Factors affecting the bandwidth occupied by IP Surveillance Cameras:

Resolution: Various resolutions are supported by IP Surveillance cameras, from QVGA to HD. Higher the resolution, higher the bandwidth required to transmit every video stream from the IP Camera to the user monitoring station (computer/ server).

Frame Rate: Various frame rates are supported by IP Surveillance cameras from 5 frames per second to 30 frames per second (for example). Higher the frame rate, higher the bandwidth required.

Compression codec: There are various types of compression schemes applied to the transmitted video like MPEG4, H.264, etc. Better compression (H.264, for example), lower the bandwidth required to transmit each video stream.

Compression ratio: A video stream can be compressed more than 90% of its original size, based on the compression codec and the compression ratio used. Better the compression ratio, lower the bandwidth required.

Type of Camera Operation: An IP Camera can be operated in fixed mode or PTZ mode. In the latter, the movement of the camera can controlled (even from a remote location) and the bandwidth occupied in this mode is higher.

Type of movement/complexity in the scene: If the movement/ complexity in a scene being shot by the IP Camera is less, the bandwidth occupied by the resultant video stream is lesser.

Other factors: Many other factors like indoor/ outdoor shooting, shooting in bright light/ dark surroundings, etc affect the amount of bandwidth occupied by each video stream. Special applications like face recognition/ license plate recognition require higher resolution/ frame rate recording and hence they will occupy more bandwidth.

Let us look at the approximate bandwidth occupied by two types of IP Cameras (VGA, 1.3 Mega pixel) at various frame rates, below.

Type: VGA Resolution

5 frames per second – 256 Kbps to 750 Kbps
8 frames per second – 384 Kbps to 1 Mbps
10 frames per second – 500 Kbps to 1.2 Mbps
15 frames per second – 750 Kbps to 1.2 Mbps
30 frames per second – 1 Mbps to 1.5 Mbps

Type: 1.3 Mega pixel

5 frames per second – 750 Kbps to 1.5 Mbps
8 frames per second – 1.2 Mbps to 2.5 Mbps
10 frames per second – 1.5 Mbps to 3 Mbps
15 frames per second – 2.5 Mbps to 4 Mbps
30 frames per second – 2.5 Mbps to 5 Mbps

Source.

These values are approximate and are provided here just to get a rough idea. The actual bandwidth occupied by each video stream varies based on a lot of factors, as mentioned above. Each IP Camera requires bandwidth as mentioned above, and for a whole IP Surveillance project one needs to add up all the bandwidth occupied by the video streams generated by every IP Camera used in the project.

Though Local Area Networks (LAN) can offer 1 Gbps of bandwidth today (and can go up to 10 Gbps), the bandwidth is shared with a number of other devices/ applications occupying the network. Multiple users accessing the same video stream (simultaneously) and multiple users accessing various video streams from remote locations need to be considered, in addition to the number of video cameras being monitored over the LAN.

So, it is very important to optimize the bandwidth occupied by the IP Surveillance cameras.

How to reduce/ Optimize the bandwidth occupied by IP Surveillance Cameras?

Some techniques that can be followed to reduce/ optimize the bandwidth occupied by IP Surveillance cameras are given below.

During nights / weekends, generally no one is expected to be in the campus being monitored. So, we can set the IP surveillance cameras to start recording (and transmitting) video streams only when some kind of motion is detected. That is the part which is required to be monitored anyway.

When multiple people need to view the same video stream (from a particular IP camera), it is better if the stream is sent as a multicast. Multicast sends one stream to multiple monitoring/ viewing stations (for the image output from the same camera) as opposed to unicast which sends one video stream per each monitoring/ viewing station. Both the IP Cameras and the network equipments should support multicast, to take advantage of this technique.

Certain IP Cameras enable streaming at constant bit rates. This ensures that there is no bandwidth spike if sudden excessive motion/ detail is observed in the scene. But the video quality is obviously reduced during those times. A camera that supports variable bit rate occupies more bandwidth during high detail/ fast motion recording and the network infrastructure should be ready to accommodate for those bandwidth spikes.

If an IP Camera is set to higher compression ratios, it is possible to achieve lower bandwidth. But the IP Camera should have adequate processing capacity and it should support such advanced compression techniques.

