JavaScript实现读取上传视频文件的时长和第一帧画面过程讲解

getVideoDuration(file) {
  var url = URL.createObjectURL(file);
  var audioElement = new Audio(url);
  var self = this;
  var result;
  audioElement.addEventListener("loadedmetadata", function() {
    // 视频时长值的获取要等到这个匿名函数执行完毕才产生
    result = audioElement.duration; //得到时长为秒，小数，182.36
    self.ruleForm.videoDuration = parseInt(result); //转为int值
  });
}

const file = '.....'
const a = new FileReader();
a.readAsDataURL(file);
a.onload = (e) => {
	const blob = new Blob([e.target.result], { type: file.type }) // 如果发现乱码检查一下type赋值的对不对
}

findvideocover() {
        let size = 160
        // 获取video节点
        const video = document.getElementById("videoPlay");
        video.width = size
        video.height = size
        video.currentTime = 1 // 第一帧
        //创建canvas对象
        const canvas = document.createElement("canvas")
        canvas.width = size
        canvas.height = size
        this.$nextTick(()=>{
          // 利用canvas对象方法绘图
          canvas.getContext("2d").drawImage(video, 0, 0, canvas.width, canvas.height);
          // 转换成base64形式
          const img = canvas.toDataURL("image/jpeg") // 这个就是图片的base64
          this.coverUrl = img
        })
      }

const arr = base64.split(',')
const type = arr[0].match(/:(.*?);/)[1]
const size = window.atob(arr[1])
let n = size.length
const u8arr = new Uint8Array(n)
while (n--) {
  u8arr[n] = size.charCodeAt(n)
}
const file = new File([u8arr], name, { type })