![INTRODUCTION
Videoconferencing (VC) is the conduct of a videoconference (also known as a video
Conference or video teleconference) by a set of telecommunication technologies which allow two
Or more locations to communicate by simultaneous two-way video and audio transmissions. It has
Also been called 'visual collaboration' and is a type of groupware.
Videoconferencing differs from videophone calls in that it's designed to serve a conference or
Multiple locations rather than individuals.[1]
It is an intermediate form of video telephony, first used
Commercially in Germany during the late-1930s and later in the United States during the early 1970s
As part of AT&T's development of Picture phone technology.
With the introduction of relatively low cost, high capacity broadband telecommunication services in
The late 1990s, coupled with powerful computing processors and video compression techniques,
Videoconferencing has made significant inroads in business, education, medicine and media.
An internet forum is a discussion area on a website. Website members can post discussions and
respond to posts by their forum members. A forum can be focused on nearly any subject and a sense of an
online community, or virtual community, tends to develop among forum members.](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-1-320.jpg)
![Videoconferencing uses audio and video telecommunications to bring people at different sites
together. This can be as simple as a conversation between people in private offices (point-to-point)
or involve several (multipoint) sites in large rooms at multiple locations. Besides the audio and visual
transmission of meeting activities, allied videoconferencing technologies can be used to share
documents and display information on whiteboards. Simple analog videophone communication could
be established as early as the invention of the television. Such an antecedent usually consisted of
two closed-circuit television systems connected via coax cable or radio. An example of that was
the German Reich Postzentralamt (post office) video telephone network serving Berlin and several
German cities via coaxial cables between 1936 and 1940.[2][3]
During the first manned space flights, NASA used two radio-frequency (UHF or VHF) video links,
one in each direction. TV channels routinely use this type of video telephony when reporting from
distant locations. The news media were to become regular users of mobile links to satellites using
specially equipped trucks, and much later via special satellite videophones in a briefcase.
This technique was very expensive, though, and could not be used for applications such
as telemedicine, distance education, and business meetings. Attempts at using
normal telephony networks to transmit slow-scan video, such as the first systems developed batty,
first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient
video compression techniques. The greater 1 MHz bandwidth and 6 Mbit/s bit rate of the Picture
phone in the 1970s also did not achieve commercial success, mostly due to its high cost, but also
due to a lack of network effect —with only a few hundred Picture phones in the world, users had
extremely few contacts they could actually call to, and interoperability with other videophone
systems would not exist for decades.
While videoconferencing technology was initially used primarily within internal corporate
communication networks, one of the first community service usages of the technology started in
1992 through a unique partnership with PictureTel and IBM Corporations which at the time were
promoting a jointly developed desktop based videoconferencing productknown as the PCS/1. Over
the next 15 years, Project (Diversified Information and Assistance Network) grew to utilize a variety
of videoconferencing platforms to create a multi-state cooperative public service and distance
education network consisting of several hundred schools, neighborhood centers, libraries, science
museums, zoos and parks, public assistance centers, and other community oriented organizations.
In the 2000s, video telephony was popularized via free Internet services such as Skype and chat,
web plug-in and on-line telecommunication programs that promoted low cost, albeit lower-quality,
videoconferencing to virtually every location with an Internet connection.
Russian President Dmitry Medvedevattending the Singapore APEC summit, holding a videoconference with
Rashid Nurgaliyev via a Tactical MXP, after anarms depot explosion in Russia (2009).](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-2-320.jpg)
![In May 2005, the first high definition video conferencing systems, produced by LifeSize
Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide
video at 30 frames per second with a 1280 by 720 display resolution.[8][9]
Polycot introduced its first
high definition video conferencing system to the market in 2006. As of the 2010s, high definition
resolution for videoconferencing became a popular feature, with most major suppliers in the
videoconferencing market offering it.
