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• Play H.264 camera streams using OpenCV

  26 octobre 2018, par peter bence

  How to play H.264 camera streams using OpenCV ? I was searching for a while but i didn’t find an answer. I think OpenCV can encode and decode h.264 videos since it uses ffmpeg and it is the documentation of the class VideoWriter ensures that as shown in this example :

  #include <iostream> // for standard I/O
  
  #include <string>   // for strings
  
  
  
  #include <opencv2></opencv2>core/core.hpp>        // Basic OpenCV structures (cv::Mat)
  
  #include <opencv2></opencv2>highgui/highgui.hpp>  // Video write
  
  
  
  using namespace std;
  
  using namespace cv;
  
  
  
  int main()
  
  {
  
      VideoWriter outputVideo; // For writing the video
  
  
  
      int width = ...; // Declare width here
  
      int height = ...; // Declare height here
  
      Size S = Size(width, height); // Declare Size structure
  
  
  
      // Open up the video for writing
  
      const string filename = ...; // Declare name of file here
  
  
  
      // Declare FourCC code
  
      int fourcc = CV_FOURCC('H','2','6','4');
  
  
  
      // Declare FPS here
  
      int fps = ...;
  
      outputVideo.open(filename, fourcc, fps, S);
  
  
  
      // Put your processing code here
  
      // ...
  
  
  
      // Logic to write frames here... see below for more details
  
      // ...
  
  
  
      return 0;
  
  }
  
  </string></iostream>

  So can OpenCV encode-decode h.264 stream as well ? if yes, please let me know how. thanks !!

• Cannot play compressed video

  23 mai 2017, par Rares

  I am trying to compress a video from gallery.
  Steps :

  1)I open gallery.

  2)Pick a video and get it’s path

  3)Create new path for the output video

  4)Compress the video using FFmpeg( the video is saved automatically)

  Can you tell me why I can’t open the compressed video in my phone ? For example I run the code below and when I go in my phone to open the created file I get an error : Cannot play video. Unsupported file type. Here is an example : http://imgur.com/a/ePHzq

  I am compressing videos with size between 50-300MB.

           String filePath = getRealPathFromURI(getApplicationContext(), data.getData());
  
  
  
                      ///get the name of file without extension
  
                      StringBuilder stringBuilder = new StringBuilder(filePath);
  
                      int start = filePath.lastIndexOf('.');
  
                      stringBuilder.delete(start, filePath.length());
  
                      //--------------
  
                      //get file extension(e.g mp4)
  
                      File file = new File(filePath);
  
                      String contentType = getFileType(file.getAbsolutePath());
  
                      //--------------
  
                      //create compressed file path=initial file path+ _compressed+(random nr.)+ extension .mp4
  
                      Random random = new Random();
  
                      int fileNr = random.nextInt(999);
  
                      String compressedFilePath = stringBuilder.toString() + "_compressed" + fileNr +"."+ contentType;
  
  
  
                      //compress file from gallery and save it with the above name
  
                      String[] command = {"-y", "-i", filePath, "-s", "640x480", "-r", "25", "-vcodec",
  
                              "mpeg4", "-b:v", "150k", "-b:a", "48000", "-ac", "2", "-ar", "22050", compressedFilePath};
  
                      executeFFmpegBinary(command);

• OpenCV CUDA VideoReader RTSP video play UNSUPPORTED Format Issue

  17 octobre 2018, par oktykrk

  I am trying to play an rtsp stream with OpenCV 3.4 built with CUDA 9.1 in C++. I have enabled FFMPEG flag while building OpenCV, however getting OpenCV error like :

  OpenCV Error: Unsupported format or combination of formats (Unsupported video source) in cv::cudacodec::detail::FFmpegVideoSource::FFmpegVideoSource, file C:\opencv-3.4.0\modules\cudacodec\src\ffmpeg_video_source.cpp, line 110

  here is the code :
  

  const cv::String fname = "rtsp://admin:admin@192.168.2.46/media/video1";
  
  cv::namedWindow("GPU", cv::WINDOW_NORMAL);
  
  
  
  cv::cuda::GpuMat d_frame;
  
  
  
  cv::Ptr d_reader = cv::cudacodec::createVideoReader(fname);
  
  
  
  for (;;)
  
  {
  
  
  
      if (!d_reader->nextFrame(d_frame))
  
          break;
  
  
  
      cv::Mat frame;
  
      d_frame.download(frame);
  
      cv::imshow("GPU", frame);
  
  
  
      if (cv::waitKey(3) > 0)
  
          break;
  
  }

  I can play the video with the same source with CPU but getting this error with cudacodec interface createVideoReader function.

  Getting the error below when debug.
  

  Can anybody help with this. Thank you all.