topic Re: OpenCV - Gstreamer pipeline in NavQ 8MMNavQ Discussion

OpenCV - Gstreamer pipeline

fabianmpa019 — Wed, 02 Sep 2020 15:05:21 GMT

Hi all,

I am trying to open a pipeline and create a VideoWriter object with OpenCV:

VideoCapture cap(" v4l2src ! video/x-raw,framerate=30/1,width=1920,height=1080 ! vpuenc_h264 ! avimux ! appsink ",CAP_GSTREAMER);
if(!cap.isOpened()){
std::cout<<"VideoCapture not opened";
exit(-1);
}
VideoWriter writer(" appsrc ! filesink location=video.avi ",0,30,Size(1920,1080),true);

It compiles, but when executed on the board i get:

Seems to be creating the pipeline but it gets stuck there.

Do you have any idea what could be happening?

Regards

Re: OpenCV - Gstreamer pipeline

iaingalloway — Wed, 02 Sep 2020 21:09:17 GMT

We'll check on this.

Re: OpenCV - Gstreamer pipeline

Landon_Haugh — Thu, 03 Sep 2020 14:28:08 GMT

Hey Fabian,

It seems as if you just created a VideoWriter object, but you aren't writing to that object. Is the source code you supplied the entirety of what you've compiled?

You need to add the following to your code in a loop:

Mat frame; cap.read(frame); writer.write(frame);

Re: OpenCV - Gstreamer pipeline

fabianmpa019 — Thu, 03 Sep 2020 15:12:46 GMT

Hi!!

Right, the code i shared was not complete.

The complete code is:

#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;

int main()
{
      VideoCapture cap("v4l2src ! video/x-raw,framerate=30/1,width=1920,height=1080 ! vpuenc_h264 ! avimux ! appsink",CAP_GSTREAMER);
      if(!cap.isOpened()){
             cout<<"VideoCapture not opened";
             return -1;
       }
      VideoWriter writer("appsrc ! filesink location=video.avi",VideoWriter::fourcc('M','J','P','G'),15,Size(1920,1080),true);

      if(!writer.isOpened()){
       cout<<"VideoWriter not opened";
             return -1;
       }
       while(1){
              Mat frame;
              cap.read(frame);
              writer.write(frame);
              if(waitKey(1) == 27){
                     break;
               }
        }
        cap.release();
        writer.release();
        return 0;
}

Re: OpenCV - Gstreamer pipeline

fabianmpa019 — Mon, 15 Feb 2021 05:43:26 GMT

Still not working this way, however, cross compiling OpeCV with Gstreamer and FFmpeg support, i am able to run scripts I had no been able to run on Navq and it seems is using Gstreamer caps. The instructions on how I achieved it are under my gitbook https://hovergames.gitbook.io/hovergames2/