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• How to Manage User Uploaded Content and Storage

  6 novembre 2014, par Ben

  I’m building an app in PHP (Laravel 4 framework) where a teacher in their account can create a digital lesson for a student. Digital lessons can contain the following content :

  • Text (text from form, .doc, .txt, .pdf, etc.)
  • Images (.gif, .png, .jpg etc.)
  • Video (.avi, .mov, .mp4, etc.)
  • Audio (.mp3, etc.)

  Raw text entered from forms can obviously be stored in the DB against the lesson_id. All the other content formats will need to be stored somewhere, where I can manage and read the files, as well as keep track of the teachers storage total as I plan to bill for storage thresholds at 5GB, 10GB etc.

  On the create a lesson page, content files need to be uploaded as lesson attachments before the lesson is saved, so a teacher can visually see all the lessons content, and then hit save to create the lesson instantly.

  Here’s what I’ve come up with :

  1. Upload all lesson file attachments to AWS S3 to the teachers dedicated bucket, before the lesson is created. Add the teachers ID and date time to each filename.

  2. Force all uploaded video / audio files to be converted to .mp4, .mp3, etc. if they are not in an iDevice friendly format or they exceed a file size limit. Use FFmpeg to do this.

  3. When the lesson is saved and created, record the S3 file URL’s against the lesson ID in the DB.

  4. If the lesson has not been created after a specific period of time, run a cron job to check for uploaded S3 files with no lesson and delete them.

  I am unsure what is the best way to solve this problem as user uploaded content management is really new to me.

  What do you think of this approach ? Can you recommend an improved or better way to solve this problem ?

• OpenCV and Network Cameras

  10 mai 2014, par Alexander

  ---

  So as a bit of context ; this program was built originally to work with USB cameras - but a few things changed. Now I’m trying to convert it to work with networked cameras, but my presence here should make it quite apparent what my level of success has been so far.

  ---

  I’m using :

  • OpenCV v2.4.6.0
  • C++
  • D-Link Cloud Camera 7100 (Installer is DCS-7010L, according to the instructions.)

  ---

  I am trying to access the DLink camera’s video feed through OpenCV.

  I can access the camera through it’s IP address with a browser without any issues. Unfourtunately ; my program is less cooperative. When attempting to access the camera the program gives the OpenCV-generated error :

  warning : Error opening file (../../modules/highgui/src/cap_ffmpeg_impl.hpp:529)

  This error occurs with just about everything I try that doesn’t somehow generate more problems.

  For reference - the code in OpenCV’s cap_ffmpeg_impl.hpp around line 529 is as follows :

  522    bool CvCapture_FFMPEG::open( const char* _filename )
  
  523    {
  
  524        unsigned i;
  
  525        bool valid = false;
  
  526
  
  527        close();
  
  528
  
  529    #if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(52, 111, 0)
  
  530        int err = avformat_open_input(&ic, _filename, NULL, NULL);
  
  531    #else
  
  532        int err = av_open_input_file(&ic, _filename, NULL, 0, NULL);
  
  533    #endif
  
  ...
  
  616    }

  ...for which I have no idea what I’m looking at. It seems to be looking for the ffmpeg version - but I’ve already installed the latest ffmpeg on that computer, so that shouldn’t be the issue.

  This is the edited down version I tried to use as per Sebastian Schmitz’s recommendation :

   1    #include <fstream>                            // File input/output
  
   2    #include <iostream>                           // cout / cin / etc
  
   3    #include                       // Windows API stuff
  
   4    #include                             // More input/output stuff
  
   5    #include <string>                         // "Strings" of characters strung together to form words and stuff
  
   6    #include <cstring>                            // "Strings" of characters strung together to form words and stuff
  
   7    #include <streambuf>                      // For buffering load files
  
   8    #include <array>                          // Functions for working with arrays
  
   9    #include <opencv2></opencv2>imgproc/imgproc.hpp>        // Image Processor
  
  10    #include <opencv2></opencv2>core/core.hpp>          // Basic OpenCV structures (cv::Mat, Scalar)
  
  11    #include <opencv2></opencv2>highgui/highgui.hpp>        // OpenCV window I/O
  
  12    #include "opencv2/calib3d/calib3d.hpp"
  
  13    #include "opencv2/features2d/features2d.hpp"
  
  14    #include "opencv2/opencv.hpp"
  
  15    #include "resource.h"                     // Included for linking the .rc file
  
  16    #include                             // For sleep()
  
  17    #include <chrono>                         // To get start-time of program.
  
  18    #include <algorithm>                      // For looking at whole sets.
  
