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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)) ===|

• How to install package ffmpeg in google colab

  15 novembre 2022, par Nikhil Wagh

  I'm trying to use Google Colab to do something. Particularly I want to use ffmpeg package to create a video from a image.

  



  But ffmpeg doesn't seems to be working fine.

  



  The output of this (in the last block) was supposed to be 400 400 instead of 0 0

  



  frame_width = int(cap.get(3))
frame_height = int(cap.get(4))
print frame_width, frame_height


  



  The same code is working fine with Azure notebooks and also on my local machine.

  



  What can be the reason for it ? And how to rectify that ?

  


• avcodec/h264_refs : Also check reference in ff_h264_build_ref_list()

  30 juin 2019, par Michael Niedermayer

  avcodec/h264_refs : Also check reference in ff_h264_build_ref_list()
  Fixes : out of array read
  
  Fixes : 15409/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_H264_fuzzer-5758846959616000
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/h264_refs.c