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• Error while creating thumb from video ubuntu ffmpeg

  1er janvier 2019, par dev21

  using below line to generate thumb from the video saved in the public folder in the laravel 4.2 application.

  exec("ffmpeg -ss 00:00:05 -i /var/www/html/project/public/".$directory."".$filename." -vf 'select=not(mod(n\,1000)),scale=320:240' /var/www/html/project/public/".$d.$thumb." >> log_file.log 2>&1 &",$output, $exit_code);

  but "log_file.log" contains the following line :

  cannot create user data directory: /var/www/snap/ffmpeg/411: Read-only file system

  I used snap to install the ffmpeg.

• Strange performance of avcodec_decode_video2

  26 janvier 2014, par John Simpson

  I am developing an Android video player. I use ffmpeg in native code to decode video frame. In the native code, I have a thread called decode_thread that calls avcodec_decode_video2()

  int decode_thread(void *arg) { 
  
     avcodec_decode_video2(codecCtx, pFrame, &frameFinished,pkt);
  
  }

  I have another thread called display_thread that uses aNativeWindow to display a decoded frame on a SurfaceView.

  The problem is that if I let the decode_thread run continuously without a delay. It significantly reduces the performance of avcodec_decode_video2(). Sometimes it takes about 0.1 seconds to decode a frame. However if I put a delay on the decode_thread. Something likes this.

  int decode_thread(void *arg) { 
  
      avcodec_decode_video2(codecCtx, pFrame, &frameFinished,pkt);
  
      usleep(20*1000);
  
  }

  The performance of avcodec_decode_video2() is really good, about 0.001 seconds. However putting a delay on the decode_thread is not a good solution because it affects the playback. Could anyone explain the behavior of avcodec_decode_video2() and suggest me a solution ?

• ffmpeg mod if case in source code

  5 février 2014, par Stephan Pokorny

  I'm working on a specific ffmpeg mod where I have to auto execute an extension within the binary call.

  Specific it is the extension -isync -af aresample=async=1000

  The binary is called by another compiled tool which escapes my input.

  For that reason I wanna rewrite the filter rule to execude in any case.

  if (audio_sync_method > 0) {
  
      char args[256] = {0};
  
  
  
      av_strlcatf(args, sizeof(args), "async=%d", audio_sync_method);
  
      if (audio_drift_threshold != 0.1)
  
          av_strlcatf(args, sizeof(args), ":min_hard_comp=%f", audio_drift_threshold);
  
      if (!fg->reconfiguration)
  
          av_strlcatf(args, sizeof(args), ":first_pts=0");
  
      AUTO_INSERT_FILTER_INPUT("-async", "aresample", args);
  
  }

  Can somebody help me to execute this AUTO_INSERT_FILTER in any case which could happen.

  I already played around to answer any if loop with the AUTO_INSERT_FILTER_INPUT("-async", "aresample", 1000) ;

  When I launch I can see that it is calling the fresh compiled version of ffmpeg but not activating the filter

  Thanks

  Stephan