BeagleBone Security System

Since the BeagleBone (and the Raspberry Pi) is Linux based, and has usb ports, it is actually very easy (and cheap) to make a security camera system. All you need are USB webcams. Just about any will do. I got four for $16 on Amazon. More expensive ones might say they have higher resolution, but what they are actually reporting is the still photo quality, not streaming video quality. Unless you get a USB 3.0 webcam, which would not be supported by either hobbyist computer, it is impossible to stream HD (1080) video, but some might be able to 720. Even if it were possible, it becomes difficult to store so many photos or videos of that size. So keep it cheap, but make sure it is Linux compatible (UVC/V4L), which can be difficult to find sometimes.

One major limitation of this kind of system is the cord length limit on USB, which is only 2-7 meters (6-17 feet). It should be possible to get around this limitation with the use of hubs and repeaters.

Motion Detection Software

Motion is a great system for security systems. It monitors the camera for any motion and saves pictures or video (or both) only when there is something happening, which is great for saving space.

Installation (BeagleBone)

Motion is actually in the Angstrom package repositories! Why does that surprise me so much? Oh wait. They're for the wrong architecture ARM7a vs ARM7l. Would it work anyway? No idea. Probably best not to try. Ok, so this isn't going to be as easy as it could be. Download the source from the motion homepage by finding a link to it in your web browser and then:

opkg install kernel-module-uvcvideo libavformat-staticdev
ln -s /usr/include/libv4l1-videodev.h /usr/include/linux/videodev.h
ln -s /usr/include/libavformat/avformat.h /usr/include/avformat.h
ln -s /usr/include/libavformat/avio.h /usr/include/avio.h
ln -s /usr/include/libavutil/avstring.h /usr/include/avstring.h
ln -s /usr/include/libavutil/attributes.h /usr/include/attributes.h
wget $URLGOESHERE
tar -xzf motion.tar.gz
#it will probably tell you the time is in the future.
#BeagleBone does not have the correct time. It has no clock.
cd motion-3.2.12/
./configure
make
make install

After all of that, I never got it to compile. I think it might be because the version of ffmpeg currently in the repo is old, but I'm not sure since this seems to have more to do with uvc.

track.c: In function 'uvc_center':
track.c:587:29: error: storage size of 'control_s' isn't known
track.c:589:24: error: 'V4L2_CID_PRIVATE_BASE' undeclared

If you use an older version of motion (3.2.6), you can get a different error involving jpeglib, but it's no easier to figure out.

This is a very good example of why Ubuntu on the BeagleBone is desirable. The installation process on Ubuntu is as easy as it is for the Raspbian (both are Debian based). So, even though I couldn't get it working in Angstrom, it is still possible to use a BeagleBone for this project

Raspberry Pi Installation

Motion is also in the Raspbian package repositories, which is not surprising since it's basically Debian.

sudo apt-get install motion

Isn't that easy? Why yes. Yes it is.

Configuration

Motion has a very usable configuration file in /etc/motion/motion.conf. Here are some useful configuration options:

width 640
height 480
framerate 10

# Threshold for number of changed pixels in an image that threshold 1500
# The quality (in percent) to be used by the jpeg compression (default: 75) quality 50

# Use ffmpeg to encode mpeg movies in realtime (default: off) ffmpeg_cap_new on

# Target base directory for pictures and films target_dir /var/log/security
#break into different folders based on days, not subdivided into hours
jpeg_filename %Y%m%d/camera-%t/motions/%H%M%S-%v%q movie_filename %Y%m%d/camera-%t/movie/%v-%Y%m%d%H%M%S # The mini-http server listens to this port for requests (default: 0 = disabled) webcam_port 8081
# Maximum framerate for webcam streams (default: 1) webcam_maxrate 10
# Restrict webcam connections to localhost only (default: on) webcam_localhost off

Saving movies instead of just images turns out to be surprisingly efficient. For example, a day in my setup yielded 7640 images and only 35 movies, which meant 210MB vs 55MB of storage space. So, to save space, "output_motion off" might be a good change. Saving both kinds of motions (video and stills) at 640x480, 2.3GB could be used on a busy day, but with an average of more like 100MB. Obviously, it will depend on how often things move in your cameras' field of view and what you have your threshold set at. In most cases, you will want a large SD card or maybe even an external USB HDD to store these on.

One really cool feature of motion is that it can stream the webcam image over HTTP as an mjpeg. So, by visiting the BeagleBone's address and webcam_port (ex http://beaglebone.local/8081), you can watch the in a browser from somewhere in your own network. However, if you do port forwarding, or the beaglebone has a public IP, you can keep an eye on things from anywhere in the world. It does not, however, have a way to password protect the stream. So keep that in mind before making it public.

Automatic Cleanup

To make sure that the local storage does not fill up, you can delete old data. This can be done automatically based on age using cron and the find program. The following crontab will search for anything over the specified age (in days) and delete it. Note that this does not guarantee that there will be enough disk space. For example, if a few days with lots of motion occur, it could fill up before influx ages enough.

crontab -e 
# m h dom mon dow command 45 1 * * * find /var/log/security/ -maxdepth 1 -ctime +145 -exec rm -rf {} \;
# delete anything (non-recursively) in /var/log/security older than 145 days