Network-Centric Security

Megapixel and H.264: Made for Each Other?

• By Steven Titch
• Oct 01, 2009

Individually, megapixel and H.264 are significant, but when brought together, they may add up to more than the sum of their parts. Indeed, they may go together as well as John Coltrane and a tenor sax.

Both technologies are instrumental in the trend toward network-centric security. But the primary value proposition of megapixel cameras is that the increase in resolution they offer dramatically improves their range and field of vision.

As users mull the cost of a digital to analog conversion, megapixel means analog cameras do not have to be replaced one-forone.

In some installations, the ratio can be one megapixel camera to three or four standard cameras. Michael Hodor, vice president of sales in North America for Arecont Vision, recalled a Wal- Mart installation in which seven megapixel cameras replaced 26 analog VGA cameras.

But megapixel cameras create a problem: their image information generates huge video files that can tax bandwidth and storage capacities. An 8 megapixel camera can produce 1 terabyte of data every three days.

Enter H.264, the video compression algorithm used in the broadcast industry and now being adopted in surveillance cameras and video management systems. While H.264 will work with any video format, it may prove invaluable to the economy of megapixel video. Simply put, it can effectively reduce data volume five to six times on average. Yet, because of the much higher amount of data contained in a megapixel image, clarity is not sacrificed for compression.

The Rules Change
“When you start to do the math, you come out on top,” Hodor said. “Now with H.264, with the reduction of bandwidth and storage that happens, it’s easy to make the justification. If a VGA camera is about 2.5 MBs at a high frame rate and I can take a 2.5 megapixel camera and run it at H.264 and be in the same ballpark -- 2.5 to 3 MBs -- that changes everything.”

TimeSight Systems is attempting to leverage megapixel and H.264 through its concept of video lifecycle management. TimeSight manufactures NVRs that reduce the size of video files over time, taking them from highest information in the first few days of recording -- the high-risk period when surveillance video is likely to be most needed -- and gradually reducing the file size over time and as the risk period declines. TimeSight claims to be unique in applying a two-fold process to VLM-dynamic H.264 compression-over-time and motion optimized recording, in which, as the name suggests, more storage capacity is reserved for images containing object in motion.

Charles Foley, TimeSight CEO, said this stands to be a solution to the storage requirements the proliferation of video presents. There are more than 100 million surveillance cameras in use worldwide, he said, and shipments double each year.

Foley cited data that forecasts 65.6 million cameras will be deployed in 2013. He identified three related factors at work: more cameras are being deployed, video data is increasing because of all these new cameras and there is more data generated per camera than ever before.

Truth is, whether you use TimeSight’s approach to VLM or not, the case for megapixel plus H.264 is compelling from a general storage and quality standpoint. From a purely apples-toapples approach, a 40 KB H.264 megapixel compressed file is superior to a 40 KB VGA H.264-compressed file.

“You’ve got more pixels to work with,” Foley said. “Think of trying to capture an image of my face. If you have a hundred points to work with, that becomes a standard of quality. What if you have a thousand points to work with? You have much more granularity. Even if you compress it, you’re not giving up the points or the pixels, you’re giving up is the degree of differentiation between them in terms of color, light or shading. So by having more pixels available to you, you’ve got a finer grain to work with as you increase compression.”

A 2 megapixel image, Foley said, can be half the size of a VGA image and still get much better clarity because there is six times as much data to work with at the outset.

Bookend Appeal
Megapixel cameras and storage have “bookend appeal” in a sale, and integrators can use that as an advantage.

“When people start seeing what cameras can do, wheels start turning,” Hodor said. Arecont will often bring a storage vendor in as part of a proposal, he added.

In some cases, H.264 also can lighten the load on central processing units in NVRs and video management systems. For Arecont Vision, this is a competitive differentiator.

“With H.264, [users] expect to see a reduction in image quality and an increase in CPU demand by virtue of the processing that’s required and the decompression of that image,” Hodor said.

That is not the case with the Arecont line because of the efficiency of the algorithms working in the camera. Hodor points to CPU usage data from partner VMS equipment.

With Exacq Technology’s systems, CPU usage with Arecont Vision’s H.264 cameras dropped to 32 percent, compared to 96 percent usage with M-JPEG. With OnSSI’s VMS, CPU use decreased to 23 percent with Arecont Vision H.264 from 42 percent with M-JPEG.

“The biggest obstacles we have is people’s understanding of what this technology means and their ability to migrate over to this technology; not just megapixel, but the move from analog to IP,” Hodor said. “It’s really not that much different when you get right down to it. A network is just a network.”

This article originally appeared in the October 2009 issue of Network-Centric Security.