Technological developments by videoconferencing developers in the 2010s have extended the
capabilities of video conferencing systems beyond the boardroom for use with hand-held mobile
devices that combine the use of video, audio and on-screen drawing capabilities broadcasting in
real-time over secure networks, independent of location. Mobile collaboration systems now allow
multiple people in previously unreachable locations, such as workers on an off-shore oil rig, the
ability to view and discuss issues with colleagues thousands of miles away. Traditional
videoconferencing system manufacturers have begun providing mobile applications as well, such as
those that allow for live and still image streaming.[10]
The core technology used in a videoconferencing system is digital compression of audio and video
streams in real time. The hardware or software that performs compression is called
a codec(coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital
stream of 1s and 0s is subdivided into labeled packets, which are then transmitted through a digital
network of some kind (usually ISDN or IP). The use of audio modems in the transmission line allow
for the use of POTS, or the Plain Old Telephone System, in some low-speed applications, such
as video telephony, because they convert the digital pulses to/from analog waves in the audio
spectrum range.
The other components required for a videoconferencing system include:
Video input: video camera or webcam
Video output: computer monitor, television or projector
Audio input: microphones, CD/DVD player, cassette player, or any other source of PreAmp
audio outlet.
Audio output: usually loudspeakers associated with the display device or telephone
Data transfer: analog or digital telephone network, LAN or Internet
Computer: a data processing unit that ties together the other components, does the
compressing and decompressing, and initiates and maintains the data linkage via the network.
There are basically two kinds of videoconferencing systems:
1. Dedicated systems have all required components packaged into a single piece of
equipment, usually a console with a high quality remote controlled video camera. These
cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom.
They became known as PTZ cameras. The console contains all electrical interfaces, the
control computer, and the software or hardware-based codec. Omni directional microphones
are connected to the console, as well as a TV monitor with loudspeakers and/or a video
projector. There are several types of dedicated videoconferencing devices:
1. Large group videoconferencings are non-portable, large, more expensive devices
used for large rooms and auditoriums.
2. Small group videoconferencings are non-portable or portable, smaller, less
expensive devices used for small meeting rooms.](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-3-320.jpg)
![3. Individual videoconferencing are usually portable devices, meant for single users,
have fixed cameras, microphones and loudspeakers integrated into the console.
2. Desktop systems are add-ons (hardware boards or software codec) to normal PCs and
laptops, transforming them into videoconferencing devices. A range of different cameras and
microphones can be used with the codec, which contains the necessary codec and
transmission interfaces. Most of the desktops systems work with the H.323standard.
Videoconferences carried out via dispersed PCs are also known as e-meetings. These can
also be nonstandard, Microsoft Lync, Skype for Business, Google Hangouts, or Yahoo
Messenger or standards based, Cisco Jabber.
3. WebRTC Platforms are video conferencing solutions that are not resident by using a
software application but are available through the standard web browser. Solutions such as
Adobe Connect and Cisco WebEx can be accessed by going to a URL sent by the meeting
organizer and various degrees of security can be attached to the virtual "room". Often the
user will be required to download a piece of software, called an "Add In" to enable the
browser to access the local camera, microphone and establish a connection to the meeting.
Conferencing layers
The components within a Conferencing System can be divided up into several different layers: User
Interface, Conference Control, Control or Signal Plane, and Media Plane.
Videoconferencing User Interfaces (VUI) can be either graphical or voice responsive. Many in the
industry have encountered both types of interfaces, and normally graphical interfaces are
encountered on a computer. User interfaces for conferencing have a number of different uses; they
can be used for scheduling, setup, and making a video call. Through the user interface the
administrator is able to control the other three layers of the system.
Conference Control performs resource allocation, management and routing. This layer along with
the User Interface creates meetings (scheduled or unscheduled) or adds and removes participants
from a conference.
Control (Signaling) Plane contains the stacks that signal different endpoints to create a call and/or a
conference. Signals can be, but aren’t limited to, H.323 and Session Initiation Protocol (SIP)
Protocols. These signals control incoming and outgoing connections as well as session parameters.
