2024-01-23-CMake編譯OpenCV-Python

Here is the minimal steps.
Here is my enviornment

• Windows 10
• Visual Studio Build Tools 2019
• CMake 3.29.0-rc1 (use default install setting)
• Gstreamer:(Use default install setting)
  MSVC 64-bit (VS 2019, Release CRT)
  1.22.10 runtime installer
  1.22.10 development installer
• Python3.8.10

For example, my gstreamer is install in D disk by default.

1. Add System Environment Variable GSTREAMER_ROOT_X86_64 value D:\gstreamer\1.0\msvc_x86_64
   gstreamer doc
2. Add enviornment variable GST_PLUGIN_PATH value D:\gstreamer\1.0\msvc_x86_64\lib\gstreamer-1.0
3. Add Path enviornment variable value D:\gstreamer\1.0\msvc_x86_64\bin
4. re-login the computer
5. create a Python venv and use it
6. pip install --verbose --no-binary opencv-python opencv-python
7. os.add_dll_directory() Shoud be add to code since from Python 3.8+, Python will NOT search DLL from PATH enviornment variable.ref
8. test code

import os
os.add_dll_directory("D:\\gstreamer\\1.0\\msvc_x86_64\\bin")
import cv2
gst = 'rtspsrc location=rtsp://192.168.8.57/live1s3.sdp timeout= 30000 ! decodebin ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1'

cap = cv2.VideoCapture(gst,cv2.CAP_GSTREAMER)
while(cap.isOpened()):
  ret, frame = cap.read()
  if not ret:
    break
  cv2.imshow('frame', frame)
  if cv2.waitKey(1) & 0xFF == ord('q'):
    break

cv2.destroyAllWindows()
cap.release()

步驟

• 安裝msvc2019 build tool
• 安裝python3.10.10
• 安裝gstreamer 1.25.90 runtime installer和development installer 都必須要裝!!
• 設定GSTREAMER_ROOT_X86_64環境變數
  gstreamer doc

<gstreamer資料夾>\1.0\msvc_x86_64

• 直接安裝source distributions版本的opencv-python(opencv 4.3.0之後的版本)
  pip install --verbose --no-binary opencv-python opencv-python

GST_PLUGIN_PATH或是GST_PLUGIN_SYSTEM_PATH(不一定要加)

gstreamer預設尋找plugin的順序如下

1. %HOMEDRIVE%%HOMEFOLDER%/.gstreamer-1.0/plugins
2. C:\gstreamer\1.0\x86\lib\gstreamer-1.0
3. ..\lib\gstreamer-1.0
4. %GST_PLUGIN_PATH%
   <gstreamer資料夾>\1.0\msvc_x86_64\lib\gstreamer-1.0

gstreamer doc

Path變數

<gstreamer資料夾>\1.0\msvc_x86_64\bin

載入時手動加入dll路徑

os.add_dll_directory()
ref

測試

import os
os.add_dll_directory("D:\\gstreamer\\1.0\\msvc_x86_64\\bin")
import cv2
gst = 'rtspsrc location=rtsp://192.168.8.57/live1s3.sdp timeout= 30000 ! decodebin ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1'

cap = cv2.VideoCapture(gst,cv2.CAP_GSTREAMER)
while(cap.isOpened()):
  ret, frame = cap.read()
  if not ret:
    break
  cv2.imshow('frame', frame)
  if cv2.waitKey(1) & 0xFF == ord('q'):
    break

cv2.destroyAllWindows()
cap.release()

gstreamer載入時錯誤檢查

1. 用 Dependencies 軟體檢查dll缺少哪一些東西
   1. 下載後免安裝直接打開DependenciesGui.exe，打開venv\Lib\site-packages\cv2\cv2.pyd
2. plugin找不到的錯誤可能是找不到plugin的dll本身，或是找不到plugin所需要的dll

安裝CUDA

CUDA 設定

從4.0之後CUDA相關的功能被移到opencv_contrib，必須要編一opencv_contrib才能啟用CUDA功能

1. set CMAKE_ARGS="-DWITH_CUDA=ON"
2. pip install –verbose –no-binary opencv-contrib-python opencv-contrib-python

(選擇性)G-API

G-API說明
https://github.com/opencv/opencv/wiki/Graph-API