wx.chooseMedia({
  count: 1,
  sourceType: ['camera'],
  mediaType: ['video'],
  maxDuration: 10,
  camera: 'front',
  success(res) {
    // 读取视频base64
    wx.getFileSystemManager().readFile({
      filePath: res.tempFiles[0].tempFilePath,
      encoding: 'base64',
      success(rep) {
        console.log(rep)
      },
    });
  }
});