The Python class c_video_frame_capture.py captures video frames as still image files in JPEG format

c_video_frame_capture.py

# 
# Name:     c_video_frame_capture.py
# Date:     January 19, 2022
# Author:   Randy Runtsch
#
# Description:
#
# The c_video_frame_capture class displays video from a webcam.
# When the user presses "p" it writes the a frame to a file
# as a JPEG image.
# 
# This classes uses the opencv library to display video and write frames.

# opencv tutorial: https://docs.opencv.org/4.x/d6/d00/tutorial_py_root.html

# Import the opencv (cv2) and datetime libraries.
import cv2
from datetime import datetime

class c_video_frame_capture:

    def __init__(self, camera_id, img_file_nm_base):

        # This constructor is designed to handle single images with the press of the 'p' key.
    
        # Base of image file location, including directory (for example, on Windows use forward slash: c:/frame_capture).
        self.img_file_nm_base = img_file_nm_base

        # Define the video capture object.
        self.vid_cap = cv2.VideoCapture(camera_id)

        if not (self.vid_cap.isOpened()):
            print("Could not open camera.")
            return

        self.capture_video()

    def capture_video(self):

        # Loop infinitely to view video.
        # When "p" is pressed, save a picture to a file.
        # When "q" is pressed, quit the program.

        while(True):
      
            # Capture the video, frame by frame
            ret, frame = self.vid_cap.read()
  
            # Display the resulting frame
            cv2.imshow('Frame', frame)
      
            # Handle key presses.
            key = cv2.waitKey(1)

            if key == 112:
                # Save frame when 'p' (ASCII code 112) is pressed.
                self.write_frame(frame)
            elif key == 113:
                # Quit programe when 'q' (ASCII code 113) is pressed.
                return

    def write_frame(self, frame):

        # Write the video frame to a JPEG file.

        now_string = self.get_now_string()
        cv2.imwrite("%s_%s.jpg" % (self.img_file_nm_base, now_string), frame)

    def get_now_string(self):

        # Return the current date time in this format: "YYYYMMDD_HHMMSS_microsecond".

        now = datetime.now()

        now_string = now.strftime("%Y") + now.strftime("%m") + now.strftime("%d") + '_' + now.strftime("%H") + now.strftime("%M") + now.strftime("%S") + '_' + now.strftime("%f")

        return now_string

get_cameras.py

# 
# Name:     get_cameras.py
# Date:     January 19, 2022
# Author:   Randy Runtsch
#
# Description:
#
# Use the pygrabber package to obtain
# the cameras active on the Windows computer.
# Note that this technique works only on Windows.

from pygrabber.dshow_graph import FilterGraph

cameras = FilterGraph().get_input_devices()
print(cameras)

run_video_frame_capture.py

# 
# Name:     run_video_frame_capture.py
# Date:     January 19, 2022
# Author:   Randy Runtsch
#
# Description:
#
# Use the c_vido_frame_capture class to write
# webcam video frames to jpeg files in the 
# specified folder.

from c_video_frame_capture import c_video_frame_capture

# Instantiate the c_video_frame_capture class with the camera ID and the name of the folder
# where frame capture JPEG files are to be stored. Note that the default camera ID is 0. To
# use other cameras, you will need to experiment. On Windows, run get_cameras.py
# obtain the list of cameras on the computer.

c_video_frame_capture(1, 'c:/frame_capture/frame')