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Videoconferencing
(VC) is a combination of full duplex audio and
video transmissions which allows people in two
different locations to see and hear each other as
if participating in a face-to-face conversation. A
camera is utilized at both end points to capture
and send the video signals. Microphones are used
at each endpoint to capture and transmit speech
which is then played through speakers. The
communications are real-time and generally not
stored.
Video
over IP
Telecom
operators have long toyed with the idea of running
video over their present infrastructures, but now
there's a couple of reasons why it might start
happening on a large scale.
First,
incumbent telcos are in a financial jam. They've
got millions of tons of copper local loops in the
ground and they're desperate to generate new
revenues from it, to compensate for declining
voice revenues.
Still,
the video market isn't exactly empty – think
cable, satellite, and the local video store –
and telco networks certainly weren't designed for
video distribution.
Encoding
of Video
A
Video Codec ( Encoder )
transports video and audio signals from
cameras , VCRs
and audio over a data network to other Video
Codecs or computers somewhere else on the network.
In a typical Networked TV application, the VCR or
TV Tuner selects video and audio from Cable TV or
the airwaves or it can get video and audio from a
VCR tape or DVD. The video and audio is connected
to the Video Codec
where they are digitised (converted to
data) and compressed (duplicate or trivial data is
removed). The encoded data is created in a
standard format known as MPEG , MJPEG
that allows interoperability between
devices from multiple vendors. Because the video
is not just a single picture but a continuous
series of snapshots of the world the camera is
pointed to, the data from the Encoder is
continuous. This continuous video data, known as a
video stream, is taken from the Encoder by a
program running on the Video Codec and sent out a
network interface to the network.
MPEG-4
MPEG-4
is an ISO/IEC standard developed by MPEG
(Moving Picture Experts
Group). The first version of the MPEG-4 standard
was finalized in 1998 and became an international
standard at the beginning of 1999. Although
defined as one standard, MPEG-4 is actually a set
of compression
/decompression formats and streaming technologies
that address the need for distributing rich
interactive media over narrow and broadband
networks. One of these efforts has led to a new
MPEG-4 based video compression standard known
as H.264. Finalization of the H.264 standard was
approved by a joint team of experts from the ITU
((International Telecommunications Union) and the
ISO (International Standards Organization).
Video
Monitoring
The
goal of the video monitoring system also affects
the type of system
installed. In vulnerable public places such as
train stations or bus stops, video cameras are
combined with other emergency communications
systems like hot phones or duress alarms. The
capacity of coax cables is limited and so the
signal that is transported is limited. When the
analog video signal is received at the control centre
it was stored on magnetic tape, an unfriendly
medium that does not allow for easy retrieval or
search.
The
development of IP networks and digital video has
changed dramatically. Video transmission over IP
networks can greatly enhance video monitoring
systems, which are fundamentally systems that use
video networking infrastructure.
Using
high quality MPEG Video for Monitoring
There
is an increasing demand that video monitoring
solutions provide DVD
quality signals so that control centres can
see exactly what is going on
at any given location. The only digital video
standard that meets these requirements is MPEG.
MPEG is an international standard that compresses
analog video signals without any perceived loss of
quality. A monitoring system based on MPEG
compression would consist of high quality analog
cameras that feed signals into an MPEG encoding
and streaming platform. The MPEG streaming
platform interfaces with the IP network and
transmits streams to a central control centre.
The
Advantages of MPEG Video and IP Networks for
Monitoring
- Quality
Today,
security and safety requirements demand excellent
video quality of video.
Monitors want to be able to see the most minute
details in all weather conditions, day or night.
MPEG, an international video compression standard
using in broadcasting and DVD creation, can
provide the top quality video required by
today’s monitoring systems. Use of existing
infrastructure Most organizations already have
high-speed networks that can support video
transmission and streaming. Most equipment
interfaces with the network at the point of
transmission and at the control centre.
How
IP Video Monitoring Works
Once
the video signal is captured and ready for
transmission, it is fed into a streaming platform
which wraps the signal in IP and transmits it over
the network to the control centre.
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