Python: use time.sleep with opencv without stopping the video footage

Question

Im using opencv for detecting a hand gesture (in this case, when i lift my index finger), when that happens it prints "hi", then i use time.sleep to pause the print for 1 second because it will print it until I put my index down, but time.sleep pauses the entire footage, so if i sleep 5 seconds, the footage wont run untile those 5 seconds have passed

What can I do to use the time.sleep without pausing the footage

while True:
  #all the opencv initial stuff
  #mediapipe functions for the hand detection

  if INDEX_UP:
     print("hi")
     time.sleep(2)
  
  cv2.imshow("Frame", frame)
  if cv2.waitKey(1) & 0xFF == 27: break

Im trying to use time.sleep inside the while loop im using for opencv, but the time.sleep pauses the footage until the time.sleep finish

you can probably package one or both loops into a `threading.Thread` — ti7, Oct 29 '22 at 21:30

score 0 · Answer 1 · answered Oct 29 '22 at 22:31

I tried to use 2 separate threads for the entire while loop and another one for the sleep, it´s not sleeping.

def sleep():
  time.sleep(2)

def main_loop():
  while True:
  #all the opencv initial stuff
  #mediapipe functions for the hand detection

  if INDEX_UP:
     print("hi")
     th.Thread(target=sleep).start()
  
  cv2.imshow("Frame", frame)
  if cv2.waitKey(1) & 0xFF == 27: break

th.Thread(target=main_loop).start()

score 0 · Answer 2 · answered Oct 29 '22 at 22:40

When you notice the index finger is lifted, get the system time, add 2 seconds and save that in a variable called pauseEndTime.

Now, in your main loop, if there is something you want to avoid doing during the pause, surround that thing with a test:

if currentTime > pauseEndTime:
   ...
   do stuff
   ...

If you want to continue acquisition during pauses, just run acquisition without that if check.

Python: use time.sleep with opencv without stopping the video footage

2 Answers2