Monday, November 16, 2009

CCTV DVR Glossary of Terms

In choosing the CCTV system that is most suitable for a specific application, we will need to consider some important parameters to meet the standards and requirements of the project. We may encounter some terms like fps, resolution and compression which are common terms in the CCTV and Video Surveillance world. We may hear them often but we don't really understand them (esp. the End-users). It would be better to know how relevant they are to the CCTV system's functionality and operation so we can evaluate if a CCTV system falls short of our requirement or is too high-level for our desired application.

Let's try to understand some of these common terms:

Analog Video Signal - Video signal which contains the luminance (brightness) and chrominance (color information) of the image, which may be carried in separate or combined channels. This is the type of camera signal used by older cameras, often called analog cameras or CCTV cameras. These cameras transmit the signal via Co-ax Cables, which are not network-ready.

ASIC - (Application Specific Integrated Circuit) Integrated circuit is customized based on the user’s specific needs. Basically, the circuit has a specific use.

Bandwidth - The channel capacity for information transmission over an internet connection. If the information flow is too much for the bandwidth, the bandwidth is said to “choke.”

CIF - (Common Intermediate Format) Video size format measuring 360 x 240 pixels for NTSC and 360 x 288 pixels for PAL.

Compression - In surveillance, compression refers to the process in which the data used to present an image or a video is reduced.

D1 - A video size format measuring 720 x 480 for NTSC and 720 x 576.

Decode/Decoding - It is the process of transforming information or data from one format into another. In surveillance, it is the process in which the compressed video data is transformed to raw video data.

Digital Video Signal - Digital video signals are digital representations of discrete-time signals. In surveillance, it is the type of camera signal used by newer cameras. These cameras transmit the signal via Cat5 Cables, which are network-ready. Digital Video Signal is also known as IP Signal.

DVR - (Digital Video Recorder) A device that records videos onto a hard disk drive.

DVR Card - Also called DVR capture card. The DVR card, which allows a computer to receive television signals, record video, and/or playback video content is the center or heart of the DVR system.

Embedded DVR - Embedded DVRs are all-in-one, often times plug and play standalone DVRs. A PDA phone is an example of embedded technology. DVRs such as Standalone DVRs or embedded DVRs are manufactured for the sole purpose of being a DVR. These typically contain a single circuit board with DVR software implanted into the chip.

Encode/Encoding - It is the process of transforming information or data from one format into another. In surveillance, it is the process in which the raw video data is transformed to compressed video format.

FPS - (Frames Per Second). A measurement standard for the viewing and recording speeds of videos. Real-time viewing and recording speed is at 30 fps for NTSC and at 25 fps for PAL. When a video plays at these speed rates, it is as good as watching the action face to face, hence the term “real-time”.

Half D1 - A video size format measuring 720 x 240 pixels for NTSC and 720 x 288 for PAL.

Hardware Compression vs. Software Compression - Hardware compression happens on the level of the microchip (or chip). Because the compression is done “physically,” none of the CPU space is eaten up. In software compression, the data is compressed using the memory and the speed of the CPU, as the software resides in the CPU. Since the CPU receives a continuous flow of data to be compressed, there is a possibility for it to be overwhelmed and thus hang. Since hardware compression uses only the microchip and does not involve the CPU, the risk of the computer hanging is totally avoided.

Hardware MPEG4 Compression - A compression capability that combines hardware compression technology and the MPEG-4 compression standard.

Hybrid DVR - A DVR capable of accepting both analog and digital video signals.

Linux - A freely available open-source operating system. As compared to other operating systems sold commercially, Linux is royalty-free, highly customizable and more stable. CentOS is one of the more popular the Linux distributions.

MPEG4 Compression - MPEG 4 is a measurement standard for digital video and digital audio compression. In the DVR market today, MPEG 4 compression is considered to be one of the higher compression rates available. Other compression standards are MPEG 1, MPEG 2, and MJPEG.

Network - A series of computers or mobile devices that are connected to each other with the purpose of communicating and sharing information. A Local Area Network (LAN) is a type of network connection usually found among the computers in an office or an internet café. A Wide Area Network (WAN) on the other hand, is a network connection that spans over a broad geographical area. For data to travel via the network, it must be in digital format.

NTSC - (National Televisions Standards Committee) Standard video signal for the US and the Philippines.

PAL - (Phase Alternating Line) Standard video signal for Europe and some countries in Asia.

PC-Based DVR - A DVR using the hardware format of a regular PC.

QCIF - (Quarter Common Intermediate Format). A video size format measuring 180 x 120 pixels for NTSC and 180 x 144 pixels for PAL.

Resolution - A measurement standard for how clear (level of detail) the video is. The resolution is usually measured by the number of pixels shown on screen. The more pixels shown, the higher the resolution.

SDK - (Software Development Kit or Systems Disk Kit). A start up kit usually offered by DVR manufacturers to users who wish to build their own DVR system.

Video Server - A device that accepts analog signal and converts it to digital signal. This allows the video to be viewed remotely via a network connection.


Kuldip Vyas said...
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dvr cards said...

This thing really seems amazing and we also get much better security on this.,..

Erin Johnson said...

In any sort of business, using these kinds of security cameras provides various gains. They are not only confined to safeguarding the business premises, employees and also consumers but they are as well used to monitor any activity that is performed in and out the business place.

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