Nvv4l2decoder rtsp delay

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

hello, i I use a webcam on nx， this is my code：

int main(void)
{
std::string pipe = “rtspsrc protocols=0x00000001 location=rtsp://admin:admin123@192.168.1.64:554/h264/ch1/main/av_stream latency=0 drop-on-latency=true max-size-buffers=0 ! rtph264depay ! nvv4l2decoder enable-max-performance=1 disable-dpb=1 ! nvvidconv output-buffers=1 ! video/x-raw, format=BGRx ! videoconvert ! video/x-raw,format=BGR ! appsink sync=0”;
cv::VideoCapture cap(pipe, cv::CAP_GSTREAMER);

    if( !cap.isOpened() )
    {
            std::cout << "Not good, open camera failed" << std::endl;
            return 0;
    }
 
    cv::namedWindow("Frame", cv::WINDOW_AUTOSIZE);
    cv::Mat frame;
    while(true)
    {
            cap >> frame;
            cv::resize(frame, frame, cv::Size(800, 640), 0, 0);
            cv::imshow("Frame", frame);
            cv::waitKey(1);
     }

}

now i got 200ms delay, I want to reduce the delay to 100 milliseconds or less，what can i do？

Screenshot from 2021-09-26 11-50-45
Screenshot from 2021-09-26 11-50-451920×1080 143 KB

2

A few things to try:

  • resize with nvvidconv instead of opencv that is CPU implementation, that may help. Just resize specifying new resolution in caps after nvvidconv:
... ! nvvidconv ! video/x-raw, format=BGRx, width=800, height=640 ! ...

  • opencv imshow is not very fast on Jetson. You may try a VideoWriter with a gstreamer pipeline to a displaysink instead. Searching this forum you may find some examples.

  • Using rtspsrc latency=0 may not lead to best latency… It depends on your network. Better start with a few (say 10) frames latency and use sync=true, then try decreasing and see.

3

thanks a lot， i will try。