视频13:52左右,说到每一帧执行时间是22毫秒,但实际代码里是33毫秒,这里应该订正一下吧?
// We start out assuming that we run at 30fps but then the heuristic tracking
// will adjust this value to a faster fps if we get more frequent animation
// frames.
var previousFrameTime = 33;
var activeFrameTime = 33;