title: fluent-ffmpeg wrong output duration
body: <p>I'm trying to stream a video using fluent-ffmpeg and without save it.</p>
  <p>I use this code but the <strong>output video was cut (12s instead of the 20s of the original video)</strong>.
  I tried many output options but without success.</p>
  <p>Precision : I want to get the stream duration in the web player.</p>
  <p>Thanks a lot for your help !</p>
  <p><a href="https://i.stack.imgur.com/nwR5l.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nwR5l.png" alt="enter image description here" /></a></p>
  
  <pre><code>let imageData = [];
  
  let tmp = {};
  tmp.filter = 'overlay';
  tmp.inputs = '[0:v][1:v]';
  tmp.options = {};
  //tmp.options.enable = `between(t,${image.startAt}, ${image.endAt})`;
  tmp.options.x = imagePositionX;
  tmp.options.y = imagePositionY;
  tmp.outputs = 'tmp';
  imageData.push(tmp);
  
  let size = await ufs(videoURL);
  
  res.status(206);
  res.set('Content-Type', 'video/mp4');
  
  if (req.headers.range) {
    let range        = req.headers.range;
    let parts        = range.replace(/bytes=/, &quot;&quot;).split(&quot;-&quot;);
    let partialstart = parts[0];
    let partialend   = parts[1];
  
    let start     = parseInt(partialstart, 10);
    let end       = partialend ? parseInt(partialend, 10) : size-1;
    let chunksize = (end-start)+1;
  
    res.set('Content-Range', 'bytes ' + start + '-' + end + '/' + size);
    res.set('Accept-Ranges', 'bytes');
    res.set('Content-Length', chunksize);
  } else {
    res.set('Content-Length', size);
  }
  
  let stream = ffmpeg(videoURL)
  .input(imageURL)
  .videoCodec('libx264')
  .audioCodec('aac')
  .fps('29.97')
  .complexFilter(imageData, 'tmp')
  .outputOptions([
    '-movflags frag_keyframe+empty_moov',
    '-frag_duration 100',
    '-pix_fmt yuv420p',
    '-map 0:a?',
    '-b:v 2400k',
    '-b:a 160k',
    '-minrate 200k',
    '-maxrate 1300k',
    '-bufsize 13000k',
    '-f mp4',
  ])
  .on('end', () =&gt; {
    console.log('file has been converted succesfully');
  })
  .on('error', (err) =&gt; {
    //console.log('error : ', err)
    console.log('error : ', err.message)
  })
  .pipe(res, {end: true})
  </code></pre>