What is IP camera ?

Network IP Cameras have been around for at over a decade now. Only recently have cabling installers began to pay attention to the technology because surveillance cameras have traditionally run on separate coaxial cable. Around 10 years ago, the first digital IP camera connected directly to a data network which changed the future of the surveillance camera industry.

During the early stages, the technology was not as professional as analog cameras. Most cameras were seen as ‘web cameras’, which were used to view objects or events over the internet or a LAN.

Today IP network cameras meet the same requirements and specifications as analog counterparts and in many areas surpass analog camera performance and features . Forecasts show that the network IP camera market share is growing at a much faster rate than its analog competitor and has surpassed the analog camera in market share.

An IP Camera is a networked digital video camera that transmits data over a Fast Ethernet link. IP Cameras (also called “network cameras”) are most often used for IP surveillance, a digitized and networked version of closed-circuit television (CCTV).

Benefits of IP camera over analog technology include:

• Remote administration from any location.
• Digital zoom.
• The ability to easily send images and video anywhere with an Internet connection.
• Progressive scanning, which enables better quality images extracted from the video, especially for moving targets.
• Adjustable frame rates and resolution to meet specific needs.
• Two-way communication.
• The ability to send alerts if suspicious activity is detected.
• Lower cabling requirements.
• Support for intelligent video.

Disadvantages of IP surveillance include greater complexity and bandwidth demands. One alternative for organizations with substantial investment in analog technology is to use a video server to, in effect, turn analog CCTV cameras to IP cameras. A video server is a small standalone server that converts analog signals to a digital format and provides the analog cameras with IP addresses.

Nevertheless, because it offers much more sophisticated capabilities, IP surveillance is increasingly replacing analog CCTV. An industry report from International Data Corporation (IDC) predicts that shipments of IP cameras and related products will increase 75% between 2012 and 2015.

NAS, DAS, or SAN? - Choosing the Right Storage Technology ?

Data is unquestionably the lifeblood of today's digital organization. Storage solutions remain a top priority in IT budgets precisely because the integrity, availability and protection of data are vital to business productivity and success. But the role of information storage far exceeds day to day functions. Enterprises are also operating in an era of increased uncertainty. IT personnel find themselves assessing and planning for more potential risks than ever before, ranging from acts of terrorism to network security threats. A backup and disaster recovery plan is essential, and information storage solutions provide the basis for its execution.

Businesses are also subject to a new wave of regulatory compliance legislation that directly affects the process of storing, managing and archiving data. This is especially true for the financial services and healthcare industries, which handle highly sensitive information and bear extra responsibility for maintaining data integrity and privacy.

Although the need for storage is evident, it is not always clear which solution is right for your organization. There are a variety of options available, the most prevalent being direct-attached storage (DAS), network-attached storage (NAS) and storage area networks (SAN). Choosing the right storage solution can be as personal and individual a decision as buying a home. There is no one right answer for everyone. Instead, it is important to focus on the specific needs and long-term business goals of your organization. Several key criteria to consider include:
• Capacity - the amount and type of data (file level or block level) that needs to be stored and shared
• Performance - I/O and throughput requirements
• Scalability - Long-term data growth
• Availability and Reliability - how mission-critical are your applications?
• Data protection - Backup and recovery requirements
• IT staff and resources available
• Budget concerns
While one type of storage media is usually sufficient for smaller companies, large enterprises will often have a mixed storage environment, implementing different mediums for specific departments, workgroups and remote offices. In this paper, we will provide an overview of DAS, NAS and SAN to help you determine which solution, or combination of solutions, will best help you achieve your business goals.


