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• My crazy linux.conf.au week

  9 février 2012, par silvia

  In January I attended the annual Australian Linux and Open Source conference (LCA). But since I was sick all of January and had a lot to catch up on, I never got around to sharing all the talks that I gave during that time.

  Drupal Down Under

  It started with a talk at Drupal Down Under, which happened the weekend before LCA. I gave a talk titled “HTML5 video specifications” (video, slides).

  I spoke about the video and audio element in HTML5, how to provide fallback content, how to encode content, how to control them from JavaScript, and briefly about Drupal video modules, though the next presentation provided much more insight into those. I explained how to make the HTML5 media elements accessible, including accessible controls, captions, audio descriptions, and the new WebVTT file format. I ran out of time to introduce the last section of my slides which are on WebRTC.

  Linux.conf.au

  On the first day of LCA I gave a talk both in the Multimedia Miniconf and the Browser Miniconf.

  Browser Miniconf

  In the Browser Miniconf I talked about “Web Standardisation – how browser vendors collaborate, or not” (slides). Maybe the most interesting part about this was that I tried out a new slide “deck” tool called impress.js. I’m not yet sure if I like it but it worked well for this talk, in which I explained how the HTML5 spec is authored and who has input.

  I also sat on a panel of browser developers in the Browser Miniconf (more as a standards than as a browser developer, but that’s close enough). We were asked about all kinds of latest developments in HTML5, CSS3, and media standards in the browser.

  Multimedia Miniconf

  In the Multimedia Miniconf I gave a “HTML5 media accessibility update” (slides). I talked about the accessibility problems of Flash, how native HTML5 video players will be better, about accessible video controls, captions, navigation chapters, audio descriptions, and WebVTT. I also provided a demo of how to synchronize multiple video elements using a polyfill for the multitrack API.

  I also provided an update on HTTP adaptive streaming APIs as a lightning talk in the Multimedia Miniconf. I used an extract of the Drupal conference slides for it.

  Main conference

  Finally, and most importantly, Alice Boxhall and myself gave a talk in the main linux.conf.au titled “Developing Accessible Web Apps – how hard can it be ?” (video, slides). I spoke about a process that you can follow to make your Web applications accessible. I’m writing a separate blog post to explain this in more detail. In her part, Alice dug below the surface of browsers to explain how the accessibility markup that Web developers provide is transformed into data structures that are handed to accessibility technologies.

• sting up ffmpeg to work in XAMPP

  1er juin 2012, par danny

  I'm trying to figuring out how to install and use ffmpeg on windows 64 with XAMPP.

  I have flow this tutorial and install the ffmpeg-php librarys and I can see the expansion in the phpinfo().

  Now I put my ffmpeg.exe in the site root folder and I run this php script :

  extension_loaded('ffmpeg') or die('Error in loading ffmpeg');
  
  
  
  function convertTo( $input, $output ) 
  
  {
  
  echo $cmd = "ffmpeg -i $input $output";
  
  $outputData = array();
  
  exec( $cmd , $outputData);
  
  echo "<br />";
  
  print_r($outputData);
  
  }
  
  
  
  convertTo( "input.mp4", "output.flv" );

  and I get this output :

  ffmpeg -i input.mp4 output.flv
  
  Array ( )

  but no encoded file.
  My php safe mode is off and the movie file is in the root folder too.

  workplace info :

  • win7 64bit
  • XAMPP 1.7.2
  • Apache 2.2
  • php 5.3.5

  Help will be appreciated.

• 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 !