python opencv設定不同的視訊編解碼器參數

環境：opencv 3.4.0 python 3.5.2讀取視訊

#環境：opencv 3.4.0    python 3.5.2
 
#讀取視訊
 
import cv2
 
cap = cv2.VideoCapture('video.avi')
 
 
#讀取攝像頭,0為攝像頭索引，當有多個攝像頭時，從0開始編号
 
cap = cv2.VideoCapture(0)
 
#從視訊或攝像頭中讀取一幀（即一張圖像）,傳回是否成功辨別ret(True代表成功，False代表失敗），img為讀取的視訊幀
 
ret,frame = cap.read()
           

完整的讀取視訊流并播放視訊流代碼

# -*- coding:utf-8 -*-
 
import cv2
 
cap = cv2.VideoCapture("video.avi")
 
while(1):
 
# 讀取視訊幀
 
    ret, frame = cap.read()
 
# 顯示視訊幀
 
    cv2.imshow("capture", frame)
 
#等候50ms,播放下一幀，或者按q鍵退出
 
if cv2.waitKey(50) &0xFF ==ord('q'):
 
    break
 
#釋放視訊流
 
cap.release()
 
#關閉所有視窗
 
cv2.destroyAllWindows()
           

建立視訊流寫入對象，VideoWriter_fourcc為視訊編解碼器，20為幀播放速率，（640，480）為視訊幀大小

#建立視訊流寫入對象，VideoWriter_fourcc為視訊編解碼器，20為幀播放速率，（640，480）為視訊幀大小
 
videoWriter = cv2.VideoWriter('video.avi', cv2.VideoWriter_fourcc('I', '4', '2', '0'), 20, (640,480))
 
#向視訊檔案寫入一幀
 
videoWriter.write(frame)
 
#詳解cv2.VideoWriter_fourcc對象(摘自Learning OpenCV3 Computer Vision with Python,坦白講不太懂)
 
#fourcc意為四字元代碼（Four-Character Codes），顧名思義，該編碼由四個字元組成,下面是VideoWriter_fourcc對象一些常用的參數，注意：字元順序不能弄混
 
#cv2.VideoWriter_fourcc('I', '4', '2', '0'),該參數是YUV編碼類型，檔案名字尾為.avi
 
#cv2.VideoWriter_fourcc('P', 'I', 'M', 'I'),該參數是MPEG-1編碼類型，檔案名字尾為.avi
 
#cv2.VideoWriter_fourcc('X', 'V', 'I', 'D'),該參數是MPEG-4編碼類型，檔案名字尾為.avi
 
#cv2.VideoWriter_fourcc('T', 'H', 'E', 'O'),該參數是Ogg Vorbis,檔案名字尾為.ogv
 
#cv2.VideoWriter_fourcc('F', 'L', 'V', '1'),該參數是Flash視訊，檔案名字尾為.flv
 
#以下為寫視訊的完整代碼
 
#-*-coding:utf-8-*-
 
import cv2
 
cap = cv2.VideoCapture('./dataset/video/cap_zhihao.avi')
 
fps =int(cap.get(cv2.CAP_PROP_FPS))
 
size = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)),
 
int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))
 
videoWriter = cv2.VideoWriter('video.avi', cv2.VideoWriter_fourcc('I','4','2','0'), fps, size)
 
ret, frame = cap.read()
 
while(ret):
 
    # 展示一幀
 
    cv2.imshow("capture", frame)
 
    videoWriter.write(frame)
 
    cv2.waitKey(fps)
 
    ret,frame = cap.read()
 
cap.release()
 
cv2.destroyAllWindows()