DAS: Ideal for Local Data Sharing Requirements

Direct-attached storage, or DAS, is the most basic level of storage, in which storage devices are part of the host computer, as with drives, or directly connected to a single server, as with RAID arrays or tape libraries. Network workstations must therefore access the server in order to connect to the storage device. This is in contrast to networked storage such as NAS and SAN, which are connected to workstations and servers over a network. As the first widely popular storage model, DAS products still comprise a large majority of the installed base of storage systems in today's IT infrastructures. Although the implementation of networked storage is growing at a faster rate than that of direct-attached storage, it is still a viable option by virtue of being simple to deploy and having a lower initial cost when compared to networked storage. When considering DAS, it is important to know what your data availability requirements are. In order for clients on the network to access the storage device in the DAS model, they must be able to access the server it is connected to. If the server is down or experiencing problems, it will have a direct impact on users' ability to store and access data. In addition to storing and retrieving files, the server also bears the load of processing applications such as e-mail and databases. Network bottlenecks and slowdowns in data availability may occur as server bandwidth is consumed by applications, especially if there is a lot of data being shared from workstation to workstation.

DAS is ideal for localized file sharing in environments with a single server or a few servers - for example, small businesses or departments and workgroups that do not need to share information over long distances or across an enterprise. Small companies traditionally utilize DAS for file serving and e-mail, while larger enterprises may leverage DAS in a mixed storage environment that likely includes NAS and SAN. DAS also offers ease of management and administration in this scenario, since it can be managed using the network operating system of the attached server. However, management complexity can escalate quickly with the addition of new servers, since storage for each server must be administered separately.

From an economical perspective, the initial investment in direct-attached storage is cheaper. This is a great benefit for IT managers faced with shrinking budgets, who can quickly add storage capacity without the planning, expense, and greater complexity involved with networked storage. DAS can also serve as an interim solution for those planning to migrate to networked storage in the future. For organizations that anticipate rapid data growth, it is important to keep in mind that DAS is limited in its scalability. From both a cost efficiency and administration perspective, networked storage models are much more suited to high scalability requirements.

Organizations that do eventually transition to networked storage can protect their investment in legacy DAS. One option is to place it on the network via bridge devices, which allows current storage resources to be used in a networked infrastructure without incurring the immediate costs of networked storage. Once the transition is made, DAS can still be used locally to store less critical data.
NAS: File-Level Data Sharing Across the Enterprise

Networked storage was developed to address the challenges inherent in a server- based infrastructure such as direct-attached storage. Network-attached storage, or NAS, is a special purpose device, comprised of both hard disks and management software, which is 100% dedicated to serving files over a network. As discussed earlier, a server has the dual functions of file sharing and application serving in the DAS model, potentially causing network slowdowns. NAS relieves the server of storage and file serving responsibilities, and provides a lot more flexibility in data access by virtue of being independent.

NAS is an ideal choice for organizations looking for a simple and cost-effective way to achieve fast data access for multiple clients at the file level. Implementers of NAS benefit from performance and productivity gains. First popularized as an entry-level or midrange solution, NAS still has its largest install base in the small to medium sized business sector. Yet the hallmarks of NAS - simplicity and value - are equally applicable for the enterprise market. Smaller companies find NAS to be a plug and play solution that is easy to install, deploy and manage, with or without IT staff at hand. Thanks to advances in disk drive technology, they also benefit from a lower cost of entry.

In recent years, NAS has developed more sophisticated functionality, leading to its growing adoption in enterprise departments and workgroups. It is not uncommon for NAS to go head to head with storage area networks in the purchasing decision, or become part of a NAS/SAN convergence scheme. High reliability features such as RAID and hot swappable drives and components are standard even in lower end NAS systems, while midrange offerings provide enterprise data protection features such as replication and mirroring for business continuance. NAS also makes sense for enterprises looking to consolidate their direct-attached storage resources for better utilization. Since resources cannot be shared beyond a single server in DAS, systems may be using as little as half of their full capacity. With NAS, the utilization rate is high since storage is shared across multiple servers.

The perception of value in enterprise IT infrastructures has also shifted over the years. A business and ROI case must be made to justify technology investments. Considering the downsizing of IT budgets in recent years, this is no easy task. NAS is an attractive investment that provides tremendous value, considering that the main alternatives are adding new servers, which is an expensive proposition, or expanding the capacity of existing servers, a long and arduous process that is usually more trouble than it's worth. NAS systems can provide many terabytes of storage in high density form factors, making efficient use of data center space. As the volume of digital information continues to grow, organizations with high scalability requirements will find it much more cost-effective to expand upon NAS than DAS. Multiple NAS systems can also be centrally managed, conserving time and resources.

