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• C++/OpenCV - VideoCapture doesn't work but it worked before with exactly the same code

  5 mars 2015, par Damià Obrador

  I’m trying to write a shot boundary detection algorithm in C++ using OpenCV. After all, I have to say that I have no experience working with OpenCV.

  I have been improving the following code (and I am still in it) during the last two weeks and everything seems the works correctly, not in terms of perfect shot detection, but every line of code did what was expected from it.

  #include <cstdlib>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>video/background_segm.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <iostream>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include 
  
  #include <istream>
  
  #include <fstream>
  
  using namespace cv;
  
  
  
  
  
  
  
  int main(){
  
  
  
      VideoCapture capture("vdevendetta.mp4");
  
      if ( !capture.isOpened() )
  
       {
  
           std::cout &lt;&lt; "Cannot open the video file";
  
           return -1;
  
       }
  
      int numFrames=capture.get(CV_CAP_PROP_FRAME_COUNT);
  
      bool SB_counter=false;
  
      Mat currentFrame;
  
      Mat frame;
  
      Mat fore;
  
      Mat back;
  
      vector<mat> frames;
  
      FileStorage file;
  
      FileStorage file2;
  
      Mat prev_Y;
  
      Mat channels[3];
  
      for(int i=0;i>currentFrame;
  
              frame=currentFrame.clone();
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              prev_Y=channels[0];
  
              SB_counter=false;
  
          }
  
          else
  
          {
  
              capture>>currentFrame;
  
              frame=currentFrame.clone();
  
              Mat channels[3];
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              Mat curr_Y=channels[0];
  
              channels[0]=prev_Y;
  
              prev_Y=curr_Y;
  
              merge(channels,3,frame);
  
              cvtColor(frame,frame,CV_Luv2BGR);
  
              cvtColor(frame,frame,CV_BGR2GRAY);
  
              frames.push_back(frame);
  
          }
  
  
  
      }
  
  
  
      vector<double> MAFDs;
  
      vector<double> MAFD;
  
      vector<double> aux;
  
      double min;
  
      double min2;
  
  
  
      for(int j=1;j14)
  
          {
  
              std::cout&lt;&lt;"De"&lt;*
  
      std::ofstream fout("MAFD.txt");
  
      if(fout.is_open()==true)
  
      {
  
        //file opened successfully so we are here
  
        std::cout &lt;&lt; "File Opened successfully!!!. Writing data from array to file" &lt;&lt; std::endl;
  
  
  
          for(int i = 0; MAFD[i] != '\0'; i++)
  
          {
  
          fout &lt;&lt; MAFD[i]; //writing ith character of array in the file
  
          }
  
        std::cout &lt;&lt; "Array data successfully saved into the file test.txt" &lt;&lt; std::endl;
  
      }
  
      else //file could not be opened
  
      {
  
          std::cout &lt;&lt; "File could not be opened." &lt;&lt; std::endl;
  
      }*/
  
      return 0;
  
  }
  
  </double></double></double></mat></fstream></istream></iostream></cstdlib>

  Three days ago I had an strange problem. The line :

  VideoCapture capture("vdevendetta.mp4");

  stopped working. I spent many hours looking for the solution but nothing seems to repair it. After reading everything related with OpenCV, VideoCapture and ffmpeg that I found on internet I decided to reinstall everything taking care of each detail, but it still didn’t work. Finally I solved it changing the line with this other one :

  VideoCapture capture("/home/damia/Documentos/Universitat/ARA/PAEAV/workspace_cpp/SBD/src/vdevendetta.mp4");

  I did not know why this solved it because the video is in the same directory than the program, but I continued working because everything seemed correct.
  Today I had the same problem again on the new line.
  The terminal doesn’t show any error comment (exceptuating "Cannot open the video file", obviously) but the code doesn’t work again.

  I’m using Ubuntu 14.04 LTS, OpenCV 2.4.9 and Eclipse.

  I think if someone test the code it will run correctly, but I would like to know if there is something I have no taking into account.

  Thank you very match.

• Is there is any Free/Open source libraries for compressing the video file /reducing file size of video file in android ?

  18 février 2015, par Manu

  My application deals video sharing. Here i need to reduce the size of videos/ compress the video, so that i can minimize the data upload/download. I went through many threads and most of the threads suggesting FFMPEG. I could integrate it with my application and it is working exactly how i want it to be. But now i came to know that it’s a commercial library, and i just have 15 days of trial period. :(

  Any other alternatives ? Free/open source libraries which satisfies my requirements ?

• Playing RTSP stream in Android

  9 décembre 2014, par Kamil

  I’m trying to play video stream on Android device. Unfortunatelly I still get the same problem with MediaPlayer/VideoView. I’m searching for a few days, but still haven’t found any working solution.
  For test purposes I’m using MediaPlayer app from API Demos (API Demos/Media/MediaPlayer/Play Streaming Video).
  Here is code snippet for playing stream

  mMediaPlayer = new MediaPlayer();
  
  mMediaPlayer.setDataSource(path);
  
  mMediaPlayer.setDisplay(holder);
  
  mMediaPlayer.prepare();
  
  mMediaPlayer.setOnBufferingUpdateListener(this);
  
  mMediaPlayer.setOnCompletionListener(this);
  
  mMediaPlayer.setOnPreparedListener(this);
  
  mMediaPlayer.setOnVideoSizeChangedListener(this);

  When I try to play stream I get this info from logcat
  http://pastebin.com/5Uib5CH5

  This is configuration of ffserver streaming the video

  Port 8090
  
  BindAddress 0.0.0.0
  
  
  
  RTSPPort 7654
  
  RTSPBindAddress 0.0.0.0
  
  
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 10000
  
  
  
  CustomLog -
  
  NoDaemon
  
  <Feed feed1.ffm>
  
  
  
  File /tmp/feed1.ffm
  
  FileMaxSize 5M
  
  
  
  Launch ffmpeg -i mmsh://tempserv.cam/vid1
  
  
  
  ACL allow 127.0.0.1
  
  
  
  </Feed>
  
  
  
  <Stream rat1.mpg>
  
  Feed feed1.ffm
  
  Format rtp
  
  NoAudio
  
  VideoBitRate 56k
  
  VideoBufferSize 40
  
  VideoFrameRate 12
  
  VideoSize 176x144
  
  VideoGopSize 12
  
  VideoCodec libx264
  
  AVPresetVideo baseline
  
  </Stream>

  If anyone can advise me how to fix it, or at least indicate an mistake, I will be grateful.