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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

• How to process single segment from fragmented mp4 container ?

  14 septembre 2020, par user14258924

  I have fragmented mp4 that I stream. First the mp4 header and then individual segments that are each one GOP. It is h264 and aac encoded video that I am getting from RTMP server.

  


  I would like to process these individual segments with ffmpeg(I doubt there are other tools available). Either adjust resolution or bitrate or even transcode to vp8/9 or avi1 if needed.

  


  But it seems that ffmpeg cannot handle this because the segment has no header. So I wodner if there is a flag or set of flags for ffmpeg to be able to process these segments without the header ? I could possibly just take the raw h264 and aac packets from the RTMP and not pack it into MP4 container beforehand, if that helps - would ffmpeg be able to process these ?

  


• Faster frame extraction than ffmpeg

  23 janvier 2013, par Ben Ford

  I have a video analytics program that processes assorted frames from a video. (Several hours long)
  The video is likely going to be an MP4 but may be other formats going forwards.

  At the moment, I have a C# wrapper around an ffmpeg call to extract an individual frame at the requested time. (I'm using the ffmpeg.exe binary. Not the libraries directly)
  At the moment, this all works. But it's slow. Very slow.

  I've found ways to improve the speed by storing the extracted frames in a ramdisk while they're being processed. Changing the stored image format etc...

  I just wanted to check if anyone could think of any way to pull individual frames out. At split-second accuracy.
  I know this is probably possible with DShow etc... I went straight to FFMPEG as I've used it before. But if DShow is likely to be faster I'll gladly change !