Another important consideration for a medium sized business or large enterprise is heterogeneous data sharing. With DAS, each server is running its own operating platform, so there is no common storage in an environment that may include a mix of Windows, Mac and Linux workstations. NAS systems can integrate into any environment and serve files across all operating platforms. On the network, a NAS system appears like a native file server to each of its different clients. That means that files are saved on the NAS system, as well as retrieved from the NAS system, in their native file formats. NAS is also based on industry standard network protocols such as TCP/IP, FC and CIFS.

SANs: High Availability for Block-Level Data Transfer

A storage area network, or SAN, is a dedicated, high performance storage network that transfers data between servers and storage devices, separate from the local area network. With their high degree of sophistication, management complexity and cost, SANs are traditionally implemented for mission-critical applications in the enterprise space. In a SAN infrastructure, storage devices such as NAS, DAS, RAID arrays or tape libraries are connected to servers using Fibre Channel. Fibre Channel is a highly reliable, gigabit interconnect technology that enables simultaneous communication among workstations, mainframes, servers, data storage systems and other peripherals. Without the distance and bandwidth limitations of SCSI, Fibre Channel is ideal for moving large volumes of data across long distances quickly and reliably.

In contrast to DAS or NAS, which is optimized for data sharing at the file level, the strength of SANs lies in its ability to move large blocks of data. This is especially important for bandwidth-intensive applications such as database, imaging and transaction processing. The distributed architecture of a SAN also enables it to offer higher levels of performance and availability than any other storage medium today. By dynamically balancing loads across the network, SANs provide fast data transfer while reducing I/O latency and server workload. The benefit is that large numbers of users can simultaneously access data without creating bottlenecks on the local area network and servers.

SANs are the best way to ensure predictable performance and 24x7 data availability and reliability. The importance of this is obvious for companies that conduct business on the web and require high volume transaction processing. Another example would be contractors that are bound to service-level agreements (SLAs) and must maintain certain performance levels when delivering IT services. SANs have built in a wide variety of failover and fault tolerance features to ensure maximum uptime. They also offer excellent scalability for large enterprises that anticipate significant growth in information storage requirements. And unlike direct-attached storage, excess capacity in SANs can be pooled, resulting in a very high utilization of resources. There has been much debate in recent times about choosing SAN or NAS in the purchasing decision, but the truth is that the two technologies can prove quite complementary. Today, SANs are increasingly implemented in conjunction with NAS. With SAN/NAS convergence, companies can consolidate block-level and file-level data on common arrays.

Even with all the benefits of SANs, several factors have slowed their adoption, including cost, management complexity and a lack of standardization. The backbone of a SAN is management software. A large investment is required to design, develop and deploy a SAN, which has limited its market to the enterprise space. A majority of the costs can be attributed to software, considering the complexity that is required to manage such a wide scope of devices. Additionally, a lack of standardization has resulted in interoperability concerns, where products from different hardware and software vendors may not work together as needed. Potential SAN customers are rightfully concerned about investment protection and many may choose to wait until standards become defined.

Conclusion

With such a variety of information storage technologies available, what is the best way to determine which one is right for your organization? DAS, NAS and SAN all offer tremendous benefits, but each is best suited for a particular environment. Consider the nature of your data and applications. How critical and processing-intensive are they? What are your minimum acceptable levels of performance and availability? Is your information sharing environment localized, or must data be distributed across the enterprise? IT professionals must make a comprehensive assessment of current requirements while also keeping long-term business goals in mind.

Like all industries, storage networking is in a constant state of change. It's easy to fall into the trap of choosing the emerging or disruptive storage technology at the time. But the best chance for success comes with choosing a solution that is cost-correct and provides long term investment protection for your organization. Digital assets will only continue to grow in the future. Make sure your storage infrastructure is conducive to cost-effective expansion and scalability. It is also important to implement technologies that are based on open industry standards, which will minimize interoperability concerns as you expand your network.

