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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)) ===|

• ModuleNotFoundError : No module named 'ffmpeg' on Spyder although ffmpeg is installed on Anaconda navigator

  1er septembre 2021, par alpha

  ffmpeg is installed on Anaconda Navigator (in base(root) environment), but when I run import ffmpeg, I got this error message :

  


  ModuleNotFoundError: No module named 'ffmpeg'


  


  Why is this module not found and how can I fix this ?

  


  

  


• configure : allow mixed declarations and code for Objective-C

  25 septembre 2024, par Marvin Scholz

  configure : allow mixed declarations and code for Objective-C
  Mixing declarations and code is quite common in Objective-C (as can be
  
  seen by the number of warnings we have for this in Objective-C files)
  
  and forcing to not do it usually results in worse code, with unnecessary
  
  widely scoped variables, which in turn makes variable shadowing and
  
  accidentally using the wrong variable more common and harder to notice.
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  

  • [DH] configure