Connecting IP Cameras to VMS System TutorialAuthor: John Honovich, Published on Nov 03, 2012
In this tutorial, we cover the fundamentals of connecting IP cameras to VMS systems, including:
- Analog vs IP
- Direct Integration
- 'Standards' - ONVIF / PSIA
- Advanced Integration - PTZ control, Panoramics
- Advanced Non Supported Functions
- Unicast vs Multicast
This tutorial reviews the key structural issues. For a lower level review of physically connecting IP cameras to VMSes, review our IP Video 101 training course.
Analog vs IP
Analog cameras, unlike IP, must be encoded / digitized before a VMS can recorded them. This is done either using encoder appliances or hybrid recorders. When analog cameras are connected to encoder appliances, the same rules and issues apply to them as for IP cameras. However, when analog cameras are connected to hybrid recorders, their video feeds are recorded directly, providing a simpler connection.
When connecting analog encoder appliances or IP cameras, one of three approaches is typically taken:
- Direct Integration
While the least commonly used, this approach is the most 'universal'. RTSP is a truly standards based video streaming protocol, used in many IP video applications beyond surveillance. Because of its wide use and maturity, it can connect almost any IP camera to most VMSes. All one needs to verify is the camera's specific RTSP URL syntax (see a list for IP cameras) and that one's VMS supports RTSP feeds. However, RTSP only connects a video stream. It providers for no other functionalities (like changing the frame rate or resolution on the VMS side, controlling PTZs, toggling i/o, etc.) Because of this, it is used mostly as a last resort to connect two otherwise incompatible systems. [See a member's discussion on RTSP pros and cons.]
Direct integration between an IP camera manufacturer and a VMS developer is the most common and reliable means of connection as the two parties share technical information and work together to ensure the integration works properly. Limitations to remember include:
- Time consuming and costly: VMS developers are often reluctant to integrate new IP camera manufacturer or those with lower sales volume. As such, while nearly all VMS vendors support direct integration with some IP camera manufacturers, many only have direct support for a fraction of all IP cameras available.
- Varies by model: Just because a VMS supports a specific manufacturer model does not mean they support all of the manufacturer's camera models. Users should check carefully that their specific model is supported and not just the manufacturer generally (i.e., do not just check if they support Sony, check if they support Sony SNC-CH240 or whatever specific model you will be using).
- Varies in depth: Just because a VMS integrates with a specific camera manufacturer model does not mean they support control or configuration of every functionality on that camera. Typically, only a small subset of the more basic ones are integrated though sometimes more advanced are available. If this is important, check on the details.
'Standards' - ONVIF / PSIA
Since 2008, the use of 'standards' to simplify and expand IP camera / VMS integration has been a big trend. Instead of directly integrating to the specifics of each IP camera manufacturer, a common method would be defined and used by all. Two significant groups emerged to battle to be that common method. ONVIF has won and PSIA has faded away for use with IP camera.
While ONVIF is not a 'true' standard, ratified by a standards body, within IP surveillance, it acts as a 'de facto' standard with the support of the biggest providers in the space and the adoption of more than 100 manufacturers. ONVIF experienced lots of problems in the field though these problems have diminished over the last 2 years.
ONVIF is a fairly reliable way to connect most cameras to most VMS systems for streaming video and control of basic functions like frame rate and resolution. However, more advanced functionalites like PTZ, i/o and motion detection still routinely suffer from integration problems. ONVIF actually uses RTSP but adds in more mechanisms to control and configure IP cameras.
Advanced Integration - PTZ Control, Panoramics
Controlling mechanical PTZs or dewarping video from panoramics are two advanced controls that are often not supported fully by VMS providers because of the significance increase in time and complexity of integrating them. Support certainly exists but the breadth of support can vary greatly among VMS providers.
Advanced Non Supported Functions
While IP cameras provide dozens of configuration options, typically only a handful of them may be configured / modified via the VMS. For instance, privacy masks, day/night settings, shutter speed and many more often must be done by connecting directly to the camera. Some VMSes do allow for configuration of more settings but it varies by VMS provider and IP camera manufacturer supported.
Unicast vs Multicast
Overwhelmingly, IP cameras use unicast to connect to VMS systems as they are direct streams from a single camera to a single recorder. However, sometimes, IP cameras use multicast to help facilitate connections to multiple recorder or live clients. For more on multicasting, see our multicasting for surveillance tutorial.
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