  19
  
  20    #ifdef __BORLANDC__
  
  21      #pragma argsused
  
  22    #endif
  
  23
  
  24    using namespace std;                      // Standard operations. Needed for most basic functions.
  
  25    using namespace std::chrono;              // Chrono operations. Needed getting starting time of program.
  
  26    using namespace cv;                           // OpenCV operations. Needed for most OpenCV functions.
  
  27
  
  28    string videoFeedAddress = "";
  
  29    VideoCapture videoFeedIP = NULL;
  
  30    Mat clickPointStorage; //Artifact from original program.
  
  31
  
  32    void displayCameraViewTest()
  
  33    {
  
  34      VideoCapture cv_cap_IP;
  
  35      Mat color_img_IP;
  
  36      int capture;
  
  37      IplImage* color_img;
  
  38      cv_cap_IP.open(videoFeedAddress);
  
  39      Sleep(100);
  
  40      if(!cv_cap_IP.isOpened())
  
  41      {
  
  42          cout &lt;&lt; "Video Error: Video input will not work.\n";
  
  43          cvDestroyWindow("Camera View");
  
  44          return;
  
  45      }
  
  46      clickPointStorage.create(color_img_IP.rows, color_img_IP.cols, CV_8UC3);
  
  47      clickPointStorage.setTo(Scalar(0, 0, 0));
  
  48      cvNamedWindow("Camera View", 0); // create window
  
  49      IplImage* IplClickPointStorage = new IplImage(clickPointStorage);
  
  50      IplImage* Ipl_IP_Img;
  
  51      
  
  52      for(;;)
  
  53      {
  
  54          cv_cap_IP.read(color_img_IP);
  
  55          IplClickPointStorage = new IplImage(clickPointStorage);
  
  56          Ipl_IP_Img = new IplImage(color_img_IP);
  
  57          cvAdd(Ipl_IP_Img, IplClickPointStorage, color_img);
  
  58          cvShowImage("Camera View", color_img); // show frame
  
  59          capture = cvWaitKey(10); // wait 10 ms or for key stroke
  
  60          if(capture == 27 || capture == 13 || capture == 32){break;} // if ESC, Return, or space; close window.
  
  61      }
  
  62      cv_cap_IP.release();
  
  63      delete Ipl_IP_Img;
  
  64      delete IplClickPointStorage;
  
  65      cvDestroyWindow("Camera View");
  
  66      return;
  
  67    }
  
  68    
  
  69    int main()
  
  70    {
  
  71      while(1)
  
  72      {
  
  73          cout &lt;&lt; "Please Enter Video-Feed Address: ";
  
  74          cin >> videoFeedAddress;
  
  75          if(videoFeedAddress == "exit"){return 0;}
  
  76          cout &lt;&lt; "\nvideoFeedAddress: " &lt;&lt; videoFeedAddress &lt;&lt; endl;
  
  77          displayCameraViewTest();
  
  78          if(cvWaitKey(10) == 27){return 0;}
  
  79      }
  
  80      return 0;
  
  81    }
  
  </algorithm></chrono></array></streambuf></cstring></string></iostream></fstream>

  Using added ’cout’s I was able to narrow it down to line 38 : "cv_cap_IP.open(videoFeedAddress) ;"

  No value I enter for the videoFeedAddress variable seems to get a different result. I found THIS site that lists a number of possible addresses to connect to it. Since there exists no 7100 anywhere in the list & considering that the install is labeled "DCS-7010L" I used the addresses found next to the DCS-7010L listings. When trying to access the camera most of them can be reached through the browser, confirming that they reach the camera - but they don’t seem to affect the outcome when I use them in the videoFeedAddress variable.

  I’ve tried many of them both with and without username:password, the port number (554), and variations on ?.mjpg (the format) at the end.

  I searched around and came across a number of different "possible" answers - but none of them seem to work for me. Some of them did give me the idea for including the above username:password, etc stuff, but it doesn’t seem to be making a difference. Of course, the number of possible combinations is certainly rather large- so I certainly have not tried all of them (more direction here would be appreciated). Here are some of the links I found :

  1. This is one of the first configurations my code was in. No dice.
  2. This one is talking about files - not cameras. It also mentions codecs - but I wouldn’t be able to watch it in a web browser if that were the problem, right ? (Correct me if I’m wrong here...)
  3. This one has the wrong error code/points to the wrong line of code !
  4. This one mentions compiling OpenCV with ffmpeg support - but I believe 2.4.6.0 already comes with that all set and ready ! Otherwise it’s not that different from what I’ve already tried.
  5. Now THIS one appears to be very similar to what I have, but the only proposed solution doesn’t really help as I had already located a list of connections. I do not believe this is a duplicate, because as per THIS meta discussion I had a lot more information and so didn’t feel comfortable taking over someone else’s question - especially if I end up needing to add even more information later.

