Video encoders : Adopting the IP path
With the current recession in mind and technological development factors to consider, choosing analog cameras supported with video encoders or servers is becoming a trend. Both video encoders and servers are devices that convert an analog video signal to a digital video signal over an IP network, such as LAN, Intranet or Internet.
With worldwide recession at the forefront, video surveillance users turn to encoders as a cost-effective and efficient migration path to IP. As video surveillance heads toward IP and analog cameras still make up most security applications, video encoders and servers demonstrate a tidy migration path to digital. With the current recession in mind and technological development factors to consider, choosing analog cameras supported with video encoders or servers is becoming a trend. Both video encoders and servers are devices that convert an analog video signal to a digital video signal over an IP network, such as LAN, Intranet or Internet.
The worldwide market for video encoders used for surveillance was estimated to about US$450 million in 2008, with Europe, Middle East and Africa (EMEA) accounting for the largest portion of sales. With the entire IP video market grew by 10 percent in 2009 and video encoders forecasted to grow by a respective 10 to 20 percent within the overall IP growth, manufacturers have honed in on certain distinguishing features of video encoders to compete in the market, included in these features are compression formats, scalability (including number of channels), preprocessing features and storage capabilities.
Rising compression standards
Currently compression formats used in encoders for video surveillance applications include M-JPEG, MPEG-2, MPEG-4, H.264 and proprietary compression formats, with MPEG-4 being the most widely used. M-JPEG compression formats compress each frame on a frame-by-frame basis, MPEG-4 provides better compression capabilities because it looks at the previous frame of video and only compresses the things that have changed from one frame to another, as opposed to compressing each frame individually. This means that users can store more video with less disk space.
Comparing MPEG -2, MPEG -4 and H.264
While MPEG- 4 is the most common compression format for video surveillance, H.264 is gaining momentum; it is a joined development between ITU-T Video Coding Experts Group (VCEG) and ISO/ IEC Motion Picture Experts Group, resulting in the best possible picture quality at the lowest bit rate. In comparison to MPEG-4, H.264 retains MPEG-4’s video quality but is three times more efficient in streaming and uses about half the storage space of MPEG-4, resulting in a 50 percent reduction of storage costs. However, one reason users today still prefer MPEG-4 is that MPEG-4 is a matured compression format and many developers of network video related software currently support it. The software developed is integrated with features of the encoder. In contrast, H.264 is still in its infant stages and many software developers are still working on its integration features. As compression algorithms can be implemented in very different ways, the standard itself does not imply quality. All H.264 is not created equally; variability exists in bit rate, video quality, resolution and the encoding profile.
An overly simple H.264 implementation may produce worse results than a proper MPEG-4 implementation, the technological struggle for H.264 lies between improving video quality image and sacrificing as little computing power as possible. As computing power increases, MPEG-2 and MPEG-4 will be replaced by H.264. The cost and availability of H.264 equipment has made the market slow to accept the new compression standard, which was more expensive than MPEG-4. Now however, due to the innovation of semiconductors, the price per channel has lowered considerably, to a point where most video encoder companies are developing products that use H.264, while these companies may still support legacy standards, most today are now geared towards H.264, and rising demands of customers will continue to spur the market.
Proprietary compression:
Bandwidth is an expensive resource, and requires better compression to utilize network resources more efficiently. Some video encoder manufacturers develop proprietary compression technologies, catering to different bandwidths to optimize video transmission and recording.
Flexible platforms:
With video encoders, flexible platforms differentiate between needs of large-scale applications and small-to-medium businesses. For less demanding applications, such as small-to-medium businesses, users may not require running multiple encoders on a single platform simultaneously. For larger applications, some vendors take one video input and use two or more compression algorithms to convert analog signals to digital, known as “dual streaming.”
Expandable channels:
Some encoders are designed in one box (with channels of 8, 16 or 32), whereas others, based on modular systems, can support more channels as the port’s requirement increases, currently there are single channel encoders (1-1 ratio of camera and encoder) or multichannel encoders that can support up to 84 channels, with redundant power supplies and network connections. Multichannel encoders can convert analog signals to digital for larger systems, where all existing cameras are connected via coaxial cables to the encoder. Large hybrid projects, including airports or railway systems with up to 3,000 cameras, can choose multichannel encoders for the solution’s modularity, allowing users to connect their analog cameras to a Wide Area Network. Placing a different spin on multichannel encoders, users can choose encoder boxes that are essentially empty cases with available slots, insert encoders in the casing and digitize cameras six at a time. When all slots are occupied, you can make the necessary port adjustments, with minimum disruption, making it cost effective for migration to IP. As an example, a 250-camera project of 20 analog cameras may connect the 20 analog cameras to an encoder box and use four six-channel video blades to support 24 analog channels, rather than choosing in-built redundant multichannel boxed solutions.
Storage solutions
Aside from flexible compression platforms and scalability, storage features receive a great deal of attention for video encoders. Because network connections may break down, memory cards are offered as a supplementary mode of storage, which can be attached directly to video encoders. These flash memory cards are used as local storage for redundancy purposes to prevent single points-of-failure that arise during streaming. Other options to record at the encoder level include recording via Internet Small Computer System Interface (iSCSI) disk arrays, where features and functionalities are similar to the embedded hard disk or memory card, but video footage can be scaled horizontally and shared over multiple disk arrays. iSCSI establishes and manages connections between IP-based storage devices, hosts and clients, using the Internet protocol for video recording and storage.
Technical challenges:
As security converges more and more into the IT world with IP networks such as LAN, Intranet, or Internet, many users are experts in safety and security, but are not familiar with its IT aspect. For encoders, there are compatibility issues for third-party software and hardware. A great deal of digital information proceeds from the camera to the video management software, involving storage, streaming to remote surveillance, and other functions. Incompatibilities between existing video management systems from one vendor and video encoders from another could pose problems that are time consuming and require maintenance. To overcome incompatibility issues, encoder vendors need to consider all relevant components of an existing system prior to installation.
Non-security applications:
Video encoders in security are expected to eventually be replaced by network cameras. However there is a range of ancillary applications for encoders that use installations and technologies similar to surveillance. These include remote monitoring, guidance and meeting, as well as broadcast, video conferencing, and video phones. The broadcast industry has used encoders in differing forms to stream broadcast TV across a network. Encoders have also been used in machine vision applications, industrial control and military applications, including robotics and UAVs, where form factors and interfaces may differ but the encoding and streaming of video is used in a similar way. Even for medical purposes, video encoders can be used to stream video sent from an ambulance to the serving hospital, speeding up processes and efficiency.
