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• Libav linking error : undefined references

  22 février 2017, par Fedech

  Here’s my problem :

  • I built ffmpeg from source (version 1.2), the libav* libraries are in /usr/local/lib and they’re static
  • I’m compiling a ns3 (www.nsnam.org) module, so my only control over the linker is through the env variable LINKFLAGS
  • In the source the headers are in a "extern C" block, so it’s not the usual g++ name mangling
  • I set LINKFLAGS="-I/usr/local/include/libavformat -I/usr/local/include/libavcodec -I/usr/local/include/libavutil -L/usr/local/lib -lavformat -lavcodec -lavutil", and the linker can’t seem to find any of the libav* functions I call (I get a lot of "undefined reference" and then "collect2 : error : ld returned status 1"

  Can anyone help me ? Thanks...

  edit : here are a few of the undefined reference messages :

      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_guess_format'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_read_frame'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avformat_write_header'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_interleaved_write_frame'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_find_stream_info'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_register_all'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_init_packet'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avformat_alloc_context'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_dump_format'
  
      ./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avio_close'

  edit2 : here is the message I get after "build failed" :

  -> task in 'scratch-simulator' failed (exit status 1): 
  
  {task 53952272: cxxprogram scratch-simulator.cc.1.o -> scratch-simulator}
  
  ['/usr/bin/g++', '-I/usr/local/include/libavcodec', '-I/usr/local/include/libavformat/',
  
   '-I/usr/local/include/libavutil/', '-L/usr/local/lib', '-I/usr/local
  
  /include/libavcodec', '-I/usr/local/include/libavformat/', '-I/usr/local/include
  
  /libavutil/', '-L/usr/local/lib', '-pthread', '-pthread', '-Wl,-z,relro', 
  
  'scratch/scratch-simulator.cc.1.o', '-o', '/home/fede/Thesis/ns-allinone-3.14.1
  
  /ns-3.14.1/build/scratch/scratch-simulator', '-Wl,-Bstatic', '-Wl,-Bdynamic', 
  
  '-Wl,--no-as-needed', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.',
  
   '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.',
  
   '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', 
  
  '-L.', '-L.', '-L.', '-L.', '-L.', '-L/usr/lib', '-lns3.14.1-test-debug', '-lns3.14.1-
  
  csma-layout-debug', '-lns3.14.1-point-to-point-layout-debug', '-lns3.14.1-netanim-
  
  debug', '-lns3.14.1-lte-debug', '-lns3.14.1-spectrum-debug', '-lns3.14.1-antenna-
  
  debug', '-lns3.14.1-aodv-debug', '-lns3.14.1-dsdv-debug', '-lns3.14.1-dsr-debug', 
  
  '-lns3.14.1-mesh-debug', '-lns3.14.1-olsr-debug', '-lns3.14.1-csma-debug', '-lns3.14.1-
  
  wimax-debug', '-lns3.14.1-applications-debug', '-lns3.14.1-virtual-net-device-debug', 
  
  '-lns3.14.1-uan-debug', '-lns3.14.1-energy-debug', '-lns3.14.1-flow-monitor-debug', 
  
  '-lns3.14.1-nix-vector-routing-debug', '-lns3.14.1-tap-bridge-debug', '-lns3.14.1-
  
  visualizer-debug', '-lns3.14.1-internet-debug', '-lns3.14.1-bridge-debug', '-lns3.14.1-
  
  point-to-point-debug', '-lns3.14.1-mpi-debug', '-lns3.14.1-wifi-debug', '-lns3.14.1-
  
  buildings-debug', '-lns3.14.1-propagation-debug', '-lns3.14.1-mobility-debug', 
  
  '-lns3.14.1-config-store-debug', '-lns3.14.1-tools-debug', '-lns3.14.1-stats-debug',
  
   '-lns3.14.1-emu-debug', '-lns3.14.1-topology-read-debug', '-lns3.14.1-network-debug', 
  
  '-lns3.14.1-qoe-monitor-debug', '-lns3.14.1-core-debug', '-lrt', '-lgsl', 
  
  '-lgslcblas', '-lm', '-ldl', '-lgtk-x11-2.0', '-lgdk-x11-2.0', '-latk-1.0', 
  
  '-lgio-2.0', '-lpangoft2-1.0', '-lpangocairo-1.0', '-lgdk_pixbuf-2.0', '-lcairo', 
  
  '-lpango-1.0', '-lfreetype', '-lfontconfig', '-lgobject-2.0', '-lglib-2.0', '-lxml2', 
  
  '-lpython2.7']

• how to save h264 stream into .264 file

  6 mars 2015, par user3547405

  I’m using nginx-rtmp-module build hls server, when I play it on safari, it does not shows image,then i use this command ffmpeg -i rtmp://192.168.4.213/hls/testH264 -c copy -map 0 -f segment -segment_list playlist.m3u8 -segment_time 5 output%03d.ts, it shows missing picture in access unit with size 28184,so i think maybe the raw h264 stream has some problem,then i directly save the h264 stream into .264 file,but when i play the .264 file with vlc,the screen is fuzzy,help

• command line closes too fast inside python using ffmpeg

  18 février 2014, par user3012914

  I am using python to create a Macro Module inside MevisLab environment. I wanted to use ffmpeg in command prompt inside Python. The Problem is the command prompt closes too fast that i couldnt read while executing ffmpeg.

  My code

    t = 'ffmpeg -r'+str(ctx.field("FrameRate").value)+'-f image2 -pix_fmt yuv44p -s 1920x1080 -i'+path+'%0d.png -vodec libx264 -crf 15'+path+'.mp4'
  
  
  
  os.system(t)