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• c++ avformat_open_input returns empty codec, width and height

  27 février 2019, par Victor Akhlynin

  I haven’t ever used ffmpeg on my own laptop. All’s ok at work, but here I met an ugly problem : library works but helpless :)
  Ubuntu 18.04, ffmpeg 4.1 (downloaded sources, ./configure, make, sudo make install), it seems to be ok.

  Application returns :
  File /home/ahlininv/Desktop/video_example.mp4 is encodec with ’’ codec, w = 0, h = 0

  I ran it under debugger. If I set format to zero, pointer changes after calling avformat_open_input(&format, file, 0, &dict), so it works and maybe works correct.

  Maybe it plays any role that compiler says that av_register_all, avcodec_register_all are deprecated, but I thought it’s not significant problem.

  I tried to change version of ffmpeg (tried to install it with apt-get, version 3.somenumber is available), nothing changed.

  I tried to run another video file (.avi), nothing changed, too.

  Guys, help=) How to this file’s info correctly ?

  main.cpp :

  #include "filereader.h"
  
  
  
  int main(int argc, char** argv) {
  
  
  
      std::string filename = "/home/ahlininv/Desktop/video_example.mp4";
  
  
  
      std::string codec;
  
      int w, h;
  
      bool open_ok = get_file_info(filename.c_str(), codec, w, h);
  
      if (!open_ok) {
  
          std::cout << "Failed to open file" << "\n";
  
          return 1;
  
      }
  
  
  
      std::cout << "File " << filename << " is encoded with '" << codec << "' codec, w = " << w << ", h = " << h << "\n";
  
  
  
      return 0;
  
  }

  filereader.h :

  #ifndef FILEREADER_H
  
  #define FILEREADER_H
  
  
  
  #include <string>
  
  #include <iostream>
  
  
  
  extern "C" {
  
  #ifndef __STDC_CONSTANT_MACROS
  
  #define __STDC_CONSTANT_MACROS
  
  #endif
  
  #include "libavcodec/avcodec.h"
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  }
  
  
  
  bool get_file_info(const char* file, std::string&amp; codec, int&amp; w, int&amp; h);
  
  
  
  #endif // FILEREADER_H
  
  </iostream></string>

  filereader.cpp

  #include "filereader.h"
  
  
  
  
  
  bool get_file_info(const char* file, std::string& codec, int& w, int& h)
  
  {
  
      codec = "";
  
      w = h = 0;
  
  
  
      av_register_all();
  
      avcodec_register_all();
  
  
  
      AVDictionary* dict = 0;
  
      AVFormatContext* format = avformat_alloc_context();
  
  
  
      char errbuf[256];
  
      int r = avformat_open_input(&format, file, 0, &dict);
  
      if (r!=0){
  
          av_strerror(r, errbuf, sizeof(errbuf));
  
          std::cout << "avformat_open_input error: " << errbuf << "\n";
  
      }
  
  
  
      if (r == AVERROR(EIO) || r == AVERROR(ENOEXEC) || !format)
  
          return false;
  
  
  
      for (size_t c = 0; c < format->nb_streams; ++c)
  
      {
  
          if (format->streams[c]->codecpar && format->streams[c]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
  
          {
  
              if (format->streams[c]->codecpar->codec_id != AV_CODEC_ID_NONE &&
  
                      format->streams[c]->codecpar->codec_id != AV_CODEC_ID_RAWVIDEO)
  
              {
  
                  w = format->streams[c]->codecpar->width;
  
                  h = format->streams[c]->codecpar->height;
  
                  codec = avcodec_get_name(format->streams[c]->codecpar->codec_id);
  
              }
  
          }
  
      }
  
      avformat_close_input(&format);
  
      return true;
  
  }

  Compile :

  g++ -o filereader main.cpp filereader.cpp -lavutil -lavformat -lavcodec -lavdevice -lz -lm -pthread -lswresample -lm -lz -I /usr/local/include/ -Wl,-rpath /usr/lib/x86_64-linux-gnu/

• ARSS returns error "This WAVE file format is not currently supported"

  22 juin 2019, par itisyeetimetoday

  I have tried to import a wav file into ARSS : http://arss.sourceforge.net/index.shtml

  I get the above error.

  Files :
  https://drive.google.com/open?id=1X24eUOzOGa5uBUHFTtrSmzptIQTz-93l

  I have tried the following commands with FFmpeg to create a "clean" wav, however, they have all failed.

  ffmpeg -i "file.wav" -f wav -bitexact -acodec pcm_s16le -ar 22050 -ac 1 "ffmpeg.wav"
  
  
  
  ffmpeg -i file.wav -c copy -fflags +bitexact new.wav

  Ffmpeg appears to convert successfully, but it still returns the same error message in ARSS.

• FFMPEG avcodec_find_decoder(2) (CODEC_ID_MPEG2VIDEO) always returns incomplete AVCodec ?

  22 octobre 2012, par Passer

  I got a problem with FFMPEG (avcodec-54.dll)
  1) I wrote a .NET wrapper. As far as I can see it works well.
  2) I try to decode something... and thats were the problem is :

  ...
  
    FFmpeg.avcodec_register_all();
  
  
  
    pAVCodec = FFmpeg.avcodec_find_decoder(CodecID.CODEC_ID_MPEG2VIDEO); //which is in int 2
  
    Console.WriteLine("CodecID " + (*pAVCodec).id);
  
    Console.WriteLine("CodecType " + (*pAVCodec).type);
  
    Console.WriteLine("CodecName " + (*pAVCodec).name);
  
  ....

  ---

  No EXC was thrown and the following output came :
  

  CodecID CODEC_ID_NONE
  
  CodecType 1790854254
  
  CodecName mpeg2video

  ---

  What confuses me the most is that the name is correct, but the id and type are wrong.
  In the previous Version if the DLL everything works fine. This behaviour came up with the new version.
  Any guesses or debugging tips ?