs.chromium.org/p/chromium/issues/detail?id=1012063的
两者似乎都暗示这不是预期的行为，所以我有点困惑。这是Chrome的错误，还是我遗漏了某种设置？