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• OpenCV [[mjpeg @ 0000000000428480] overread 8] during reading a frame from camera

  8 octobre 2015, par wojcienty

  I have a very annoying OpenCV error, that i can’t understand, and handle with.
  I write an application which gets mjpg’s stream from ip camera, and process it, but when i try to load image from stream, sometimes i have

  [mjpeg @ 0000000000428480] overread 8

  error, and i don’t know why.
  Even if i try to skip this issue, and try to load next frame from the stream, the application stucks on

  frameStatus = cameraHandler->read(mat);

  This is code for connection establishing :

  void ImageProcessor::connectWithCamera(VideoCapture * cameraHandler) {
  
      if (cameraHandler != nullptr) {
  
          Logger::log("Closing existing camera stream.");
  
          cameraHandler->release();
  
          delete cameraHandler;
  
      }
  
      Logger::log("Camera configuration and connection establishing.");
  
      cameraHandler = new VideoCapture();
  
      cameraHandler->set(CV_CAP_PROP_FRAME_WIDTH, config.RESOLUTION_WIDTH);
  
      cameraHandler->set(CV_CAP_PROP_FRAME_HEIGHT, config.RESOLUTION_HEIGHT);
  
      cameraHandler->set(CV_CAP_PROP_FPS, config.CAMERA_FPS);
  
      cameraHandler->set(CV_CAP_PROP_FOURCC, CV_FOURCC('M', 'J', 'P', 'G'));
  
      while (!cameraHandler->open(config.LINK)) {
  
          Logger::log("Cannot connect to camera! Trying again.");
  
      }
  
  }

  And this is code for capturing images :

  void ImageProcessor::start() {
  
  
  
      VideoCapture * cameraHandler = new VideoCapture();
  
      this->connectWithCamera(cameraHandler);
  
      this->connectWithServer(this->serverConnection);
  
  
  
      Logger::log("Id sending.");
  
      serverConnection->send(config.TOKEN + "\n");
  
      Logger::log("Computations starting.");
  
  
  
      Mat mat;
  
      Result * result = nullptr;
  
      int delta = 1000 / cameraHandler->get(CV_CAP_PROP_FPS);
  
      char frameErrorCounter = 0;
  
      bool frameStatus;
  
  
  
      while (true) {
  
          frameStatus = false;
  
          cv::waitKey(delta);
  
  
  
          try {
  
              frameStatus = cameraHandler->read(mat);
  
          } catch (std::exception& e) {
  
              std::string message = e.what();
  
              Logger::log("Critical camera error! : " + message);
  
          }
  
  
  
          if (!frameStatus) {
  
              Logger::log("Cannot read a frame from source. ");
  
              ++frameErrorCounter;
  
              if (!cameraHandler->isOpened() || frameErrorCounter >= this->GET_FRAME_ERROR_COUNTER) {
  
                  Logger::log("Probably camera is disconnected. Trying to establish connection again.");
  
                  frameErrorCounter = 0;
  
                  this->connectWithCamera(cameraHandler);
  
                  Logger::log("Computations starting.");
  
              }
  
              continue;
  
          }
  
  
  
          result = processImage(mat);
  
  
  
          std::string stringResult;
  
          if (result == nullptr) {
  
              stringResult = this->NO_RESULT;
  
              delete result;
  
              result = nullptr;
  
          } else {
  
              stringResult = result->toJson();
  
          }
  
  
  
          if (!serverConnection->send(stringResult)) {
  
              Logger::log("Server connection lost, trying to establish it again.");
  
              serverConnection->close();
  
              while (!serverConnection->isOpen()) {
  
                  this->connectWithServer(serverConnection);
  
              }
  
          }
  
  
  
          mat.release();
  
      }
  
  
  
  }

  Thanks in advance !

• ffmpeg streaming camera with directshow

  17 novembre 2015, par atu0830

  I am trying use ffmpeg to streaming one camera. The command is

  ffmpeg.exe -y  -f dshow -i video="AmCam" -c:v copy  -framerate 7.5 -map 0:0 -f ssegment -segment_time 4 -segment_format mpegts  -segment_list "web\stream.m3u8"  -segment_list_size 720  -segment_list_flags live  -segment_wrap 10 -segment_list_type m3u8  "web\segments\s%%d.ts"

  And I create a html in web folder

                                        
  
                                  
  
                                       
  
                                    
  
      <video controls="controls" width="720" height="405" autoplay="autoplay">   
  
          <source src="stream.m3u8" type="application/x-mpegURL"></source>           
  
      </video>                                    
  
                                       
  
   

  All ts file generated but looking Safari on iPad looding but it always show dark player and loading

• when ffmpeg is waiting to reconnect to camera, add blank frames ?

  7 décembre 2016, par moeiscool

  The command I am using is this one.

  It takes an MJPEG stream and saves it to WEBM for one output and another output is straight to stdout as I use it for something else.

  ffmpeg -loglevel warning -reconnect 1 -f mjpeg -r 5 -i http://MJPEGURL/ -vcodec libvpx -r 5 -q:v 1 filename.webm -vf fps=1 -s 640x480 -f image2pipe pipe:1

  It works great. The only issue is that when connection drops to the camera it just stitches together from where it reconnects.

  I would like to add blank frames in between where it disconnects. Is there an option or a way to detect it ? Then maybe i can push some data with stdin ?

  The purpose for adding blank frames is so that is has the proper length even if its "missing frames" from the actual stream itself.