[Python] Python OpenCV 視訊應用與比圖運算

#https://stackoverflow.com/questions/33650974/opencv-python-read-specific-frame-using-videocapture?newreg=2495db9d80934aa3b199f6d8d7489f89
#opencv for python3 => http://www.lfd.uci.edu/~gohlke/pythonlibs/
#video guide : https://www.youtube.com/watch?v=ulJdZn0qBCQ

 

2021/3/29 更新 : python打印raw date : b'.............' 一個jpeg開始於\xff\xd8\xff\

2021/03/10 更新 : python3.8 在pycharm程式中 可以在File -> Setting -> Python Interpreter安裝

透過找尋opencv-python

或用 pip install opencv-python

確保python目錄下有cv2.cp38-win_amd64 重開pycharm即可使用

2021/03/11 更新

若安裝完opencv-python還是出現問題 如 :

https://blog.csdn.net/qq_37369201/article/details/108936470

使用系統管理者身分執行cmd : python -m pip -U opencv-contrib-python

Python OpenCV應用總整理

https://jennaweng0621.pixnet.net/blog/post/403630133-%5bpython%5d-opencv%E6%87%89%E7%94%A8%E7%B8%BD%E6%95%B4%E7%90%86

超完整版程式開始

import matplotlib
import numpy as np
import cv2

import imutils //https://stackoverflow.com/questions/29645278/webcam-open-cv-python-black-screen

cv2.namedWindow("preview") #設定視訊框的名稱
#此層放置了可讓 cv2.VideoCapture的視訊源範例

capture= cv2.VideoCapture(0) #新增一個視訊擷取物件為vc

#capture= cv2.VideoCapture('my_video.avi') #改寫成這樣就是放影片

#capture= cv2.VideoCapture("rtsp://user:password@192.168.2.0/h264") #改寫成這樣就是放串流

#reference :https://www.wongwonggoods.com/python/python-opencv-rtsp/

#此層放置了可讓 cv2.VideoCapture的視訊源範例

#capture.set(3,640) //3 = 寬 https://stackoverflow.com/questions/29645278/webcam-open-cv-python-black-screen

#capture.set(4,480) //4 = 高 https://stackoverflow.com/questions/29645278/webcam-open-cv-python-black-screen

#以上或可寫成: 

#capture.set(cv2.CAP_PROP_FRAME_WIDTH, 640)

#capture.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

width = capture.get(cv2.CAP_PROP_FRAME_WIDTH) #取得訊框寬

height = capture.get(cv2.CAP_PROP_FRAME_HEIGHT) #取得訊框高

print("Image Size: %d x %d" % (width, height)) #印出訊框寬高

# 若要儲存視訊可用

sz = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)), int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))

#fourcc = cv2.VideoWriter_fourcc(*'mpeg')

#fps=25

#out = cv2.VideoWriter('./videoCapture/output2.avi', fourcc,fps,sz)

# 若要儲存視訊可用

# 取得 Codec 名稱

fourcc = capture.get(cv2.CAP_PROP_FOURCC)

fourcc = int(fourcc)

codec = "".join([chr((fourcc >> 8 * i) & 0xFF) for i in range(4)])

print("Codec: " + codec)

# 取得 Codec 名稱

if capture.isOpened():  #嘗試打開capture物件並取得偵
    rval, frame = capture.read() #讀取偵並返回其布林直確定可以讀取
else:
    rval = False

while rval: #假設可以打開  也可使用capture.isOpened()來判斷
    

    # 若要儲存視訊可用

    #out.write(frame) # 開始儲存視訊

    # 若要儲存視訊可用

    cv2.imshow("preview", frame) #將cv2視訊框裡投放 capture物件讀取的frame訊框

    

    #設定成灰階

    #gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    #cv2.imshow('frame', gray)

    #設定成灰階

    rval, frame = vc.read() # 一幀一幀的獲取影象 while 持續讀取

   #frame = imutils.resize(frame, width=400) //https://stackoverflow.com/questions/29645278/webcam-open-cv-python-black-screen
    key = cv2.waitKey(20)
    if key == 113: # 按q拍照, 比照ASCII碼
        cv2.imwrite("fangjian2.jpeg", frame) #拍照存檔檔名
        break
    if key == 27: # 按esc停止, 比照ASCII碼
        break
capture.release()
cv2.destroyAllWindows() #強制摧毀所有頁框
cv2.destroyWindow("preview") #摧毀名為preview的視訊框


#While可以存在更多的功能鍵，只要比對ASCII碼即可‧

Python - OpenCV 播放影片

https://ricky10116.pixnet.net/blog/post/265683920-python---opencv-%E6%92%AD%E6%94%BE%E5%BD%B1%E7%89%87

import cv2

import time 

# 開啟影片檔案

cap = cv2.VideoCapture('C:\\Users\\Ricky\\Desktop\\Jurassic Park Trailer.webm')

# 以迴圈從影片檔案讀取影格，並顯示出來

while(cap.isOpened()):

  ret, frame = cap.read()

  #time.sleep(0.05) 

  cv2.imshow('frame',frame)

  if cv2.waitKey(1) & 0xFF == ord('q'):

    break

cap.release()

cv2.destroyAllWindows()

opencv-python啟用攝像頭錄影

https://www.itread01.com/content/1547376124.html

import cv2

cap = cv2.VideoCapture(0)

cap.set(3,320)#寬

cap.set(4,240)#高

sz = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)),

       int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))

# 為儲存視訊做準備

fourcc = cv2.VideoWriter_fourcc(*'mpeg')

fps=25

out = cv2.VideoWriter('./videoCapture/output2.avi', fourcc,fps,sz)

while True:

    # 一幀一幀的獲取影象

    ret,frame = cap.read()

    if ret == True:

        frame = cv2.flip(frame, 1)

        # 在幀上進行操作

        # gray = cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)

        # 開始儲存視訊

        out.write(frame)

        # 顯示結果幀

        cv2.imshow("frame", frame)

        if cv2.waitKey(1) & 0xFF == ord('q'):

            break

    else:

        break

# 釋放攝像頭資源

cap.release()

out.release()

cv2.destroyAllWindows()