用http模块拉了qq音乐的一首歌，但是不能播放，怎么回事啊？

"use strict";

let http = require('http');

let cp = require('fs-cp');

let stream = require('stream');

var req = http.get('http://cc.stream.qqmusic.qq.com/C200004BhQke4adHcf.m4a?vkey=7F45E770F941BD2A946BEB6AE146D004E64BD935EAF6FB8E54A500EC287E9AA3B60BC635D478E7CD35E2A5585A859A83CD0345282988E905&guid=7295540986&fromtag=30',(res)=>{
    //res.setEncoding('utf8');
    var data ='';
    res.on('data',(chunk)=>{
        data+=chunk;
    })
    res.on('end',()=>{
        var s = new stream.Readable();
        s.push(data);
        s.push(null);
        cp(s,'d:/gks/testbuild/music.mp3').then(err=>{console.log(err)})
    })
})

播放器显示错误。