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• FFmpeg : Concatenated clips extracted using -ss and -t, hang or go out of sync while playing

  20 juillet 2013, par Yogi

  I have a set of movies in different formats, and I am trying to extract small clips from these source movies, and concatenate them into one movie.

  My workflow has been the following :

  1. Convert all the source movies to the same format (width, height, fps, codec)T the scale and pad options are so that all movies oare of the same size, even if their aspect ratio is different.

     fmpeg  -i $infile -vcodec libx264 -strict -2  -vf scale=iw*sar*min(${MAX_WIDTH}/(iw*sar)\,${MAX_HEIGHT}/ih):ih*min(${MAX_WIDTH}/(iw*sar)\,${MAX_HEIGHT}/ih),pad=${MAX_WIDTH}:${MAX_HEIGHT}:(ow-iw)/2:(oh-ih)/2 -b:v 500k -b:a 64k -movflags +faststart -g 10  -r 25 ${outbasename}.mp4

  2. extract clips :

     ffmpeg -ss $starttime -t $duration -i $in_file -vcodec copy -acodec copy $out_file

  3. Then finally combine clips by first making a concat_list.txt file which contains the list of clips to be concatenated, and their duration, and then using ffmpegs's concat demux :

     ffmpeg -f concat -i concat_list.txt -c copy -movflags +faststart $oname

  The problem I am facing is that many of the final videos hang or go out of sync, somewhere in the middle of playing. I have tried using mjpeg as the codec, but I still get the same behavior. I can play the individual extracted clips, and then all seem to play fine in most players. Does anybody know what I am doing wrong ? I am using ffmpeg version 1.2.1.

• fftools : add DPI awareness manifest

  7 août 2022, par Timo Rothenpieler

  fftools : add DPI awareness manifest
  Some filters, like gdigrab, rely on this to be set to see and report
  
  proper dimensions.
  

  • [DH] fftools/Makefile
  • [DH] fftools/fftools.manifest
  • [DH] fftools/fftoolsres.rc

• ffmpeg causes browser to hang up ?

  24 juillet 2012, par Itai Sagi

  I'm using ffmpeg to convert videos on the fly, as they say, and I'm facing with a very annoying, unsolvable and unreferenced problem (as of yet ;) ), when I run my php script, it basically works - takes the file, uses ffmpeg, starts converting it, but halway through it's finished, the browser hangs, I don't understand why or how to resolve it :
  (even with set_time_limit the bastard won't work).

  function convertToMp4(){
  
      /*
  
       * Converts a file to mp4, returns the new file name
  
       */
  
      set_time_limit(0);
  
      $tmpFile = $this->fileName;
  
      $newFile = uniqid();
  
      $outputFile = "output/$justFile.mp4";
  
      exec("ffmpeg -i " . $tmpFile . " -acodec copy -ar 44100 -ab 96k " . $outputFile. " &");
  
      unlink($tmpFile);
  
      return $outputFile;
  
  }

  Ideas ?