The Media Plane controls the audio and video mixing and streaming. This layer manages Real-Time
Transport Protocols, User Datagram Packets (UDP) and Real-Time Transport Control
Protocol (RTCP). The RTP and UDP normally carry information such the payload type which is the
type of codec, frame rate, video size and many others. RTCP on the other hand acts as a quality
control Protocol for detecting errors during streaming.[11]
Multipoint videoconferencing
Main article: Multipoint Control Unit
Simultaneous videoconferencing among three or more remote points is possible by means of
a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a
similar way to the audio conference call). All parties call the MCU, or the MCU can also call the
parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based
videoconferencing. There are MCUs which are pure software, and others which are a combination of
hardware and software. An MCU is characterized according to the number of simultaneous calls it](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-4-320.jpg)
![can handle, its ability to conduct transposing of data rates and protocols, and features such as
Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-
alone hardware devices, or they can be embedded into dedicated videoconferencing units.
The MCU consists of two logical components:
1. A single multipoint controller (MC), and
2. Multipoint Processors (MP), sometimes referred to as the mixer.
The MC controls the conferencing while it is active on the signaling plane, which is simply where the
system manages conferencing creation, endpoint signaling and in-conferencing controls. This
component negotiates parameters with every endpoint in the network and controls conferencing
resources. While the MC controls resources and signaling negotiations, the MP operates on the
media plane and receives media from each endpoint. The MP generates output streams from each
endpoint and redirects the information to other endpoints in the conference.
Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or
otherwise. These use a standards-based H.323 technique known as "decentralized multipoint",
where each station in a multipoint call exchanges video and audio directly with the other stations
with no central "manager" or other bottleneck. The advantages of this technique are that the video
and audio will generally be of higher quality because they don't have to be relayed through a central
point. Also, users can make ad-hoc multipoint calls without any concern for the availability or control
of an MCU. This added convenience and quality comes at the expense of some increased network
bandwidth, because every station must transmit to every other station directly.[11]
Videoconferencing modes
Videoconferencing systems use several common operating modes:
1. Voice-Activated Switch (VAS);
2. Continuous Presence.
In VAS mode, the MCU switches which endpoint can be seen by the other endpoints by the levels of
one’s voice. If there are four people in a conference, the only one that will be seen in the conference
is the site which is talking; the location with the loudest voice will be seen by the other participants.
Continuous Presence mode, displays multiple participants at the same time. The MP in this mode
takes the streams from the different endpoints and puts them all together into a single video image.
In this mode, the MCU normally sends the same type of images to all participants. Typically these
types of images are called “layouts” and can vary depending on the number of participants in a
conference.[11]](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-5-320.jpg)
![Echo cancellation
A fundamental feature of professional videoconferencing systems is Acoustic Echo
Cancellation (AEC). Echo can be defined as the reflected source wave interference with new wave
created by source. AEC is an algorithm which is able to detect when sounds or utterances reenter
the audio input of the videoconferencing codec, which came from the audio output of the same
system, after sometime delay. If unchecked, this can lead to several problems including:
1. the remote party hearing their own voice coming back at them (usually significantly delayed)
2. strong reverberation, which makes the voice channel useless, and
3. howling created by feedback.
Echo cancellation is a processor-intensive task that usually works over a narrow range of sound
delays.
Cloud-based video conferencing
Cloud-based video conferencing can be used without the hardware generally required by other video
conferencing systems, and can be designed for use by SMEs,[12]
or larger international companies
like Facebook.[13][14]
Cloud-based systems can handle either 2D or 3D video broadcasting.[15]
Cloud-
based systems can also implement mobile calls, VOIP, and other forms of video calling. They can
also come with a video recording function to archive past meetings.[16]
FEATURES:
Voice Activated Switching: In this mode, all participants see the video image of the current speaker.
The speaker sees the video image of the previous speaker. When a new speaker begins talking, the
video switches to the new speaker.
Continuous Presence: Continuous presence creates a picture consisting of the video from multiple sites
participating in the conference. This feature allows participants to see up to 9 sites at one time.
Gateway Service: Enables endpoints with varying networks and audio & video formats to communicate
in the same conference whether you're using new HD endpoints or legacy equipment, or Private or Public
networks.
