Integrating video, access control and building management systems

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The world of DVR functionality seems to be advancing daily. Integrating DVR processes with access control systems and building management systems adds powerful new verification features. Displaying live video gives immediate visual feedback to a security manager when an event occurs. Incident creation can now include video evidence as part of the audit trail. Video icons can be placed on access control or building management facility maps giving immediate access to live views.

An access control or building management system provider adds video functionality directly into their applications using the API (Application Programming Interface) of a DVR. The Microsoft COM (Common Object Model) ActiveX control is a commonly used interface mechanism for a DVR API. The ActiveX control can be accessed from most programming languages under the Microsoft Windows operating system.

The API provides a set of programmatic interfaces that support various functional areas of the DVR. With that in mind, the three functional areas that companies need to consider are live video, video playback, events and control.

Live Video

Live video integrated into an access control system allows verification of building access. A security manager can view video of the individuals entering a building as a door is accessed. Multiple live video streams may be displayed showing views from several cameras covering the access event.

The access control system contains a database that maps building access points to cameras on specific DVRs. The camera access information includes the IP address, port, and camera input of the recorder. The live video ActiveX component establishes communications to the DVR, requests the appropriate video stream, decompresses it, and displays it to the computer screen.

PTZ control is also provided through the live video control. The control either displays a control interface directly or allows the application to implement its own PTZ interface by calling methods on the video control. The PTZ control interface can be used to call up a specific preset upon an event in the access control or building management system.

At a minimum the live display control shows a single camera. The control may also provide multiple display panes with each pane showing a camera from a different DVR. This allows the application to show video from multiple DVRs at the same time.

Video Playback

Another important element to consider is video playback control, which allows archived video data stored on the DVR to be recalled and displayed. The building management or access control system stores the beginning and ending times of events in their internal databases. The video playback control is called with the camera access information (IP Address, port and camera input) and the begin/end times. It initiates a connection to the DVR, requests the stored video data, retrieves the video data, decompresses it and displays it to the computer screen.

The playback control provides a programmatic interface that allows the control of play speed and direction. The control may also implement a user interface to control the playback of the video.

The retrieved video data can be stored into a file for archiving purposes on the building management or access control computer. Some DVR APIs include the ability to retrieve and display multiple cameras simultaneously. Audio can also be retrieved and played with the video. In addition, image enhancement tools may be provided. These tools allow images to be brightened or sharpened. They also allow image stills to be saved to bitmap or JPEG files for e-mailing or inclusion in incident reports.

A video export capability lets the video data be converted from proprietary formats to standard formats. This allows video to be easily e-mailed to other parties that may not have the necessary software installed to display the proprietary DVR video format.

Events and Control

Finally, the DVR is also a source of event data for access control or building management systems. DVR motion detection events, video loss events or contact closure events can all be logged into the access control or building management system databases. The DVR API has interfaces that call back to the remote system as events are generated.

DVR API control interfaces let a remote system modify the record mode, set pre-alarm record durations or generate alarm events. An access control system can use these interfaces to trigger recording of video only upon detection of events within their systems. A camera covering a building entrance could be set up to record with a 15 second pre-alarm period only when an alarm is generated. When the access control system triggers a door access event it can remotely generate an alarm on the DVR. This causes the DVR to record the video from that camera for a specified duration with a 15 second pre-alarm period.

Frequently asked questions

Is there a standard API for interfacing with a DVR?
There is currently no industry standard for accessing a DVR. Most manufacturers define their own programming interfaces to support the functionality provided by their recorders. The Microsoft COM object model is commonly used to provide visual components that can be integrated into applications.

Can I combine DVRs from multiple vendors into my system?
Individual access control or building management vendors may provide a common interface layer within their systems. Their application uses this common interface layer to hide the details of how to communicate with different DVRs and their APIs. In effect, this creates a standard API for their application to talk to DVRs from different vendors.

How much bandwidth does the video require on the network?
Video data inherently has much higher bandwidth requirements than typical access control or building management data. Video bandwidth depends on a number of factors including: compression technology, resolution, quality, scene complexity and rate. A typical MJPEG video frame at CIF quality is approximately 5KB of data. At a rate of 5 images per second this requires 25KByte/second. MPEG or proprietary inter-frame encoded compression technologies can reduce this rate significantly depending on the amount of motion contained in the scene. Some DVR APIs allow the overall bandwidth of the live or stored video connections to be throttled to a specified level.