TCP VS UDP & IP Topics

Can you explain the difference between UDP and TCP internet protocol (IP) traffic and its usage with an example?
A. Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)is a transportation protocol that is one of the core protocols of the Internet protocol suite. Both TCP and UDP work at transport layer TCP/IP model and both have very different usage.

Difference between TCP and UDP

TCP	UDP
Reliability: TCP is connection-oriented protocol. When a file or message send it will get delivered unless connections fails. If connection lost, the server will request the lost part. There is no corruption while transferring a message.	Reliability: UDP is connectionless protocol. When you a send a data or message, you don't know if it'll get there, it could get lost on the way. There may be corruption while transferring a message.
Ordered: If you send two messages along a connection, one after the other, you know the first message will get there first. You don't have to worry about data arriving in the wrong order.	Ordered: If you send two messages out, you don't know what order they'll arrive in i.e. no ordered
Heavyweight: - when the low level parts of the TCP "stream" arrive in the wrong order, resend requests have to be sent, and all the out of sequence parts have to be put back together, so requires a bit of work to piece together.	Lightweight: No ordering of messages, no tracking connections, etc. It's just fire and forget! This means it's a lot quicker, and the network card / OS have to do very little work to translate the data back from the packets.
Streaming: Data is read as a "stream," with nothing distinguishing where one packet ends and another begins. There may be multiple packets per read call.	Datagrams: Packets are sent individually and are guaranteed to be whole if they arrive. One packet per one read call.
Examples: World Wide Web (Apache TCP port 80), e-mail (SMTP TCP port 25 Postfix MTA), File Transfer Protocol (FTP port 21) and Secure Shell (OpenSSH port 22) etc.	Examples: Domain Name System (DNS UDP port 53), streaming media applications such as IPTV or movies, Voice over IP (VoIP), Trivial File Transfer Protocol (TFTP) and online multiplayer games etc

Further readings

UDP is the faster protocol as it doesn't wait for acknowledgement so it is not at all having reliability as  compared to TCP.

Bridging the Analog-IP Gap

The name "encoder" does not really do these technological miracles justice. These investment-protecting, budget-saving marvels build a bridge between two generations of surveillance technology and bring harmony to your network.

IP-based video surveillance systems bring many important benefits. The image quality they deliver is a vast improvement. The networks are more scalable and cheaper to run. Better still, computerization means you can automate systems to bring about event management and intelligent video. Nevertheless, it is too early to claim that this development has rendered analog CCTV surveillance systems obsolete.

One option to installers would be to replace everything analog. This would mean getting rid of the existing analog cameras, the coaxial cables that have been laid inside and outside the buildings, the recording systems (AVRs or DVRs) and the management system. It would then be necessary to introduce an entirely new Ethernet cabling infrastructure, which would involve not insubstantial disruption, along with new IP-compatible storage hardware and a management system suited to IP or network video.

In many cases, that would be a waste of time and money, and the people who bought analog systems are not going to write off their investment any time soon, especially when around 95 percent of the estimated 40 million surveillance cameras installed in the world are still analog.

While analog technology is being fast eclipsed by IP video, which is growing at 30 percent a year according to IMS Research, there is no reason why the two infrastructures cannot be rationalized together, apart from a few technological hurdles. These barriers to integration are, in most cases, easily surmountable.

For most installations, the most valuable service you can offer your clients is to migrate them from analog to IP video by making judicious use of their existing network. The key to this magic passage is the video encoder. Encoders help convert analog networks into IP-friendly formats, putting the existing investment in cameras and coaxial cable to good use.

Basics of Internet Communication

To send data between a device on one local area network to another device on another LAN, a standard way of communicating is required since local area networks may use different types of technologies. This need led to the development of IP addressing and the many IP-based protocols for communicating over the Internet, which is a global system of interconnected computer networks. (LANs may also use IP addressing and IP protocols for communicating within a local area network, although using MAC addresses is sufficient for internal communication.) Before IP addressing is discussed, some of the basic elements of Internet communication such as routers, firewalls and Internet service providers are covered below.

