Dashcam script

My dashcam script

import picamera
import time
import os
import datetime as dt


def oldest_file_in_tree(rootfolder, extension=".avi"):
    return min(
        (os.path.join(dirname, filename)
        for dirname, dirnames, filenames in os.walk(rootfolder)
        for filename in filenames
        if filename.endswith(extension)),
        key=lambda fn: os.stat(fn).st_mtime)



video_dir = "/home/pi/Dashcam/video/"

camera = picamera.PiCamera()
camera.resolution = (1920, 1080)
#camera.brightness = 55
camera.sharpness = 30
#camera.contrast = 10
camera.rotation = 270

while True:
    b = os.statvfs(video_dir)
    space_remaining = (b.f_bsize * b.f_bavail) / 1500000

    while space_remaining < 500:
        print space_remaining
        os.remove(oldest_file_in_tree(video_dir, ".h264"))

        b = os.statvfs(video_dir)
        space_remaining = (b.f_bsize * b.f_bavail) / 1500000
        print space_remaining

    camera.annotate_background = picamera.Color('black')
    camera.annotate_text = dt.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    camera.start_recording(video_dir + str(time.strftime("%Y%m%d-%H%M%S")) + ".h264", quality=18)
    start = dt.datetime.now()

    while (dt.datetime.now() - start).seconds < 300:
        camera.annotate_text = dt.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
        camera.wait_recording(0.2)

    camera.stop_recording()