Making streamable / seekable video

const http = require('http');
const fs = require('fs');
const ffmpeg = require('fluent-ffmpeg');

var server = http.createServer(function(req, res) {
    var pathToMovie = __dirname + '/src/test.mkv';
    var stat = fs.statSync(pathToMovie);

    var range = req.headers.range || 'bytes=0-';
    var parts = range.replace(/bytes=/, "").split("-");

    var total = stat.size;
    var start = parseInt(parts[0], 10);
    var end = parts[1] ? parseInt(parts[1], 10) : total-1;
    var chunksize = (end-start)+1;

    var file = fs.createReadStream(pathToMovie, {start: start, end: end});

    res.writeHead(206, {
        'Content-Range': 'bytes ' + start + '-' + end + '/' + total,
        'Accept-Ranges': 'bytes',
        'Content-Length': chunksize,
        'Content-Type': 'video/mp4',
        'Connection':'keep-alive'
    });

    var proc = new ffmpeg(file)
    .outputOptions(['-frag_duration 100','-movflags frag_keyframe+empty_moov+faststart'])
    //.withSize('1440x?')
    .toFormat('mp4')
    .on('error', function(err,stdout,stderr) {
        console.log('an error happened: ' + err.message);
        console.log('ffmpeg stdout: ' + stdout);
        console.log('ffmpeg stderr: ' + stderr);
    })
    .pipe(res, { end: true });
});
server.listen(8080);

an error happened: Output stream closed
ffmpeg stdout: undefined
ffmpeg stderr: undefined

an error happened: ffmpeg exited with code 1: Error opening filters!

ffmpeg stdout: 
ffmpeg stderr: ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.2.4 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libavresample   3.  1.  0 /  3.  1.  0
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fbdcf002600] stream 0, offset 0x4f: partial file
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fbdcf002600] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1920x1080, 6539 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'pipe:0':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp41isom
    creation_time   : 2017-03-23T04:41:39.000000Z
    date            : 2017
  Duration: 00:03:19.34, bitrate: N/A
    Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 1920x1080, 6539 kb/s, 60 fps, 60 tbr, 60k tbn, 120k tbc (default)
    Metadata:
      creation_time   : 2017-03-23T04:41:39.000000Z
      handler_name    : VideoHandler
      encoder         : AVC Coding
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 116 kb/s (default)
    Metadata:
      creation_time   : 2017-03-23T04:41:39.000000Z
      handler_name    : SoundHandler
[buffer @ 0x7fbdcee00400] Unable to parse option value "-1" as pixel format
    Last message repeated 1 times
[buffer @ 0x7fbdcee00400] Error setting option pix_fmt to value -1.
[graph 0 input from stream 0:0 @ 0x7fbdcee00280] Error applying options to the filter.
Error opening filters!