Routers

To forward data packages from one LAN to another LAN via the Internet, a networking equipment called a network router must be used. A router routes information from one network to another based on IP addresses. It forwards only data packages that are to be sent to another network. A router is most commonly used for connecting a local network to the Internet. Traditionally, routers were referred to as gateways.

Firewalls

A firewall is designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks that are connected to the Internet. Messages entering or leaving the Internet pass through the firewall, which examines each message, and blocks those that do not meet the specified security criteria.

Internet connections

In order to connect a LAN to the Internet, a network connection via an Internet service provider (ISP) must be established. When connecting to the Internet, terms such as upstream and downstream are used. Upstream describes the transfer rate with which data can be uploaded from the device to the Internet; for instance, when video is sent from a network camera. Downstream is the transfer speed for downloading files; for instance, when video is received by a monitoring PC.

In most scenarios — for example, a laptop that is connected to the Internet — downloading information from the Internet is the most important speed to consider. In a network video application with a network camera at a remote site, the upstream speed is more relevant since data (video) from the network camera will be uploaded to the Internet.

IP addressing

Any device that wants to communicate with other devices via the Internet must have a unique and appropriate IP address. IP addresses are used to identify the sending and receiving devices. There are currently two IP versions: IP version 4 (IPv4) and IP version 6 (IPv6). The main difference between the two is that the length of an IPv6 address is longer (128 bits compared with 32 bits for an IPv4 address). IPv4 addresses are most commonly used today.

IPv4 addresses

IPv4 addresses are grouped into four blocks, and each block is separated by a dot. Each block represents a number between 0 and 255; for example, 192.168.12.23.

Certain blocks of IPv4 addresses have been reserved exclusively for private use. These private IP addresses are 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255 and 192.168.0.0 to 192.168.255.255. Such addresses can only be used on private networks and are not allowed to be forwarded through a router to the Internet. All devices that want to communicate over the Internet must have its own individual, public IP address. A public IP address is an address allocated by an Internet service provider. An ISP can allocate either a dynamic IP address, which can change during a session, or a static address, which normally comes with a monthly fee.

Ports

A port number defines a particular service or application so that the receiving server (e.g., network camera) will know how to process the incoming data. When a computer sends data tied to a specific application, it usually automatically adds the port number to an IP address without the user’s knowledge.

Port numbers can range from 0 to 65535. Certain applications use port numbers that are pre-assigned to them by the Internet Assigned Numbers Authority (IANA). For example, a web service via HTTP is typically mapped to port 80 on a network camera.

Setting IPv4 addresses

In order for a network camera or video encoder to work in an IP network, an IP address must be assigned to it. Setting an IPv4 address for an Axis network video product can be done mainly in two ways: 1) automatically using DHCP (Dynamic Host Configuration Protocol), and 2) manually by either entering into the network video product’s interface a static IP address, a subnet mask and the IP address of the default router, or using a management software tool such as AXIS Camera Management.

DHCP manages a pool of IP addresses, which it can assign dynamically to a network camera/ video encoder. The DHCP function is often performed by a broadband router, which in turn gets its IP addresses from an Internet service provider. Using a dynamic IP address means that the IP address for a network device may change from day to day. With dynamic IP addresses, it is recommended that users register a domain name (e.g., www.mycamera.com) for the network video product at a dynamic DNS (Domain Name System) server, which can always tie the domain name for the product to any IP address that is currently assigned to it.

Using DHCP to set an IPv4 address works as follows. When a network camera/video encoder comes online, it sends a query requesting configuration from a DHCP server. The DHCP server replies with an IP address and subnet mask. The network video product can then update a dynamic DNS server with its current IP address so that users can access the product using a domain name.

With AXIS Camera Management, the software can automatically find and set IP addresses and show the connection status. The software can also be used to assign static, private IP addresses for Axis network video products. This is recommended when using video management software to access network video products. In a network video system with potentially hundreds of cameras, a software program such as AXIS Camera Management is necessary in order to effectively manage the system.