  Thank you for reading this far. I realize that I am asking a somewhat specific question - although I would appreciate any advice you can think of regarding OpenCV & network cameras or even related topics.

  ---

  TLDR : Network Camera and OpenCV are not cooperating. I’m unsure if
  it’s the address I’m using to direct the program to the camera or the
  command I’m using - but no adjustment I make seems to improve the
  result beyond what I’ve already done !

• OpenCV and Network Cameras -or- How to spy on my neighbors ?

  12 mai 2014, par Alexander

  ---

  A bit of context ; this program was built originally to work with USB cameras - but because of the setup between where the cameras needs to be and where the computer is it makes more sense to switch to cameras run over a network. Now I’m trying to convert the program to accomplish this, but my efforts thus far have met with poor results. I’ve also asked this same question over on the OpenCV forums. Help me spy on my neighbors ! (Totally with their permission, of course !) :D

  ---

  I’m using :

  • OpenCV v2.4.6.0
  • C++
  • D-Link Cloud Camera 7100 (Installer is DCS-7010L, according to the instructions.)

  ---

  I am trying to access the DLink camera’s video feed through OpenCV.

  I can access the camera through it’s IP address with a browser without any issues. Unfourtunately ; my program is less cooperative. When attempting to access the camera the program gives the OpenCV-generated error :

  warning : Error opening file (../../modules/highgui/src/cap_ffmpeg_impl.hpp:529)

  This error occurs with just about everything I try that doesn’t somehow generate more problems.

  For reference - the code in OpenCV’s cap_ffmpeg_impl.hpp around line 529 is as follows :

  522    bool CvCapture_FFMPEG::open( const char* _filename )
  
  523    {
  
  524        unsigned i;
  
  525        bool valid = false;
  
  526
  
  527        close();
  
  528
  
  529    #if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(52, 111, 0)
  
  530        int err = avformat_open_input(&ic, _filename, NULL, NULL);
  
  531    #else
  
  532        int err = av_open_input_file(&ic, _filename, NULL, 0, NULL);
  
  533    #endif
  
  ...
  
  616    }

  ...for which I have no idea what I’m looking at. It seems to be looking for the ffmpeg version - but I’ve already installed the latest ffmpeg on that computer, so that shouldn’t be the issue.

  This is the edited down version I tried to use as per Sebastian Schmitz’s recommendation :

   1    #include <fstream>                            // File input/output
  
   2    #include <iostream>                           // cout / cin / etc
  
   3    #include                       // Windows API stuff
  
   4    #include                             // More input/output stuff
  
   5    #include <string>                         // "Strings" of characters strung together to form words and stuff
  
   6    #include <cstring>                            // "Strings" of characters strung together to form words and stuff
  
   7    #include <streambuf>                      // For buffering load files
  
   8    #include <array>                          // Functions for working with arrays
  
   9    #include <opencv2></opencv2>imgproc/imgproc.hpp>        // Image Processor
  
  10    #include <opencv2></opencv2>core/core.hpp>          // Basic OpenCV structures (cv::Mat, Scalar)
  
  11    #include <opencv2></opencv2>highgui/highgui.hpp>        // OpenCV window I/O
  
  12    #include "opencv2/calib3d/calib3d.hpp"
  
  13    #include "opencv2/features2d/features2d.hpp"
  
  14    #include "opencv2/opencv.hpp"
  
  15    #include "resource.h"                     // Included for linking the .rc file
  
  16    #include                             // For sleep()
  
  17    #include <chrono>                         // To get start-time of program.
  
  18    #include <algorithm>                      // For looking at whole sets.
  
  19
  
  20    #ifdef __BORLANDC__
  
  21      #pragma argsused
  
  22    #endif
  
  23
  
  24    using namespace std;                      // Standard operations. Needed for most basic functions.
  
  25    using namespace std::chrono;              // Chrono operations. Needed getting starting time of program.
  
  26    using namespace cv;                           // OpenCV operations. Needed for most OpenCV functions.
  
