LibVNC

Zoneminder can not only record cameras, but can also do screen recording of Windows/Linux/Mac or any computer that uses VNC. LibVNC in 1.36 is a way to record VNC sessions. Any VNC server should be able to be used, but this guide has tested only TightVNC.

Setup

Using TightVNC on Windows

1. Install TightVNC. https://www.tightvnc.com/download.html

2. Setup a view only user with a password. Disable the primary user and also disable the java client. There is also the Access Control page where you can optionally put firewall rules in to only allow access to the ZM server.

Error creating thumbnail: Unable to save thumbnail to destination

My settings in Zoneminder look something like this. Note that I've specified to record only 2 FPS. For LibVNC, you should specify a max FPS. 2 is enough for my use case. Also note that there is no username, and instead just a password is used. The resolution may be any value that you want to record at. I have not tested how it affects performance, but have had success with both 1600x600 and also at say 320x240.

NOTE: on the firewall page, the proper syntax for blocking all ips is:

allow ip low  ip high
block 0.0.0.0 255.255.255.255

In that order. You can't simply put block 0.0.0.0, you must put the whole range there.

Settings

Error creating thumbnail: Unable to save thumbnail to destination

Error creating thumbnail: Unable to save thumbnail to destination

The frame rate should be set to a limit, otherwise LibVNC may run at 200+fps. LibVNC also is unable to use h264 passthrough, as it doesn't use FFMPEG, therefore you must either save JPEGs or encode. Because of this, if you don't set an FPS limit, and/or you use too high a framerate, you could run into swapping/high CPU usage. So, beware.

If everything goes right, you should have the computer screen recording in Zoneminder. Note: There has been a bug where the computers, if shut down then the recording will freeze in ZM. This can be avoided by restarting the monitor or ZM service after the computer is shut off (e.g. overnight).

Error creating thumbnail: Unable to save thumbnail to destination

Tips/Troubleshooting

Library Link Missing for LibVNCClient

In ZM 1.36 on Debian 11, you will have to manually add a symbolic link from /usr/lib/x86-64-linux-gnu/libvncclient.so.1 to libvncclient.so. ZM looks for the library without the .1 appended to it. This may also apply to other Debian releases.

See Also

• https://thetechnologyteacher.wordpress.com/vncthumbnailviewer/ Another project which screen records computers using VNC.