loki@loki:~$ ./ffmpeg_bin_main/ffmpeg -f x11grab -r 200 -s 1920x1080 -i :0.0 -c copy -f rawvideo - | ./ffmpeg_bin_main/ffmpeg -pix_fmt bgr0 -f rawvideo -i - -r 60 -s 1920x1080 -vcodec nvenc -f matroska -y /dev/null
./ffmpeg_bin_main/ffmpeg: /usr/lib/x86_64-linux-gnu/libOpenCL.so.1: no version information available (required by ./ffmpeg_bin_main/ffmpeg)
./ffmpeg_bin_main/ffmpeg: /usr/lib/x86_64-linux-gnu/libOpenCL.so.1: no version information available (required by ./ffmpeg_bin_main/ffmpeg)
ffmpeg version N-71095-gdf43d03 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --prefix=/home/loki/ffmpeg_build --bindir=/home/loki/ffmpeg_bin_main --enable-nonfree --enable-gpl --enable-version3 --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libopencv --enable-opencl --enable-x11grab --enable-opengl --enable-openssl --enable-nvenc
  libavutil      54. 20.101 / 54. 20.101
  libavcodec     56. 30.100 / 56. 30.100
  libavformat    56. 26.101 / 56. 26.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 13.101 /  5. 13.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
ffmpeg version N-71095-gdf43d03 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --prefix=/home/loki/ffmpeg_build --bindir=/home/loki/ffmpeg_bin_main --enable-nonfree --enable-gpl --enable-version3 --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libopencv --enable-opencl --enable-x11grab --enable-opengl --enable-openssl --enable-nvenc
  libavutil      54. 20.101 / 54. 20.101
  libavcodec     56. 30.100 / 56. 30.100
  libavformat    56. 26.101 / 56. 26.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 13.101 /  5. 13.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
[x11grab @ 0x2236480] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, x11grab, from ':0.0':
  Duration: N/A, start: 1427395037.943324, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1920x1080, 200 fps, 200 tbr, 1000k tbn, 200 tbc
Output #0, rawvideo, to 'pipe:':
  Metadata:
    encoder         : Lavf56.26.101
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1920x1080, q=2-31, 200 fps, 200 tbr, 200 tbn, 200 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[IMGUTILS @ 0x7ffc76b87e60] Picture size 0x0 is invalid
[IMGUTILS @ 0x7ffc76b879b0] Picture size 0x0 is invalid
[rawvideo @ 0x1bf0320] Could not find codec parameters for stream 0 (Video: rawvideo (BGR[0] / 0x524742), bgr0, -4 kb/s): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
pipe:: could not find codec parameters
Input #0, rawvideo, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, -4 kb/s, 25 tbr, 25 tbn, 25 tbc
Output #0, matroska, to '/dev/null':
Output file #0 does not contain any stream
loki@loki:~$