  27
  
  28    string videoFeedAddress = "";
  
  29    VideoCapture videoFeedIP = NULL;
  
  30    Mat clickPointStorage; //Artifact from original program.
  
  31
  
  32    void displayCameraViewTest()
  
  33    {
  
  34      VideoCapture cv_cap_IP;
  
  35      Mat color_img_IP;
  
  36      int capture;
  
  37      IplImage* color_img;
  
  38      cv_cap_IP.open(videoFeedAddress);
  
  39      Sleep(100);
  
  40      if(!cv_cap_IP.isOpened())
  
  41      {
  
  42          cout &lt;&lt; "Video Error: Video input will not work.\n";
  
  43          cvDestroyWindow("Camera View");
  
  44          return;
  
  45      }
  
  46      clickPointStorage.create(color_img_IP.rows, color_img_IP.cols, CV_8UC3);
  
  47      clickPointStorage.setTo(Scalar(0, 0, 0));
  
  48      cvNamedWindow("Camera View", 0); // create window
  
  49      IplImage* IplClickPointStorage = new IplImage(clickPointStorage);
  
  50      IplImage* Ipl_IP_Img;
  
  51      
  
  52      for(;;)
  
  53      {
  
  54          cv_cap_IP.read(color_img_IP);
  
  55          IplClickPointStorage = new IplImage(clickPointStorage);
  
  56          Ipl_IP_Img = new IplImage(color_img_IP);
  
  57          cvAdd(Ipl_IP_Img, IplClickPointStorage, color_img);
  
  58          cvShowImage("Camera View", color_img); // show frame
  
  59          capture = cvWaitKey(10); // wait 10 ms or for key stroke
  
  60          if(capture == 27 || capture == 13 || capture == 32){break;} // if ESC, Return, or space; close window.
  
  61      }
  
  62      cv_cap_IP.release();
  
  63      delete Ipl_IP_Img;
  
  64      delete IplClickPointStorage;
  
  65      cvDestroyWindow("Camera View");
  
  66      return;
  
  67    }
  
  68    
  
  69    int main()
  
  70    {
  
  71      while(1)
  
  72      {
  
  73          cout &lt;&lt; "Please Enter Video-Feed Address: ";
  
  74          cin >> videoFeedAddress;
  
  75          if(videoFeedAddress == "exit"){return 0;}
  
  76          cout &lt;&lt; "\nvideoFeedAddress: " &lt;&lt; videoFeedAddress &lt;&lt; endl;
  
  77          displayCameraViewTest();
  
  78          if(cvWaitKey(10) == 27){return 0;}
  
  79      }
  
  80      return 0;
  
  81    }
  
  </algorithm></chrono></array></streambuf></cstring></string></iostream></fstream>

  Using added ’cout’s I was able to narrow it down to line 38 : "cv_cap_IP.open(videoFeedAddress) ;"

  No value I enter for the videoFeedAddress variable seems to get a different result. I found THIS site that lists a number of possible addresses to connect to it. Since there exists no 7100 anywhere in the list & considering that the install is labeled "DCS-7010L" I used the addresses found next to the DCS-7010L listings. When trying to access the camera most of them can be reached through the browser, confirming that they reach the camera - but they don’t seem to affect the outcome when I use them in the videoFeedAddress variable.

  I’ve tried many of them both with and without username:password, the port number (554), and variations on ?.mjpg (the format) at the end.

  I searched around and came across a number of different "possible" answers - but none of them seem to work for me. Some of them did give me the idea for including the above username:password, etc stuff, but it doesn’t seem to be making a difference. Of course, the number of possible combinations is certainly rather large- so I certainly have not tried all of them (more direction here would be appreciated). Here are some of the links I found :

  1. This is one of the first configurations my code was in. No dice.
  2. This one is talking about files - not cameras. It also mentions codecs - but I wouldn’t be able to watch it in a web browser if that were the problem, right ? (Correct me if I’m wrong here...)
  3. This one has the wrong error code/points to the wrong line of code !
  4. This one mentions compiling OpenCV with ffmpeg support - but I believe 2.4.6.0 already comes with that all set and ready ! Otherwise it’s not that different from what I’ve already tried.
  5. Now THIS one appears to be very similar to what I have, but the only proposed solution doesn’t really help as I had already located a list of connections. I do not believe this is a duplicate, because as per THIS meta discussion I had a lot more information and so didn’t feel comfortable taking over someone else’s question - especially if I end up needing to add even more information later.

  Thank you for reading this far. I realize that I am asking a somewhat specific question - although I would appreciate any advice you can think of regarding OpenCV & network cameras or even related topics.

  ---

  TLDR : Network Camera and OpenCV are not cooperating. I’m unsure if
  it’s the address I’m using to direct the program to the camera or the
  command I’m using - but no adjustment I make seems to improve the
  result beyond what I’ve already done ! Now my neighbors will go unwatched !