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• Muting ffmpeg warnings when loading video with OpenCV

  26 mai 2017, par cbuchart

  I’m using OpenCV to process a set of MPEG videos. For some of them following warning is displayed when reading a frame or seeking (it is printed by the ffmpeg library).

  [mpeg2video @ 026b0d20] warning : first frame is no keyframe

  The thing is that such messages are printed together other valid output of my application and they are bothering final users. Is there any way to suppress such warning messages programmatically, other than re-coding the videos with an external tool ?

  I’m already muting the standard output and error, as well as using a custom (dummy) OpenCV error handler. Below a MCVE for testing.

  PS : I understand the warning and actually the full project handles those scenarios so videos are correctly read.

  ---

  Example code to reproduce the problem

  #include <iostream>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  
  
  int handleError(int status, const char* func_name,
  
                  const char* err_msg, const char* file_name,
  
                  int line, void* userdata)
  
  {
  
    return 0;
  
  }
  
  
  
  int main()
  
  {
  
    std::cout &lt;&lt; "Start!" &lt;&lt; std::endl;
  
  
  
    cv::VideoCapture reader;
  
    if (!reader.open("Sample.mpg")) {
  
      std::cout &lt;&lt; "Failed opening video" &lt;&lt; std::endl;
  
      return 0;
  
    }
  
  
  
    cv::redirectError(handleError);
  
  
  
    std::cout.setstate(std::ios_base::failbit);
  
    std::cout &lt;&lt; "std::cout mute test..." &lt;&lt; std::endl; // OK, muted
  
  
  
    std::cerr.setstate(std::ios_base::failbit);
  
    std::cerr &lt;&lt; "std::cerr mute test..." &lt;&lt; std::endl; // OK, muted
  
  
  
    cv::Mat tmpImage;
  
    try {
  
      tmpImage = tmpImage * tmpImage; // OK, OpenCV error muted
  
    } catch (...) {}
  
  
  
    // Here the warning is printed
  
    reader.read(tmpImage);
  
  
  
    std::cout.clear();
  
    std::cerr.clear();
  
    std::cout &lt;&lt; "Finished!" &lt;&lt; std::endl;
  
  
  
    return 0;
  
  }
  
  </iostream>

  The Sample.mpg video can be downloaded from the Internet Archive : https://archive.org/download/ligouHDR-HC1_sample1/Sample.mpg

  This is the current output of the program :

  

  ---

  I’m using VS 2010 and OpenCV 2.4.10. Following DLLs are the only ones with the executable (no other OpenCV-related DLL is reachable in the PATH).

  • opencv_core2410.dll
  • opencv_ffmpeg2410.dll
  • opencv_highgui2410.dll

• Muting ffmpeg warnings when loading video

  25 mai 2017, par cbuchart

  I’m using OpenCV to process a set of MPEG videos. For some of them following warning is displayed when reading a frame or seeking (it is printed by the ffmpeg library).

  [mpeg2video @ 026b0d20] warning : first frame is no keyframe

  The thing is that such messages are printed together other valid output of my application and they are bothering final users. Is there any way to suppress such warning messages programmatically, other than re-coding the videos with an external tool ?

  I’m already muting the standard output and error, as well as using a custom (dummy) OpenCV error handler. Below a MCVE for testing.

  PS : I understand the warning and actually the full project handles those scenarios so videos are correctly read.

  ---

  Example code to reproduce the problem

  #include <iostream>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  
  
  int handleError(int status, const char* func_name,
  
                  const char* err_msg, const char* file_name,
  
                  int line, void* userdata)
  
  {
  
    return 0;
  
  }
  
  
  
  int main()
  
  {
  
    std::cout &lt;&lt; "Start!" &lt;&lt; std::endl;
  
  
  
    cv::VideoCapture reader;
  
    if (!reader.open("Sample.mpg")) {
  
      std::cout &lt;&lt; "Failed opening video" &lt;&lt; std::endl;
  
      return 0;
  
    }
  
  
  
    cv::redirectError(handleError);
  
  
  
    std::cout.setstate(std::ios_base::failbit);
  
    std::cout &lt;&lt; "std::cout mute test..." &lt;&lt; std::endl; // OK, muted
  
  
  
    std::cerr.setstate(std::ios_base::failbit);
  
    std::cerr &lt;&lt; "std::cerr mute test..." &lt;&lt; std::endl; // OK, muted
  
  
  
    cv::Mat tmpImage;
  
    try {
  
      tmpImage = tmpImage * tmpImage; // OK, OpenCV error muted
  
    } catch (...) {}
  
  
  
    // Here the warning is printed
  
    reader.read(tmpImage);
  
  
  
    std::cout.clear();
  
    std::cerr.clear();
  
    std::cout &lt;&lt; "Finished!" &lt;&lt; std::endl;
  
  
  
    return 0;
  
  }
  
  </iostream>

  The Sample.mpg video can be downloaded from the Internet Archive : https://archive.org/download/ligouHDR-HC1_sample1/Sample.mpg

  This is the current output of the program :

  

  ---

  I’m using VS 2010 and OpenCV 2.4.10. Following DLLs are the only ones with the executable (no other OpenCV-related DLL is reachable in the PATH).

  • opencv_core2410.dll
  • opencv_ffmpeg2410.dll
  • opencv_highgui2410.dll

• Use FFMPEG process to get all frame from rtsp

  10 octobre 2015, par LEONARDO VERNAZA

  process to run a command that reads a RTSP stream with FFMPEG, and I need to catch each frame to display it in a picturebox ; I’m receiving the data in void OnOutputDataReceived(object sender, DataReceivedEventArgs e), but once I transform e.data to byte[] and I generate the bitmap the app crashes.

  my code :

  private void Form1_Load_1(object sender, EventArgs e)
  
      {
  
          Process proc = new Process();
  
          proc.StartInfo.FileName = "ffmpeg";
  
          proc.StartInfo.Arguments = "-i rtsp://user:foscam@50.197.211.181:9826/videoMain -an -vcodec mjpeg -s 640x480 -threads 1 -aspect 16:9 -q:v 2 -updatefirst 1 -b:v 64k -f -";
  
          proc.StartInfo.RedirectStandardError = true;
  
          proc.StartInfo.UseShellExecute = false;
  
          proc.StartInfo.RedirectStandardOutput = true;
  
          proc.OutputDataReceived += OnOutputDataReceived;
  
          if (!proc.Start())
  
          {
  
              Console.WriteLine("Error starting");
  
              return;
  
          }
  
          proc.BeginOutputReadLine();
  
          StreamReader reader = proc.StandardError;
  
          string line;
  
          while ((line = reader.ReadLine()) != null)
  
          {
  
              Console.WriteLine(line);
  
          }
  
          proc.Close();
  
      }
  
  
  
      void OnOutputDataReceived(object sender, DataReceivedEventArgs e)
  
      {
  
          byte[] bytes = new byte[e.Data.Length * sizeof(char)];
  
          System.Buffer.BlockCopy(e.Data.ToCharArray(), 0, bytes, 0, bytes.Length);
  
          Bitmap bmp;
  
          using (var ms = new MemoryStream(bytes))
  
          {
  
      // CRASH SITE
  
  
  
              bmp = new Bitmap(ms);
  
          }
  
          pictureBox1.Image = bmp;
  
      }

  Bytes

  Crash