ffmpeg version N-82579-g28d8789 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.2) 20160609
  configuration: --prefix=/home/vagrant/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/vagrant/ffmpeg_build/include --extra-ldflags=-L/home/vagrant/ffmpeg_build/lib --bindir=/home/vagrant/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libspeex --enable-nonfree
  libavutil      55. 40.100 / 55. 40.100
  libavcodec     57. 66.106 / 57. 66.106
  libavformat    57. 58.100 / 57. 58.100
  libavdevice    57.  2.100 / 57.  2.100
  libavfilter     6. 67.100 /  6. 67.100
  libswscale      4.  3.101 /  4.  3.101
  libswresample   2.  4.100 /  2.  4.100
  libpostproc    54.  2.100 / 54.  2.100
Input #0, matroska,webm, from '/vagrant/tmp/records/nego73-37-1493038810646-y6cZuG-stream-f1982650-28ed-11e7-9051-c9985ca3b5af-4ji62qbnkoivr1as22reeotedk.webm':
  Metadata:
    encoder         : Lavf54.59.106
  Duration: 00:00:30.35, start: 0.066000, bitrate: 384 kb/s
    Stream #0:0: Audio: vorbis, 48000 Hz, stereo, fltp (default)
    Stream #0:1: Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30k fps, 29.97 tbr, 1k tbn, 1k tbc (default)
Input #1, matroska,webm, from '/vagrant/tmp/records/nego73-16-1493038801849-uDD8b0-stream-ece8a800-28ed-11e7-8194-edbb17e1c61b-kqgg7g5hqeup6fp634sgm86s36.webm':
  Metadata:
    encoder         : Lavf54.59.106
  Duration: 00:00:39.15, start: 0.010000, bitrate: 565 kb/s
    Stream #1:0: Audio: vorbis, 48000 Hz, stereo, fltp (default)
    Stream #1:1: Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30k fps, 30 tbr, 1k tbn, 1k tbc (default)
[Parsed_amerge_0 @ 0x42ec380] No channel layout for input 1
[Parsed_amerge_0 @ 0x42ec380] Input channel layouts overlap: output layout will be determined by the number of distinct input channels
[libopus @ 0x42ebd80] No bit rate set. Defaulting to 96000 bps.
Output #0, opus, to '/vagrant/tmp/records/players/nego73-merge-1493038816000.opus':
  Metadata:
    encoder         : Lavf57.58.100
    Stream #0:0: Audio: opus (libopus), 48000 Hz, stereo, flt, 96 kb/s (default)
    Metadata:
      encoder         : Lavc57.66.106 libopus
Stream mapping:
  Stream #0:0 (vorbis) -> amerge:in0
  Stream #1:0 (vorbis) -> amerge:in1
  amerge -> Stream #0:0 (libopus)
Press [q] to stop, [?] for help
size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown