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Video Surveillance Glossary of Terms [V]
- » Variofocal lens
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This type of lens has the capability of
varying its focal length in order to zoom in on images. An
auto iris feature is required in order to achieve this.
Variofocal lenses are contrasted with fixed focal lenses,
which are less expensive and often allows more light to pass
through them at their set length, enabling better detection
in low light circumstances.
- » Vertical resolution
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The number of horizontal lines resolved
in a picture is called the vertical resolution, and is
determined by the television scanning method, be it NTSC,
PAL, or some other format.
- » Vibration sensor
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A device that activates when it detects
vibrations in its detection zone, and then activates a
specific surveillance camera is known as a vibration sensor.
- » Video amplifier
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This device boosts the strength of a
video signal.
- » Video compression
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This technique (often a MPEG format)
compresses video into lower bit rates for easier Internet
transmission, often along narrower bandwidths. Video or
audio is compressed to shrink file size, ensuring acceptable
transfer speed. Compressed video can sometimes be of a
noticeably lower quality, but still clear enough to be
useful. AVC is the successor to MPEG as the new video
compression standard.
- » Video distribution amplifier
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This amplifier is able to boost signal
strength and also to create multiple video signal outputs.
- » Video intercom
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Used at door entryways, this system
utilizes audio and video for communication or movement
control of people.
- » Video server
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This enables an analog camera to be
converted into an IP camera, able to stream digital video
over an office network, phone, or ISDN connection.
Therefore, an analog based surveillance system can be
upgraded and networked to function as an IP surveillance
system.
- » Video streaming
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Streaming video delivers compressed
multimedia content over the Internet in a stream of
packets. Viewers view the file as it downloads, instead of
downloading the entire file first. Streaming video first
initializes the transfer, and then buffers it. Bandwidth
determines both picture quality and whether or not the
viewed video catches up with the downloading content, which
causes the video to stop. RealPlayer is one of the most
popular free streaming video players available. Video
streaming is commonly used for viewing live feeds from
security cameras, with RTSP/RTP being the main streaming
technology currently in use.
- » Video surveillance
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This term refers to the use of CCTV and
DVR to monitor secure sites, or portions thereof. Video
Surveillance systems can start with a few as one camera.
For systems using more than 16 cameras, enterprise video
surveillance systems are preferable. The many terms defined
in this glossary give an idea of the many options available
for different security needs and situations. In today’s
professional world, Video Surveillance (often referred to as
CCTV) is the most cost effective way to achieve loss
prevention.
About the Author
Ben Davidson is an experienced freelance writer of
technological subjects. His work provides clear and valuable
information about
video
surveillance,
night vision
cameras, and
wireless security
systems for consumers looking to purchase video security
equipment for their home or business.
Also See:
[
How
IP Based Video Surveillance Works ]
[
History of
Video Surveillance ]
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