The rise of IP video surveillance needs to account for existing analog devices, with video encoders easing the transition to networked solutions, as detailed by Samuel Lee, Product Marketing Manager, Bosch Security Systems.
The rise of IP video surveillance needs to account for existing analog devices, with video encoders easing the transition to networked solutions, as detailed by Samuel Lee, Product Marketing Manager, Bosch Security Systems.
Over the last five years, there has been an increased digitalization of the analog video signals from surveillance cameras. This trend is accelerating, with more cost-effective IP video surveillance solutions, as well as greater IP knowledge among customers about the advantages and challenges in implementing such solutions.
Hybrid IP and analog systems hold the allure of reducing the risks of a complete system overhaul, while easing cost through the reuse of existing system components, such as analog cameras already installed. Users can also choose from a wide array of analog cameras, from budget to specialty, available from a variety of manufacturers. Migrating recording to DVRs was the first step in the IP migration. With advances in networking technology and the drastic drop in the prices of embedded processors, moving the digitalization towards the edge through the use of encoders is the next logical step.
There is a mind-boggling array of encoders available in the market: Single-channel, multichannel, ruggedized and even some featuring video content analysis. While these features, along with price, are important factors to consider, system integrators and consultants also need to consider whether the encoder fits into the overall design of the security system.
Compression
There are various compression algorithms the end user can choose from. The most commonly available algorithms include H.264 — also known as MPEG-4 part 10 — and H.263, better known as MPEG-4. These video compression standards generally take advantage of the statistical similarity of adjacent pixels and have a strong time correlation of consecutive frames. These compression algorithms are used for a broad range of applications. H.264 is commonly used in HDTV, portable video, multimedia and video conferencing, offering approximately three times the encoding efficiency of MPEG-2. The downside is it requires two to three times the computational power, but the cost of providing this performance is dropping quickly.
While H.264 is an international standard, it does permit a degree of variation in implementation due to technological constraints. The standard describes a “toolbox” with various compression techniques, such as variable block-size motion compensation (VBSMC), deblocking filter and context-adaptive variable length coding (CAVLC). Different combinations of these techniques constitute a profile. The different profiles include baseline, main, extended and high profiles. Baseline and main profiles are the most commonly implemented profiles in IP video surveillance.
The most common H.264 profile found in encoders is the baseline profile, as it is easier to implement with lower-performance and lower-cost hardware. The end user must be aware that they will not be able to take advantage of the 30 percent improvement in bit rate efficiency conferred by using the main profile. A lower bit rate from the encoder will also mean less stress on the network hardware — an important factor in an IP video surveillance solution.
Product Adopted:Codecs