9. OpenCV compilation and installation

Many customers encounter problems with OpenCV, and they mostly focus on how to obtain the data of the mipi camera. Because the V4l2 protocol used by OpenCV is different from the mipi camera driver protocol written by Rockchip, the camera API of OpenCV cannot be used directly. This section describes how to compile Opencv and add GStreamer API support.

9.1. Require:

  • OS: Ubuntu18.04 / Debian 10

  • OpenCV version: 3.4.15

  • Board: RK3399

9.2. Compile and install

  1. Build a python3.7 virtual environment

    # Install compilation environments such as gcc and cmake in turn
    # Install python3.7-tk and python3.7-dev
    # Install virtualenv virtual environment
    sudo apt install gcc cmake git build-essential \
    python3-tk python3.7-dev \
    virtualenv
    
  2. Create a python3.7 virtual environment

    virtualenv -p /usr/bin/python3.7m /home/firefly/venv
    # Use a virtual environment, if you want to quit, you can enter deactivate in the terminal
    source /home/firefly/venv/bin/activate
    
  3. Install the required environment packages for Opencv

    # Install the compilation environment, gtk package and related codec libraries
    sudo apt install cmake build-essential libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev libtbb2 libtbb-dev libjpeg-dev libpng-dev libtiff-dev libdc1394-22-dev libjasper-dev
    
    # Notice! If rknn_toolkit(or lite) is installed, you do not need to install Python-numpy, otherwise rknn_toolkit(or lite) will be unavailable
    sudo apt install python-numpy
    
  4. Download Opencv

    # Create folder
    mkdir opencv
    cd opencv
    
    # Download opencv-3.4.15.zip
    wget https://github.com/opencv/opencv/archive/refs/tags/3.4.15.zip
    unzip opencv-3.4.15.zip
    
  5. Configure

    mkdir build
    cd build
    
    # Making connections between OpenCV and Python3
    cmake -D CMAKE_BUILD_TYPE=RELEASE \
    -D 	PYTHON_DEFAULT_EXECUTABLE=$(python -c "import sys; print(sys.executable)")\
    -D PYTHON3_EXECUTABLE=$(python -c "import sys; print(sys.executable)")  \
    -D PYTHON3_NUMPY_INCLUDE_DIRS=$(python -c "import numpy; print (numpy.get_include())")  \
    -D PYTHON3_PACKAGES_PATH=$(python -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())")  \
    ../opencv-3.4.15
    
  6. To support Gstreamer API, perform the following configuration operations, otherwise skip

    sudo apt install libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev
    cmake -D WITH_GSTREAMER=ON ../opencv-3.4.15
    
  7. Compile and install

    # If the board memory does not exceed 2G, it is recommended not to exceed -j4
    make -j6
    # The installation process requires sudo privileges
    sudo make install
    

9.3. Test

  1. Test

    source /home/firefly/venv/bin/activate
    git clone https://gitlab.com/firefly-linux/test_code/rkisp-v4l2.git
    cd mipi_video_demo/OpenCV_Python
    python3 opencv_gst_test.py
    
  2. opencv_gst_test.py code

    import numpy as np
    import cv2 as cv
    import os
    import time
    
    cap = cv.VideoCapture('v4l2src device=/dev/video1 ! video/x-raw, format=NV12, width=640, height=480, framerate=30/1 ! videoconvert ! appsink', cv.CAP_GSTREAMER)
    
    if not cap.isOpened():
        print("Cannot capture from camera. Exiting.")
        os._exit()
    last_time = time.time()
    
    while(True):
    
        ret, frame = cap.read()
        this_time = time.time()
        print (str((this_time-last_time)*1000)+'ms')
        last_time = this_time;
        cv.imshow('frame', frame)
    
        if cv.waitKey(1) & 0xFF == ord('q'):
            break
    
    cap.release()
    cv.destroyAllWindows()