Setting a higher frame rate for local viewing (LAN) and lower frame rate for remote viewing (WAN) can reduce the bandwidth required to see the video streams from a remote location. Obviously, the image quality is compromised but various devices (like cell phone screens, etc) that are used to see these remote video streams support a lower resolution anyway.

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In certain sites like construction sites, large farms, parks, ports, roads, highway toll collection centers, remote office locations, workshops, etc. its either not possible to carry cables to connect / power the IP surveillance cameras or its not feasible (cost of trenching, labor, etc).

In such situations, one could look at using Solar powered wireless IP surveillance cameras.

This set up usually includes the following – Solar panels, wireless IP surveillance cameras, batteries, voltage regulation circuitry, appropriate cable connections and an optional pole (on which all these components are mounted).

Solar Panels, power this system by generating electrical power for the functioning of IP Cameras. Since IP Cameras do not need much power, a relatively small sized panel might be sufficient and keeps costs lower. The Solar Panels can generate power when exposed to sunlight.

Since sunlight is not available throughout the day, a battery back-up system is used to store excess electrical power generated by the solar panels during the day, which can be used to power the IP Surveillance camera during the night. The Voltage regulation circuitry ensures that excessive voltage going towards the IP Camera is always redirected to the batteries.

The electrical power generating capacity of the solar panels and the storage capacity of the batteries are important factors. Higher their capacity, more the cost. There are certain such systems that can even power the camera for a few days without any sun-light. But more economical systems might be able to store enough power to last for a few hours or a day. So, low capacity systems may not be suitable for outdoor applications in countries that have poor sunlight (in winter, for example).

In normal sites (where power cable could be carried to the cameras), it is possible to use the AC mains (normal power) to power the IP Cameras and provide the back-up using solar panels (with appropriate electrical circuitry) instead of UPS systems. The only issue is the higher price of solar panels. In some places, there are solar energy credits provided by the Government. So, companies might consider having a full fledged solar panel system for back-up if the lower running costs (including rebates) justifies the higher capital expenditure involved with solar panels.

In order to eliminate the other cable (data cable) which is required for transmitting images from IP Surveillance cameras, there are wireless IP surveillance cameras that can work without cables, using the Wi-Fi technology. Wi-Fi can provide connectivity over the long-range – one mile or a couple of kilo-meters (with minor obstructions), if the wireless technology is optimized for such access.

In a wireless IP Camera, a wireless adapter (wi-fi adapter) is built into the camera and there maybe an external high-power antenna to enhance the distance over which the data is transmitted on the wireless medium. If proper encryption and frequency selection is used by the system, others cannot tap-into it and the interference due to other wi-fi devices operating in the area would be minimum. Its better if the IP Camera can select its frequency of operation dynamically, in order to avoid wireless interference issues, as they occur.

So, if multiple such wireless IP Cameras along with the solar panel/ battery system is placed in the middle of a field (for example), their output can be monitored from a central monitoring location (a room/ house), even if it is about a mile away. If this central monitoring station is connected to the Internet, the output of the IP Cameras can be viewed from anywhere on earth remotely (provided there is enough up-link bandwidth at this location). Technologies like DDNS enable one to view IP Camera output over the Internet, without requiring Static-IP addresses for each camera. It is even possible to switch-on / off some of these cameras from a remote location.

Some cameras might support local recording of events. An event can be movement of people/ vehicle (for example). The camera’s output can be seen at all times, but the camera starts recording when a specified event takes place (and stops after the event ends). With some IP Cameras the needed information is recorded on the camera itself (Using an SD Card, etc), or in most cases, the surveillance output is recorded in the monitoring station. Some might prefer continuous recording (with voice), and even this is possible with sufficient storage infrastructure.

Of course, there are a lot of limitations of such Solar powered Wireless IP Surveillance Cameras. The first and major limitation being its cost. Solar panels are pretty expensive. But if the total cost of an electrical installation is considered (including cables, trenches, running costs etc), perhaps the solar system might provide a faster Return on Investment. The second issue is the standardization of technology and support. Can your local electrician install and maintain these systems and if otherwise, is support available in your area? Lack of sunlight (continuously over a period of days) might be another limitation that needs to be addressed in certain locations.

Even after considering the limitations, one could still say that this is a very promising technology that should be explored actively by IT infrastructure providers. For some reason, alternative energy generation has not been on the agenda for many IT managers!

