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• FFmpeg insufficient thread locking only when deploying application using homebrew

  20 décembre 2012, par Kikohs

  I have the strangest bug of my life.
  I have installed ffmpeg using homebrew. I use it from a dll.
  I have set a lock manager because I use ffmpeg from multiple threads.

  In Engine.h :

  class EXPORT_LIB Engine
  
  {
  
  public:
  
      static int initEngine();    
  
      static int closeEngine();
  
  };

  In Engine.cpp :

  static int ff_lockmgr(void **mutex, enum AVLockOp op)
  
  {
  
  if (NULL == mutex)
  
      return -1;
  
  
  
  switch(op)
  
  {
  
  case AV_LOCK_CREATE:
  
  {
  
      *mutex = NULL;
  
      boost::mutex * m = new boost::mutex();
  
      *mutex = static_cast(m);
  
      break;
  
  }
  
  case AV_LOCK_OBTAIN:
  
  {
  
      boost::mutex * m =  static_cast(*mutex);
  
      m->lock();
  
      break;
  
  }
  
  case AV_LOCK_RELEASE:
  
  {
  
      boost::mutex * m = static_cast(*mutex);
  
      m->unlock();
  
      break;
  
  }
  
  case AV_LOCK_DESTROY:
  
  {
  
      boost::mutex * m = static_cast(*mutex);
  
      delete m;
  
      break;
  
  }
  
  default:
  
      break;
  
  }
  
  return 0;
  
  }
  
  
  
  
  
  int Engine::initEngine()
  
  {
  
      int res = -1;
  
      res = av_lockmgr_register(&ff_lockmgr);
  
      av_register_all();
  
      av_log_set_level(AV_LOG_QUIET); // ERROR, PANIC
  
      // Av lock manager success
  
      if( res == 0 ) {
  
          res = MULTITHREAD;
  
      }
  
      else {
  
          res = SINGLETHREAD;
  
      }
  
      return res;
  
  }
  
  
  
  int Engine::closeEngine()
  
  {
  
      int res = 0;
  
      res = av_lockmgr_register(NULL);
  
      return res;
  
  }

  So far so good, everything works as expected.

  When I deploy my app using CMake fix_bundle. I have an error message

  insufficient thread locking around avcodec_open/close()

  If I compile ffmpeg by hand in a custom location, when I deploy the app everything works as expected. What is wrong with homebrew ?

• avutil/crc : Dont limit CRC32 standard tables

  1er juin 2013, par James Almer

  avutil/crc : Dont limit CRC32 standard tables
  Currently, standard tables like AV_CRC_32_IEEE and such are being generated (or
  
  provided in case the user compiles with hardcoded tables) with only 257 elements.
  
  We’re missing a considerable boost in performance by not making them with a size
  
  of 1024 elements instead.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavutil/crc.c

• Error in ffmpeg when reading from UDP stream

  24 juillet 2013, par six6and1one

  I'm trying to process frames from a UDP stream using ffmpeg. Everything will run fine for a while but av_read_frame() will always eventually return either AVERROR_EXIT (Immeditate exit requested) or -5 (Error number -5 occurred) while the stream should still be running fine. Right before the error it always prints the following message to the console

  [mpeg2video @ 0caf6600] ac-tex damaged at 14 10
  
  [mpeg2video @ 0caf6600] Warning MVs not available
  
  [mpeg2video @ 0caf6600] concealing 800 DC, 800 AC, 800 MV errors in I frame

  (the numbers in the message vary from run to run)

  I have a suspicion that the error is related to calling av_read_frame too quickly. If I have it run as fast as possible, I usually get an error within 10-20 frames, but if I put a sleep before reading it will run fine for a minute or so and then exit with an error. I realize this is hacky and assume there is a better solution. Bottom line : is there a way to dynamically check if 'av_read_frame()' is ready to be called ? or a way to supress the error ?

  Psuedo code of what I'm doing below. Thanks in advance for the help !

  void getFrame()
  
  {
  
      //wait here?? seems hacky...
  
      //boost::this_thread::sleep(boost::posix_time::milliseconds(25));   
  
  
  
      int av_read_frame_error = av_read_frame(m_input_format_context, &m_input_packet);           
  
      if(av_read_frame_error == 0){       
  
          //DO STUFF - this all works fine when it gets here
  
      }
  
      else{               
  
          //error
  
          char errorBuf[AV_ERROR_MAX_STRING_SIZE];
  
          av_make_error_string(errorBuf, AV_ERROR_MAX_STRING_SIZE, av_read_frame_error);
  
          cout << "FFMPEG Input Stream Exit Code: " << av_read_frame_error << "   Message: " << errorBuf << endl;             
  
      }
  
  }