Squeeze Play – Wonders and Dangers of H.264
For Chris Hugman, it is both simple and complex.
“You can better manage bandwidth. You can store security video more efficiently,” he says. But with any tech advance, complexities – some hidden while others are more visible – can make or break an installation.
Right off the bat, enterprise security leaders face an alphabet soup of jargon.
H.264 (And yes, there were .263 and .262, along this evolutionary tree.) is really MPEG-4 Part 10. A holy alliance of the Moving Picture Experts Group and the Video Coding Experts Group, they developed a standard that promised to outperform earlier versions, providing better compression of video images and entitled Advanced Video Coding or AVC, published jointly as Part 10 of MPEG-4 and ITU-T Recommendation H.264. The ITU Telecommunication Standardization Sector (ITU-T) is one of three sectors the International Telecommunication Union which coordinates standards for telecommunications among private firms and public countries.
The digital video codec, finalized in 2003, aims at compressing video data to a very low bitrate while maintaining high quality video.
Evolution from Large-Scale Applications
Points out Kostas Mellos, who covers video and transmission for UTC's Interlogix, “Early implementations of the H.264 technology was primarily for large scale applications. As security manufacturers became more comfortable with implementing H.264 and the price of the devices utilizing the technology became more affordable, the adoption rate has increased. H.264 is now the preferred method of compression within the security industry.”
There is also that big difference between broadcast and movie needs, for example with cable modems and Blu-ray recorders, and security video applications. The former apps have the time to compress, transmit and decompress video while security video must be handled more quickly, sometimes in milliseconds, observes Fredrik Nilsson, general manager for Axis Communications.
OK, enough of the techie background.
In a pure business sense, as more video surveillance manufacturers implement H.264 in their cameras, encoders, video recorders and video management systems, end users and their IT owners of the corporate infrastructure see decreasing effects of multiple video streams over the network while significantly increasing storage capacity.
Mellos says, “The result is better images, faster refresh rates and longer recording time.”
There are a couple of tradeoffs, however. There is a need for more processing power at the backend to handle and unzip the data. And the gains of H.264 when compared to MJPEG, for instance, diminish somewhat when cameras capture more motion in scenes, a common situation in many security applications.
In a classic series of tests by Anixter’s Infrastructure Solutions Lab that compared the differences in bandwidth consumption between H.264 and MJPEG, when the camera viewed little or no motion, the H.264 compressed video stream required roughly 10 percent of an equivalent MJPEG. In tests with a high degree of motion, the H.264 stream used more bandwidth, resulting in a smaller, but still substantial, difference in network consumption. The Lab estimated the H.264 video quality was approximately 95 percent as good as the video produced by the MJPEG compression method.
Check the Compression Profile
The standard includes a number of sets of capabilities and tools, called profiles, each targeting specific classes of applications. High Profile is for broadcast and disk storage applications, particularly for high definition television adapted into HD-DVD and Blu-ray disk.
On the security video side, there is Baseline Profile (BP), primarily for lower cost applications with limited computing resources, and used widely in videoconferencing, mobile applications and originally in security video. More recently, security manufacturers are moving to Main Profile (MP), which was originally intended as the mainstream consumer profile for broadcast and storage applications.
Baseline is typically considered the least efficient of the H.264 profiles but also the least demanding of computing resources. By contrast, MP is considered to be more bandwidth efficient but also more demanding. Increasingly, new IP cameras are using main profile by default while previous generation security gear was more likely to use baseline.
“Virtually every video project we do now includes H.264,” says Hugman, with integrator Knight Security Systems.
For example, a major video surveillance project with the Texas Department of Aging and Disability Services boasts more than 3,200 H.264 HD megapixel cameras installed in 336 buildings on 12 separate campuses located throughout the state. The project includes IQeye Alliance-pro and 4-Series dome cameras, servers, operating software, and an end-to-end network infrastructure with 35 miles of fiber optic cable to connect all the buildings together on each campus.
By using H.264, the integrator was able to put more cameras on a single gigabit link and the state was able to maintain an extended video archive without paying for exorbitant storage capacity.
In another H.264 example at the University of Miami, IQeye HD megapixel cameras cover the main campus in Coral Gables in order to create a safer environment for students, staff and visitors. Most of the newer cameras feature H.264 Main Profile compression, which has significantly reduced bandwidth and storage demands for the university.
“We are continuing on the same path we’ve been on for the last year or so, working with the campus police to identify high crime areas and then covering those areas with megapixel cameras. Right now, we’re focusing on bike theft and deploying cameras in about eight different areas to more effectively combat those incidents,” adds Steve Weatherly, senior security engineer at the university.
Impact of Megapixel Cameras
An important enabler for H.264 is migration to megapixel and HD cameras, according to Greg Sparrow, director of system integration at Signet Electronic Systems, and who agrees that such a step-up “requires more horsepower at the camera and at processing.”
Greg Peratt, who covers video solutions integration at Panasonic, adds that “the growing need for higher resolution images to be transmitted at higher frame rates across local and wide area networks highlights the benefits of H.264 compression and will be a driving force to expand use of the format. The growth of HD and megapixel cameras increases market demand for H.264’s ability to provider smaller data files and to enable longer periods of storage using high-capacity disk drives.” Enterprise security leaders get the benefit of higher resolution and faster frame rates in addition to longer storage.
But are all H.264s the same? Says Peratt, “Not all manufacturers use the same H.264 coding format. Within the H.264 standard, there are profile levels or quality levels. Higher profiles produce better picture quality but also require more processing power to encode/decode the file.” Sparrow suggests that end users and their integrators need to test things out and validate what is being proposed. “There are differences, compatibility issues, firmware and software versions. It is more important in the long run to concentrate on what you are trying to capture and what you will be doing with the images.”
Adds Nilsson, “The camera that can better filter the image can do better” more generally. “And, if an encoder says it supports H.264, it can receive any type of image.”
There are network limitations.
Says Mellos, “H.264 is well suited for large deployments where video feeds are streamed to multiple viewing and storage locations. In this type of installation, it is important that the integrator fully understands the limitations of the deployed network and be able to fully design and deploy a system that takes advantage of main and sub-streams embedded within devices. This will provide end users with the most appropriate solution for their needs.”
Mellos adds that “H.264 addresses only the compression needs of the system. Focus should also be placed on the devices and their performance within specific applications. For example, the real performance of a camera installed in adverse light and environmental conditions can be just as important as how much bandwidth the particular camera feed will consume.”
Video analytics is another advance which runs on a track that also contains H.264. At the late March 2012 ISC West, for instance, Axis Communications unveiled its new ARTPEC-4 camera chip, which it says offers increased image quality, more efficient H.264 compression and enhanced processing power to help improve video analytic capabilities.