opencv讀寫視頻流

讀取視頻

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開始編號

cap = cv2.VideoCapture(0)

#從視頻或攝像頭中讀取一幀（即一張圖像）,返回是否成功標識ret(True代表成功，False代表失敗），img為讀取的視頻幀

ret,frame = cap.read()

 

#完整的讀取視頻流並播放視頻流代碼

# -*- coding:utf-8 -*-

import cv2

cap = cv2.VideoCapture("video.avi")

while(1):

# 讀取視頻幀

    ret, frame = cap.read()

# 顯示視頻幀

    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

#釋放視頻流

cap.release()

#關閉所有窗口

cv2.destroyAllWindows()

 

#創建視頻流寫入對象，VideoWriter_fourcc為視頻編解碼器，20為幀播放速率，（640，480）為視頻幀大小

videoWriter = cv2.VideoWriter('video.avi', cv2.VideoWriter_fourcc('I', '4', '2', '0'), 20, (640,480))

#向視頻文件寫入一幀

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意為四字符代碼（Four-Character Codes），顧名思義，該編碼由四個字符組成,下面是VideoWriter_fourcc對象一些常用的參數，注意：字符順序不能弄混

#cv2.VideoWriter_fourcc('I', '4', '2', '0'),該參數是YUV編碼類型，文件名后綴為.avi

#cv2.VideoWriter_fourcc('P', 'I', 'M', 'I'),該參數是MPEG-1編碼類型，文件名后綴為.avi

#cv2.VideoWriter_fourcc('X', 'V', 'I', 'D'),該參數是MPEG-4編碼類型，文件名后綴為.avi

#cv2.VideoWriter_fourcc('T', 'H', 'E', 'O'),該參數是Ogg Vorbis,文件名后綴為.ogv

#cv2.VideoWriter_fourcc('F', 'L', 'V', '1'),該參數是Flash視頻，文件名后綴為.flv

#以下為寫視頻的完整代碼

#-*-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()