How to Selecting the right CCTV video compression

If you are responsible for planning or designing a new CCTV video surveillance system, you have to make a technology choice regarding which video compression technique to use.

For sure, it will be digital. But which video compression scheme is the most suitable for your application?

1. Motion JPEG CCTV video compression
The JPEG standard was developed by the Joint Photographic Expert Group (part of ISO) for efficient storage of individual frames. Motion JPEG or M-JPEG is a series of separate JPEG images that form a video sequence. When 16 JPEG image frames or more are joined together per second, the result is an illusion of motion video. Video reproduction at 30 frames per second (FPS) for NTSC signals or 25 FPS for PAL signals is called full motion video or continuous-motion video.

Although Motion JPEG is an unlicensed standard it is widely compatible with many applications that require low frame rates or technologies such as Video Analytics where frame by frame analysis is crucial.

Advantages
1. Ability to support multi-mega pixel resolution.
2. Ideal for courtroom single frame evidence.
3. Clearer images at lower frame rates than MPEG-4.
4. Frame by frame playback offers more frames to view.
5. Technology is simpler; this can reduce the cost of a camera or video codec.
6. At low bandwidth priority is given to Image Resolution.
Disadvantages
1. High bit rate for scenes with little or no activity increases bandwidth and storage.
2. Video quality deteriorates at higher compression ratios.
3. No M-JPEG standard often means incompatibility issues.
4. Converting M-JPEG into another format reduces video quality.
5. Dated technology superseded by more bandwidth-efficient encoding techniques.

MPEG-4 CCTV video compression
MPEG-4 is a compression standard that was introduced in late 1998 by the Moving Picture Experts Group. In video surveillance applications MPEG-4 Part 2, also known as MPEG-4 Visual is the version of MPEG-4 most commonly used. MPEG-4 supports both low-bandwidth applications and those applications that require high quality images, with virtually unlimited bandwidth and no limitations in frame-rate. Typically most MPEG-4 based encoders and cameras support video up to DVD quality.

MPEG-4 is much more efficient than M-JPEG because video frames are analysed prior to being sent across the network. The first compressed image (I frame) is used as a reference point, the following images only contain information that differs to the initial I frame reference image. Periodically I frames are transmitted within the video sequence to ensure a recent reference point. The distance between these I frames is known as the GOP (Group of Pictures). The distance between I frames is usually user definable depending on the application and activity in the scene. For example a 25 FPS video stream with a GOP of 50 would mean a new I frame with GOP change information is sent every 2 seconds. The viewing application on the receiving end of the transmission then reconstructs all images based on this information and displays the video.

Advantages
1. MPEG-4 up to 5 times more efficient than M-JPEG at low bandwidths.
2. Increases the amount of time video can be stored compared with M-JPEG.
3. Uses less network bandwidth when compared with M-JPEG.
4. Very efficient at high frame rates.
Disadvantages
1. When the bit-rate is limited video quality suffers.
2. Low efficiency at very low frame-rates or extremely high scene activity.
3. Can be liable to “blurring” on freeze frame or very high motion.

H.264 CCTV video compression
H.264 is the latest MPEG standard for video encoding that is geared to take video beyond the realms of DVD quality by supporting Hi Definition CCTV video. H.264 can also reduce the size of digital video by more than 80% compared with M-JPEG and as much as 50% with MPEG-4, all without compromising image quality. This means that much less network bandwidth and storage space are required. Since the typical storage costs for surveillance projects represent between 20 and 30 percent of the project cost significant savings can be made.

Like many sectors of our industry, the devil is in the detail and system integrators and end-users who wish to see the benefits of an IP-based solution should look to someone who really knows the technology and can give an impartial view. It is common sense that manufacturers will only support their own hardware and will promise the earth for it, whereas a distributor will have evaluated a number of solutions from different vendors and be able to say that product A is the best for solution B because of XYZ whereas product Y is the best for solution C because of etc etc.

Advantage
1. H.264 cameras is that they reduce the amount of bandwidth needed.if your megapixel camera needed 10 Mb/s before (with MJPEG), it might now need only 1.5 Mb/s. So for each camera, you will save a lot of bandwidth.
2. Eliminates barriers: Enables many more networks to support megapixel cameras.
3. The bitstream is fully compatible with existing decoders with no error/drift.
Disadvantages
1. Using analytics with these cameras reduces the H.264 benefit.
2. Costs few hundred dollars more per camera.

