CV2 read video - and save image or video

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title: cv2 Read video , And save images or videos
date: 2022-07-02 18:10:24
tags: opencv

@TOC

cv2 Read video , And save images or videos

cv2 The general process of reading video

1. Get video cap = cv2.VideoCapture()
2. Judge whether the obtained video is successful , If the video object is successfully read, it returns True. cap.isOpened()
3. Read by frame ret, frame = cap.read()
4. Show the image cv2.waitKey(1)

Read the local file video and show

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


def read_video_show(videoName):
    ''' opencv  Read video  cv2.VideoCapture(filename) # Read local video  cv2.VideoCapture(index) # Get the camera  '''

    #1.  Read video 
    cap = cv2.VideoCapture(videoName) # If the parameter is 0,  Local camera 
    
    #2.  Judge whether the read video stream is successful 
    while cap.isOpened(): # When successful 
        
        #3.  Get images per frame 
        ret, frame = cap.read() # If successful ,ret by True, Otherwise False;frame It's an image 
        
        if ret: # Successfully obtained image 
            cv2.imshow('frame', frame) # Two parameters , One is the name of the display , One is pixel content 
            key = cv2.waitKey(25) #  Stop 25ms, When it comes to 0 The jam will not continue in the first frame 
            if key == ord(' ') or key == ord('q'): # When typing a space or q when , The exit while loop 
                break

    cap.release() # Release video 
    cv2.destroyAllWindows() # Release all windows that display images 

def read_video_save(videoName):

    ''' opencv  Save the video  cv2.VideoWriter(filename, fourcc, fps, frameSize, [isColor]) '''

    cap = cv2.VideoCapture(videoName)

    # Video properties 
    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) # Get the width of the original video 
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) # Get the original video 
    fps = int(cap.get(cv2.CAP_PROP_FPS)) # Frame rate 
    fourcc = int(cap.get(cv2.CAP_PROP_FOURCC)) # Video coding 

    # Output of video object 
    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) # Write video 

        if key == ord('q'):
            
            break
    cap.release() # Release video 
    out.release()
    cv2.destroyAllWindows() # Release all display windows 

def read_video_write(videoName):
    '''  Read the video and save the screenshot  cv2.imwrite(filename, frame) '''
    cap = cv2.VideoCapture(videoName)

    # Video properties 
    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) # Get the width of the original video 
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) # Get the original video 
    fps = int(cap.get(cv2.CAP_PROP_FPS)) # Frame rate 
    fourcc = int(cap.get(cv2.CAP_PROP_FOURCC)) # Video coding 

    n, i = 0, 0 # Total frames , Save the second i A picture 
    
    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) # Save to snapshot 
                cv2.imshow('frame', frame)
                key = cv2.waitKey(25)
                if key == ord('q'):
                    break
    cap.release()
    cv2.destroyAllWindows()