你好请问你复现的手机是什么型号，我这边华为是可以获取数据的

drawImage 绘制 video Demo

query.select('#video0').context(res => {
       const video =  res.context

  const canvas = wx.createOffscreenCanvas({type: '2d', width: w, height: h})
  const context = canvas.getContext('2d')
        
  context.drawImage(video, 0, 0, w, h);
  //  将canvas画布内容转base64
  const base64 = context.canvas.toDataURL('image/png');
  // base64 to 本地地址
  const tempUrl = base64src(base64)
  // todo
  上传 或者 保存至相册
}).exec()

// 工具函数
const base64src = (base64) => {
  const time = new Date().getTime();
  const imgPath = wx.env.USER_DATA_PATH + "/poster" + time + "share" + ".png";
  //如果图片字符串不含要清空的前缀,可以不执行下行代码.
  const imageData = base64.replace(/^data:image\/\w+;base64,/, "");
  const file = wx.getFileSystemManager();
  file.writeFileSync(imgPath, imageData, "base64");
  return imgPath
};