OpenCV webcam example

webcam.py

# import packages.
import numpy as np
import cv2
import time
  
# Initialize the fist webcam as webCam
webCam = cv2.VideoCapture(0)  
  
# Define the codec, fps, and resolution, to create the VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
fps = 30
width = 1280
height = 720
out = cv2.VideoWriter('output.mp4', fourcc, fps, (width, height))

# Initialize font, framecount, and start time.
font = cv2.FONT_HERSHEY_SIMPLEX
frameCount = 0
start = time.time()

# record
while(True):
    # read frame from webcam 
    ret, frame = webCam.read() 
    end = time.time()
    
    # calculate fps: frames per second
    fps  = int(1 / (end - start))
    fps_str = "Estimated frames per second : {0}".format(fps)
    # reset clock
    start = time.time()
      
    # output the frame to video
    out.write(frame) 
       
    # show webcam stream with fps
    cv2.putText(frame, fps_str, (7, 70), font, 1, (100, 255, 0), 3, cv2.LINE_AA)
    cv2.imshow('frame', frame)
        
    # break if 'q' key is pressed.
    key = cv2.waitKey(1) & 0xFF
    if key == ord('q'):
        break
  
# release webcam and video writer
webCam.release()
out.release() 

# close windows
cv2.destroyAllWindows()