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• FFMPEG : undefined reference to `avcodec_register_all' does not link

  18 février 2024, par Alex Botev

  So I have a very sample code for trying to decode a FFMPEG video stream.
My problem is avcodec does not want to link, to do so I made a clean installation of Ubuntu 13.04. I have build ffmpeg from source following the guide here : https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

  


  I just want to compile my file. Note that my ubuntu does not have any implementations or header files for avcodec. The command line I use is :

  


  


  gcc -I/home/USER/ffmpeg_build/include -L/home/USER/ffmpeg_build/lib -lavcodec -o test.exe Downloads/auv/src/dronerosvideo/src/ar2.cpp

  


  /tmp/ccKTprFq.o : In function `fetch_and_decode(int, int, bool)' :

  


  ar2.cpp :(.text+0x36e) :
undefined reference to `avcodec_register_all'

  


  ar2.cpp :(.text+0x378) :
undefined reference to `av_log_set_level'

  


  ar2.cpp :(.text+0x382) :
undefined reference to `avcodec_find_decoder'

  


  ar2.cpp :(.text+0x3b1) :
undefined reference to `avcodec_alloc_context3'

  


  ar2.cpp :(.text+0x3d6) :
undefined reference to `avcodec_open2'

  


  ar2.cpp :(.text+0x46d) :
undefined reference to `av_init_packet'

  


  ar2.cpp :(.text+0x50a) :
undefined reference to `avcodec_decode_video2'

  


  ar2.cpp :(.text+0x534) :
undefined reference to `av_free_packet'

  


  /tmp/ccKTprFq.o :(.eh_frame+0x13) : undefined reference to
`__gxx_personality_v0'

  


  collect2 : error : ld returned 1 exit status

  


  


  Just for a sane test if I remove the -L argument compiler says :

  


  /usr/bin/ld: cannot find -lavcodec


  


  Which means that the linker finds the library in /home/USER/ffmpeg_build/lib. Also if we check the library for implementation it exists :

  


  nm ffmpeg_build/lib/libavcodec.a | grep "register_all"
0000000000000000 T avcodec_register_all


  


  Also as advised since it is C++ I have exten "C" around the include of the library.

  


  At this point I'm falling out of any ideas at all, why exactly compilation fails ?

  


• h264 : improve behaviour with invalid reference lists

  17 décembre 2015, par Anton Khirnov

  h264 : improve behaviour with invalid reference lists
  Before 741b494fa8cd28a7d096349bac183893c236e3f9, when the reference list
  
  modification description was invalid, the code would substitute the
  
  corresponding reference from the initial ("default") reference list.
  
  After that commit, it will just return an error.
  Since there are apparently invalid samples in the wild that used to play
  
  fine with the old code, it is a good idea to re-add some sort of error
  
  resilience here. So, when the reference list modification results in a
  
  missing frame, substitute a previous reference frame for it. The
  
  relevant sample again decodes fine with the same output as previously.
  

  • [DBH] libavcodec/h264_refs.c

• Revision 51875 : Slogan, mise à jour de la description et des auteurs, (google translate ...

  26 septembre 2011, par yffic@… — Log

  Slogan, mise à jour de la description et des auteurs, (google translate pour l’Italien). Kent1, je ne sais pas pour la borne sup si tu as testé sous spip3 ? Moi, pas.