Lecture Mode: In this mode, one location's video, audio and data are viewed by all the other endpoints.
The lecturer views the other locations one after another for a fixed duration of time. (This feature is not
available with the Conference Basic bridging option.)
Presentation Viewing: Presentation Viewing allows the speaker to share a presentation with the other
endpoints. (Note: Not all endpoint equipment supports this feature. Please check with your equipment
manufacturer to determine your videoconferencing equipments capabilities.)
Site Certification: A conference coordinator will conduct an endpoint equipment certification in advance
of the actual conference to ensure connectivity and perform quality checks.](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-6-320.jpg)
![CONCLUSION
Videoconferencing provides students with the opportunity to learn by participating in two-way
communication forums. Furthermore, teachers and lecturers worldwide can be brought to remote or
otherwise isolated educational facilities. Students from diverse communities and backgrounds can
come together to learn about one another, although language barriers will continue to persist. Such
students are able to explore, communicate, analyze and share information and ideas with one
another. Through videoconferencing, students can visit other parts of the world to speak with their
peers, and visit museums and educational facilities. Such virtual field trips can provide enriched
learning opportunities to students, especially those in geographically isolated locations, and to the
economically disadvantaged. Small schools can use these technologies to pool resources and
provide courses, such as in foreign languages, which could not otherwise be offered.
A few examples of benefits that videoconferencing can provide in campus environments include:
faculty members keeping in touch with classes while attending conferences;
guest lecturers brought in classes from other institutions;[33]
researchers collaborating with colleagues at other institutions on a regular basis without loss of
time due to travel;
schools with multiple campuses collaborating and sharing professors;[34]
schools from two separate nations engaging in cross-cultural exchanges;[35]
faculty members participating in thesis defenses at other institutions;
administrators on tight schedules collaborating on budget preparation from different parts of
campus;
faculty committee auditioning scholarship candidates;
researchers answering questions about grant proposals from agencies or review committees;
student interviews with an employers in other cities, and
teleseminars.
References
1. Jump up^ "PDS and Vidtel Enable Affordable, Cloud-Based, Interoperable Video Conferencing for
Southeast Michigan Businesses".Information Technology Newsweekly. December 27, 2011.
Retrieved February 19, 2014.
2. Jump up^ Ralph Stair and George Reynolds (2013). Principles of Information Systems. Cengage
Learning. p. 288. RetrievedFebruary 19, 2014.
3. Jump up^ Stacy Collett (January 30, 2014). "Facebook CIO Supports Video Calls to Preserve
Employee Culture". CIO Magazine. Retrieved February 19, 2014.
4. Jump up^ ""Cloud-Based Interoperability Platform for Video Conferencing" in Patent Application
Approval Process". Politics & Government Week. May 23, 2013. Retrieved February 19, 2014.
Bibliography
Mulbach, Lothar; Bocker, Martin; Prussog, Angela. "Telepresence in Videocommunications: A
Study on Stereoscopy and Individual Eye Contact", Human Factors, June 1995, Vol.37, No.2,
pg.290, ISSN 0018-7208, Gale Document Number: GALE|A18253819. Accessed December 23,
2011 via General Science eCollection (subscription).](https://image.slidesharecdn.com/videoconferencing-151118115041-lva1-app6892/85/Video-Conferencing-9-320.jpg)
Video Conferencing
- 1. INTRODUCTION Videoconferencing (VC) is the conduct of a videoconference (also known as a video Conference or video teleconference) by a set of telecommunication technologies which allow two Or more locations to communicate by simultaneous two-way video and audio transmissions. It has Also been called 'visual collaboration' and is a type of groupware. Videoconferencing differs from videophone calls in that it's designed to serve a conference or Multiple locations rather than individuals.[1] It is an intermediate form of video telephony, first used Commercially in Germany during the late-1930s and later in the United States during the early 1970s As part of AT&T's development of Picture phone technology. With the introduction of relatively low cost, high capacity broadband telecommunication services in The late 1990s, coupled with powerful computing processors and video compression techniques, Videoconferencing has made significant inroads in business, education, medicine and media. An internet forum is a discussion area on a website. Website members can post discussions and respond to posts by their forum members. A forum can be focused on nearly any subject and a sense of an online community, or virtual community, tends to develop among forum members.