NAT (Network address translation)

When a network device with a private IP address wants to send information via the Internet, it must do so using a router that supports NAT. Using this technique, the router can translate a private IP address into a public IP address without the sending host’s knowledge.

Port forwarding

To access cameras that are located on a private LAN via the Internet, the public IP address of the router should be used together with the corresponding port number for the network camera/video encoder on the private network.

Since a web service via HTTP is typically mapped to port 80, what happens then when there are several network cameras/video encoders using port 80 for HTTP in a private network? Instead of changing the default HTTP port number for each network video product, a router can be configured to associate a unique HTTP port number to a particular network video product’s IP address and default HTTP port. This is a process called port forwarding.

Port forwarding works as follows. Incoming data packets reach the router via the router’s public (external) IP address and a specific port number. The router is configured to forward any data coming into a predefined port number to a specific device on the private network side of the router. The router then replaces the sender’s address with its own private (internal) IP address. To a receiving client, it looks like the packets originated from the router. The reverse happens with outgoing data packets. The router replaces the private IP address of the source device with the router’s public IP address before the data is sent out over the Internet.

Internet pic

Thanks to port forwarding in the router, network cameras with private IP addresses on a local network can be accessed over the Internet. In this illustration, the router knows to forward data (request) coming into port 8032 to a network camera with a private IP address of 192.168.10.13 port 80. The network camera can then begin to send video.

Port forwarding is traditionally done by first configuring the router. Different routers have different ways of doing port forwarding and there are web sites such as www.portfoward.com that offer step-by-step instruction for different routers. Usually port forwarding involves bringing up the router’s interface using an Internet browser, and entering the public (external) IP address of the router and a unique port number that is then mapped to the internal IP address of the specific network video product and its port number for the application.

To make the task of port forwarding easier, Axis offers the NAT traversal feature in many of its network video products. NAT traversal will automatically attempt to configure port mapping in a NAT router on the network using UPnP™. In the network video product interface, users can manually enter the IP address of the NAT router. If a router is not manually specified, then the network video product will automatically search for NAT routers on the network and select the default router. In addition, the service will automatically select an HTTP port if none is manually entered.

IPv6 addresses

An IPv6 address is written in hexadecimal notation with colons subdividing the address into eight blocks of 16 bits each; for example, 2001:0da8:65b4:05d3:1315:7c1f:0461:7847.

The major advantages of IPv6, apart from the availability of a huge number of IP addresses, include enabling a device to automatically configure its IP address using its MAC address. For communication over the Internet, the host requests and receives from the router the necessary prefix of the public address block and additional information. The prefix and host’s suffix is then used, so DHCP for IP address allocation and manual setting of IP addresses are no longer required with IPv6. Port forwarding is also no longer needed. Other benefits of IPv6 include renumbering to simplify switching entire corporate networks between providers, faster routing, point-to-point encryption according to IPSec, and connectivity using the same address in changing networks (Mobile IPv6).

An IPv6 address is enclosed in square brackets in a URL and a specific port can be addressed in the following way: http://[2001:0da8:65b4:05d3:1315:7c1f:0461:7847]:8081/

Setting an IPv6 address for an Axis network video product is as simple as checking a box to enable IPv6 in the product. The product will then receive an IPv6 address according to the configuration in the network router.

Data transport protocols for network video

The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are the IP-based protocols used for sending data. These transport protocols act as carriers for many other protocols. For example, HTTP (Hyper Text Transfer Protocol), which is used to browse web pages on servers around the world using the Internet, is carried by TCP.

TCP provides a reliable, connection-based transmission channel. It handles the process of breaking large chunks of data into smaller packets and ensures that data sent from one end is received on the other. TCP’s reliability through retransmission may introduce significant delays. In general, TCP is used when reliable communication is preferred over transport latency.

UDP is a connectionless protocol and does not guarantee the delivery of data sent, thus leaving the whole control mechanism and error-checking to the application itself. UDP provides no transmissions of lost data and, therefore, does not introduce further delays.

