Resolving IP Camera / VMS Time Sync Problems

Author: Ethan Ace, Published on Nov 07, 2011

One issue which IP surveillance systems must address is syncing of time between cameras and the VMS in a surveillance network. In our experience, and as discussed in a recent lively discussion in our LinkedIn group, this is often overlooked, yet it is an extremely important issue. Cameras and recorders being out of sync could very well result in evidentiary video being thrown out in court. More commonly and mundane, out of synch cameras can result in 'lost' video and headaches for both users and integrators.

In this update, we look at the key issues including Network Time Protocol servers, GPS time appliances, and how IP cameras and VMS servers handle timing.

How Cameras Handle Time

Different manufacturers of IP cameras manage the camera's internal clock in different ways. Fundamentally, there are two options: manual and automatic via network time protocol.

Manual: This option requires the user to enter the current time in the camera's web interface. It allows for precise entry, but must be maintained manually. In some cases, the manual entry may be accomplished via a "sync to PC" button, which sets the time on the camera to the time of the workstation the user is accessing it from.

Maintaining a handful of cameras' internal time is easy to manage, though also easily forgotten, so manual entry is never recommended. In mid- to large-sized systems, manual entry is out of the question. Systems on a larger scale require too much time to manually update. There is also a higher risk that a camera will be missed or incorrectly set.

Automatic: Most current cameras may be synchronized to a network time protocol (NTP) source, whether it be a public source such as time.gov, or a private source, such as GPS master clock or dedicated time server. Synchronizing cameras automatically has multiple benefits. For one, no work is required to update the cameras in the future. Once the time source is set up, the process is automatic.

Most importantly, it ensures the cameras all have the same time. It should be noted that in many cases, this time does not have to be exact. It is much better to have all cameras say it is 2:10PM when it is in fact 2:14 than it is to have one say 2:05, another say 1:59, and another say 2:43. If one camera shows a theft occuring at 1PM, but the subject enters the building on another camera showing 4PM, there's a possibility this video may be inadmissable in court.

How Recorders Handle Timestamps

Just as cameras handle time differently, recorders may handle timestamps differently as well. The two most common ways a VMS may handle time are by stamping frames upon arrival, or using the camera's timestamp.

Get Video Surveillance News In Your Inbox
Get Video Surveillance News In Your Inbox

Stamping on arrival is exactly what it sounds like. The VMS system marks the time it receives each frame of video. This avoids issues with cameras being out of sync, since the server is using its own stamp on each camera. However, in very large systems, or systems with high latency, it may take longer for frames from one camera to arrive than frames from another camera, which will cause video to be out of sync. In most cases, this shouldn't be a large span of time. We would guess less than a second, unless the network is extremely high latency. However, users should at least be aware that this may occur.

Other systems use the timestamp added to video by the camera. If all cameras are synchronized, this is not an issue, and may be more accurate than stamping video upon arrival, due to the latency issues described above. However, if cameras are not synched, it can cause massive issues. If a camera's clock is off by two hours, video on the VMS system will be marked as two hours off. Attempting to use synchronized playback will especially get difficult, as recorded video will simply not be where the user expects it.

Software Solutions

In order to synchronize cameras, they need an NTP source from which to pull the current time. Internet servers, such as time.gov and ntp.org may be used, but this requires that the cameras be on a network with access to the internet, with ports opened for this communication. Many users regard this as an unacceptable security hole in their network, and choose to run sources internal to their network instead. There are at least two means by which this can be accomplished. The first method is via software. 

It should be noted that Windows is capable of running as a time server. However, there are some issues with doing so. First, in order to set any given server as an Authoritative Time Server, users must edit the Windows registry. Many users will not be comfortable with this process. Second, by default, Windows updates time from a master server once per week. In order to change this, users must once again edit the registry.

To simplify this process, third party NTP clients have been created. One popular client is NetTime. Using programs such as these, users may more easily set different parameters, such as a server list or update interval. Any given PC may be easily set to act as a master server, also. 

Hardware Solutions

In situations where it's undesirable to run a master time server on an existing server, dedicated hardware options exist. 

GPS-based: For systems which need to have accurate time, but do not want to open ports to the internet to retrieve it from an NTP source, GPS master clocks may be the only option. These clocks retrieve time from GPS satellites, which means they require clear antenna line of site to the sky. This is accomplished in one of two ways:

  • Window-mounted: The GPS antenna is mounted inside the building, in a window with a clear view of the sky. The obvious disadvantage to these models is that they need unobstructed access to a properly oriented window. In some cases, this may be hard to come by.
  • Exterior: Using units with exterior antennas is the second method. A receiver and master clock, is rack-mounted, located with other network equipment in the system. The antenna is located outside the facility, either wall- or roof-mounted. This places the antenna above other obstacles which may obstruct its connection to satellites. However, this is an obvious added expense, since exterior walls and roofs can be difficult and costly to penetrate.

