At the moment, I am now playing with the Nemesis security cam software written by John Ferlito. Again, this seems to be a topical question on the SLUG list, so I thought I would put a few notes up on my WWW server from how I set it up. This is an attempt to provide alternate documentation on stuff I could not easily find out about Nemesis and that would have made it's installation easier. The version I used was Nemesis V1.0.
Nemesis software is at http://nemesis.inodes.org. At the time of installation, Nemesis was a system to capture images from one video camera and save the images as separate files to 24 different directories depending upon the hour of capture.
All this information on obtaining and setting up cam hardware and software is available on my page. So, I am not going to repeat it here. Nemesis software is just a specialised use.
Now, Nemesis runs by each hour, using cron to kick off a script (start_hour.pl) that requests a perl script (stream.pl)
to collect X number of images, where X is determined by the number of frames per second
and the time to the next hour.
So each hour, the script looks up a table to determine which sub-directory the image should be stored in.
So you need to allocate (up to) 24 subdirectories to hold these images. Firstly, you need to determine how
big an images is and how much space you will need. The software documentation gives some estimates.
How I did it was on the physical disk location /mnt/disk1/camera/, establish
24 directories ##, from 00, 01, 02, .......22, 23, 24. Then
"ln -s /mnt/disk1/camera /cam" to establish a root directory
sub-directory /cam.
(20000531)Also change the %k to %L in start_hour.sh. %k returns 0, 1, to 22, 23,
%I returns 00, 01, ... 22, 23.
Okay, I'm lazy, but it is smart lazy and a whole lot easier to enter /cam/00 to /cam/24, then to enter twenty four times "/mnt/disk1/camera/00".
You will need to enter this information twice. Once in stream.pl, where it is easy to spot the line to modify.
The second time is in nemesisrc, which is where vplay, the image viewer program looks to find the images to display.
It is a trivial mental exercise to realise that /cam can easily be come /cam1, ... /camy in your root directory to allow
for the twenty four directories to be spread over different hard disks.
Once you have the software, it is a simple matter of reading the doco and running ./configure,
make and make install. Of course, you have to do this three times. First with glib, then gtk,
then the Nemesis software.
I had problems with gtk 1.2.6 and I had to invoke the --ignore-something-or-other options before
it would configure okay. It basically kept on telling me that it had a pre 1.2.4 version of glib.
I will try and remember what the actual option was, but I can tell you that there is a ./configure --help
that may help you out if you strike problems.
The only other problem that I ran into was getting vplay, the image viewer working. Firstly was finding
out about nemesisrc, the file that tells vplay where to look for the files for each hour.
The next problem was understanding what the four fields in the player were for. These turned out to
be for hour, minute, second and hundredth of seconds. Basically, just use the up and down triangles to
increment or decrement the value in the boxes, then hit the play button. You can continually hold down the left
mouse button to have it zoom forward or backwards.
The only thing you need to be aware of is that vplay takes the values in the fields, applies a formula
and looks for an image #####.jpg depending on the time values. The play button causes it to attempt to
rotate through the five images for the second. If you have reduced the fps (frames per second) in stream.pl,
you may see error messages about not being able to find #####.jpg and the image displayed will not be
for that time, but will be from a later time. I assume increasing the fps will cause vplay to display earlier images.
The explanation as to why this happens is that stream.pl simply calls a program streamer and tells it to
spit out sequentially numbered images from 00000.jpg until it stops.
As well as the usual crowd (Richard Stallman for GNU, Linus Torvalds for Linux), thanks should John Ferlito who hacked it all together. TAAH.
You know the patter - if you use this info, you do so at your own risk. I have no idea whether this software meets any legal or privacy considerations. As I understand it, you can capture any image in a public street, but need a warning sticker to advise people that their image/photo may be taken if they enter a private place. There is something about having date and time and crc if you want to use this in a legal forum to charge people with criminal acts.