HD-SDI and megapixel network cameras are being widely debated among manufactures,
end-users and media. However, which one will be more suitable for future video surveillance system as both HD-SDI and network camera can reach megapixel resolution, and both attract attention in the video surveillance market. This article is Sunell's opinion. The article will analyze and compare these two products from five different aspects, including, capability, performance, cost, ease of use and reliability.
HD-SDI and megapixel network cameras are being widely debated among manufactures, end-users and media. However, which one will be more suitable for future video surveillance system as both HD-SDI and network camera can reach megapixel resolution, and both attract attention in the video surveillance market. This article is Sunell's opinion. The article will analyze and compare these two products from five different aspects, including, capability, performance, cost, ease of use and reliability.
Capability
Network camera can achieve video capturing, encoding, video stream network distribution and storage. Embedded Web browser features video applications and network camera, itself, even supports intelligent analytic functions.Consequently, network camera has all the core features of the video surveillance system. Therefore, theoretically, a video surveillance system can be constructed by only using the network cameras.
Some people might not agree with this: if the network camera can build the video surveillance system independently, what are NVR and VMS for? The reason of NVR's existence is due to storage capacity limitations of SD cards in network cameras, and potential risk of its data leakage. As capacity of the SD card keep increasing and network security technology continues to develop, there will be revolutionary changes of video storage in the future.
The VMS system's main function is to act as a centralized management for devices. This function can be distributed and deployed to network cameras, while CPU performance increases as well as the development of cloud computing technology. Therefore, network cameras are the core in the network-based video surveillance system.
On the other hand, the function of the HD-SDI camera is only video capturing, which is identical to the conventional analogue cameras, the only difference is the image resolution has improved from D1 resolution to megapixels. Hence, HD-SDI DVRs are crucial in the HD-SDI-based video surveillance system.
Performance
HD-SDI camera's advocates emphasize two points — image quality and latency of live video. As HD-SDI cameras' live video has not been encoded, the image quality is better than network cameras' in principle, but this is from a mathematical point of view. Due to the limitation of human eye to identify image details, there is almost no difference between megapixel network cameras and HD-SDI cameras.
As for latency of live video, it basically does not exist for HD-SDI cameras. While for network cameras, the theoretical latency of network cameras at 30fps is 140 milliseconds, and 60fps is only 70 milliseconds. However, in real applications latency of network cameras is normally more than one second because of unstable network. If network camera developers pay enough attention to this problem and can reach the theoretical minimum latency, then there is no difference between network cameras and SD-HDI cameras.
Cost
A transmitter module, which modulating megapixel digital video signals to HD-SDI signals, is needed in HD-SDI cameras, while HD-SDI DVR has a corresponding receiver module which demodulating HD-SDI signals to megapixel digital video signals. This is extra cost for HD-SDI system, but multiple HD-SDI cameras can share one video encoding chip of HD-SDI DVR, while every network camera needs an independent video encoding chip. If it is possible to lower costs of multiple channel megapixel video encoding chips, it will compensate the extra transmitter and receiver cost of HD-SDI systems.
At this moment, the cost of HD-SDI modulating chip and multiple channel megapixel video encoding chips are considerably high, which leads to a non-affordable HD-SDI system. On the contrary, the chip price is based on quantity. The camera which enjoys greater market share would be able to offer a lower price.
Ease of Use
A potential advantage of HD-SDI based video surveillance systems is that traditional surveillance systems can easily upgrade by replacing analogue cameras and DVRs with HD-SDI cameras and HD-SDI DVRs. However, the bandwidth of HD-SDI signal is far beyond the analog video signal. Therefore re-wiring may be needed if the current coaxial cable is not good enough. What kind of potential risk that this problem may cause is still uncertain.
The current society is an information society, all new buildings have considered a layout of information points, and it will become very easy to construct a network-based video surveillance system. HD-SDI advocates sometimes claim the traditional installers have no necessary expertise of IP system. Actually, it is not as hard as they think. A lot of IT providers are expanding to security industry, which will help conventional security system integrators on the network construction. With deeper convergence of video and end-users' information, the system integrators with IP network expertise would show its values.
Some people complain that configuration of network camera is complicated. It is not an inherent problem for network cameras. East of use is the key factor to IT products and it lies in software design. By optimizing the software, this issue can easily be solved.
Reliability
In a HD-SDI based system, it consists of a HD-SDI DVR and several cameras. However, a failed HD-SDI DVR will break down whole system. In a network-based system, every camera is regarded as an independent subsystem, which means network-based system provides higher reliability.
Conclusion
Some DVR manufacturers prefer to support HD-SDI cameras because they wish to maintain the existing DVR market share and product advantage. Those players from IT industry usually prefer network cameras because they expect to optimize their experience in the networking industry. Which is the future, network cameras or HD-SDI cameras? Sunell think it is not necessary to make any final conclusion. What we need to do is to have an open mind on both developments. By analyzing both advantages and disadvantages, we can have a better understanding of the video security market and can keep on providing customers with near-to-perfect video security solutions.