title: cv2讀取視頻,并保存圖像或視頻 date: 2022-07-02 18:10:24 tags: opencv

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cv2讀取視頻,并保存圖像或視頻

cv2讀取視頻的一般流程

1. 獲取視頻 cap = cv2.VideoCapture()
2. 判斷獲取的視頻是否成功，成功讀取視頻對象則返回True。 cap.isOpened()
3. 按幀讀取 ret, frame = cap.read()
4. 展示圖像 cv2.waitKey(1)

讀取本地文件視頻并展示

from turtle import color
import numpy as np
import cv2 as cv
import cv2


def read_video_show(videoName):
    '''
    opencv 讀取視頻

    cv2.VideoCapture(filename) #讀取本地視頻
    cv2.VideoCapture(index) #獲取攝像頭
    '''

    #1. 讀取視頻
    cap = cv2.VideoCapture(videoName) #若參數(shù)為0， 則是本地攝像頭
    
    #2. 判斷讀的視頻流是否成功
    while cap.isOpened(): #當(dāng)成功時
        
        #3. 獲取每幀圖像
        ret, frame = cap.read() #若獲取成功，ret為True，否則為False；frame是圖像
        
        if ret: #成功獲取圖像
            cv2.imshow('frame', frame) #兩個參數(shù)，一個是展示畫面的名字，一個是像素內(nèi)容
            key = cv2.waitKey(25) # 停留25ms，當(dāng)為0的時候則堵塞在第一幀不會繼續(xù)下去
            if key == ord(' ') or key == ord('q'): #當(dāng)鍵入空格或者q時，則退出while循環(huán)
                break

    cap.release() #釋放視頻
    cv2.destroyAllWindows() #釋放所有顯示圖像的窗口

def read_video_save(videoName):

    '''
    opencv 保存視頻

    cv2.VideoWriter(filename, fourcc, fps, frameSize, [isColor])
    '''

    cap = cv2.VideoCapture(videoName)

    #視頻屬性
    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) #獲取原視頻的寬
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) #獲取原視頻的搞
    fps = int(cap.get(cv2.CAP_PROP_FPS)) #幀率
    fourcc = int(cap.get(cv2.CAP_PROP_FOURCC)) #視頻的編碼

    #視頻對象的輸出
    out = cv2.VideoWriter('video_output.avi', fourcc, 20.0, (width, height))
    # out = cv2.VideoWriter('out.avi', fourcc, 20.0, (width, height))
    
    while cap.isOpened():
        ret, frame = cap.read()
        cv2.imshow('fame', frame)
        key = cv2.waitKey(25)

        out.write(frame) #寫入視頻

        if key == ord('q'):
            
            break
    cap.release() #釋放視頻
    out.release()
    cv2.destroyAllWindows() #釋放所有的顯示窗口

def read_video_write(videoName):
    '''
    讀取視頻并保存截幀

    cv2.imwrite(filename, frame)
    '''
    cap = cv2.VideoCapture(videoName)

    #視頻屬性
    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) #獲取原視頻的寬
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) #獲取原視頻的搞
    fps = int(cap.get(cv2.CAP_PROP_FPS)) #幀率
    fourcc = int(cap.get(cv2.CAP_PROP_FOURCC)) #視頻的編碼

    n, i = 0, 0 #總的幀數(shù)，保存的第i張圖片
    
    while cap.isOpened():

        ret, frame = cap.read()
        
        if ret:
            n += 1
            if n % fps == 0:
                i += 1
                filename = '{:0>4}.jpg'.format(str(i))
               
                cv2.imwrite(filename, frame) #存入快照
                cv2.imshow('frame', frame)
                key = cv2.waitKey(25)
                if key == ord('q'):
                    break
    cap.release()
    cv2.destroyAllWindows()

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