The Inside Scoop on H.264
Jun 1, 2008 12:00 PM, By Fredrik Nilsson
H.264 is a new video compression standard that offers end-users many advantages and far fewer disadvantages than previous standards. Some say that within two years, more than 50 percent of all network video installations will use H.264 to deliver maximum surveillance benefit to end-users. Here are some frequently asked questions about H.264 and its potential benefits to digital video.
Q: Does the video surveillance industry really need yet another compression standard?
A: There have been many compressions standards for the video surveillance industry over the years: Motion JPEG (M-JPEG), H.263, H.261, MPEG-2, JPEG 2000 and MPEG-4. Of those, M-JPEG has been very popular, despite the shortcoming with the creation of large data files. MPEG-4 has also gained wide acceptance but has been so bastardized that when different vendors say that their products use MPEG-4, they all mean something different. Not only does this confuse the end-user, but it creates compatibility issues between components. Additionally, if the image contains a lot of motion, the bandwidth is almost the same as M-JPEG. MPEG-2 lacks flexibility in adjusting frame rates and bit rates; and H.261/263 do not have enough image quality for video surveillance applications, as they are geared toward teleconferencing.
With more companies adopting standards, there has been increased pressure for someone to provide a universal standard that everyone can agree on. H.264 offers great promise. It is the first compression standard jointly developed by the IT and telecom industries. It is a very well-built standard that solves a majority of the problems the previous standards were incapable of handling.
Q: H.264 became a ratified standard back in 2003. Why has it taken five years to be adopted by the network video surveillance industry?
A: One of the reasons why it takes so long for a ratified standard to be adopted is that it takes a while for supporting products to enter the market. Outside the video surveillance industry, there are a number of companies incorporating H.264 into their products. iPhones, iPods and Blu-Ray for high-definition DVDs all use H.264 because it is such a good compression standard. Video surveillance equipment manufacturers, however, have been slower to get products on the market because the security industry has to be able to do compression in real-time. This capability requires some very advanced processors. It has only been this year that we have started to see such advanced processors become available.
Q: What is the biggest benefit of using H.264 for the end-user?
A: Reduced storage cost is the biggest benefit. Compared to M-JPEG, H.264 takes just one-fifth of the bandwidth and storage to maintain the same quality image. Compared to MPEG-4, H.264 takes only half of the bandwidth and storage for the same image quality. In most video surveillance projects, storage costs represent between 20 and 30 percent of the project. Alternatively, for the same budget you could install more cameras or include megapixel resolution cameras for the same storage costs as regular cameras. You could also increase the frame rate and image quality of the cameras you operate or do a mix of those four things. So, in essence, you can either improve your entire surveillance system for the same amount of money or get the same system as in the past for a 10 to 15 percent lower cost.
Q: Are there any drawbacks to using H.264?
A: Some people contend M-JPEG is better because it provides clearer images at lower frame rates. While that was true when compared with MPEG-4, it is actually not true when compared to H.264. Even if you decide to use I-frames only in H.264 (complete frames with no references between frames, just like in M-JPEG), it will still be only half the size file of an M-JPEG compression and provide better image quality.
But what is true with H.264 is that it is a more complex compression standard. It needs more computing power inside the network camera, and not all network cameras have the computing power necessary to accommodate H.264.
On the decoder side, you have the drawback that it is going to take more decoding or processing power to decode and show the video in the PC. Studies have shown, however, that 99 percent of recorded video is never monitored — just stored and then discarded or recorded over a few days later. In addition, as PC graphics cards begin to move more quickly to the H.264 standard, the industry will continue making vast improvements in the full spectrum of video surveillance appliances and, eventually, overcome this particular drawback.
Q: How can you guarantee compression compatibility between different system components such as network cameras and video management software?
A: When it comes to video compression standards, there are always two parts to it: the encoder and the decoder. When it comes to the encoding in the network camera or video encoder, it is really up to manufacturers to select how advanced they want the encoding to be. There are a number of so-called tools within the compression standard that can be used. While manufacturers can choose whatever H.264 compression tools they want to use at the network camera end, the decoder in the video management software needs to support the full suite of tools within the H.264 standard, not just a subset.
About the Author
Fredrik Nilsson is general manager of Axis Communications, a provider of IP-based network video solutions that include network cameras and video servers for remote monitoring and security surveillance.
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