while True:
    ok, frame = capture.read()
    if not ok:
        break

    frame_count += 1
    raw_mask = subtractor.apply(frame)
    _, foreground_mask = cv.threshold(raw_mask, 254, 255, cv.THRESH_BINARY)
    writer.write(cv.cvtColor(foreground_mask, cv.COLOR_GRAY2BGR))

    if frame_count > args.warmup:
        foreground_pixels = cv.countNonZero(foreground_mask)
        if foreground_pixels:
            active_frames += 1
        if foreground_pixels > peak_pixels:
            peak_pixels = foreground_pixels
            peak_mask = foreground_mask.copy()