CCTV IP Camera
IP cameras are Closed-circuit television (CCTV) cameras that use Internet Protocol to transmit image data and control signals over a Fast Ethernet link. As such, IP cameras are also commonly referred to as network cameras. IP cameras are primarily used for surveillance in the same manner as analog closed-circuit television. A number of IP cameras are normally deployed together with a digital video recorder (DVR) or a network video recorder (NVR) to form a video surveillance system.
A Network IP Camera is a stand-alone device which allows a user to view live, full motion video from anywhere on a computer network, even over the Internet, using a standard web-browser.
A network camera can be configured to send video over an IP network for live viewing and/or recording either continuously, at scheduled times, on an event or on request from authorized users. Captured images can be streamed as Motion JPEG, MPEG-4 or H.264 video using various networking protocols, or uploaded as individual JPEG images using FTP, e-mail or HTTP (Hypertext Transfer Protocol).

Until very recently, video security and surveillance was accomplished using Closed Circuit Television or CCTV. This technology included analog cameras, coaxial cable and video tape recorders. Video security and surveillance started entering the digital age with the advent of CCD sensors which digitized image capture in the camera. However, transmission was still analog via coax to analog VCR's. The next step was the introduction of Digital Video Recorders (DVR's) connected directly to analog cameras, which made storing, searching and retrieving video much more efficient. PC's were then introduced for display of the images through a modem or network connection to the DVR.

The entire system has now been digitized with the introduction of Network Cameras incorporating onboard processors and web server software. These Network Cameras can be connected directly to existing IP networks, eliminating the need for separate and expensive coaxial cable networks. Images can be viewed and cameras managed from anywhere via a web browser, plus any hard disk on the network can be set up to record the video output.

Another significant technology called Video Servers, allow existing CCTV installations to gain the benefit of Network Video, while protecting investments in analog cameras. Video Servers connect to IP Networks and convert the signal from analog cameras to digital format. Like Network Cameras, Video Servers contain onboard processors and web server software that makes each camera IP addressable. Essentially, Video Servers turn CCTV cameras into IP Network Cameras.
When you’re shopping around for an IP-based video surveillance system, you will need to be particularly cautious about what exactly you’re looking at and what the individual terms mean. How IP-based video surveillance works is open to interpretation as far as some video surveillance and security salespeople are concerned -- not because they are trying to confuse the issues, but because there is no genuine consensus on what the term “IP-based” or related ones such as “networked” or “web-based” means.

In addition to capturing video, Axis network cameras provide event management and intelligent video functionalities such as video motion detection, audio detection, active tampering alarm and auto-tracking. Most network cameras also offer input/output (I/O) ports that enable connections to external devices such as sensors and relays. Other features may include audio capabilities and built-in support for Power over Ethernet (PoE). Axis network cameras also support advanced security and network management features.

If you are considering a network-based IP CCTV solution, we are able to offer the following three levels of service through our specialist IP CCTV Partner company:

1. Simply sales and supply of selected 'Best of Breed' IP CCTV hardware and software. You will be able to see the equipment and software solutions on the web, check the specifications, read the reviews and buy online. Our Partner offers Free Delivery, a Price Match Promise, and a 14-day 'Buy & Try' Scheme, so you can rest assured with these rock solid offers that you can select and prove your new IP CCTV solution in total confidence.
2. Expert professional advice and guidance; based upon years of CCTV design & application experience, our specialist IP CCTV Partner will discuss your application with you by phone or email and develop the optimum IP CCTV solution to meet your Operational Requirement. You can then revert to option 1 above and progress to build your solution in-house by purchasing IP CCTV components and software online OR you may opt to choose option 3 below and progress to have us manage a fully turnkey solution (including installation) for you.
3. Complete design service. Our Partner company will take a full brief from you, visit your site to fully understand your Operational Requirements and produce a professional specification which will be submited to three proven installation companies. Each company will then submit a tender directly to you. In the majority of cases this service is free of charge.