IPCCTV Design - Network Requirements

Designing a IP CCTV System - Network Requirements
Manufacturers of IP Video equipment provide excellent tools for helping security and IT professionals design digital CCTV systems and in particular compute the bandwidth requirements of the network. It’s fundamentally a very simple process; decide how many cameras are required, decide what video quality for viewing and recording is required and decide how many days of recording are needed. These can then be used to calculate how much bandwidth and recording storage is required.
Each device connected to the network is then assigned an IP address, ensuring they are all on the same sub-net and can therefore ‘see’ each other. The ‘Site Builder’ software tools provided then interrogate the network and discover all the appropriate devices and automatically build a site database and recording schedule.
In many cases the bandwidth requirements can be easily accommodated on the existing corporate LAN/WAN, giving the proposed IP Video system another significant advantage over analog CCTV by removing the need for additional cabling. This also means the network can be shared with the normal IT traffic and facilities such as Voice-over-IP. IP Video has many clever features which ensure that the bandwidth impact is kept to a minimum. Positioning NVRs locally to relevant camera clusters can reduce network traffic and improve redundancy. The compressed video can be transmitted across the network using TCP, UDP Unicast or UDP Multicast protocols. The advantage of Multicast is that it uses the same amount of network traffic for 1000 operators to view a camera as it would for one operator.
Activity Controlled Framerate (ACF is another feature designed to reduce network traffic. This facility relies on processing data at the camera IP transmitter/receiver unit. If no movement is detected in the camera scene then the bandwidth used is dramatically reduced. This feature is most effective in places where low activity occurs, such as in corridors, on fire escapes, or in buildings which are unoccupied at night. Searching recorded video can be a time-consuming activity with a corresponding increase in network traffic. However, clever thumbnail search facilities can be provided by the video and alarm management The typical NVR solution simply requires a PC platform and hard disk storage. However, for more demanding fault tolerant applications NVRs can be packaged in stand-alone units with removable hard disk drives. Transmitter/receiver modules transmit MPEG-4 quality digital video, audio and control data over the IP Network. Software. The system can analyse movement in a scene and display thumbnail images that represent frames from recordings containing the specified movement. Clicking on one of the thumbnails then replays that section of video. This feature can search 24 hours of recorded video and display the thumbnails in just a few seconds. Changing the search variables allows the operator to sift through vast quantities of recorded material quickly and efficiently. The use of thumbnails allows a vast amount of video to be analysed with little extra impact on the network.
Don’t Throw Out the Old Cameras – Handling Legacy Systems:
It is clear to see the advantages of IP Video for large enterprise systems, with its underlying flexibility and scalability. However, it is also an ideal solution for smaller CCTV systems and in particular for upgrades to existing installations. When upgrading from an existing analog system the obsolete equipment such as the matrix and DVRs can be replaced, but all the cameras, domes, monitors and keyboards can be kept. Using IP transmitter/receiver units, all existing cameras and monitors can be interconnected; in fact existing control room configurations can largely remain unchanged. With the addition of a PC or two, all the advanced features of IP CCTV can be made available without the need to change the familiar surroundings of the control room. Once the migration is complete it’s very easy to expand the system in the future. It is now becoming common practice for IP Video systems to be used to expand existing analog CCTV systems based on cost alone – it’s often just too costly to cable in new cameras from remote locations.

