截取视频video首帧为图片

this.url = "https://xxx.com/video/demo.mp4"

1.把视频放进canvas，在通过canvas 拿到视频的第一帧。

var cut = function() {
    let canvas = document.createElement("canvas");//创建画布
    canvas.width = video.videoWidth * scale;
    canvas.height = video.videoHeight * scale;//设定宽高比
    canvas.getContext('2d').drawImage(video, 0, 0, canvas.width, canvas.height);//将视频此刻帧数画入画布
    let img = document.createElement("img");
    img.src = canvas.toDataURL("image/png");
    Dom.appendChild(img);//写入到Dom
};
video.addEventListener('loadeddata',cut);//在视频帧数已加载时执行截取

2.通过拼接属性获取视频首帧图片

this.cover = this.videoUrl + "?x-oss-process=video/snapshot,t_1,m_fast"
this.videoCover 就直接可以在vue里作为封面来用。