Ok it’s been a good while since my last post, and it’s not that I haven’t been doing anything, just not writing about it. Which just creates problems when I need to remember how what I did and how.
I needed something to get my monitors back on my similar to my windows setup. That used to rotate around the cameras and would bring to the front specific cameras when motion was detected.
After a bit of searching I found xlib_shm http://www.zoneminder.com/wiki/index.php/Xlib_shm
Although it says it only works with 1.22.3, I’m currently running 1.24.2 on Ubuntu 11.04.
So after installing it and trying to run via the command line “./xlib_shm -m 11 -m 12 -m 3 -m 13 -m 14 -c 2 -k 0x7a6d0000” it complained about not being able to open the display. of course I’m running it from a terminal on the server itself, but gdm is already lauched and I’d alt+ctrl+f1’d out of it. So I stopped gdm with “/etc/init.d/gdm stop” and tried again, hey presto it runs.
So now how do I get this to run on boot?
One option is to have gdm auto login and then auto run xlib_shm. I had a few problems with this approach, First the login counter, it takes a few seconds to auto login and kick in xlib_shm and it’s just a bit untidy. Second xlib_shm launches in a window doesn’t look very pretty and I’d prefer full screen. Third was the mouse pointer happily sat smack in the middle of the screen, not a huge problem for a 4 split, but single screen or 9 and it’s in the way of the main detail on the picture.
So kill that idea, I want it straight in no hassle as quick as it can. So the best thing I could come up with was stop gdm launching and make a new script to startup xlib_shm. unfortunately this approach seemed to hit it’s own problems. killing gdm wasn’t as easy as it should have been because of changes in the way it’s now started in Ubuntu 11.04, and adding xlib_shm into the init.d was proving unreliable sometimes it beat gdm and grabbed the screen othertimes it didn’t.
So I had to find another way, and my answer was to try and figure out how X was started.
I ended up editing ‘/etc/X11/xinit/xinitrc’
commenting out the ‘/etc/X11/Xsession’ line and adding ‘exec /usr/sbin/xlib_shm -m 11 -m 12 -m 3 -m 13 -m 14 -m 15 -m 18 -m 19 -m 20 -c 3 -k 0x7a6d0000’ to the bottom.
now starting X with “startx” fires up xlib_shm full screen with a 9 split.
Problem hit though with the screen turning itself off.
Found out that setting a couple of dpms options then starting x would solve this so added the following into the xinitrc file after the exec line
xset s off &
xset -dpms &
Now to get this starting with the boot. Solution edit the ‘/etc/init.d/zoneminder’
Within the start section add ‘startx &’ and in the stop section add ‘killall -9 xlib_shm’.
Now on each reboot X starts up with xlib_shm and the screen doesn’t shutoff at all.
I’ve no doubt theres bits in here that I’ve missed, I got this all running months ago. When I did the same similar on a 2nd system, it was pretty straight forward and similar but I did hit another issue.
For some reason xlib_shm would occasionally crash out and return to the command prompt. However between this change and installing that I’d setup scripts to pull a few webcams and display them on a zoneminder monitor rotating the image. As that script fires a rotate every 10 seconds, my answer to the crashing was to add a check into this script to see if xlib_shm was running and if not to startx &.
So that’s the brief outline of me getting xlib_shm to work with Zoneminder 1.24.2 on Ubuntu 11.04.
One thing to note, restarting zoneminder via the interface is not the same as running /etc/init.d/zoneminder restart. Because of this via the interface does not restart xlib_shm. This causes problem (mainly when I was testing) because the zoneminder feeds would shutdown and xlib_shm would then crash. I got used to only restarting via the commendline, but the script mentioned above would counter this problem should xlib_shm crash now.