The Roadmap to IP Video

The security surveillance market is changing. A system that simply solves today’s problems is not enough. Integrators need to make choices that provide customers an upgrade path that is forward-compatible with IP architecture.

In progressive scan, the lines that make up the monitor picture are displayed all at once in sequence. It renders all lines in a single top-to-bottom pass, which requires twice as much data per pass as interlaced scanning. Thus, when migrating from analog to digital, the video data format needs converting from one that is compatible with interlaced fields to one that provides progressive frames. This process is called de-interlacing.

Properly processing the video from its native interlace form factor to high-quality progressive-scan data is extremely important to the overall quality of the resulting image. Not only will any de-interlacing artifacts be visible but they also increase the work the codec must do to compress the image, resulting in lower quality at a given data rate.

Importance of Storage Location

Integrators must be pay special attention of where the customer plans to store the video. Placing a camera on the edge of the network and bringing the images all the way back to the central station is doing the customer no favors. You are simply overloading the network with unneeded video. Instead, store video as close to the camera as possible.

Even in a single facility, put the recorder in the closest possible closet to a camera. With multiple sites, consider a recording device at each site. This lets you isolate video streams to keep them off the general network. Instead, the only video on the general network is the video needing to be viewed.

In addition, make sure that video storage and management are done on a software platform on a conventional server. At present, most video management software (VMS) platforms run on a box, which can add too much complexity and cost, especially for smaller applications.

There are places for the VMS approach, but you and your customer may be better served by a near-future line of products that are appliance-based. This means the servers and software are configured and running on the network. When migrating to IP video surveillance, integrators want to assure customers their new video hardware provides an agnostic interface that allows them to use whatever software they want.

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Analog Vs. Digital Resolution

The measurement of resolution (normally horizontal) in the analog world depends upon the perceived differentiation between lines on a standard NTSC or PAL resolution chart. This resolution depends upon how fast the electron beam can change its intensity as it traces the image.

In the digital world, resolution is determined by the actual number of pixels that make up an image, measured in horizontal
and vertical rows. The more pixels you have in an image, the more resolution you will have. 

The charged coupler devices (CCDs) used in cameras today are available in two resolutions. The lower resolution imager contains 510 horizontal rows and 484 vertical rows of pixels, or about 250,000 pixels. The higher resolution imager contains 768 horizontal rows and 494 vertical rows of pixels, or about 380,000 pixels.

The equivalence between the two methods of measurement can be accomplished by multiplying the number of horizontal rows of pixels by .75 to provide the equivalent lines of resolution. Thus, the typical analog resolution equivalence is 380 TVL for the 250,000 pixel (510 X .75 = 382.5) imager; and 540 TVL for the 380,000 pixel imager (768 X .75 = 576).

Other imagers in megapixel formats are available in resolutions of 1 million to 5 million pixels. These imagers are just now becoming popular in the surveillance industry. When recording these images, the picture is then resized to various standard sizes measured in pixels recorded as follows:

QCIF — 176 X 144 pixels

CIF* — 352 X 288 pixels

4CIF — 704 X 576 pixels

D1 — 720 X 576 pixels

*- Common Intermediate Format

In the analog world, the resolutions are limited by the number of lines the magnetic head can trace on video tape. In the digital world, the resolutions of images that can be recorded are much higher and are limited by the industry compression standards (e.g. MJPEG, MPEG4, H.264).

Take a Close Look at the Monitor

The preceding transformation is done in the DVR but, again, beware: Not all DVRs are created equal. Before selecting one DVR unit vs. another, look at the results. The biggest caveat in creating a high-resolution IP video surveillance system is to remember that what your customer looks at is the monitor.

Remember, if the cameras are analog and the monitor is digital, de-interlacing creates a progressive scan at the DVR and passes it on to the digital monitor. But when customers want to get a couple of more years out of their analog monitors, the progressive scan needs to be reconverted back to the interlacing method. This is the step at which the image can get softened and jaggy.

In addition, don’t forget high-resolution cameras that ultimately feed their images to a lower resolution monitor will only provide the user with lower resolution images. The two key specifications integrators need to remember involve contrast and response time. It is imperative the monitor provides 1,000:1 contrast. Secondly, you don’t want blurs. Remember the lower the millisecond response time, the better the picture, so specify at least a 5ms response time to assure moving video will be viewed cleanly.

Start Selling Total Integration

When companies switch from analog to digital video systems, IP surveillance provides more options for their overall security systems. Not only can the surveillance system be integrated with the data network, it can also interface with the alarm system, alarm sensors and/or the access control system — solutions you are probably already marketing.

Mike Capulli is Senior V.P. of North American Sales for SAMSUNG | GVI Security.

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