There are two companies that I came across (over the Internet) who claim to provide Solar powered Wireless IP Surveillance Cameras with Solar Panels and batteries. Of course, we are not in any way connected to them and you need to verify about the services offered by them in case you wish to explore such systems for your facility. They are -

Skyway Security wireless solar powered camera pole mount systems.
Solcam Solar powered wireless IP Camera.

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Resolution & Frame Rate in IP Video Surveillance:

Resolution is defined as the number of pixels (independent picture elements, usually expressed in terms of width x height) that make up each picture frame. This is a one-dimensional definition used to describe an image, which is what an individual picture frame is made up of.

But a video stream consists of multiple picture frames that are continuously displayed one after the other. A term called FPS – Frames Per Second is used to represent the frame rate, which actually represents the motion aspect of a video stream.

So while resolution indicates the clarity of images displayed in each frame, FPS indicates the quality of the video motion.

Two things we need to remember in Video Surveillance:

Higher resolution + Higher Frame rate = Higher Quality Video Stream
But,
Higher resolution + Higher Frame rate = Higher bandwidth & Higher storage requirements for Video Stream

It is always better to balance the two aspects based on the application requirements. Certain applications like face recognition, license plate reading, etc. might require a higher resolution/ higher frame rate. But with certain applications like traffic monitoring, perimeter security, etc. a lower resolution/ low frame rate might be sufficient.

Video Surveillance Cameras used today support the following common resolutions:

QVGA Cameras – 320 x 240 Pixels
VGA Cameras – 640 x 480 Pixels
Megapixel Cameras – 1280 x 1024 Pixels
HDTV Cameras – 1280 x 720 Pixels, 1920 x 1080 Pixels

There might be other resolutions used by certain cameras, as well.

The commonly utilized frame rates might vary from 15 frames per second to 30 frames per second. In many cameras, one can actually select the frame rate they want based on the video image quality/ available bandwidth/ storage space, etc. A frame rate of at least 10 frames per second is recommended for the human eye to be able to comprehend the motion properly.

In certain applications like face recognition, etc. a higher resolution might be more important than a higher frame rate because the images need to be clear enough for people to identify certain individual aspects clearly in order to aid the investigation process.

Some video surveillance applications allow video streams to be transmitted at different frame rates and resolutions. For example, a video can be transmitted to a monitor at a different frame rate/resolution but the same can be recorded at a different frame rate/resolution.

Compression in IP Video Surveillance:

Compression techniques are used to transmit video streams from one location to another in the most efficient manner in order to save as much bandwidth as possible. To do this, compression techniques often eliminate data that is repetitive/ redundant.

Each video frame might contain almost the same information as the previous frame except for minor changes. So, instead of sending entire frames, video compression algorithms send only the changes to each frame and individual frames are reconstructed using this information, at the other end.

MJPEG is a lossless compression format because each frame is individually compressed and decompressed. With this format, there is no data loss but the efficiency / level of compression that can be obtained, is very less.

MPEG-4 & H.264 (MPEG-4 Part 10/ AVC) are two of the most commonly used compression formats in IP Video surveillance. They use complex mathematical algorithms to eliminate the redundant data in each frame. They can achieve much more efficiency/bandwidth reduction (compared to MJPEG method), but some data might be lost during transmission (lossy compression technique).

H.264 compression technique might achieve around 25% better compression rates/ bandwidth reduction when compared to MPEG-4 technique, but it consumes more processing power.

High Definition (HDTV) in IP Video Surveillance:

With the popularity of High Definition Video in Video Conferencing and Consumer electronic devices like HDTV, the High Definition format is sought after in the video surveillance industry as well, as it provides higher quality images.

As mentioned before, there are two common High Definition resolutions – 1280 x 720 & 1920 x 1080. HDTV follows the 16:9 aspect ratio.

There are two types of scanning that are popular with High Definition systems – Interlaced Scanning (denoted by ‘i’) and Progressive Scanning (denoted by ‘p’). Progressive Scanning gives a better video quality than interlaced scanning but it requires more bandwidth to be transmitted.

For example, 720p refers to a video resolution of 1280 x 720 and progressive scanning (and) 1080i refers to a video resolution of 1920 x 1080 and interlaced scanning.

