motion detection and recording video with webcam

Question

I want to record a video with a webcam when a PIR sensor detect motion, I have the picamera library installed, can any one help, thank you?

import RPi.GPIO as GPIO
import time
import picamera
import datetime  # new

def get_file_name():  # new
    return datetime.datetime.now().strftime("%Y-%m-%d_%H.%M.%S.h264")

sensor = 4

GPIO.setmode(GPIO.BCM)
GPIO.setup(sensor, GPIO.IN, GPIO.PUD_DOWN)

previous_state = False

current_state = False

cam = picamera.PiCamera()

while True:

    time.sleep(0.1)

    previous_state = current_state
    current_state = GPIO.input(sensor)
    if current_state != previous_state:
        new_state = "HIGH" if current_state else "LOW"
        print("GPIO pin %s is %s" % (sensor, new_state))

        if current_state:
            fileName = get_file_name()  # new
            cam.start_preview()
            cam.start_recording(fileName)  # new
        else:
            cam.stop_preview()
            cam.stop_recording()  # new

Answer 1

If you don't need any custom logic, then you could install motion (sudo apt install motion), tweak its config file at /etc/motion/motion.conf, and have it record videos in your desired format (mp4, avi, swf, flv, etc..) when a 'motion event' occurs.

If you want movies to be saved to files, then make sure you set:

ffmpeg_output_movies on
ffmpeg_video_codec mp4  # can also use other formats
stream_localhost off  # otherwise only localhost connections are allowed
output_pictures off

It includes an HTTP MJPG streaming server which you can watch from your browser or hook to specialized webcam apps (see stream_port in the config).

You can run your own scripts or commands on certain event hooks. The useful ones are:

• on_event_start — fires when motion is detected
• on_movie_end — fires after a movie has been created, receives the path of the created video file, meaning you can e.g. automatically email it to yourself or send to a telegram chat.
• on_camera_lost — a hook you can use to take action in case something fails, i.e. restart the motion service or reboot your rpi.

Getting it to work the way you want involves getting your config right, and googling will return enough results for different scenarios, e.g. like this one.