- 2. Videoconferencing uses audio and video telecommunications to bring people at different sites together. This can be as simple as a conversation between people in private offices (point-to-point) or involve several (multipoint) sites in large rooms at multiple locations. Besides the audio and visual transmission of meeting activities, allied videoconferencing technologies can be used to share documents and display information on whiteboards. Simple analog videophone communication could be established as early as the invention of the television. Such an antecedent usually consisted of two closed-circuit television systems connected via coax cable or radio. An example of that was the German Reich Postzentralamt (post office) video telephone network serving Berlin and several German cities via coaxial cables between 1936 and 1940.[2][3] During the first manned space flights, NASA used two radio-frequency (UHF or VHF) video links, one in each direction. TV channels routinely use this type of video telephony when reporting from distant locations. The news media were to become regular users of mobile links to satellites using specially equipped trucks, and much later via special satellite videophones in a briefcase. This technique was very expensive, though, and could not be used for applications such as telemedicine, distance education, and business meetings. Attempts at using normal telephony networks to transmit slow-scan video, such as the first systems developed batty, first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient video compression techniques. The greater 1 MHz bandwidth and 6 Mbit/s bit rate of the Picture phone in the 1970s also did not achieve commercial success, mostly due to its high cost, but also due to a lack of network effect —with only a few hundred Picture phones in the world, users had extremely few contacts they could actually call to, and interoperability with other videophone systems would not exist for decades. While videoconferencing technology was initially used primarily within internal corporate communication networks, one of the first community service usages of the technology started in 1992 through a unique partnership with PictureTel and IBM Corporations which at the time were promoting a jointly developed desktop based videoconferencing productknown as the PCS/1. Over the next 15 years, Project (Diversified Information and Assistance Network) grew to utilize a variety of videoconferencing platforms to create a multi-state cooperative public service and distance education network consisting of several hundred schools, neighborhood centers, libraries, science museums, zoos and parks, public assistance centers, and other community oriented organizations. In the 2000s, video telephony was popularized via free Internet services such as Skype and chat, web plug-in and on-line telecommunication programs that promoted low cost, albeit lower-quality, videoconferencing to virtually every location with an Internet connection. Russian President Dmitry Medvedevattending the Singapore APEC summit, holding a videoconference with Rashid Nurgaliyev via a Tactical MXP, after anarms depot explosion in Russia (2009).
- 3. In May 2005, the first high definition video conferencing systems, produced by LifeSize Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide video at 30 frames per second with a 1280 by 720 display resolution.[8][9] Polycot introduced its first high definition video conferencing system to the market in 2006. As of the 2010s, high definition resolution for videoconferencing became a popular feature, with most major suppliers in the videoconferencing market offering it. Technological developments by videoconferencing developers in the 2010s have extended the capabilities of video conferencing systems beyond the boardroom for use with hand-held mobile devices that combine the use of video, audio and on-screen drawing capabilities broadcasting in real-time over secure networks, independent of location. Mobile collaboration systems now allow multiple people in previously unreachable locations, such as workers on an off-shore oil rig, the ability to view and discuss issues with colleagues thousands of miles away. Traditional videoconferencing system manufacturers have begun providing mobile applications as well, such as those that allow for live and still image streaming.[10] The core technology used in a videoconferencing system is digital compression of audio and video streams in real time. The hardware or software that performs compression is called a codec(coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1s and 0s is subdivided into labeled packets, which are then transmitted through a digital network of some kind (usually ISDN or IP). The use of audio modems in the transmission line allow for the use of POTS, or the Plain Old Telephone System, in some low-speed applications, such as video telephony, because they convert the digital pulses to/from analog waves in the audio spectrum range. The other components required for a videoconferencing system include: Video input: video camera or webcam Video output: computer monitor, television or projector Audio input: microphones, CD/DVD player, cassette player, or any other source of PreAmp audio outlet. Audio output: usually loudspeakers associated with the display device or telephone Data transfer: analog or digital telephone network, LAN or Internet Computer: a data processing unit that ties together the other components, does the compressing and decompressing, and initiates and maintains the data linkage via the network. There are basically two kinds of videoconferencing systems: 1. Dedicated systems have all required components packaged into a single piece of equipment, usually a console with a high quality remote controlled video camera. These cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom. They became known as PTZ cameras. The console contains all electrical interfaces, the control computer, and the software or hardware-based codec. Omni directional microphones are connected to the console, as well as a TV monitor with loudspeakers and/or a video projector. There are several types of dedicated videoconferencing devices: 1. Large group videoconferencings are non-portable, large, more expensive devices used for large rooms and auditoriums. 2. Small group videoconferencings are non-portable or portable, smaller, less expensive devices used for small meeting rooms.
