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• Reading images from AXIS ip camera using OpenCV

  14 juin 2016, par batuman

  I am trying to access AXIS IP camera from my program using OpenCV.
  My OpenCV version is 3.1. I follow this tutorial link.

  I have all libraries installed.
  My following program can load mp4 video successfully. That means ffmpeg and necessary libraries are working fine.

  #include <iostream>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  
  
  using namespace std;
  
  int main() {
  
      cv::VideoCapture vcap("test.mp4");
  
      cv::Mat image;
  
  //    const string address = "rtsp://root:pass@192.168.0.90/axis-media/media.amp?camera=1";
  
  //    if(!vcap.open(address)){
  
  //      std::cout &lt;&lt; "Error opening video stream or file " &lt;&lt; std::endl;
  
  //      return -1;
  
  //    }
  
      for(;;){
  
          if(!vcap.read(image)){
  
              std::cout &lt;&lt; "No frame" &lt;&lt; std::endl;
  
              cv::waitKey(0);
  
          }
  
          cv::imshow("Display", image);
  
          cv::waitKey(1);
  
      }
  
      return 0;
  
  }
  
  </iostream>

  When I tried to access the IP Camera as follow

  cv::VideoCapture vcap("rtsp://root:pass@192.168.0.90/axis-media/media.amp?camera=1");

  I have the following error

  GStreamer Plugin: Embedded video playback halted; module source reported: Could 
  
  not open resource for reading and writing.
  
  OpenCV Error: Unspecified error (GStreamer: unable to start pipeline
  
  ) in cvCaptureFromCAM_GStreamer, file /home/Softwares/opencv/opencv/modules
  
  /videoio/src/cap_gstreamer.cpp, line 818
  
  terminate called after throwing an instance of 'cv::Exception'
  
    what():  /home/Softwares/opencv/opencv/modules/videoio/src/cap_gstreamer.
  
  cpp:818: error: (-2) GStreamer: unable to start pipeline
  
   in function cvCaptureFromCAM_GStreamer

  User is root and password is pass and ip 192.168.0.90 are all defaults.

  My if config gave me

  ifconfig
  
  eth0      Link encap:Ethernet  HWaddr b8:2a:72:c6:b8:13  
  
            inet6 addr: fe80::ba2a:72ff:fec6:b813/64 Scope:Link
  
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
  
            RX packets:723959 errors:0 dropped:0 overruns:0 frame:0
  
            TX packets:116637 errors:0 dropped:0 overruns:0 carrier:0
  
            collisions:0 txqueuelen:1000 
  
            RX bytes:199422245 (199.4 MB)  TX bytes:13701699 (13.7 MB)
  
  
  
  lo        Link encap:Local Loopback  
  
            inet addr:127.0.0.1  Mask:255.0.0.0
  
            inet6 addr: ::1/128 Scope:Host
  
            UP LOOPBACK RUNNING  MTU:65536  Metric:1
  
            RX packets:24829 errors:0 dropped:0 overruns:0 frame:0
  
            TX packets:24829 errors:0 dropped:0 overruns:0 carrier:0
  
            collisions:0 txqueuelen:0 
  
            RX bytes:2502903 (2.5 MB)  TX bytes:2502903 (2.5 MB)
  
  
  
  wlan0     Link encap:Ethernet  HWaddr a0:a8:cd:99:92:60  
  
            UP BROADCAST MULTICAST  MTU:1500  Metric:1
  
            RX packets:0 errors:0 dropped:0 overruns:0 frame:0
  
            TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
  
            collisions:0 txqueuelen:1000 
  
            RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

  What could be the problem for this access to the camera ?

  Thanks

• Raspberry / Nginx RTMP video streaming player

  28 mai 2016, par Emmanuel Brunet

  I’ve set up a Nginx RTMP server that receives a flv stream from a raspberry cam using raspivid and avconv (ffmpeg)

  on the pi side I run

  /opt/vc/bin/raspivid -n -fl -mm matrix -w 800 -h 600 -fps 25 -g 80 -t 0 -b 6000000 -o - | avconv -re -i - -nostats -c copy -f flv rtmp://mercure/cam/live

  note : the target host is called mercure

  the Nginx rtmp module on mercure is set like bellow

  rtmp {
  
      server {
  
          listen 1935;
  
          # chunk_size 8192; # This might positively affect CPU load
  
          chunk_size 4096;
  
  
  
          application cam {
  
  
  
                  # max_connections 100;
  
                  live on;
  
                  # meta copy;
  
                  allow play all;
  
  
  
                  record all;
  
                  record_path /var/CCTV;
  
                  record_interval 1800s;
  
                  record_suffix -%Y-%m-%d-%T.flv;
  
  
  
                  hls on;
  
                  # hls_nested on;
  
                  hls_path /tmp/HLS;
  
          }
  
  }

  in the http section I’ve defined a hls location

      location /hls {
  
  
  
              root /tmp/HLS;
  
              types {
  
                      video/MP2T ts;
  
                      application/vnd.apple.mpegurl m3u8;
  
              }
  
      }

  when I run

  ffplay rtmp://mercure/cam/live

  it works like a charm but I can’t get it working with Vlc using the same url.

