Cctv and Video Monitoring – How it Works

admin    Flash Video     Cctv, Monitoring, Video, Works.

CCTV stands for Closed Circuit TV. CCTV uses one or more video cameras to transmit video images and sometimes audio images to a monitor, set of monitors or video recorder. The difference between CCTV and standard TV is that standard TV openly broadcasts signals to the public.

CCTV is not openly transmitted to the public. CCTV uses either wireless transmission or a wired transmission to send the broadcast from the video cameras to the monitor(s) or recording device. Most CCTV systems are used for surveillance which can include security monitoring, spying or for safety monitoring purposes.

A video monitoring system is more commonly known as Closed Circuit Television Systems (CCTV). A CCTV system is an on premises system consisting of a television camera, video monitor, and a transmission medium (Cable, fiber or wireless) connecting the two. It is used to monitor the premises. Probably the most widely known use of CCTV is in security systems and such applications as retail shops, banks, government establishments, etc.

Main features:

• Video clip (desirable time duration) and/or single snapshot images

• JPEG and MPEG-4 compression

• Images can be saved on a local microSD card

• Lens can be selected according to user requirements and needs

• Built-in microphone for audio surveillance

• Built-in Web server for monitoring via standard browser

• Built-in VPN client (optionally)

• Quad Band 850/900/1800/1900 MHz GPRS/EDGE network

Video monitoring system for transmission of high resolution video and single images via GPRS/EDGE network. So even in places with no Internet connection available – ideal for remote surveillance and monitoring of temporary or distant sites or mobile assets. The images can be acquired automatically with programmable period and/or upon external triggers such as motion sensors or door contacts.

The video and single images can be viewed on a PC or a handheld device, and can also be transmitted to FTP-server and/or by e-mail. The video and single images can be recorded on a local miniSD card and later downloaded or reviewed via built-in Web server.

CCTV Remote Monitoring and video recording services are particularly relevant for sites with little out-of-hours activity, where the value of maintaining a manned presence is limited.

Selecting the right Digital Video Recorder for your CCTV application

admin    Flash Video     application, Cctv, Digital, Recorder, Right, Selecting, Video

Next to choosing the right camera for your surveillance needs, the selection of an appropriate recording device is the second most important decision you will make. There are a lot of different options to choose from, each with their own pros and cons.

The easiest decision to make is that of the recording media. VCR type recorders that use VHS tapes to make time lapse videos are pretty much a thing of the past. They have all but been replaced with Digital Video Recorders (DVR) that store recorded video in a digital format onto a fixed storage device.

Digital Video Recorders are available as stand alone devices, or can be purchased as a card that is added to an existing PC.

Stand alone DVR devices are about the size of a DVD player and do not require additional hardware to function (other than a monitor). Be aware that some models do not include a hard drive – you must install one inside the unit yourself. If you do not want to be bothered with doing this, purchase a model with a hard drive already installed.

Stand alone DVR’s are very convenient and reliable. You simply plug your cameras into the device and configure your recording preferences and before you know it, your are done! No fuss, no mess. Some models even feature a network port that allows you to access and view your cameras from the Internet. Others have built-in USB ports and DVD burners to export video clips.

Video capture cards are used to add DVR capabilities to an existing PC. They tend to be less expensive than a dedicated DVR, but they require quite a bit of legwork to get up and running. The first issue to deal with is compatibility. Some cards only work with specific video card chipsets and operating systems – therefore it is important to be very diligent when looking over the system requirements before making your purchase. Video capture cards usually include the necessary software to monitor your cameras.

The second issue with video capture cards is the nature of their installations – your computer must stay powered on in order for the software to function, and the installation is highly dependent upon the reliability of the computer operating system. It is for these reasons that I prefer the ?install it and forget about it? nature of stand alone Digital Video Recorders.

Is is also important to take into account how many cameras you need to monitor and record. DVR prices start at about $100 for a basic video capture card and can reach up into the thousands of dollars. The more cameras you need to record, the more the unit will cost. For most residential and small business needs, a 4 or 8 camera DVR will do just fine. Expect to pay about $100 per camera port for a good stand alone DVR.

The next thing you want to verify is the recording resolution and frame rate. It is important that your DVR have the capability of recording at the same or higher resolution than your camera feeds. If you cameras transmit 480 lines of resolution, make sure your DVR can handle it. Digital video recorders now use several different video compression standards to store video. Try to get a unit that supports either H.264 or MPEG4 – they will allow you to store more video on your hard drive at higher resolutions and frame rates.

