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• FFMPEG Can't Display The Duration Of a Video

  27 juillet 2015, par Malkavian

  I’m trying to use ffmpeg to capture frames from a video file, but I can’t even get the duration of a video. everytime when I try to access it with pFormatCtx->duration I’m getting 0. I know the pointer initialized and contains the correct duration because if I use av_dump_format(pFormatCtx, 0, videoName, 0); then I actually get the duration data along with other information about the video.
  This is what I get when I use av_dump_format(pFormatCtx, 0, videoName, 0); :

  Input #0, avi, from ’futurama.avi’ :

  Duration : 00:21:36.28, start : 0.000000, bitrate : 1135 kb/s

  Stream #0.0 : Video : mpeg4 (Advanced Simple Profile), yuv420p, 512x384

  [PAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc

  Stream #0.1 : Audio : ac3, 48000 Hz, stereo, s16, 192 kb/s

  I don’t understand why av_dum_format can display duration and I can’t. I checked the function definition, to display the duration, the function also uses pFormatCtx->duration. It’s not just the duration other member variables also don’t display the proper data when I call them in main.cpp

  Here’s my main.cpp :

  extern "C" {
  
      #include<libavcodec></libavcodec>avcodec.h>
  
      #include<libavformat></libavformat>avformat.h>
  
      #include<libswscale></libswscale>swscale.h>
  
  }
  
  
  
  
  
  int main(int argc, char *argv[]) {
  
      AVFormatContext *pFormatCtx = NULL;
  
  
  
      const char videoName[] = "futurama.avi";
  
  
  
      // Register all formats and codecs.
  
      av_register_all();
  
      cout &lt;&lt; "Opening the video file";
  
      // Open video file
  
      int ret = avformat_open_input(&amp;pFormatCtx, videoName, NULL, NULL) != 0;
  
      if (ret != 0) {
  
          cout &lt;&lt; "Couldn't open the video file." &lt;&lt; ret ;
  
          return -1;
  
      }
  
      if(avformat_find_stream_info(pFormatCtx, 0) &lt; 0) {
  
          cout &lt;&lt; "problem with stream info";
  
          return -1;
  
      }
  
  
  
      av_dump_format(pFormatCtx, 0, videoName, 0);
  
      cout &lt;&lt; pFormatCtx->bit_rate &lt;&lt; endl; // different value each time, not initialized properly.
  
      cout &lt;&lt; pFormatCtx->duration &lt;&lt; endl; // 0
  
      return 0;
  
  }

  I don’t know if it helps but, I use QtCreator on Ubuntu and linked the libraries statically.

  Thank you for your help.

• FFMPEG Can't Display The Duration Of a Video

  30 août 2021, par Malkavian

  I'm trying to use ffmpeg to capture frames from a video file, but I can't even get the duration of a video. everytime when I try to access it with pFormatCtx->duration I'm getting 0. I know the pointer initialized and contains the correct duration because if I use av_dump_format(pFormatCtx, 0, videoName, 0); then I actually get the duration data along with other information about the video.
This is what I get when I use av_dump_format(pFormatCtx, 0, videoName, 0); :

  


  Input #0, avi, from 'futurama.avi':
Duration: 00:21:36.28, start: 0.000000, bitrate: 1135 kb/s
Stream #0.0: Video: mpeg4 (Advanced Simple Profile), yuv420p, 512x384
[PAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Stream #0.1: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s 


  


  I don't understand why av_dump_format can display duration and I can't. I checked the function definition, to display the duration, the function also uses pFormatCtx->duration. It's not just the duration other member variables also don't display the proper data when I call them in main.cpp

  


  Here's my code :

  


  extern "C" {&#xA;    #include<libavcodec></libavcodec>avcodec.h>&#xA;    #include<libavformat></libavformat>avformat.h>&#xA;    #include<libswscale></libswscale>swscale.h>&#xA;}&#xA;&#xA;int main(int argc, char *argv[]) {&#xA;    AVFormatContext *pFormatCtx = NULL;&#xA;&#xA;    const char videoName[] = "futurama.avi";&#xA;&#xA;    // Register all formats and codecs.&#xA;    av_register_all();&#xA;    cout &lt;&lt; "Opening the video file";&#xA;    // Open video file&#xA;    int ret = avformat_open_input(&amp;pFormatCtx, videoName, NULL, NULL) != 0;&#xA;    if (ret != 0) {&#xA;        cout &lt;&lt; "Couldn&#x27;t open the video file." &lt;&lt; ret ;&#xA;        return -1;&#xA;    }&#xA;    if(avformat_find_stream_info(pFormatCtx, 0) &lt; 0) {&#xA;        cout &lt;&lt; "problem with stream info";&#xA;        return -1;&#xA;    }&#xA;&#xA;    av_dump_format(pFormatCtx, 0, videoName, 0);&#xA;    cout &lt;&lt; pFormatCtx->bit_rate &lt;&lt; endl; // different value each time, not initialized properly.&#xA;    cout &lt;&lt; pFormatCtx->duration &lt;&lt; endl; // 0&#xA;    return 0;&#xA;}&#xA;

  


  I don't know if it helps but, I use QtCreator on Ubuntu and linked the libraries statically.

  


• lavf : Use wchar functions for filenames on windows for mkdir/rmdir/rename/unlink

  17 novembre 2014, par Martin Storsjö

  lavf : Use wchar functions for filenames on windows for mkdir/rmdir/rename/unlink
  This makes sure that the internal utf8 path names are handled
  
  properly - the normal file handling functions assume path names
  
  are in the native codepage, which isn’t utf8.
  This assumes that the tools outside of lavf don’t use the mkdir
  
  definition. (The tools don’t do the same reading of command line
  
  parameters as wchar either - they probably won’t handle all possible
  
  unicode file parameters properly, but at least work more predictably
  
  if no utf8/wchar conversion is involved.)
  This is moved further down in os_support.h, since windows.h shouldn’t
  
  be included before winsock2.h, while io.h needs to be included before
  
  the manual defines for lseek functions.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/internal.h
  • [DH] libavformat/os_support.h