Transmitter/receiver modules transmitMPEG-4 quality digital video, audio and control data over the IP network the typical NVR solution simply requiresa PC platform and hard disk storage. However, for more demanding fault tolerant applications NVRs can be packaged in stand-alone units with removable hard disk drives IP Video allows potential end users to easily trial the system at first-hand without commitment to large scale change from day one. Even though IP Video is an established technology, users will always want to convert to new technology at their own pace.
The integration with intruder alarm and access control systems is also providing advantages as they are now moving to IP networks as well. These systems are also seeing the benefits and flexibility of replacing cable with a network. The CCTV video and data from these systems can share the network without any problems, in fact this level of integration provides some interesting features. For example, a security alarm can provide an input to the IP Video system, which automatically moves a camera to cover the incident and displays the video feed on a monitor in the control room together with a map of the location providing multiple perspectives on the incident. Digital Video Recording – the NVR is important to differentiate between Digital Video Recorders and network Video recorders (NVRs), as both are often termed ‘digital’. A DVR digitally compresses analog video feeds and stores them on a hard-drive, the term ‘digital’ referring to the compression and storage technology, not the transmitted video images. The DVR therefore has to be located near the analog feeds. In contrast an NVR stores digital images directly from the IP Network.
Therefore the most obvious difference between the DVR and NVR is that the DVR records analog streams from analog cameras, whereas the NVR records video streams that have already been encoded at the cameras. Thus you find no video connectors anywhere on a NVR; its inputs and outputs are IP data, comprising of compressed and encoded video. NVRs can be either PC software based or dedicated stand-alone units.
The huge advantage of an architecture based on NVRs is that they can be located anywhere on a network – at the monitoring centre, adjacent to camera clusters, on the edge of a network or collected together in a hardened environment. In use their location is transparent to an operator; the recorded video stream from any camera can be viewed by any operator at any point on the network. NVRs record and replay simultaneously and recordings on any one machine can be remotely viewed by a number of authorised operators spread across the network simultaneously, all totally independently and without affecting each other. The independence of physical location is an important factor. By calculating the required network traffic and strategically placing NVRs accordingly, the impact of video streaming on bandwidth usage can be minimised. Typically an NVR might be placed near (in network terms, not necessarily physically) a camera cluster so that the load is carried by the local LAN capable of absorbing it easily, thus saving capacity on other, perhaps more restricted, parts of the network.
“Mirroring” techniques are now often used to duplicate the recording of video streams on additional NVRs located at different parts of the network, which provides a high level of protection against network failure; if one part goes down the other is there as a backup. You can have as many NVRs across a system as you like - there is no requirement for additional video cabling. Evidence from the NVR can be exported in the standard MPEG-4 format allowing it to be viewed by any 3rd party viewer such as QuickTime for Windows Media Player. However, the exported video includes encryption and watermarking to allow extremely secure detection of tampering such as frame removal, reordering or modification.
Advanced Analytics – The Future Analytics is the processing of video images to detect such events as congestion, stolen objects, cars parked too long outside a building, people moving the wrong way through security checkpoints, etc. Analytics are available as an add-on to analog systems which makes it difficult to realise the true benefits of this technology. In IP systems however, analytics can be completely integrated so their full benefits can be realised. IP-based analytics can be run in two modes: real time within the IP transmitter/receiver at the camera, and post-processing, on any operator’s PC. The real time mode allows the system to automatically identify events as they occur. Post processing allows operators to run many different scenarios on recorded video, e.g. look for cars parked for more than 2 minutes. These two modes offer the best of both worlds, using analytics to identify events as they occur, and also providing advanced search tools for operators to analyse previous situations. Human operators are particularly poor at watching video monitors for long periods of time, but are generally very good at confirming whether something is an incident or not, once it has been flagged automatically by the system.
Many of the latest developments in IP Video are centered on these types of features; here are just some of the analytics algorithms that are appearing on the market:
1. Congestion Detection - too many people in too small a space
2. Motion Detection - person or vehicle moving, say, from left to right across a scene
3. Abandoned Object Detection - suitcase abandoned in an airport terminal
4. Counter Flow - person moving against an immigration route
5. Virtual Tripwire - detection and alarm upon breach of a defined line
6. Shape-Based Detection – e.g. vehicle detection
7. Object Tracking and Theft Detection - object removed from a busy scene

Advanced analytics is one of the outstanding applications of IP Video that simply cannot be matched by traditional analog CCTV systems and offers so many advantages that this feature alone can often justify the IP solution. It can be expected that huge productivity improvements will result from using analytics software during the searching of recorded material in post-event analysis - and for this, the NVR is the key.


Sources:
http://www.gobeyondsecurity.com/forum/topics/designing-the-ip-cctv-system
http://www.gobeyondsecurity.com/forum/topics/what-is-a-dvr-what-is-a-nvr