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The number of different network video standards is steadily growing, and each of them has its own advantages and disadvantages. Ajit Dubey, senior project manager of the embedded systems group at eInfochips, will try to find the differences.
According to IPVideoMarket.info, IP video surveillance sales are projected to increase by 200% from 2010 to 2012. According to the Global IP Video Surveillance Markets report by Frost & Sullivan, the market is expected to reach $1.38 billion in gross revenue by 2012.
Several factors driving this growth include the emergence of low-cost 1.3-megapixel HD cameras. On the storage side, hybrid DVRs and NVRs are removing barriers for legacy equipment to migrate to IP. Finally, the emergence of standards and protocols for network cameras and devices should reduce costs and simplify the implementation of IP video surveillance.
Despite the wide connectivity options of IP solutions, there are also a number of difficulties that can be encountered. Manufacturers offer a wide range of video coding standards, each of which has different parameters. There are even more differences in streaming video protocols, recording storage formats and video analytics. Setting up PTZ functionality in third-party video devices also causes difficulties. Therefore, the functional compatibility of devices is the key to solving the problems faced by security system integrators who implement PTZ devices and network ports into existing systems with already installed equipment.
The development of IP video surveillance depends on the quality of service and the width of the data transmission channel. The H.264 codec allows for better data compression and does not load the channel. For comparison: M-JPEG, MPEG-4 and MPEG-2 codecs require much more channel bandwidth for the same quality.
Cameras, DVRs and NVRs support RTP/RTSP and HTTPS protocols, the most common protocols on the market. Legal regulations in some countries prohibit storing audio data for privacy or confidentiality reasons, which adds to the system's uniqueness. Video-only devices can store regular data streams as such, while devices with video, audio and metadata require data containers such as MP4, MOV, 3GP, AVI and MPEG-2-TS.
The advent of video analytics increases the performance of archives for video systems that support alarm recording. There are more than 20 PTZ control protocols created by camera manufacturers.
Standards Specifications
As the video surveillance market grows, so does the demand for open standards. Two organizations have emerged in the industry, the Open Network Video Interface Forum (ONVIF) and the Physical Security Interoperability Alliance (PSIA), thanks to companies recognizing that network camera standards are needed to mature and expand the IP surveillance market.
PSIA and ONVIF were founded within months of each other in 2008 to create standardized interfaces for physical security devices and software platforms. Both organizations share a single goal: interoperable IP-based security systems. The ONVIF forum is led by Axis Communications, Sony Corporation, and Bosch Security Systems, which are currently showcasing 14 interoperable network video products from 9 companies. The forum now has 103 members, including 12 full members, 13 sponsor members, and 78 user members. ONVIF released its first draft specification in November 2008.
PSIA is a global consortium of more than 50 physical security manufacturers and system integrators. In September 2008, PSIA released its specification, which now includes 8 companies with interoperable products.
ONVIF vs. PSIA
A July 2009 IMS Research report states: «ONVIF members control more than 40% of the global video surveillance market, compared to 25% for PSIA members. When we dive into the context of network video surveillance equipment, the difference becomes even more striking. ONVIF members control approximately 60% of the market, compared to 20% for PSIA members.»
It is clear that manufacturers and integrators are suffering from indecision in their choice when both organizations are pushing their exclusive specifications.
ONVIF seems to focus on IP video, specifically cameras and analytics, focusing exclusively on the interface between a network video transmitter (NVT) and a network video client (NVC). The specification covers device discovery, device configuration, events, PTZ protocol, video analytics, and live streaming features. PSIA has defined more general specifications for the broader physical security market, which includes access control, storage systems, etc.
Here are a few differences between ONVIF and PSIA that may impact which standard is adopted for the IP video surveillance market:
1. The ONVIF specification is based on web service standards. Web service is a standardized method for integrated applications using independent open platform standards such as XML, SOAP, SOAP 1.2 and WSDL (WSDL 1.1) on an IP network. XML is used as a data description language, SOAP is used to transmit messages, and WSDL is used to describe the services themselves. SOAP is an XML-based message protocol and is designed to encode information in a web application request and response before the information is transmitted over the network. SOAP is considered complex, but at the same time more difficult to use.
On the other hand, PSIA uses the representational state transfer (REST) architecture, which is the latest approach used in almost all web applications today. REST is easier to use than SOAP and requires only a simple XML parser with less processing. REST requires fewer resources than SOAP. Another advantage of REST is the ability to read protocol messages, which can be easily integrated into the debugging system. Due to the high requirements for computing resources and the data transmission channel, SOAP seems less attractive for use. SOAP requires a fully compliant HTTP server, SSL, and an XML parser.
For example, changing the PTZ position in ONVIF requires a SOAP header description of about 12 KB. In PSIA, changing the PTZ position requires only going to the URL, which requires only a few bytes.
2. ONVIF uses a Microsoft-centric (WS Discovery) technology-based mechanism for network device discovery. This means that all ONVIF-compliant devices must support WS Discovery, which in turn guarantees 100% compatibility between ONVIF-specification devices when discovering each other over the network.
In turn, PSIA offers more ways to search for devices on the network, such as Zeroconf, UPnP and Bonjour. However, despite the greater flexibility in choosing and using one or another discovery method, there are also difficulties in the joint operation of devices that support PSIA. For example, a PSIA-compatible camera with Bonjour support cannot be connected to a video control system that meets the PSIA standards, but supports the UPnP method. And all this despite the fact that both the camera and the video processing system meet the PSIA requirements.
3. The ONVIF event notification system is based on WS-Notify. These requirements clearly define how the camera should pass event information to the next level, compared to the generalized message format for events and notifications specified in PSIA. Again, this does not guarantee 100% compatibility between PSIA devices.
4. The PSIA interface for integrating analytics is simpler than the strict requirements in ONVIF.
5. The REST architecture makes implementing PSIA standards easier than using the SOAP structure in ONVIF.
6. PSIA has already defined requirements for media stream recording and storage method, while ONVIF has not yet defined the storage system specification. It may appear in future versions of the standard.
7. Since PSIA requirements cover more aspects of physical security, this standard has technical requirements for the integration of physical security information management (PSIM) systems.
Setting Standards
While the battle between ONVIF and PSIA over network camera standardization continues, a closer look reveals that the two standards are similar. Both provide common requirements for management and control devices to ensure interoperability across products. Each specification provides mechanisms and guidelines for device discovery and management, network configuration, analytics, and PTZ functionality, as well as HTTP/RTSP video streaming and security.
Manufacturers can use the ONVIF standard for professional video devices with analytics and camera configuration.
For those companies that need to control PTZ devices along with other services such as storage systems and PSIM, PSIA can be used. Since PSIA is based on the REST architecture, it is more suitable for other areas of the physical security industry.
The structural model is not that different either. Considering that the requirements for network cameras are more of a logical standard than a physical one, it is possible that a manufacturer will apply both standards to a camera, or these requirements will merge into a single representation. For example, Cisco and Milestone support both specifications for their solutions. eInfochips also plans to support both standards for its control software, cameras, and DVR/NVR devices.
The general standardization of network cameras will certainly speed up the integration process and provide the ability to work together with equipment from different manufacturers. Ultimately, this will reduce the costs of video surveillance systems.
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