原视频：

canvas简易视频播放器：

跨域的视频，使用getImageData()会报错，《 'CanvasRenderingContext2D': The canvas has been tainted by cross-origin data. =》画布已经被跨源数据污染了》。正常同源环境下getImageData()得到的数据是：（每4个数值为一组，即rgba形式颜色）

Uint8ClampedArray(56320) [75, 85, 65, 255, 76, 86, 67, 255, 75, 86, 66, 255, 72, 84, 64, 255, 77, 90, 69, 255, 84, 98, 78, 255, 91, 106, 85, 255, 94, 109, 86, 255, 96, 112, 88, 255, 88, 104, 78, 255, 87, 102, 77, 255, 86, 99, 74, 255, 89, 102, 78, 255, 85, 96, 72, 255, 75, 85, 62, 255, 71, 84, 59, 255, 78, 93, 66, 255, 89, 107, 78, 255, 91, 109, 80, 255, 83, 99, 71, 255, 81, 96, 70, 255, 89, 102, 77, 255, 94, 108, 82, 255, 95, 108, 82, 255, 90, 101, 75, 255, …]