OpenCv, calculate average fps in python

After having left the app to run for a couple of hours, I noticed that the memory had more than doubled.

From 70MB to 150MB of "Real Memory" as Mac's Activity Monitor puts it.

What was happening is that I had created a list that was growing with each frame in order to calculate the average of the frames.

I decided to get rid of this, first creating a circular counter in Python using a generator that resets to 0 when reaches a max value. Then initiating a fixed-size list that the generator will fill the fps in a circular manner.

It looks like this:

def circular_counter(max):
    """helper function that creates an eternal counter till a max value"""
    x = 0
    while True:
        if x == max:
            x = 0
        x += 1
        yield x

class CvTimer(object):
    def __init__(self):
        self.tick_frequency = cv2.getTickFrequency()
        self.tick_at_init = cv2.getTickCount()
        self.last_tick = self.tick_at_init
        self.fps_len = 100
        self.l_fps_history = [ 10 for x in range(self.fps_len)]
        self.fps_counter = circular_counter(self.fps_len)
    def reset(self):
        self.last_tick = cv2.getTickCount()
    def get_tick_now(self):
        return cv2.getTickCount()
    @property
    def fps(self):
        fps = self.tick_frequency / (self.get_tick_now() - self.last_tick)
        self.l_fps_history[self.fps_counter.next() - 1] = fps
        return fps
    @property
    def avg_fps(self):
        return sum(self.l_fps_history) / float(self.fps_len)

In your frame-by-frame while loop:

#Timecv:
cv2.putText(self.a_frame, "fps=%s avg=%s" % (timer.fps, timer.avg_fps),
            (10, 75), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255,255,255))

And finally in the app window: