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• Can't lock std::mutex again

  16 juillet 2017, par user3567631

  Sorry for poor English.
  I referenced this FFMPEG to make ffmpeg decoder.
  The open will block, I make it run in detach thread.
  I added std::unique_lock to lock mutex in beginning of open.

  bool FFmpegWrapper::open(std::string strFileName)
  
  {
  
  std::unique_lock lock(g_Mutex, std::try_to_lock);
  
  
  
  m_pFormatContext = avformat_alloc_context();
  
  m_pFormatContext->probesize = 4 * 1024 *100;
  
  m_pFormatContext->max_analyze_duration = 0 * AV_TIME_BASE;
  
  
  
  if (avformat_open_input(&m_pFormatContext, strFileName.c_str(), nullptr, nullptr) != 0)
  
      return false; 
  
  
  
  if (avformat_find_stream_info(m_pFormatContext, NULL) < 0)
  
      return false; 
  
  
  
  m_iVideoStream = m_iAudioStream = -1;
  
  for (unsigned int i = 0; i < m_pFormatContext->nb_streams; i++)
  
  {
  
      if ((m_iVideoStream < 0) && (m_pFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO))
  
      {
  
          m_iVideoStream = i;
  
      }
  
      else if ((m_iAudioStream < 0) && (m_pFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO))
  
      {
  
          m_iAudioStream = i;
  
      }
  
  }
  
  
  
  if (!(hasVideo() || hasAudio()))
  
      return false; // Didn't find video or audio stream
  
  
  
  if (hasVideo())
  
  {
  
      if (!openVideoStream())
  
          return false;
  
  }
  
  
  
  if (hasAudio())
  
  {
  
      if (!openAudioStream())
  
          return false;
  
  }
  
  
  
  retrieveFileInfo();
  
  
  
  m_bIsFileOpen = true;
  
  m_strFileName = strFileName;
  
  
  
  if (isImage())
  
  {
  
      m_dDurationInMs = 0;
  
      m_dFps = 0;
  
      m_lCurrentFrameNumber = 1;
  
      decodeImage();
  
  }
  
  
  
  m_bIsThreadRunning = false;
  
  if (m_bIsFileOpen)
  
      CCLOG("FFmpeg open stream succeed");
  
  else
  
      CCLOG("FFmpeg open stream failed"); 
  
  m_iState = eOpened;
  
  
  
  return m_bIsFileOpen;
  
  }

  and added unique_lock in close beginning like this.

  void FFmpegWrapper::close()
  
  {
  
  std::unique_lock lock(g_Mutex, std::try_to_lock);
  
  while (!lock.owns_lock()) 
  
  { 
  
      lock.try_lock()
  
  }
  
  
  
  stop(); 
  
  
  
  if (m_pVideoBuffer != nullptr)
  
  {
  
      delete m_pVideoBuffer;
  
      m_pVideoBuffer = nullptr;
  
  }
  
  
  
  if (m_pVideoFrameRGB != nullptr)
  
  {
  
      av_free(m_pVideoFrameRGB);
  
      m_pVideoFrameRGB = nullptr;
  
  }
  
  
  
  if (m_pVideoFrame != nullptr)
  
  {
  
      av_free(m_pVideoFrame);
  
      m_pVideoFrame = nullptr;
  
  }
  
  
  
  if (m_pAudioFrame != nullptr)
  
  {
  
      av_free(m_pAudioFrame);
  
      m_pAudioFrame = nullptr;
  
  }
  
  
  
  
  
  if (m_pSwScalingContext != nullptr)
  
  {
  
      sws_freeContext(m_pSwScalingContext);
  
      m_pSwScalingContext = nullptr;
  
  }
  
  
  
  if (m_pVideoCodecContext != nullptr)
  
  {
  
      avcodec_close(m_pVideoCodecContext);
  
      m_pVideoCodecContext = nullptr;
  
  }
  
  if (m_pAudioCodecContext != nullptr)
  
  {
  
      avcodec_close(m_pAudioCodecContext);
  
      m_pAudioCodecContext = nullptr;
  
  }
  
  
  
  if (m_pFormatContext != nullptr)
  
  {
  
      avformat_free_context(m_pFormatContext);    
  
      m_pFormatContext = nullptr;
  
  }
  
  if(m_pSwr != nullptr)
  
      swr_free(&m_pSwr);
  
  
  
  CCLOG("CLOSE DONE");
  
  }

  When open is still running ,I want lock mutex again in close in main thread.
  it failed to get mutex ownership it is no problem. But even while loop waited the open() done, try_lock still can’t get the mutex ownership.I thought unique_lock out of scope will unlock mutex ,but it didn’t. I want to know how can I lock the mutex correctly.Thank you !

• Failed to obtain lock for new video threads [closed]

  31 août 2023, par taha zahid

  We are facing issue with a software which uses ffmpeg for conversion to h264

  


  During a routine test for multiple camera for video loss on the software for more that 2 minutes

  


  We get below message
"Failed to obtain lock for new video thread"

  


  Since i am not into software developement i need to understand how we can optimise this so that this application can minimise cpu usage to 50% and or less but still no compromise on h264 quality during streaming and also recover video without any error during a failover test

  


  Since i am not into software i could not test anything

  


• Revision 5671 : Un lock sur les champs readonly +des couleurs différentes

  9 août 2011, par kent1 — Log

  Un lock sur les champs readonly +des couleurs différentes