mirror-to-yesterday/webcam.py

from datetime import datetime, date, time, timedelta
import cv2


def five_minute_segment_from(the_time):
    return the_time.replace(minute=(the_time.minute // 1)*1, second=0, microsecond=0)

def video_address_for(time_stamp):
    return 'videos/' + str(time_stamp) + '.mkv'

queue = [(False, None)] * 100 #queue of recent frames
last_time_stamp = five_minute_segment_from(datetime.now()) 
  
# live webcam feed
camera = cv2.VideoCapture(0) 
camera.set(cv2.CAP_PROP_FPS, 30.0)
if not camera.isOpened():
    print("Cannot open camera")
    exit()

# video writer
fourcc = cv2.VideoWriter_fourcc(*'H264')
out = cv2.VideoWriter(video_address_for(last_time_stamp), fourcc, camera.get(cv2.CAP_PROP_FPS), (int(camera.get(3)),int(camera.get(4))))

# video feed from previously captured video
old_time = cv2.VideoCapture(video_address_for(last_time_stamp))

idx = 0 
offset = 0
longterm = False
while(True): 
    if last_time_stamp != five_minute_segment_from(datetime.now()):
        out.release()
        out = cv2.VideoWriter(video_address_for(last_time_stamp), 
            fourcc, 
            camera.get(cv2.CAP_PROP_FPS), 
            (int(camera.get(3)), int(camera.get(4)))
            )
        if old_time.isOpened():
            old_time.release()
        old_time = cv2.VideoCapture(video_address_for(five_minute_segment_from(datetime.now() - timedelta(minutes=10))))

    last_time_stamp = five_minute_segment_from(datetime.now())

    ret, frame = camera.read() 
    frame = cv2.flip(frame, 1)

    #recod the frame
    out.write(frame)
    queue[idx] = ret, frame


    showo, fr = queue[(idx - offset) % len(queue)]
    if longterm:
        ret2, frame2 = old_time.read()
        if ret2:
            cv2.imshow('vid', frame2)
    elif showo:
        cv2.imshow('vid', fr)
      
    # the 'q' button is set as the  quitting button you may use any  desired button of your choice 
    key = cv2.waitKey(1) & 0xFF
    if key == ord('q'): 
        break
    if key == ord('a'):
        offset += 1
    if key == ord('d'):
        offset -= 1
    if key == ord('z'):
        longterm = not longterm

    idx = (idx + 1) % len(queue)
  
# After the loop release the cap object 
camera.release()
out.release()
# Destroy all the windows 
cv2.destroyAllWindows()