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• ffmpeg code does not link (undefined reference to avcodec_register_all

  28 janvier 2013, par Sriram

  I am trying to compile a simple introductory program using ffmpeg that tries to check if the mp3 codec is available. While the code compiles OK, I am facing difficulty in solving linker errors. Here is the code :

  #include 
  
  #include 
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  
  
  float *generateSinusoid(unsigned int sampleRate, unsigned int nSecondsAudio) {
  
  
  
    unsigned int nsamples = (nSecondsAudio * sampleRate);
  
    float *arr;
  
    arr = (float*) malloc(sizeof(float) * nsamples);
  
    int i = 0;
  
  
  
    for(i = 0; i &lt; nsamples; i++) {
  
      arr[i] = 20 * sin(2.f * (M_PI) * (330/sampleRate) * i);  /*frequency of 330H
  
  z*/
  
    }
  
  
  
    return arr;
  
  
  
  }
  
  
  
  int main(int argc, char *argv[]) {
  
  
  
    avcodec_register_all();
  
  
  
    AVCodec *codec;
  
  
  
    unsigned int sampleRate = 22050;  /*assumed.*/
  
    unsigned int nSecondsAudio = 4;
  
    float *arr;
  
    arr = (float *) malloc(sizeof(float) * nSecondsAudio * sampleRate);
  
  
  
    /*Step 1. Generate sinusoid.*/
  
    arr = generateSinusoid(sampleRate, nSecondsAudio);
  
  
  
    /* Step 2. See if encoder exists.*/
  
    /*codec = avcodec_find_encoder(AV_CODEC_ID_MP3);*/
  
  
  
    if(!codec) {  /*codec = NULL.*/
  
      printf("MP3 codec not found!!!!");
  
    } else {
  
      printf("MP3 codec found!!!");
  
    }
  
  
  
     return 0;
  
  }  

  The code is compiled and linked like so :

  encoding_mp3: encoding_mp3.o
  
          gcc encoding_mp3.o -o encoding_mp3 -L/cygdrive/c/Users/Desktop/webserver/cygnus/lib/w32api -L/cygdrive/c/Users/Desktop/webserver/cygnus/ffmpeg/ffmpeg_dev/lib -lm -luser32 -lpthread -lavcodec
  
  
  
  encoding_mp3.o: encoding_mp3.c
  
          gcc -I/cygdrive/c/Users/Desktop/webserver/cygnus/ffmpeg/ffmpeg_dev/include -I/cygdrive/c/Users/Desktop/webserver/cygnus/usr/include -g -c encoding_mp3.c -o encoding_mp3.o
  
  
  
  clean:
  
          rm encoding_mp3.o encoding_mp3  

  Linking gives the following error :

  gcc -I/cygdrive/c/Users/Desktop/webserver/cygnus/ffmpeg/ffmpeg_dev/include -I/cygdrive/c/Users/Desktop/webserver/cygnus/usr/include -g -c encoding_mp3.c -o encoding_mp3.o
  
  gcc encoding_mp3.o -o encoding_mp3 -L/cygdrive/c/Users/Desktop/webserver/cygnus/lib/w32api -L/cygdrive/c/Users/Desktop/webserver/cygnus/ffmpeg/ffmpeg_dev/lib -lm -luser32 -lpthread -lavcodec
  
  encoding_mp3.o: In function `main':
  
  /cygdrive/c/Users/Desktop/webserver/cygnus/ffmpeg/work/encoding_mp3.c:31: undefined reference to `_avcodec_register_all'
  
  collect2: ld returned 1 exit status
  
  make: *** [encoding_mp3] Error 1  

  I have gone through most of the threads on SO regarding this problem and here is what I have tried so far :
  
   Put libraries at the end of all non-option arguments
  
   Commented out code that references functions. This seems to work. The undefined reference errors go away after all function calls are removed, though the presence of a struct AVCodec does not cause any problems.

  Any help on this is most welcome.

• ffmpeg_sched : return better error code

  21 décembre 2024, par Gyan Doshi

  ffmpeg_sched : return better error code
  The existing code of 'No space left on device' leaves end users confused
  
  since the issue isn't of disk space.
  

  • [DH] fftools/ffmpeg_sched.c

• Anomalie #2524 (Nouveau) : vieux code dans genie/optimiser ??

  9 février 2012, par Julien -

  Dans .../genie/optimiser.php : optimiser_base_disparus la section # les liens d’auteurs d’articles effaces est t-elle nécessaire ? (vieux code ?) Le code qui suit : $n+= objet_optimiser_liens(array(’auteur’=>’*’),’*’) ; N’effectue t-il pas déjà le boulot (...)