uni.sendSocketMessage 发送buffer不生效的问题

this.recorderManager.onStop((res) => {  
      this.getLocalFileBuffer(res)  
        .then(buffer => {  
          // uni.sendSocketMessage 似乎无效，服务端没收到消息  
          uni.sendSocketMessage({  
            data: buffer  
          })  
        })  

    });  

getLocalFileBuffer(res) {  
    return new Promise((solve) => {  
      plus.io.resolveLocalFileSystemURL(res.tempFilePath, entry => {  
        entry.file(file => {  

          var fileReader = new plus.io.FileReader();  
          fileReader.readAsDataURL(file, 'utf-8');  
          fileReader.onloadend = function(evt) {  
            const buffer = uni.base64ToArrayBuffer(evt.target.result);  
            solve(buffer);  
          }  
        })  
      })  
    })  
  }

怀疑是类似问题 https://ask.dcloud.net.cn/question/161872