GPS models are available in various price ranges. Veracity's TIMENET ($700-800 online) is a common option, and uses an interior window antenna. The latest version of TIMENET is PoE-powered, so it may be remotely located without need of a local power outlet, unlike its predecessor. For more systems requiring more precise capabilities and an exterior antenna, a number of manufacturers are available, such as Spectracom, Symmetricom, and Meinberg. Units such as these are commonly 2-3x the price of other options, however, and are normally only used when absolutely necessary.

Network Time-based: Master time servers which obtain their time from an NTP source are also available, and from many of the same sources as GPS clocks. The disadvantage to dedicated NTP servers is that once again, ports to the internet need to be opened, which will be unacceptable to some users. Generally, master clocks drawing time from NTP sources are only used when there is a reason users don't want to make an existing server into a master time server.

 

1 report cite this report:

Hikvision iVMS-4200 Tested on Sep 14, 2015
Though best known for their camera and recorders, mega Chinese manufacturer also makes their own VMS software. In this report, we share test...
Comments : PRO Members only. Login. or Join.

Related Reports

IBM / Genetec Surveillance System Investigated Over Philippines Human Rights Abuses on Mar 22, 2019
A lengthy investigation into an IBM video surveillance project in the Philippines, raising concerns IBM helped local police conduct a bloody...
Eagle Eye Favorability Results 2019 on Mar 21, 2019
Eagle Eye has been the biggest spender in the cloud VMS market including (via their owner) acquiring Brivo for $50 million and CameraManager from...
Large Hospital Security End User Interview on Mar 21, 2019
This large single-state healthcare system consists of many hospitals, and hundreds of health parks, private practices, urgent care facilities, and...
Covert IP Camera Shootout - Axis, Hanwha, Hikvision, March, Vivotek on Mar 20, 2019
Covert cameras were one of the last holdout areas for analog cameras. However, in the past few years, IP / HD covert cameras have become...
Genetec Security Center 5.8 Tested on Mar 19, 2019
Genetec has released Version 5.8. This comes after a wait of more than a year that caused frustrations for many Genetec partners. Our previous...
Large US University End-User Video Surveillance Interview on Mar 18, 2019
Schools have become targets in modern days of active shooters and terrorist fears. The need for video and access security is high. Universities...
Hikvision Favorability Results 2019 on Mar 18, 2019
Hikvision favorability results declined significantly in IPVM's 2019 study of 200+ integrators. While in 2017 Hikvision's favorability was...
ONVIF Favorability Results 2019 on Mar 15, 2019
In the past decade, ONVIF has grown from a reaction to the outside Cisco-lead PSIA challenge, to being the de facto video surveillance standard...
City Physical Security Manager Interview on Mar 14, 2019
This physical security pro is the Physical Security Manager for the City of Calgary. He is a criminologist by training with an ASIS CPP credential....
Pelco GFC 4K Dome Camera Tested (IMP831-1ERS) on Mar 12, 2019
Pelco has finally released their first 4K IP camera, after years of competitors' releases. Is this move too late? Or is their new GFC Professional...

Most Recent Industry Reports

UTC Interlogix Series 6 Tested on Mar 25, 2019
UTC Interlogix has long been deceptively OEMing Hikvision as our 2017 results show. Now, Interlogix is back with their newest IP camera series,...
Outdoor Camera Installation Guide on Mar 25, 2019
Outdoor camera installation can be fraught with problems. Creating a sturdy and weather tight mount is key for camera performance and longevity,...
Favorite Video Storage / Server Manufacturers 2019 on Mar 25, 2019
189 integrators answered this question: "What is your favorite storage device / server manufacturer for recording video? Why?" In general...
IBM / Genetec Surveillance System Investigated Over Philippines Human Rights Abuses on Mar 22, 2019
A lengthy investigation into an IBM video surveillance project in the Philippines, raising concerns IBM helped local police conduct a bloody...
Eagle Eye Favorability Results 2019 on Mar 21, 2019
Eagle Eye has been the biggest spender in the cloud VMS market including (via their owner) acquiring Brivo for $50 million and CameraManager from...
Large Hospital Security End User Interview on Mar 21, 2019
This large single-state healthcare system consists of many hospitals, and hundreds of health parks, private practices, urgent care facilities, and...
Silicon Valley Cybersecurity Insurance Startup Coalition Profile on Mar 20, 2019
Many industry people believe cybersecurity insurance is not worth it, as the voting and debate in our Cybersecurity Insurance For Security...
Covert IP Camera Shootout - Axis, Hanwha, Hikvision, March, Vivotek on Mar 20, 2019
Covert cameras were one of the last holdout areas for analog cameras. However, in the past few years, IP / HD covert cameras have become...
Top Metrics For Ensuring Integrator Profitability - Statistics on Mar 20, 2019
How do integrators ensure the profitability of their projects? As part of our profitability study, 100+ integrators answered the following...
Avigilon Launches 'Renewed Products Program' on Mar 19, 2019
There are lots of 'pre-owned' cars but pre-owned IP cameras? While such programs are common in other industries, in video surveillance, they are...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact