参考资料：js获取上传音视频文件的时长

直接通过element-ui自带的上传组件结合js即可，代码如下：

HTML：

        <el-upload class="upload-demo" :action="actionUrl" :show-file-list="false" :on-success="handleAvatarSuccess"
          :before-upload="beforeAvatarUpload">
          <button class="ce-button not-hover primary">
            <i class="ce-icon_upload"></i>
            <span>重新上传</span>
          </button>
        </el-upload>

js：

     beforeAvatarUpload(file) {
        var fileName = file.name || ''
        var ext = fileName.split('.')[fileName.split('.').length - 1]
        if (ext !== "doc" && ext !== "docx" && ext !== "xls" && ext !== "xlsx"
          && ext !== "ppt" && ext !== "pptx" && ext !== "pdf" && ext !== "mp4") {
          this.$notify({
            title: "失败",
            message: "上传资源只能是 doc/docx/xls/xlsx/ppt/pptx/pdf/mp4 格式!",
            type: "error",
            duration: 3000
          });
          return false
        }
        // ppt(10MB)，word(10MB)，excel(5MB)
        if (ext == "doc" || ext == "docx" || ext == "ppt" || ext == "pptx") {
          debugger
          if (parseInt(file.size) > parseInt('10485760‬')) {
            this.$notify({
              title: "失败",
              message: "上传word、ppt文件上限为10MB!",
              type: "error",
              duration: 3000
            });
            return false
          }
        }

        if (ext == 'mp4') { // 获取视频时长
          var url = URL.createObjectURL(file);
          var audioElement = new Audio(url);
          var duration;
          audioElement.addEventListener("loadedmetadata", function (_event) {
            duration = audioElement.duration; //时长为秒，小数，182.36
            this.$parent.$data.wDuration = parseInt(duration)
            console.log(duration);
          });
        }

        this.$parent.$data.wFileName = file.name
        this.$parent.$data.wSize = parseFloat(file.size / 1024).toFixed(2) //获取文件大小
      }