CODEWITHSUNDEEP
pythonpython-3.xopencvtimewhile-loop
simonEE
simonEE

Reputation: 91

time.sleep for only a part of the code inside infinite while loop

I'm working with a code that analyzes frames from a live stream with OpenCV and if a condition is met saves the current frame to file.

The infinite loop to analyze the video frame by frame is something like this:

while True:
  ret,frame = stream.read()
  if conditionisMet :
     pil_image = Image.fromarray(frame)
     pil_image.save("/path/to/folder/image.jpg")
  cv2.imshow("LiveStream", frame)

What I want to add is that if the condition is met again too soon (20-30 sec) the image does not have to be saved and the while loop has to grab another frame and continue its work. I've tried with time.sleep(30.0) inside the if statement but it blocks the while loop waiting for the 30 sec to pass. Is there a way to use time.sleep in this case, or another method suitable for my needs?

Thanks in advance

Upvotes: 0

Views: 685

Answers (3)

jeffpkamp
jeffpkamp

Reputation: 2866

you could do something like this:

last_grab=time.time()-30  # this to get things started
while True:
    if condition and time.time()-last_grab > 30:
        last_grab=time.time()
        # Do things here
    else:
        continue

Upvotes: 2

user5780947
user5780947

Reputation:

Why not just capture the amount of time running then save image if greater than the given amount of time....

a = dt.now()
b = dt.now()
c = b - a
if c < x:
    do something

Upvotes: 1

Bubble Bubble Bubble Gut
Bubble Bubble Bubble Gut

Reputation: 3358

Just add a variable to keep track of your last saving time:

last_save_time = time.time()

while True:
  ret,frame = stream.read()

  if conditionisMet and time.time() - last_save_time() > 20:
     pil_image = Image.fromarray(frame)
     pil_image.save("/path/to/folder/image.jpg")

     # update last save time
     last_save_time = time.time()

  cv2.imshow("LiveStream", frame)

Upvotes: 1

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