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• undefined reference in ffmpeg (use code blocks)

  6 février 2015, par Yonghao Zhao

  I am currently testing a video encoding program using ffmepg codeblocks.I encountered several undefined reference warning. I have checked on internet and add extern "c" to the headers but it still doesnt work. Please help me check.

  Here is part of the code :

  extern "C" {
  
  
  
  #include "libavcodec/avcodec.h"
  
  #include "libavutil/channel_layout.h"
  
  #include "libavutil/common.h"
  
  #include "libavutil/imgutils.h"
  
  #include "libavutil/mathematics.h"
  
  #include "libavutil/samplefmt.h"
  
  
  
  
  
  }
  
  
  
  #include 
  
  #include "libavutil/opt.h"
  
  
  
  static void video_encode_example(const char *filename, int codec_id)
  
  {
  
  
  
  AVCodec *codec;
  
  AVCodecContext *c= NULL;
  
  int i, ret, x, y, got_output;
  
  FILE *f;
  
  AVFrame *frame;
  
  AVPacket pkt;
  
  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  printf("Encode video file %s\n", filename);
  
  /* find the mpeg1 video encoder */
  
  codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  if (!codec) {
  
  fprintf(stderr, "Codec not found\n");
  
  exit(1);
  
  }
  
  c = avcodec_alloc_context3(codec);
  
  if (!c) {
  
  fprintf(stderr, "Could not allocate video codec context\n");
  
  exit(1);
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
  avcodec_register_all();
  
  video_encode_example("test.mpg", AV_CODEC_ID_MPEG1VIDEO);
  
  
  
  return 0;
  
  }

  The error given :

  ||=== Build : Debug in ffmepg_video_en (compiler : GNU GCC Compiler) ===|
  obj/Debug/main.o||In function

  video_encode_example':|
codeblocksfile/ffmepg_video_en/main.cpp|36|undefined reference to

  avcodec_find_encoder’|
  codeblocksfile/ffmepg_video_en/main.cpp|41|undefined reference to

  avcodec_alloc_context3'|
codeblocksfile/ffmepg_video_en/main.cpp|63|undefined reference to

  av_opt_set(void*, char const*, char const*, int)’|
  codeblocksfile/ffmepg_video_en/main.cpp|65|undefined reference to

  avcodec_open2'|
codeblocksfile/ffmepg_video_en/main.cpp|74|undefined reference to

  av_frame_alloc’|
  codeblocksfile/ffmepg_video_en/main.cpp|85|undefined reference to

  av_image_alloc(unsigned char**, int*, int, int, AVPixelFormat, int)'|
codeblocksfile/ffmepg_video_en/main.cpp|92|undefined reference to

  av_init_packet’|
  codeblocksfile/ffmepg_video_en/main.cpp|112|undefined reference to

  avcodec_encode_video2'|
codeblocksfile/ffmepg_video_en/main.cpp|120|undefined reference to

  av_free_packet’|
  codeblocksfile/ffmepg_video_en/main.cpp|126|undefined reference to

  avcodec_encode_video2'|
/home/yonghao/codeblocksfile/ffmepg_video_en/main.cpp|134|undefined reference to

  av_free_packet’|
  codeblocksfile/ffmepg_video_en/main.cpp|140|undefined reference to

  avcodec_close'|
codeblocksfile/ffmepg_video_en/main.cpp|141|undefined reference to

  av_free’|
  codeblocksfile/ffmepg_video_en/main.cpp|142|undefined reference to

  av_freep'|
codeblocksfile/ffmepg_video_en/main.cpp|143|undefined reference to

  av_frame_free’|
  obj/Debug/main.o||In function

  main':|
codeblocksfile/ffmepg_video_en/main.cpp|151|undefined reference to

  avcodec_register_all’|
  ||=== Build failed : 16 error(s), 0 warning(s) (0 minute(s), 1 second(s)) ===|

• Porting code from Windows 7 to Linux using using NReco.VideoConverter

  2 février 2017, par Omar Salem

  I trying to port code from Windows 7 to Linux (RHEL 7). I am using the component to connect to a webcam and capture audio and video to a file and also capture frames as images to files. On Windows 7 I used the following code which works :

  var ffMpegTask = videoConv.ConvertLiveMedia(
  
      @"/dev/video0", // @"video=Logitech ... :audio=Microphone ..." on Windows
  
      "v4l2",                       // "dshow"  on Windows
  
      rawBmpOutputStream,
  
      null,               
  
      new ConvertSettings() {
  
              CustomOutputArgs = String.Format(" -r 5 -t 10 output.wmv -r 5 -t 10 output.mp3 -r 5 -t 10 -f rawvideo -s {0}x{1} -pix_fmt bgr24 ",
  
                      outputWidth, outputHeight)  });    

  This code compiles and executes on RHEL and MonoDevelop but does not generate the audio, video or image files. The webcam blinks for a second and goes away.

• Révision 22423 : Documentation du code :

  25 septembre 2015, par amemo@rezo.net

  - objet_associer (par pierretux) : Rajout d’accent
  - translitteration_complexe (par Ybbet) : Correction de l’accent du a` confondu avec un code markdown
  - ecrire_meta (par Ybbet) : Faute de frappe
  - verifier_session (par pierretux) : Lien vers la doc inutile
  - nettoyer_uri (par Ybbet) : L’url vers code.spip.net cassait la mise en page sur le site.

  Relecteur : Matthieu Marcillaud