When simply grabbing a 1920x1080 image and displaying to screen, the OAK 4D is demonstrating over 5 seconds of latency. This is significantly different from our OAK-D S2 model which is able to grab a 1920x1080 image and display it to screen with nearly imperceptible latency. Is this all explained due to the different connection types (POE vs USB2)? If not, are there any suggestions for how to reduce the OAK-4D latency?

    Shai
    Can you share the script you are using to retrieve the frames? Or are you using OAK viewer?

    Thanks,
    Jaka

      For the OAK-D S2, we are using the pre-made rgb_preview.cpp example (except we changed the resolution output):

      #include <iostream>

      // Includes common necessary includes for development using depthai library

      #include "depthai/depthai.hpp"

      int main() {

      using namespace std;

      // Create pipeline

      dai::Pipeline pipeline;

      // Define source and output

      auto camRgb = pipeline.create<dai::node::ColorCamera>();

      auto xoutRgb = pipeline.create<dai::node::XLinkOut>();

      xoutRgb->setStreamName("rgb");

      // Properties

      camRgb->setPreviewSize(1920, 1080);

      camRgb->setBoardSocket(dai::CameraBoardSocket::CAM_A);

      camRgb->setResolution(dai::ColorCameraProperties::SensorResolution::THE_1080_P);

      camRgb->setInterleaved(false);

      camRgb->setColorOrder(dai::ColorCameraProperties::ColorOrder::RGB);

      camRgb->setFps(30); // Set FPS to 30

      // Linking

      camRgb->preview.link(xoutRgb->input);

      // Connect to device and start pipeline

      dai::Device device(pipeline, dai::UsbSpeed::SUPER);

      cout << "Connected cameras: " << device.getConnectedCameraFeatures() << endl;

      // Print USB speed

      cout << "Usb speed: " << device.getUsbSpeed() << endl;

      // Bootloader version

      if(device.getBootloaderVersion()) {

      cout << "Bootloader version: " << device.getBootloaderVersion()->toString() << endl;

      }

      // Device name

      cout << "Device name: " << device.getDeviceName() << " Product name: " << device.getProductName() << endl;

      // Output queue will be used to get the rgb frames from the output defined above

      auto qRgb = device.getOutputQueue("rgb", 4, false);

      while(true) {

      auto inRgb = qRgb->get<dai::ImgFrame>();

      // Retrieve 'bgr' (opencv format) frame

      cv::imshow("rgb", inRgb->getCvFrame());

      int key = cv::waitKey(1);

      if(key == 'q' || key == 'Q') {

      break;

      }

      }

      return 0;

      }

      For the OAK 4D, we are using the premade camera_output.cpp exampe:

      #include <iostream>

      #include <memory>

      #include <opencv2/opencv.hpp>

      #include "depthai/depthai.hpp"

      #include <chrono>

      int main() {

      // Create device

      std::shared_ptr<dai::Device> device = std::make_shared<dai::Device>();

      // Create pipeline

      dai::Pipeline pipeline(device);

      // Create nodes

      auto cam = pipeline.create<dai::node::Camera>()->build();

      //auto videoQueue = cam->requestOutput(std::make_pair(640, 400))->createOutputQueue();

      std::cout << "FPS: " << cam->getMaxRequestedFps() << std::endl;

      auto videoQueue = cam->requestOutput(std::make_pair(1920, 1080))->createOutputQueue();

      videoQueue->setBlocking(false);

      videoQueue->setMaxSize(1);

      // Start pipeline

      pipeline.start();

      while(true) {

      auto videoIn = videoQueue->get<dai::ImgFrame>();

      if(videoIn == nullptr) continue;

      cv::imshow("video", videoIn->getCvFrame());

      if(cv::waitKey(1) == 'q') {

      break;

      }

      }

      return 0;

      }

        Hi Shai
        I would expect there is a slightly lower latency going from USB connection on the S2 to the POE on the OAK4, but 5 seconds is too much and points toward an issue in your network.
        Are you using WIFI perhaps? Or are there multiple jumps/NATs between your PC and your device?

        Thanks,
        Jaka