- 4. 3. Individual videoconferencing are usually portable devices, meant for single users, have fixed cameras, microphones and loudspeakers integrated into the console. 2. Desktop systems are add-ons (hardware boards or software codec) to normal PCs and laptops, transforming them into videoconferencing devices. A range of different cameras and microphones can be used with the codec, which contains the necessary codec and transmission interfaces. Most of the desktops systems work with the H.323standard. Videoconferences carried out via dispersed PCs are also known as e-meetings. These can also be nonstandard, Microsoft Lync, Skype for Business, Google Hangouts, or Yahoo Messenger or standards based, Cisco Jabber. 3. WebRTC Platforms are video conferencing solutions that are not resident by using a software application but are available through the standard web browser. Solutions such as Adobe Connect and Cisco WebEx can be accessed by going to a URL sent by the meeting organizer and various degrees of security can be attached to the virtual "room". Often the user will be required to download a piece of software, called an "Add In" to enable the browser to access the local camera, microphone and establish a connection to the meeting. Conferencing layers The components within a Conferencing System can be divided up into several different layers: User Interface, Conference Control, Control or Signal Plane, and Media Plane. Videoconferencing User Interfaces (VUI) can be either graphical or voice responsive. Many in the industry have encountered both types of interfaces, and normally graphical interfaces are encountered on a computer. User interfaces for conferencing have a number of different uses; they can be used for scheduling, setup, and making a video call. Through the user interface the administrator is able to control the other three layers of the system. Conference Control performs resource allocation, management and routing. This layer along with the User Interface creates meetings (scheduled or unscheduled) or adds and removes participants from a conference. Control (Signaling) Plane contains the stacks that signal different endpoints to create a call and/or a conference. Signals can be, but aren’t limited to, H.323 and Session Initiation Protocol (SIP) Protocols. These signals control incoming and outgoing connections as well as session parameters. The Media Plane controls the audio and video mixing and streaming. This layer manages Real-Time Transport Protocols, User Datagram Packets (UDP) and Real-Time Transport Control Protocol (RTCP). The RTP and UDP normally carry information such the payload type which is the type of codec, frame rate, video size and many others. RTCP on the other hand acts as a quality control Protocol for detecting errors during streaming.[11] Multipoint videoconferencing Main article: Multipoint Control Unit Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a similar way to the audio conference call). All parties call the MCU, or the MCU can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCUs which are pure software, and others which are a combination of hardware and software. An MCU is characterized according to the number of simultaneous calls it
- 5. can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand- alone hardware devices, or they can be embedded into dedicated videoconferencing units. The MCU consists of two logical components: 1. A single multipoint controller (MC), and 2. Multipoint Processors (MP), sometimes referred to as the mixer. The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls. This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference. Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or otherwise. These use a standards-based H.323 technique known as "decentralized multipoint", where each station in a multipoint call exchanges video and audio directly with the other stations with no central "manager" or other bottleneck. The advantages of this technique are that the video and audio will generally be of higher quality because they don't have to be relayed through a central point. Also, users can make ad-hoc multipoint calls without any concern for the availability or control of an MCU. This added convenience and quality comes at the expense of some increased network bandwidth, because every station must transmit to every other station directly.[11] Videoconferencing modes Videoconferencing systems use several common operating modes: 1. Voice-Activated Switch (VAS); 2. Continuous Presence. In VAS mode, the MCU switches which endpoint can be seen by the other endpoints by the levels of one’s voice. If there are four people in a conference, the only one that will be seen in the conference is the site which is talking; the location with the loudest voice will be seen by the other participants. Continuous Presence mode, displays multiple participants at the same time. The MP in this mode takes the streams from the different endpoints and puts them all together into a single video image. In this mode, the MCU normally sends the same type of images to all participants. Typically these types of images are called “layouts” and can vary depending on the number of participants in a conference.[11]