As far as storage is concerned, the bigger the hard drive, the more footage you can store. Combining motion activated recording with today’s larger hard drives should allow you to store months of footage on a 4 or 8 camera setup.

Finally, you will want to look into features such as the availability of motion based recording, scheduled recording and remote access to both real time feeds and stored video. These features are now pretty standard on newer models. Also make sure that the unit makes it easy to search and export video clips.

H.264 compression versus MPEG4 compression for cctv video storage and transmission

admin    Flash Video     Cctv, Compression, H.264, Mpeg4, Storage, transmission, versus, Video

Today many security managers and business professionals are switching to digital options for their CCTV. While this represents a slightly larger investment, it also largely increases flexibility, quality and efficiency through a variety of different options and functions. One of these options is the ability to select which format to compress videos in.

On your computer you may have downloaded a variety of videos; if you look at each of these by right clicking on them and selecting ‘properties’, you will notice that some of them are different file types. These will vary from .WMV to .MPEG to .AVI and each has different properties. What this refers to is the videos’ ‘compression type’. If you consider the size (in terms of kilobites or megabites) that an image size takes up, you can imagine why it’s important that these images are somehow ‘cut down’ in order to save space when potentially millions of them are strung together to create a video. This happens at the level of the code (the language that the computer or video device reads), but can be visible in the videos’ appearances as washed out colours, lower resolutions, blurry edges or fuzzy motion. The aim here is to find a satisfactory balance between viewing quality and file size – so that you can store as much information onto a hard drive or disk as possible without sacrificing too much detail.

When recording with a DVR (digital video recorder), this works in much the same way and the videos must be compressed when they’re saved. Only in cases of CCTV, compression type is far more crucial as you’re not only dealing with larger quantities of footage (sometimes hours’ and hours’ worth) but also with delicate situations that require the highest possible frame-rates and resolutions if you are to correctly identify problems. For these reasons, when purchasing a DVR it’s highly important that you find out what compression types it supports (sometimes referred to simply as ‘video formats’) and what the different titles represent.

The two main types of compression format for digital CCTV are ‘H.264 format’ and ‘MPEG’ (AKA Motion JPEG, and by which is usually meant MPEG2). The key thing to note here however, is that H.264 format is also known as MPEG4, meaning that it is in fact an updated version of the alternate format. H.264 video compression format therefore drastically reduces both the bandwidth and storage requirements of the files by keeping them small while keeping the image quality high. Usually however this results in a lower ‘bit rate’ for the video which means that fewer ‘bits’ of information are available per second, but the method of encoding ensures that these lost ‘bits’ are unnecessary (high frequencies for example). With an average set up with four cameras at thirty frames per second and a resolution of 320 x 240 (with motion sensors), you can expect MPEG4 compression to provide 80 hours worth of footage at 20-25 gigabites.

However unlike MP2, MP4 has no government enforced standard and as such does not have universal interchange across codecs of various designs. This means that MP2 is more flexible and adaptable as well as having a higher bit rate giving it its own unique advantages. Fortunately however, today most cameras support both formats and even where they do not file conversion is often available.

Cctv: Video Compression in Dvrs

admin    Flash Video     Cctv, Compression, Dvrs, Video

DVR stands for Digitals Video Recorder. Advantage of using a DVR technology over analog recording is that the Digital Data recorded by DVR can be compressed and saved in special hard disk and can be reviewed later. Video compression plays an important role in overall operation, properly compressed video can also save disk space.

All DVRs use some kind of compression algorithm called a codec to keep the digital video files at a manageable size. The average size of an uncompressed still image frame at 320×240 resolution in 24-bit true color is about 230400 Byte or 2.3 Mega Byte. Same image frame in 32 bit color is about 307200 Byte or 3.07 Mega Byte.

An hour’s worth of one channel of uncompressed video at 25 frames per second would take up 21,600 megabytes (21.6 GB)

Uncompressed video of one hour will take hard disk space

Frame size 320*240 Pixel at 25 frames per second would take up

25*3600* 230400 Byte = 20736 Mega bytes

= 20.736 GB (24 bit color)

25*3600* 307200 Byte = 27648 Mega bytes

= 27.648 GB (32 bit color)

Get CCTV technology in India from Digitals India. Visit www.digitalsindia.com/cctv.html