title: node.js child_process spawn stdout lower highWaterMark
body: <p>is there a way to lower the highWaterMark for stdout when doing a child_process.spawn?</p>
  
  <p>i read that there might be a way to to lower it for exec, but i actually need to start a process to which i can pass data via stdin and read out the result via stdout.</p>
  
  <p>the highWaterMark is set to high resulting in unacceptable delays for reading the stdout.</p>
  
  <p>i have tried to pass stream objects to the spawn link this:</p>
  
  <pre><code>avconv = spawn("avconv", params, {
    stdio: [process.stdin, process.stdout, process.stderr]
  });
  </code></pre>
  
  <p>which works fine, but when i try to create my own stream for witch i could define a custom highWaterMark:</p>
  
  <pre><code>var readable = new stream.Readable();
  
  avconv = spawn("avconv", params, {
    stdio: [process.stdin, readable, process.stderr]
  });
  </code></pre>
  
  <p>node wont accept it. resulting in a type error.</p>