hopper@hopper-xubuntu:~$ ffmpeg -f v4l2 -i /dev/video0 -video_size 1280x720 -framerate 30 -vcodec mjpeg -i /dev/video1 -video_size 1280x720 -framerate 30 -vcodec mjpeg  -filter_complex hstack -threads 0 outputsplit.ts^C
hopper@hopper-xubuntu:~$ ^C
hopper@hopper-xubuntu:~$ ffmpeg -f v4l2 -video_size 1280x720 -framerate 30 -vcodec mjpeg  -threads 1 -i /dev/video0 outputgeneric.tsffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  libavutil      54. 31.100 / 54. 31.100
  libavcodec     56. 60.100 / 56. 60.100
  libavformat    56. 40.101 / 56. 40.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 40.101 /  5. 40.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.101 /  1.  2.101
  libpostproc    53.  3.100 / 53.  3.100
[video4linux2,v4l2 @ 0x1be9420] The driver changed the time per frame from 1/30 to 1/60
[mjpeg @ 0x1bea200] Changeing bps to 8
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 413197.881435, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, -10 kb/s, 60 fps, 60 tbr, 1000k tbn, 1000k tbc
File 'outputgeneric.ts' already exists. Overwrite ? [y/N] y
[swscaler @ 0x1bfaca0] deprecated pixel format used, make sure you did set range correctly
No pixel format specified, yuv422p for MPEG-2 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
Output #0, mpegts, to 'outputgeneric.ts':
  Metadata:
    encoder         : Lavf56.40.101
    Stream #0:0: Video: mpeg2video, yuv422p, 1280x720, q=2-31, 200 kb/s, 60 fps, 90k tbn, 60 tbc
    Metadata:
      encoder         : Lavc56.60.100 mpeg2video
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> mpeg2video (native))
Press [q] to stop, [?] for help
Past duration 0.639153 too large     536kB time=00:00:00.41 bitrate=10543.6kbits/s
frame=  400 fps= 29 q=31.0 Lsize=    2543kB time=00:00:14.38 bitrate=1448.3kbits/s
video:2309kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 10.147630%
Exiting normally, received signal 2.