High Definition (HDTV) images can be directly shown on computer monitors without requiring any additional conversion/ de-interlacing techniques to be applied. HDTV Video (High Definition Video) can be compressed using H.264 compression for effective transmission that can achieve both good quality and reduced bandwidth.

Reference:

1. White Paper – Video Surveillance Trade-off’s; A Question of Balance: Finding the right combination of image quality, frame rate and bandwidth by Motorola.
2. White Paper – HDTV (High Definition Television) and Video Surveillance by Axis Communications.

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Video Analytics or Video Content Analytics are not new. Video motion detection technologies exist for the last 25 years. With time, they have matured and these days some Intelligent video analytics functions and algorithms are built right into IP Cameras! This saves a lot of processing power, bandwidth and space required in the Network Video Recorder Servers as the cameras record only if certain results are found while analyzing video footage. Let us look at some applications of Video Analytics below.

Video Motion Detection: This function detects if there has been a considerable amount of motion (of interest) in the field of view of a network camera or just a small area of interest within the field of the IP camera. This could be used to protect a store or museum or factory at nights when no one is supposed to enter the premises. If there is considerable suspicious movement inside the surveillance zones, the IP Camera can intimate the owner’s cell phone/ email & start recording. This will also prevent a lot of unwanted video recording (processing power, space and bandwidth) as only the events with considerable amount of movement need to be/ will be recorded.

People Counting: One of the applications of Video Motion Detection is to count the number of people / vehicles moving in a particular direction. This would be useful to locate traffic violations (one way violation), monitoring the popularity of certain sections of a large store based on the total number of people visiting that section, etc.

Camera Tampering Detection: What if an intruder covers the camera with an opaque sheet or just applies some spray paint over the lens? IP cameras can detect them and send alert messages back to the owners.

Digital Fencing/ Cross Line Detection: IP Cameras can detect if an object or a person crosses across a virtual line, where they are not supposed to go. For example, the boundary wall of a company could be monitored by IP cameras and if a person or object crosses the wall, the owners could be notified.

License Plate Recognition: IP Cameras, can recognize and record the license plate numbers for cars parked in a company parking, for example. They can even record numbers from moving vehicles, which might be required for law enforcement agencies.

Facial Recognition: An IP Surveillance system can recognize if a face matches any of the faces already stored in a database. This could be useful for access control, automatic attendance updation, locating a fugitive in a public place, etc.

Object Tracking: Its possible to zoom, center and track a particular object of interest automatically by PTZ Cameras. For example, when a truck is entering into a factory premises, you might want to zoom in and record the truck movement and activities.

Zone Movement: With IP Cameras its possible to designate certain sub-zones in a frame and monitor if they move or people are getting too close to that area. This could be useful in a museum to monitor and protect rare and valuable objects. The system can intimate the owner when an object is moved (and start recording simultaneously) or it can alert people who are going too close (through a loud speaker system).

Many IP Surveillance systems/ IP Cameras have API (Application Programming Interfaces) to allow external analytics programs to interface with them. Something is possible doesn’t mean that its feasible, and hence such applications should always be tested for your particular requirements. One of the biggest issue with Intelligent Video Analytics are false positives & to a small extant, false negatives.

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You should be familiar with Video Conferencing. Now,  have a look at this video (Youtube, 1:00) to have an idea of what a Telepresence meeting looks like. I know, that’s not the best video on Telepresence out there, but its short and sufficient to get an idea.

Generally, a Video Conferencing system adapts to the meeting room/ board room environment. But with Telepresence, a special studio needs to be created according to certain predefined specifications that helps to create an environment optimized for the best possible audio-visual experience.

Everything from the lights, to the room acoustics including sound-echo absorption materials used in the walls, placement of the speakers for 3D experience, placement of mic(s) that pick up voice from anywhere in the room but leave out murmuring/ interfering sounds, placement of the cameras including multiple cameras required for a clear and equidistant view of all the participants, placement of screens and determining the number and sizes of screens required to display life-size images of the far-end participants, conference table size and shape in order to make everyone involved in the conference look like sitting around a single table, textures, colors, dimensions used for each material in the room, and pretty much everything else is pre-defined and followed scrupulously to the last detail.

