Slightly modified example to simulate motion detection and incrementing video file names

gistfile1.txt

import io
import picamera

def detect_motion(camera):
    stream = io.BytesIO()
    camera.capture(stream, format='jpeg', use_video_port=True)
    # Detect motion in the captured image. Presumably one would need a prior
    # image here to compare to ... this is left as an exercise for the reader!

    from random import randint
    motion_detected = (randint(0,10) == 0)    # fake motion detection
    print "Motion detected" if motion_detected else "No motion"
    return motion_detected

global_counter = 0

def get_filename():
    global global_counter
    global_counter += 1
    return 'motion%d.h264' % global_counter


def write_video(stream):
    # Write the entire content of the circular buffer to disk
    with io.open(get_filename(), 'wb') as output:
        with stream.lock:
            for frame in stream.frames:
                if frame.header:
                    stream.seek(frame.position)
                    break
            while True:
                buf = stream.read1()
                if not buf:
                    break
                output.write(buf)

def main(camera):

    stream = picamera.PiCameraCircularIO(camera, seconds=20)
    camera.start_recording(stream, format='h264')
    try:
        while True:
            camera.wait_recording(1)
            if detect_motion(camera):
                # Once we've detected motion, keep recording for 10 seconds
                # and only then dump the stream to disk
                camera.wait_recording(10)
                write_video(stream)
    finally:
        camera.stop_recording()


if __name__ == '__main__':
    with picamera.PiCamera() as camera:
        camera.resolution = (1280, 720)
        camera.vflip = True
        camera.hflip = True
        main(camera)