[root@jeff:/tmp] 1 # ffmpeg -i "concat:input1.mkv|input2.mkv" -c copy output.mkv
ffmpeg version 0.10.16 Copyright (c) 2000-2015 the FFmpeg developers
  built on Aug 26 2016 13:01:36 with gcc 4.4.7 20120313 (Red Hat 4.4.7-17)
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  libavutil      51. 35.100 / 51. 35.100
  libavcodec     53. 61.100 / 53. 61.100
  libavformat    53. 32.100 / 53. 32.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 61.100 /  2. 61.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  6.100 /  0.  6.100
  libpostproc    52.  0.100 / 52.  0.100
Input #0, matroska,webm, from 'concat:input1.mkv|input2.mkv':
  Metadata:
    ENCODER         : Lavf57.84.100
  Duration: 00:02:13.20, start: 0.000000, bitrate: 2893 kb/s
    Stream #0:0: Video: h264 (High), yuvj420p, 1280x720, SAR 1:1 DAR 16:9, 60 fps, 59.94 tbr, 1k tbn, 120 tbc (default)
    Metadata:
      DURATION        : 00:02:13.200000000
    Stream #0:1: Audio: aac, 48000 Hz, stereo, s16 (default)
    Metadata:
      title           : Track1
      DURATION        : 00:02:13.141000000
Output #0, matroska, to 'output.mkv':
  Metadata:
    encoder         : Lavf53.32.100
    Stream #0:0: Video: h264 (H264 / 0x34363248), yuvj420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 1k tbn, 1k tbc (default)
    Metadata:
      DURATION        : 00:02:13.200000000
    Stream #0:1: Audio: aac ([255][0][0][0] / 0x00FF), 48000 Hz, stereo (default)
    Metadata:
      title           : Track1
      DURATION        : 00:02:13.141000000
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[matroska,webm @ 0x22d5bc0] Unknown entry 0x1A45DFA3
[matroska,webm @ 0x22d5bc0] Unknown entry 0x18538067
frame= 7991 fps=  0 q=-1.0 Lsize=   18631kB time=00:02:13.13 bitrate=1146.4kbits/s
video:15394kB audio:3139kB global headers:0kB muxing overhead 0.529243%