Telepresence systems often include A/V Control systems that have certain programmable preset configurations for controlling almost every aspect of the room with a single touch. For example, you can press one button to dim the lights and focus on the output of the digital projector (presentation). Another button might bring you back to the normal meeting room mode. With a Video Conferencing system, a lot of things need to be done manually – right from initiating the VC, closing the windows, dimming the lights, switching on the projector, zooming/ focusing on individual personnel using a manual remote control, connecting your laptop to make a presentation, etc. It is possible to individually integrate a lot of components to create a Telepresence-like atmosphere with Video Conferencing systems itself, but that’s another topic.

Of course, Telepresence systems come at a huge cost. Often the costs for Telepresence system can range anywhere between 10x to 100x of a traditional video conferencing system installation cost. Add to it the huge dedicated bandwidth requirements of 2-10 Mbps (in order to minimize latency) every month, you have considerable recurring expenditure as well.

Video Conferencing, on the other hand has been steadily improving and High Definition Video Conferencing is very common and affordable these days. A Video Conference system can call a Telepresence unit and vice versa. So, interoperability is also not an issue. It has never been an issue in the Video Conferencing industry, except for the latest H.264-SVC Codec.

Both Video Conferencing and Telepresence have one major goal – To enable instant video communication/ meetings between people irrespective of their geographic locations & to reduce the travel related expenses / time/ efforts, especially for top executives. The ROI on a Video Conferencing system is very quick.

Considering all these factors, would you go for Telepresence in your company over Video Conference?

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Before a couple of years, I came across a massive Video Conference system installation of over 225 Video Conferencing systems completely over ISDN network. Their reason for choosing ISDN network? In around 70% of the locations where they were installing the video conferencing systems, IP Network (Internet Leased Lines) were simply not available! But in all the locations, ISDN Lines were available. Of course, most of the locations were small towns spread across the state.

Advantages of Video Conferencing over ISDN:

• Lower cost of procurement (ISDN lines) and lower recurring usage (bandwidth) costs – especially for low volume video conferencing requirements.
• Dedicated, Non-fluctuating bandwidth. 128 Kbps in ISDN = 128 Kbps of effective bandwidth, due to lack of packet loss in ISDN networks.
• ISDN Lines / ISDN Video Conferencing systems could be a good back-up to existing IP Networks – Both for video as well as Internet bandwidth.
• ISDN is a separate network – So, VC usage will not affect other critical network services like data, voice, etc.
• ISDN services are available where ever basic phone services are available. Internet Leased Lines/ MPLS Lines are not available everywhere.
• A four-party multi-conference (including the host) could be comfortably made using four ISDN lines. Of course, each site connects at 128 Kbps.
• Most of the ISDN based Video Conferencing systems are IP enabled. So, its possible to use them with IP networks later on if required.
• ISDN Network is a dedicated switched network and hence there is no interference from other forms of traffic. There are no firewall blocking/ NAT traversal issues.
• Multi-party conferencing / higher bandwidth is possible through ISDN-PRI / T1 / E1 Lines.
• ISDN gateways can connect ISDN based Video Conferencing systems to the IP Network, if required. But they are quite expensive.
• While 128 Kbps of ISDN (1 line) might be sufficient for Video Conferencing, broadband connections cannot be used with Video Conferencing systems because the upload and download speeds vary significantly.

Almost all the enterprise companies / large organizations have standardized on IP based Video Conferencing systems. This is partially due to the steep decline in the bandwidth costs and the fact that there is no time based usage limitation for the ordered bandwidth. If at all you want to talk to a partner or a customer, you’ll find that they most probably have IP based Video Conferencing systems.

Advantages of Video Conferencing over IP Network:

• IP Network is already available for Data transfer / Inter-branch Connectivity (Internet Leased Lines/ MPLS Network) in many organizations. Why not use it for Video too?
• IP Networks are great for high volume/ frequent video conferences as there is no usage based / time based restrictions (mostly). With ISDN, there are monthly rental charges as well as per-minute usage charges.
• The bandwidth available in IP networks might fluctuate due to packet loss, but it is easy to upgrade to higher bandwidth. This is especially useful for multi-party video conferencing.
• IP Network is packet switched network and hence the same WAN connection can be used for multiple conferences as long as the required bandwidth is available and the VC system supports it.
• Video Conferencing over IP networks is great if you need to frequently keep moving and initiating conferences from many locations.
• Video Conferencing works over IP networks by default. For ISDN connectivity, additional expensive modules are required.
• With IP Networks, it is easier to pro-actively monitor the health of both the network as well as the VC system.
• There is no cost difference between a VC call to Mumbai / VC call to Frankfurt / VC call to Los Angeles over the IP Network. With ISDN, the charges increase with increasing distance between the two parties.
• Video Conferencing over IP networks are extremely scalable. Its easy to implement desktop video conferencing (for example) to hundreds of users anywhere in the company.
• QoS – Quality of Service parameters in an IP Network allow some bandwidth to be dedicated for mission critical network applications / video conference sessions.