- 6. Echo cancellation A fundamental feature of professional videoconferencing systems is Acoustic Echo Cancellation (AEC). Echo can be defined as the reflected source wave interference with new wave created by source. AEC is an algorithm which is able to detect when sounds or utterances reenter the audio input of the videoconferencing codec, which came from the audio output of the same system, after sometime delay. If unchecked, this can lead to several problems including: 1. the remote party hearing their own voice coming back at them (usually significantly delayed) 2. strong reverberation, which makes the voice channel useless, and 3. howling created by feedback. Echo cancellation is a processor-intensive task that usually works over a narrow range of sound delays. Cloud-based video conferencing Cloud-based video conferencing can be used without the hardware generally required by other video conferencing systems, and can be designed for use by SMEs,[12] or larger international companies like Facebook.[13][14] Cloud-based systems can handle either 2D or 3D video broadcasting.[15] Cloud- based systems can also implement mobile calls, VOIP, and other forms of video calling. They can also come with a video recording function to archive past meetings.[16] FEATURES: Voice Activated Switching: In this mode, all participants see the video image of the current speaker. The speaker sees the video image of the previous speaker. When a new speaker begins talking, the video switches to the new speaker. Continuous Presence: Continuous presence creates a picture consisting of the video from multiple sites participating in the conference. This feature allows participants to see up to 9 sites at one time. Gateway Service: Enables endpoints with varying networks and audio & video formats to communicate in the same conference whether you're using new HD endpoints or legacy equipment, or Private or Public networks. Lecture Mode: In this mode, one location's video, audio and data are viewed by all the other endpoints. The lecturer views the other locations one after another for a fixed duration of time. (This feature is not available with the Conference Basic bridging option.) Presentation Viewing: Presentation Viewing allows the speaker to share a presentation with the other endpoints. (Note: Not all endpoint equipment supports this feature. Please check with your equipment manufacturer to determine your videoconferencing equipments capabilities.) Site Certification: A conference coordinator will conduct an endpoint equipment certification in advance of the actual conference to ensure connectivity and perform quality checks.
- 7. Training: Video conferencing training, coordination and support services include working with your key personnel to determine appropriate training requirements, identifying target audiences, and setting training schedules. Custom video training initiatives can be developed for an additional fee. Service Introduction: Service introduction includes providing standard video room aids such as table tents, informational signs, and schedule holders. Materials may also be distributed to your user community to illustrate the benefits of video conferencing. As an option, customized and branded materials can be developed. Video Help Desk: The Help Desk will provide users with telephone assistance for their video conferencing. Help Desk services include assistance with the call launch process, reservations, and bridge related issues. Optional Features Audio Add-on: Audio Add-on allows participants to join the audio portion of a video conference using their phone. Recording Services: A DVD or Media File (.wmv) recording of a conference can be made for later viewing. (This feature is not available with the Conference Basic bridging option.) Customized Branding: Conference Plus can provide a branded video reservations line. This service is also available for the Account Dashboard. Advantages of video conferencing 1. No time constraint: Video conferencing can be conducted at any time of the day. Time differences between countries do not matter when people use this method of communication because they do not actually need to travel to attend meetings. 2. Dramatic travel saving: Not only is video conferencing a direct replacement for many in-person business trip, but also there is virtually no cost for people to be involved in a virtual meeting, you can easily bring the right them together. 3. Easy communication: People can use video conferencing to communicate with anyone with HD video and other collaboration tools such as whiteboard, text exchange, file sharing, media sharing, screen sharing, remote control, electronic voting, conference recording etc. 4. Increased productivity: By eliminating time and district barriers, meetings can be hold anytime, anywhere with anyone. In this way, meetings
