Node.js NodeJ使用缓冲区将二进制数据写入可写流

下面的代码尝试将WAV文件的头写入流 使用缓冲区，然后将其写入可写流

  var fs = require("fs") 

  var samplesLength = 1000;
  var sampleRate = 44100;

  var outStream = fs.createWriteStream("zaz.wav")

  var b = new Buffer(1024)        
  b.write('RIFF', 0);
  /* file length */    
  b.writeUInt32LE(32 + samplesLength * 2, 4);
  //b.writeUint32LE(0, 4);

  b.write('WAVE', 8);
  /* format chunk identifier */
  b.write('fmt ', 12);

  /* format chunk length */
  b.writeUInt32LE(16, 16);

  /* sample format (raw) */
  b.writeUInt16LE(1, 20);
  /* channel count */
  b.writeUInt16LE(2, 22);
  /* sample rate */
  b.writeUInt32LE(sampleRate, 24);
  /* byte rate (sample rate * block align) */
  b.writeUInt32LE(sampleRate * 4, 28);
  /* block align (channel count * bytes per sample) */
  b.writeUInt16LE(4, 32);
  /* bits per sample */
  b.writeUInt16LE(16, 34);
  /* data chunk identifier */
  b.write('data', 36);
  /* data chunk length */

  //b.writeUInt32LE(40, samplesLength * 2);    
  b.writeUInt32LE(40, 0);


  outStream.write(b.slice(0,50))
  outStream.end()

由于某些原因，文件的前8个字节是错误的：

hexdump -C zaz.wav 00000000 28 00 00 00 f0 07 00 00 57 41 56 45 66 6d 74 20 |(.......WAVEfmt | 00000010 10 00 00 00 01 00 02 00 44 ac 00 00 10 b1 02 00 |........D.......| 00000020 04 00 10 00 64 61 74 61 80 5a 57 ac ef 04 00 00 |....data.ZW.....| 00000030 18 57 |.W| 它需要：

b.writeUInt32LE(0, 40);

---

前8位由

b.writeUInt32LE（40,0）写入

=在偏移量0处以小尾数写入（int）40（=0x28）

我不知道你到底想要什么，但这就是问题所在。
这确实是问题所在。感谢
b.writeUInt32LE(40, 0);

b.writeUInt32LE(0, 40);