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]]> http://www.excitingip.com/2285/video-conferencing-over-isdn-vs-video-conferencing-over-ip-which-is-better/feed/ 2 http://www.excitingip.com/2259/some-ip-network-cameras-come-with-upto-35x-36x-optical-zoom/ http://www.excitingip.com/2259/some-ip-network-cameras-come-with-upto-35x-36x-optical-zoom/#comments Wed, 27 Jul 2011 20:52:47 +0000 admin http://www.excitingip.com/?p=2259 IP Network Cameras have their advantages over CCTV Surveillance, but I had overlooked this one! Can you imagine what  you can do with a Surveillance Camera that has an 35x-36x Optical zoom? These IP Surveillance Cameras make a lot of interesting applications possible!

For example, if you have a huge factory floor, normally you may have to install multiple cameras at multiple locations to get a good view of what is going on. Of course you need to get the cables to those locations, form a decent backbone network to carry the video signals, etc. But with high zoom capable IP network cameras, probably a couple of them placed at strategic locations will do for a birds eye view of the entire premises. You can always zoom into a particular area if you want to watch something closer.

IP Network Cameras with high optical zoom levels might be very useful for outdoor surveillance requirements like car parking, school / college campus, perimeter surveillance, airports / sea-ports / bus terminus, public utilities, etc. In most of the situations a birds eye view is generally sufficient and when the security officer wants a closer view, he can always zoom in to a particular area. This reduces the number of IP surveillance cameras required for a surveillance project.

You may not be able to zoom in to a video footage that has already been recorded but you can always do that during a live surveillance session. Optical zoom expands the images using physical lens magnification techniques and doesn’t reduce the clarity of the images (un)like the digital zoom. So, 3x optical zoom factor might expand the images up to three times its normal visible size. That means, you can get three times closer to the object in the image due to the magnification ratio of 3:1. Imagine 35x / 36x optical zoom!

In this video (Youtube – See up to 2:30) you can actually see how the IP network camera is kept far away (in a car parking) but is still able to zoom in and read the info on the number plate! There are at least three IP network cameras from prominent manufacturers (here here and here) that come with such high levels of optical zoom (35x-36x). Of course, you might not always need such a high zoom factor and hence you can look at various models that come with slightly lesser optical zoom capabilities depending on your requirement and cost considerations.

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Advantages of Wireless IP Surveillance Cameras:

1. Wi-Fi based wireless broadband services could be used for public surveillance systems (Surveillance of a locality, street, traffic junctions, etc).

2. Wireless surveillance cameras can be useful in situations where it is difficult to lay cables – Museums, Heritage buildings, Industrial plants, etc.

3. Wireless surveillance system is cost effective (when compared to wired networks involving Fiber Cables, Trenching, etc) to install and maintain.

4. Wireless Networks can be deployed quickly and wireless surveillance can be used for providing temporary Wi-Fi to fairs/ exhibitions, etc.

5. Wireless Point-to-Point back-haul networks could extend the network to more than 5 KM over the wireless medium, if required.

6. Wireless networks are quite secure these days as most of them use 802.1x authentication & encrypt communications using WPA2.

7. Wi-Fi Mesh networks can connect to each other (over the wireless medium) to form a nearly all wireless network in a given location. These Mesh networks allow multi-path propagation & can automatically choose alternate paths to avoid single point (link/device) failure.

8. A Wi-Fi network supports QoS (Quality of Service) parameters to be configured for carrying real-time traffic. Basically, the real time traffic is identified in the network and is given higher priority over data traffic.

9. Wireless IP Surveillance cameras can be moved from one place to another without worrying if cable/network jack is available at the new location. In fact, entire wireless setup (including access points, etc) can be moved to a new location easily and quickly.