- 8. are shorter and more effective. And also with the rich collaboration tools, decisions can be made faster. Disadvantages of video conferencing 1. Lack of personal interaction: Some meetings require a personal touch to be successful. Video conferencing can be less personal than meeting face to face, and it can be possible to miss out on vital body language when you’re struggling with a pixilated image or stuttering video. 2. Technical problems: The major disadvantages are the technical difficulties associated with smooth transmissions that could result from software, hardware or network failure. Remote connections are sometimes known to be hampered by environmental changes. On some occasions, the absence of technical support personnel creates difficulty for participants who are unfamiliar with the videoconferencing technological concepts. 3. International time zones: One of the very real disadvantages of using video conferencing is that if you communicate regularly with people in other countries you will be available at different times to them. Unfortunately without the skills of a time lord there’s not really a practical way to overcome this. 4. High cost of setup: Setting up video conferencing in an office can be a bit expensive for small-sized companies. Simple features can fit into the budget, but if advanced features are required, and then a substantial am ount of expenditure must be done. In my opinion, Video conferencing advantages definitely outweigh its disadvantages. It enables people from different place to communicate with each other in a more convenient way.
- 9. CONCLUSION Videoconferencing provides students with the opportunity to learn by participating in two-way communication forums. Furthermore, teachers and lecturers worldwide can be brought to remote or otherwise isolated educational facilities. Students from diverse communities and backgrounds can come together to learn about one another, although language barriers will continue to persist. Such students are able to explore, communicate, analyze and share information and ideas with one another. Through videoconferencing, students can visit other parts of the world to speak with their peers, and visit museums and educational facilities. Such virtual field trips can provide enriched learning opportunities to students, especially those in geographically isolated locations, and to the economically disadvantaged. Small schools can use these technologies to pool resources and provide courses, such as in foreign languages, which could not otherwise be offered. A few examples of benefits that videoconferencing can provide in campus environments include: faculty members keeping in touch with classes while attending conferences; guest lecturers brought in classes from other institutions;[33] researchers collaborating with colleagues at other institutions on a regular basis without loss of time due to travel; schools with multiple campuses collaborating and sharing professors;[34] schools from two separate nations engaging in cross-cultural exchanges;[35] faculty members participating in thesis defenses at other institutions; administrators on tight schedules collaborating on budget preparation from different parts of campus; faculty committee auditioning scholarship candidates; researchers answering questions about grant proposals from agencies or review committees; student interviews with an employers in other cities, and teleseminars. References 1. Jump up^ "PDS and Vidtel Enable Affordable, Cloud-Based, Interoperable Video Conferencing for Southeast Michigan Businesses".Information Technology Newsweekly. December 27, 2011. Retrieved February 19, 2014. 2. Jump up^ Ralph Stair and George Reynolds (2013). Principles of Information Systems. Cengage Learning. p. 288. RetrievedFebruary 19, 2014. 3. Jump up^ Stacy Collett (January 30, 2014). "Facebook CIO Supports Video Calls to Preserve Employee Culture". CIO Magazine. Retrieved February 19, 2014. 4. Jump up^ ""Cloud-Based Interoperability Platform for Video Conferencing" in Patent Application Approval Process". Politics & Government Week. May 23, 2013. Retrieved February 19, 2014. Bibliography Mulbach, Lothar; Bocker, Martin; Prussog, Angela. "Telepresence in Videocommunications: A Study on Stereoscopy and Individual Eye Contact", Human Factors, June 1995, Vol.37, No.2, pg.290, ISSN 0018-7208, Gale Document Number: GALE|A18253819. Accessed December 23, 2011 via General Science eCollection (subscription).