Python OpenCV视频文件相关操作教程

import numpy as np
import cv2 as cv
cap=cv.VideoCapture("video.mp4")
#判断是否获取成功
while(cap.isOpened()):
    #获取每一帧图像
    ret,frame=cap.read()
    #是否获取成功
    if ret == True:
        cv.imshow("frame",frame)
    if cv.waitKey(25)&0xFF==ord("q"):
        break;
cap.release()
cv.destoryAllwindows()

import numpy as np
import cv2 as cv
#读取视频
cap=cv.VideoCapture("video.mp4")
width=int(cap.get(3))
height=int(cap.get(4))
out=cv.VideoWriter("out.avi",cv.VideoWriter_fourcc("M","J","P","G"),10,(width,height))
while(True):
    ret,frame=cap.read()
    if ret==True:
        out.write(frame)
    else:
        break
cap.release()
out.release()
cv.destroyAllWindows()

import numpy as np
import cv2 as cv
# 1.获取图像
cap=cv.VideoCapture('video.mp4')
#指定追踪目标
ret,frame=cap.read()
#行、高、列、宽
r,h,c,w=347, 301, 700, 308
win=(c,r,w,h)#追踪窗口为列行宽高
#追踪目标
roi = frame[r:r + h, c:c + w]
#计算直方图（HSV)
hsv_roi=cv.cvtColor(roi, cv.COLOR_BGR2HSV)
roi_hist=cv.calcHist([hsv_roi], [0], None, [180], [0, 180])
cv.nORMalize(roi_hist,roi_hist,0,255,cv.NORM_MINMAX)
# 4. 目标追踪，设置窗口搜索终止条件：最大迭代次数，窗口中心漂移最小值
term=(cv.TERM_CRITERIA_EPS|cv.TERM_CRITERIA_COUNT, 10, 1)
while (True):
    ret, frame=cap.read()
    if ret == True:
        #计算直方图的反向投影
        hsv=cv.cvtColor(frame, cv.COLOR_BGR2HSV)
        dst=cv.calcBackProject([hsv],[0],roi_hist,[0, 180],1)
        #进行meanshift追踪
        ret,win = cv.meanShift(dst,win,term)
        #追踪的位置绘制在视频上
        x,y,w,h=win
        img2 = cv.rectangle(frame, (x,y), (x+w, y+h), 255, 2)
        cv.imshow('frame',img2)
        if cv.waitKey(60) & 0xFF == ord('q'):
            break
    else:
        break
cap.release()
cv.destroyAllWindows()