title: Problem when deploy NodeJS with FFMpeg to IIS server by IISNode
body: <p>I have a nodeJs project stream RTSP to HTML.<br/>
  I use rtsp-ffmpeg with socket io<br/>
  server.js:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var cams = arrData.map(function(device, index) {
              var config = JSON.parse(device.CauHinhThietBi);
              var rtspUri = getRtspUrl(config.IPLAN, config.RstpPort, config.Username, config.Password, streamType.MainStream);
              console.log(rtspUri);
              debugger;
              var stream = new rtsp.FFMpeg({input: rtspUri, rate: 25, resolution: '640x480', quality: 3});
              stream.on('start', function() {
                  console.log('stream ' + device.TenThietBi + ' started');
              });
              stream.on('stop', function() {
                  console.log('stream ' + device.TenThietBi + ' stopped');
              });
              return stream;
          });
      
          cams.forEach(function(camStream, i) {
              var ns = io.of('/cam' + arrData[i].ThietBiID);
              ns.on('connection', function(wsocket) {
                  console.log('connected to /cam' + arrData[i].ThietBiID);
                  var pipeStream = function(data) {
                      wsocket.emit('data', data);
                  };
                  camStream.on('data', pipeStream);
          
                  wsocket.on('disconnect', function() {
                      console.log('disconnected from /cam' + arrData[i].ThietBiID);
                      camStream.removeListener('data', pipeStream);
                  });
              });
          });
          
          io.on('connection', function(socket) {
              socket.emit('start', arrData);
          });
          
          app.get('/', function (req, res) {
              res.sendFile(__dirname + '/index.html');
          });</code></pre>
  </div>
  </div>
  </p>
  <p>When I run it in Visual Studio Code, It's well<br/>
  But when I deploy to IIS with IISNode, Had below error:</p>
  <blockquote>
  <p>Error: FFMpeg executable wasn't found. Install this package and check
  FFMpeg.cmd property
  at ChildProcess. (D:\2. Demo\DemoNodeJs\DemoNodeJs\DemoNodeJs\node_modules\rtsp-ffmpeg\lib\rtsp-ffmpeg.js:118:10)
  at ChildProcess.emit (events.js:315:20)
  at Process.ChildProcess._handle.onexit (internal/child_process.js:273:12)
  at onErrorNT (internal/child_process.js:469:16)
  at processTicksAndRejections (internal/process/task_queues.js:84:21)</p>
  </blockquote>
  <p>Please help me</p>