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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.

• CANNOT LINK EXECUTABLE error with required libs loaded. How to link them properly ? [duplicate]

  4 avril 2013, par dentex

  This question already has an answer here :

  • Android NDK - Library not found CANNOT LINK EXECUTABLE - how to set LD_LIBRARY_PATH ?
    

    1 answer

  edit : I'm aware of the possible duplicate, but the answer it's not directly applicable. I'm using ProcessBuilder and not Runtime.getRuntime().exec :

  public int execProcess(List<string> cmds, ShellUtils.ShellCallback sc) {    
  
      StringBuilder cmdlog = new StringBuilder();
  
      for (String cmd : cmds) {
  
           cmdlog.append(&#39; &#39;);
  
      }
  
      Utils.logger("v", cmdlog.toString(), DEBUG_TAG);
  
  
  
      ProcessBuilder pb = new ProcessBuilder();
  
      pb.directory(mBinFileDir);
  
      pb.command(cmds);
  
  
  
      Process process = null;
  
      int exitVal = 1; // Default error
  
      try {
  
          process = pb.start();
  
  
  
          StreamGobbler errorGobbler = new
  
          StreamGobbler(process.getErrorStream(), "ERROR", sc);
  
  
  
          StreamGobbler outputGobbler = new
  
          StreamGobbler(process.getInputStream(), "OUTPUT", sc);
  
  
  
          errorGobbler.start();
  
          outputGobbler.start();
  
  
  
          exitVal = process.waitFor();
  
  
  
          sc.processComplete(exitVal);
  
  
  
       } catch (Exception e) {
  
           Log.e(DEBUG_TAG, "Error executing ffmpeg command!", e);
  
       } finally {
  
           if (process != null) {
  
               Utils.logger("w", "destroyng process", DEBUG_TAG);
  
               process.destroy();
  
           }
  
      }
  
      return exitVal;
  
  }
  
  </string>

  ---

  I have two versions on FFmpeg compiled for android : with and without liblame enabled.

  When I load in /data/data/<>/app_bin/ the FFmpeg binary compiled with NO lame support, it extracts audio from video without an issue. But when I use the one with lame support enabled, I get the error below into the log.

  Required libs, also compiled for android, are correctly loaded when shipped into the libs project folder with System.loadLibrary("lame").

  I was wondering if there is something else to do in order to properly make the FFmpeg binary find the libs.
  Those are the same libs given to the NDK to build the FFmpeg binary.

  D/dalvikvm(13741): Trying to load lib /data/app-lib/<>/liblame.so 0x40ffed08
  
  D/dalvikvm(13741): Added shared lib /data/app-lib/<>/liblame.so 0x40ffed08
  
  D/dalvikvm(13741): No JNI_OnLoad found in /data/app-lib/<>/liblame.so 0x40ffed08, skipping init
  
  D/FfmpegController(13741): Trying to chmod '/data/data/<>/app_bin/ffmpeg' to: 755
  
  V/FfmpegController(13741): /data/data/<>/app_bin/ffmpeg -y -i /storage/sdcard0/Download/video.webm -vn -acodec copy /storage/sdcard0/Download/audio.ogg 
  
  >>>>>> ---------- <<<<<<
  
  D/DownloadsService(13741): soinfo_link_image(linker.cpp:1673): could not load library "liblame.so" needed by "/data/data/<>/app_bin/ffmpeg"; caused by load_library(linker.cpp:771): library "liblame.so" not foundCANNOT LINK EXECUTABLE
  
  >>>>>> ---------- <<<<<<
  
  I/DownloadsService(13741): FFmpeg process exit value: 255

  I'm not attaching code because it's fairly straightforward :

  • download the FFmpeg binary (it's not shipped with the app) ;
  • copy the binary from the download folder to /data/data/<>/app_bin/ ;
  • chmod 755 ;
  • execute from there and read the output.

  Please comment if something else is required.

• configure : link with built libs when pc-uninstalled is used

  6 octobre 2013, par Lukasz Marek

  configure : link with built libs when pc-uninstalled is used
  Signed-off-by : Lukasz Marek <lukasz.m.luki@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] configure