OpenCV 编译和安装

不少客户遇到OpenCV的问题多集中在如何获取mipi摄像头的数据。因为OpenCV使
用的V4l2协议和Rockchip编写的mipi摄像头驱动协议不同，所以不能直接使用
OpenCV的摄像头API。本节讲述如何编译Opencv并添加GStreamer API支持。

要求

OS： Ubuntu18.04 / Debian 10

OpenCV version： 3.4.15

Board: RK3399

编译和安装

搭建python3.7虚拟环境  # 依次安装gcc和cmake等编译环境 # 安装
python3.7-tk 和 python3.7-dev # 安装virtualenv虚拟环境 sudo apt
install gcc cmake git build-essential \ python3-tk python3.7-dev \
virtualenv

创建python3.7虚拟环境  virtualenv -p /usr/bin/python3.7m
/home/firefly/venv # 使用虚拟环境，如果想退出可以在终端输入 deactivate
source /home/firefly/venv/bin/activate

安装Opencv所需的环境包  # 安装编译环境、gtk包和相关编解码库 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  # 注意！如果安装了
rknn_toolkit(or lite)则不需要再安装Python-numpy，否则会导致
rknn_toolkit(or lite)无法使用 sudo apt install python-numpy

下载Opencv  # 创建文件夹 mkdir opencv cd opencv  # 下载
opencv-3.4.15.zip wget
https://github.com/opencv/opencv/archive/refs/tags/3.4.15.zip unzip
opencv-3.4.15.zip

配置  mkdir build cd build  # 让 OpenCV 和 Python3 之间建立联系 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

如需支持Gstreamer API，则进行以下配置操作否则跳过  sudo apt install
libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev cmake -D
WITH_GSTREAMER=ON ../opencv-3.4.15

编译安装  # 如果板子内存不超过2G，建议不超过-j4 make -j6 # 安装的过程
需要sudo权限 sudo make install

测试

测试  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 代码  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()