10. Mobile video footage capture – Its possible to capture video footage using a wireless IP surveillance camera installed over a police car when it is moving (for example).

11. The quality of indoor wireless cameras could be enhanced by using Wireless Controllers to create and maintain a wireless network.

12. Digital Compression techniques like H.264 & H.264 SVC offer a quality video stream in low bandwidths.

Dis-advantages of Wireless IP Surveillance Cameras:

1. If the wireless network is not properly configured, there would be interference from access points operating in the same channel (From internal and neighboring AP’s) which would reduce the quality of the Wi-Fi network.

2. The most commonly used Wi-Fi network band – 2.4 Ghz has only three non-overlapping channels and is always over-crowded. Besides, non Wi-Fi devices like Microwave Owens, Bluetooth devices, etc can interfere with Wireless networks.

3. For long-haul backbone wireless networks, Line of Sight might be required. Even for Wi-Fi access networks (that don’t require a Line of Sight), the signal strength and signal quality might be affected due to interfering objects like Glass, Trees, Elevators, Metallic Racks, etc.

4. Wireless networks offer sufficient bandwidth when IP Surveillance Cameras are placed near the Wireless Access Points. But the bandwidth decreases with increasing distance.

5. IEEE 802.11n is the latest wireless standard that offers more bandwidth + increased wireless coverage distance. But many Wireless IP Surveillance Cameras do not support this standard and even if they do, they might support a reduced MIMO configuration.

6. Packets arriving out-of-order (due to wireless transmission) may result in degraded video quality & stateful compression techniques are intolerant to packet loss.

7. Performance of Wireless Mesh Networks decreases considerably with each (additional) hop. So, the area that a mesh network can cover (and hence its size) is limited.

8. Quality of Service (QoS) parameters should be set end to end to ensure good quality video transmission over IP networks and all the active devices used in the network should be configured for consistent QoS settings.

9. POE Injectors / POE Switches cannot be used with Wireless IP Surveillance Cameras. So, power cables / power source should be arranged for each of them separately.

10. Each video stream occupies a certain bandwidth. So when a lot of video streams are simultaneously transmitted over a wireless network, it might be overwhelmed.

So, what has been your experience with Wireless IP Cameras? Would you go for an all wireless IP surveillance implementation in your campus?

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Day-Night IP Surveillance Cameras:

Images are produced when the eye sees the reflected light from an object. We are basically talking about the visible light (white light) which is actually a small part of the electromagnetic spectrum (wavelength range 400 to 700 nm). Visible light is measured in Lux, which is basically Lumens per Square Meter.

But the electromagnetic spectrum extends well beyond the visible light, and Day-Night IP Surveillance cameras can record images using the reflected near-infrared (IR) rays, instead of visible light. The near-infrared spectrum extends over wavelengths of 700 to 1100 nm, and their intensity is measured in mW per square meter.

The Day-Night IP Surveillance cameras require a minimum light source to function effectively, and cannot work in pitch darkness. Most of them produce black and white images, but some of them can produce coloured images as well using colour corrected illuminators but these are mostly restricted to scientific applications as the scope of error with them, is higher.

But there are certain places which become totally dark during nights. For those places, either an artificial white light based illuminator could be used (or) an IR illuminator that can produce near-infrared light (which can be invisible to the human eye) can be used, to enhance the images in extreme low light/ night conditions. An IR illuminator can illuminate larger spaces than normal light at the same power levels.

These Day-Night Cameras use IR Cut filter in the day in order to record normal coloured images reflected by white light, and disallow the IR waves. But during the night the IR Cut filter automatically gets removed allowing black & white images to be recorded, based on IR reflections.

Thermal IP Surveillance Cameras:

While Day-Night Cameras can be used for detection and identification of objects in low brightness conditions, Thermal IP Surveillance cameras can be used only for detection of objects in nil (or) zero darkness conditions. So, basically you can know that someone is passing through a secured area, but you cannot know who.

This is because, Thermal cameras detect and use the thermal heat (radiation) emitted by a body/ material to produce images. These images are a function of the temperature of the body, and all materials emit some degree of heat. Hotter bodies emit more thermal radiation and colder bodies emit lesser thermal radiation. The varying temperatures are represented by varying colours to produce a negative like image (digitally) using Thermal Cameras, which use Germanium or similar alloys to block the visible light and allow thermal radiation, instead of glass.

