Subscriber Discussion

VMS Automatically Adjusts For Daylight Savings?

In most of the US, daylight savings ends in a few days, on Nov 3rd.

I just read this article that worries video evidence could be thrown out because people fail to change the times on their surveillance systems to account for daylight savings. Does this not automatically happen on the computer/vms being used with the system? Do most people have to go do this manually?

While most PCs should without issue, a lot of cameras might not. I've seen quite a few that don't default to adjusting for daylight savings time. This might not be an issue, but some VMSs use the time sent by the camera instead of stamping video as it's received, in which case it would be problematic.

Its not the VMS that should/would accommodate daylight time changes, but rather the PC the server is installed on that should do it automatically. In regards to camera time:

I believe it is best practice to have the camera time stamp (in the video) to be turned off and have the VMS manage the time stamp rather than each individual camera. Otherwise, any camera reboots, resets or power outage may require a manual correction of the right time and when many cameras are installed it could get quite inefficient. Moreover, in case of a camera time stamp/VMS stamp of video discrepancies it could deem the video inadmissible I would think.

It isn't simply a matter of the time stamp being overlaid in the video (though that being incorrect is bad, too). A lot of cameras send metadata with the on board time, as well. If this is off it can drive some VMSs nuts. I've seen Exacq shift video from a Vivotek camera 8 hours into the future, for example, because camera time was off. Try syncing that up with cameras which don't suffer from the problem...

Interesting, so in essence it is a must to have each camera synched to a time server and must be configured individually?

All cameras point to one master NVR or VMS or server farm (server cluster) and this server point to a NTP server using GPS and automatic timing. (so no need to use internet connection) Veracity got some small linux POE box for example

When PC sever is taken care of time

why bother with syncing cameras ?

My experience lately only with Avigilon

when I never have to log in to camera at all

Some VMSes rely on each camera to provide their own time. In general, I think that is problematic.

Yea, agree

Now, I recal this with Exacq having problem long time ago

You're right, one point . OnlyIf you are using individual camera functions like SD recording in case of Network failure or extra FTP / Email alarms.

Good point. Edge recording (even if it's later transferred to a central server) certainly requires its own time at the camera.

All devices in a security system should run NTP and be synchronised to a master NTP time source. This includes cameras, VMS servers, storage systems, access control servers, and of course front-end client PCs and operator workstations. Ideally the master NTP time source should be local, as internet time sources are weaker evidentially and obviously require an open internet connection, which may not always be available.

It is worth noting that Windows-based systems are very bad at keeping time. (Even Microsoft admit this on their knowledge base website, saying that Windows is not suitable for use with time-critical applications). We recommend installation of a special driver to sync the Windows PC/server's hardware clock to the right time, and far more frequently than Windows does as standard. There is little point in having all the security devices correctly synced if the viewing/control/playback system clock is wrong.

Note further that all recordings of data (video, audio, ACS events, alarm events, meta-data, other data logging etc.) should all be timestamped with UTC time (Universal Co-ordinated Time) and then the local time-zone offset added at the playback/review/live view point. If everything is recorded referenced to UTC then the data is rock-solid evidentially with regard to time, even if some servers or workstations have screwed up their daylight savings time adjustments or time zone settings.

As we move into a world where more and more is being done in the camera and the central servers become less important, then it is even more vital that cameras are all capable of running NTP and are properly synchronised to a reliable (and verifiable) reference time source.