  Any idea ?

  otherwise I’m also trying to install a javascript rtmp / hls video player does anybody succeed or experienced using an open source component like flowplayer ? I’ve read a lot of doc about that but each time installs fail or some components are missing.

  please help me getting this stream available thru a web broser. thanks in advance

• WinAPI multithreading access violation when writing in local variable

  26 février 2016, par JustPingo

  I’m making a multithreaded program using Visual C++, Win32 API (using _beginthread) that also uses FFmpeg (it is claimed to be thread-safe, and I’m using it only with one single thread anyway).

  Here is the part of my thread’s code that causes problems (everything is inside of the thread function) :

  Arena* arena = NULL;
  
  
  
  switch (task) {
  
      case TaskOne:
  
          arena = (Arena*) malloc(sizeof(Arena));
  
          for (uint i = 0; i < FIGHTSPERROUND; i++) {
  
              generateArena(arena, ARENAWALLSAMOUNT, ARENAWIDTH, ARENAHEIGHT, ARENAMAXENTITIES, 255);
  
              spawnPlayer(arena, playerOne, 3, 1, 0, 0, ARENAPLAYERLIFE);
  
              spawnPlayer(arena, playerTwo, 2, 2, ARENAWIDTH-1, ARENAHEIGHT-1, ARENAPLAYERLIFE);
  
  
  
              do {
  
                  tickArena(arena);
  
              } while ((result = getResult(arena)) == 0);
  
  
  
              switch (result) {
  
                  case 1: teamOneScore++; break;
  
                  case 2: teamTwoScore++; break;
  
                  default: break;
  
              }
  
  
  
              freeArena(arena);
  
              clearMemory(playerOne);
  
              clearMemory(playerTwo);
  
              clearBrain(playerOne);
  
              clearBrain(playerTwo);
  
          }
  
          threadTeamOneScore[threadID] = teamOneScore;
  
          threadTeamTwoScore[threadID] = teamTwoScore;
  
          break;
  
  
  
      default: break;
  
  }

  Here is how I generate my arena :

  void generateArena(Arena* arena, uint wallsAmount, uint xSize, uint ySize, uint maxEntities, uint maxTurns) {
  
      CasesTypes** map;
  
      map = (CasesTypes**) malloc(xSize * sizeof(CasesTypes*));
  
      memset(map, 0, xSize * sizeof(CasesTypes*));
  
      for (uint i = 0; i < xSize; i++) {
  
          map[i] = (CasesTypes*)malloc(ySize * sizeof(CasesTypes));
  
          memset(map[i], 0, ySize * sizeof(CasesTypes));
  
      }
  
  
  
      arena->map = map;
  
      arena->entities = (Entity*) malloc(maxEntities * sizeof(Entity));
  
      memset(arena->entities, 0, maxEntities * sizeof(Entity));
  
      arena->width = xSize;
  
      arena->height = ySize;
  
      arena->maxEntities = maxEntities;
  
      arena->maxTurns = maxTurns;
  
      arena->currentTurn = 0;
  
      arena->entitiesAmount = 0;
  
      for (uint i = 0; i < wallsAmount; i++)
  
          arena->map[random2(1, xSize-1)][random2(1, ySize-1)] = Wall;
  
  }

  This works as expected 4 times in 5.
  But sometimes, for some reason, arena = (Arena*) malloc(sizeof(Arena)); throws an access violation exception.

  For example, Visual Studio 2015’s debugger once said :
  Exception thrown at 0x77DBE389 (ntdll.dll) in MyProgram.exe: 0xC0000005: Access violation writing location 0x007C160F.

  When I used the debugger to find what ((void*) 0x007C160F) was, it always happened to be something similar to :

  avformat-57.dll!0x007c160f (load symbols for additional information)

  avformat is a part of FFmpeg. The address was different every times, but it always had something to do with FFmpeg.

  I can’t figure out what is causing the problem.
  If that can help, sometimes the arena also happens to get corrupted (some of its fields get extremely big while generating them with generateArena although it is never changed and only set once to an integer, this leads to a crash later).

  Thank you in advance !