As you might have guessed, Thermal cameras are quite expensive and are used in certain specific applications like military, securing high net-worth places (like oil fields), sensitive national boundaries, etc. Thermal cameras perform well under total darkness, fog, rain, smoke, haze and other such vision inhibitors, as they are not based on reflected light.

There are different types of Thermal cameras. Some of them use cryogenic cooling at very low temperatures for producing more sensitive/ clear images, but are very expensive to buy and maintain. Some of them use micro-bolometers which still require a good degree of cooling. There are other thermal cameras which use uncooled thermal image sensors. The third category of thermal cameras are popular for enterprise surveillance applications as they are relatively less expensive to buy and can last for years without requiring much maintenance.

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These days, video based applications are on the rise and the Internet is expected to satisfactorily cater to the bandwidth intensive and latency sensitive video content, notwithstanding its shortcomings like packet loss, etc. While we cannot do much about the physical network that makes  up the Internet, we can sure make video encoding techniques more efficient and effective. If H.264-SVC is standardized to give interoperability and backward compatibility, we might just hit gold!

The above image gives a glimpse of what H.264-SVC is. You can click here to read about its predecessor technology H.264-AVC, which by the way is the most widely used video coding technique today.

Getting slightly technical, In SVC, there is a base layer of video stream & there are multiple enhancement layers above it. H.264-SVC is a set of improvements over H.264 AVC and it introduces Temporal, Spatial and Quality Scalability.

The base layer has a single video stream with a certain frame rate, and the temporal scalability adds enhancement layers with additional frame rates (For example, base layer might contain qCIF-176×144 while the enhancement layers contain CIF-352×288 & 4CIF-704×576). Similarly, spatial scalability adds additional resolutions in the enhancement layers (Eg. 7.5 frames per second, 15 fps, 30 fps, etc). The Quality Scalability improves the SNR (Signal to Noise Ratio) in the enhancement layers (Eg. 128 Kbps, 256 Kbps, 512 Kbps, etc).

So, an SVC stream incorporates multiple streams in a single stream for transmission and storage of video. But it is not always necessary to provide all types of scalability for every video stream and hence SVC stream  can be customized according to the needs of an application.

H.264-SVC has multiple advantages. One obvious advantage is the ability to send a single video stream to multiple heterogeneous clients. One can also do that by using transcoding, and video conferencing systems use that technique for rate matching, but this takes up a relatively large amount of processor load as the video stream sent to each client needs to be encoded individually. Also, transcoding introduces some latency on its own.  And H.264-SVC is useful even for multi-casting.

An SVC video stream is just 10-20% larger than the size of the largest stream it carries. So, when one SVC stream is sent instead of multiple individual video streams, a lot of bandwidth and storage space is saved. More over, the base video stream layer of lower quality can be stored separately, instead of storing all the layers. This might be useful for video surveillance.

Its believed that H.264 SVC can give a decent (manageable) picture quality even at 20-40% packet loss in the network while the maximum tolerable packet loss  for H.264 AVC might be around 1-5%.

Also, since H.264 SVC algorithms are implemented in software, SVC clients can run on a variety of network devices like PC, Laptop, Cell Phone, Tablets, desktop/ room Video Conferencing systems, video surveillance systems, etc.

But the picture is not totally rosy! As of today, H.264-SVC is not a full standard like the H.264 AVC, which means, there is little or no inter-interoperability between the SVC based clients of different vendors. Which means, all the devices need to be from a single vendor to realize the SVC advantages! Actually, even when the VOIP industry and various other industries were struggling with proprietary technologies, the video industry set an example by following open standards (like H.264 AVC). But to take a huge step backwards now, when the whole industry is standardizing is a little strange! But lets hope everyone agrees on standards and interoperability sooner.

Also, SVC requires that the base stream be transmitted safely across the network even if the enhancement layers are subjected to packet loss. They have worked some methods to achieve this, but on a private network, one could always enable end to end QoS with base layer transmission having the highest priority. This cannot be applied to the Internet though!

There is a workaround for the lack of interoperability – Introducing Gateways that can do the translation. In some cases, gateways are required even between the same vendor H.264 SVC and AVC devices, as they are not always able to talk to each other! But adding gateways increases the cost, complexity and also latency.

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