Raspberry Pi Camera Motion Detection via simple script

Question

I have started out my simple security camera project. I am able to take a picture and email it so far. Allegedly most people are using PIR sensors. Do I need a PIR sensor for motion detection?

How can I detect motion with my "Raspberry Pi Camera Module V2"?

I have the Raspberry Pi 3 Model B, any simple scripts appreciated.

Answer 1

download the latest os, and check if libcamera-* is available in terminal via autocomplete. Several options are available

• libcamera-hello libcamera-jpeg libcamera-raw libcamera-still libcamera-vid libcamerify
  If you wonder where raspistill and raspivid went the got replaced by a new stack and i confirm it works well. Python lib not out yet, still you can do motion detection.

Start by reading doc and then build the binaries into python via subprocess

Example:
before: mkdir /home/user/camera; paste motion_detect.json to dir
run via python capture.py

$ cat motion_detect.json
{
    "motion_detect" :
    {
    "roi_x" : 0,
    "roi_y" : 0,
    "roi_width" : 1,
    "roi_height" : 1,
    "difference_m" : 0.2,
    "difference_c" : 20,
    "region_threshold" : 0.005,
    "frame_period" : 30,
    "hskip" : 2,
    "vskip" : 2,
    "verbose" : 1
    }
}

import subprocess
import shutil
from datetime import datetime as dt
import os


def printc(s):
    print('\033[1;36mINFO\033[0m ' + s)


def get_sorted_filenames():
    filenames = [s for s in os.listdir('/home/user/camera') if s.startswith('vid')]
    filenames.sort()
    return filenames


def get_last_filenr():
    filenames = get_sorted_filenames()
    if len(filenames) == 0:
        return 0
    return int(filenames[-1].partition('_')[0].removeprefix('vid'))


def start_detect():
    return subprocess.Popen(['libcamera-still',
                             '--timeout', '0',
                             '--nopreview',
                             '--lores-width', '1280', '--lores-height', '720',
                             '--post-process-file', '/home/user/camera/motion_detect.json'],
                            stderr=subprocess.PIPE,
                            stdout=subprocess.DEVNULL,
                            text=True)


def start_recording():
    filename = f'vid{get_last_filenr() + 1}_{dt.utcnow().strftime("%Y-%m-%d-%H:%M:%S")}.h264'
    return subprocess.run(['libcamera-vid', '--timeout', '10000', '--framerate', '3', '-o', filename],
                          text=True, timeout=15, capture_output=True, check=True)


def free_disk_space():
    filenames = get_sorted_filenames()
    if len(filenames) > 100:
        to_delete = filenames[:len(filenames) // 4]
        for filename in to_delete:
            os.remove('/home/user/camera/' + filename)
        print(to_delete)
        printc('Delete done.')


p1 = start_detect()
p2 = None
while True:
    s = p1.stderr.readline()
    print(s, end='')
    if 'Motion detected' in s:
        printc('Motion detected, recording...')
        try:
            p1.terminate()
        except Exception as e:
            print(e)
            p1.kill()
        try:
            p2 = start_recording()
            printc('Video recorded.')
            print(p2)
        except Exception as e:
            print(e)
        p1 = start_detect()
        printc('Motion checking...')

    stats = shutil.disk_usage('/')
    if stats.used / stats.total > 0.9:
        printc('Disk almost full!')
        free_disk_space()

The specific motion capture used is found in https://github.com/raspberrypi/libcamera-apps/blob/main/post_processing_stages/motion_detect_stage.cpp