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.

Require

OS： Ubuntu18.04 / Debian 10

OpenCV version： 3.4.15

Board: RK3399

Compile and install

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

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

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

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

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

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

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

Test

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

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()