# server 
seece@vbox:~/temp$ ffmpeg -video_size 640x480 -framerate 30 -f x11grab -i :0.0+100,200 -r 30 -c:v libx264 -preset fast -f mpegts udp://localhost:6666?pkt_size=188?buffer_size=65535
ffmpeg version N-57102-gfa7e9f9 Copyright (c) 2000-2013 the FFmpeg developers
  built on Oct 13 2013 16:30:34 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --enable-gpl --enable-x11grab --enable-libx264 --enable-libvorbis --disable-debug --enable-libmp3lame
  libavutil      52. 46.101 / 52. 46.101
  libavcodec     55. 35.100 / 55. 35.100
  libavformat    55. 19.100 / 55. 19.100
  libavdevice    55.  4.100 / 55.  4.100
  libavfilter     3. 88.101 /  3. 88.101
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
[x11grab @ 0xaa45f20] device: :0.0+100,200 -> display: :0.0 x: 100 y: 200 width: 640 height: 480
[x11grab @ 0xaa45f20] shared memory extension found
Input #0, x11grab, from ':0.0+100,200':
  Duration: N/A, start: 1382863559.950501, bitrate: 294912 kb/s
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 640x480, 294912 kb/s, 30 tbr, 1000k tbn, 30 tbc
[swscaler @ 0xaa3ff80] deprecated pixel format used, make sure you did set range correctly
No pixel format specified, yuv444p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[libx264 @ 0xaa59e40] using cpu capabilities: MMX2 SSE2Slow SlowCTZ
[libx264 @ 0xaa59e40] profile High 4:4:4 Predictive, level 3.0, 4:4:4 8-bit
Output #0, mpegts, to 'udp://localhost:6666?pkt_size=188?buffer_size=65535':
  Metadata:
    encoder         : Lavf55.19.100
    Stream #0:0: Video: h264 (libx264), yuv444p, 640x480, q=-1--1, 90k tbn, 30 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> libx264)
Press [q] to stop, [?] for help
[swscaler @ 0xaa3ff80] Warning: data is not aligned! This can lead to a speedloss
frame=  317 fps= 30 q=29.0 size=     327kB time=00:00:09.46 bitrate= 283.1kbits/s dup=22 drop=0ýýýwCýýýýýý;Bý3ýý,ýýý  X–ý,ýýH^b
frame= 5175 fps= 30 q=29.0 size=    2356kB time=00:02:51.40 bitrate= 112.6kbits/s dup=90 drop=17    



# client
seece@vbox:~$ ffplay -vcodec h264 -f mpegts -i udp://localhost:6666
ffplay version N-57102-gfa7e9f9 Copyright (c) 2003-2013 the FFmpeg developers
  built on Oct 13 2013 16:30:34 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --enable-gpl --enable-x11grab --enable-libx264 --enable-libvorbis --disable-debug --enable-libmp3lame
  libavutil      52. 46.101 / 52. 46.101
  libavcodec     55. 35.100 / 55. 35.100
  libavformat    55. 19.100 / 55. 19.100
  libavdevice    55.  4.100 / 55.  4.100
  libavfilter     3. 88.101 /  3. 88.101
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mpegts, from 'udp://localhost:6666':0KB sq=    0B f=0/0   
  Duration: N/A, start: 1.466667, bitrate: N/A
  Program 1 
    Metadata:
      service_name    : Service01
      service_provider: FFmpeg
    Stream #0:0[0x100]: Video: h264 (High 4:4:4 Predictive) ([27][0][0][0] / 0x001B), yuv444p, 640x480, 30 fps, 30 tbr, 90k tbn, 60 tbc
Segmentation fault (core dumped)   0KB vq=   46KB sq=    0B f=0/0