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Video conferencing is the live chat between two or more group of people from any multimedia device. It is used to exchange the ideas and voice conversation of two groups of maybe a community. In other words ,we can do almost everything in a video conference with any distance I,e the people maybe living in different countries or city.
Video conferencing may involve scanned images such as photos,3D images,and charts). High quality audio can me made in the video conferencing application with the help of the network or voice.We will be able to exchange the files throught in computer system or the devices which have the video conferencing capability. Video cnferencing is transmission of images and audio clips directly without any interuption between two different locations through the use of simple camers, one microphone for audio files transfer and a speaker for the audio output.In simple words through video conferencing we can look at the people in display screen and can see them clearly based on the resolution of the camera. The images which are trasfered from one device to another can be live or recorded. The scope for the clarity of the image or the object display is based on the screen resolution as we as the quality of the camera which is megapixel. whenever the conference is started the camera must be in stable position as it can cause the image getting blured. The physical objects must be cear as the camera records all the images and its movements and sends directly through the network to the other device without any data loss. In this technology the user can send all the files and the text.
Dr lynne convenry. (1987). Video Conferencing in Higher Education. Available: http://www.vnseameo.org/bblam/forum/ICT/vc%20in%20higher%20education.pdf. Last accessed dec 10
AT&T first used this method in 1964 and presented in world fair by connecting by videophone through LAN though it was invented it could not shaped until in 1980's as the cost of this is high. The technology that is used prensed was invented by picturetel in 1984-88. It is possible due to new compression technology, new cameras etc. The first videoconference system invented totally relies on hardware. The cost of hardware restricted its usage to auditoriums and conference rooms.
Later the hardware needed to run video conferencing on desktops come in to existent in 1994. The difference by desktop video conferencing & normal video conferencing system is that we can view the speaker though a window, where as we can view as a big screen in later case in addition there will be no breaks in picture transmission in normal video conferencing. It anyone wants a fill flexed videoconference system it may cost upto 5 lakhs where as desktop units range from 10,000.
1.Two cameras , microphones,speakers.
2. Video conferencing workstations main hub.
3. Good high speed network connection.
4. Internet protocol for network stations.
Video conferencing is a facility to common by the people or more through telephone, ISDN and network medium. Videoconference cuts the various costs like travelling charges, boarding & lodging time. Suppose if we want to meet a person in Mumbai for your business transaction it incurs a lot of risk & costs. Through videoconference you can have a direct interactive with the person and can demonstrate your product you can wish to your relative personally. The advantage of video conferencing facilitated to send pictures and sound from one place to another sitting right on you're home.
In the present situation the architecture for the implementing of the video conferencing from the computer systems or any multimedia device is generally done over the network connection which maybe wired or wireless. An conferencing between the two or more people can be of tele conferencing which involves only the audio transfers. In video conferencing both the image and the audio files get sinchronized by the device and then sends then to the local network through it is send to the dedicated link or the network device. Sometimes there will be some delay in the image and audio adjustments. In a video conferencing network if the video signal from ant singal workstation will be reaches all the other work stations in the network. Each workstation on the network path will send the required information units to all the other work stations which will help the user to not loose his information. As it will be present in all the other networks. Before there were only telephone conference which doesn't include any video path but only the audio signals. The computer systems the got the ability to send the video files through the network or the internet including the audio files.In this direction the amplifiers which are located will make sure that the audio signals get syncronised with the video clips and sends them to the workstations which are closer to the head end unit.
The approach in sending the video and audio to the nearest workstations from the head end unit to the signal which is sent to the farthest workstation unit has a lots of data. As there will be less network link between the nearest and the farthest workstation.
There are four methods in video conferencing
One-to-one video conferencing
One-to-group video conferencing.
Group-to-group video conferencing.
Multi-point video conferencing
1.One-to-one video conferencing
In point-to-point conferencing communication is set up between two people
2. One to group video conferencing
In this video conferencing there will be only single person at one end of the camera and that person will have a video conferencing with the group of people on the other side.
3. Group-Group video conferencing
In this type of video conferencing there will be two groups involved in the video conferencing.
4.Multi-point video conferencing
In this type one main system is connected to both personal and group with the video conference.
In the past years there were only transfer of audio through the telephone. Then after the video conference started with the help of computer system and the web cameras. After some period of time there were cameras in the cell phones which helped in video conferencing with cameras fixed to them. The cell phones having a front facing cameras can be used for the video conferencing. Here we can directly see the person on the other side and even we can hear the voice of the person. The main network link for the cell phones are the wi fi or the 3g networks. But for video conferencing the internet quality should be good and speed. Now if we implement 3D in the cell screens then we can see the 3D image of the person in the other side and will be quite good. If we make a polarised lens for the front camera then it will record the image into a 3D dimensional view. When a stereoscopic lens is installed on the phone which is connected to the camera then automatically the images or the videos taken by the lens will be seen in a 3dimensional view. If the depth of the image is more then the clarity and the view of the image will be more perfect.
The pictures in video conferencing are available in two resolutions are
1.QCIF (Quarter Common Interface Format)
2.CIF (Common Interface Format)
In QCIF we get a picture in a window with a resolution of 176*144 pixels. In CIF we get double the resolution in both sides. Hence we can view of picture 4 times bigger than the in QUIF. The quality of videoconference lies on how many frames that we can send in a second. In general we get 30 frames per second. In ISDN lines are used to transmit we can send to near to this quality. The quality of picture depends on bandwidth
When there is a very wide variety of software and hardware is use for desktop video conferencing system. There are only three widely accepted methods of connecting desktop to desktop, there are
POTS(Plain Old Telephone Service)
It is a key enabling technology for video conferencing. The ISDN basic rate interface provides 128kbs data channel, with compression, this is adequate for video conferencing. Systems running over a single ISDN circuit can provide frame rate of 15 to 30 frames/second depending on the picture size and hardware. The ISDN lines are combined together with an inverse multiplexer a device that allows video conferencing codes to threat multiple ISDN lines as one single data channel. Two or three ISDN lines are enough to provide TV quality. ISDN lines are digital networks specially designed for high bandwidth. We attain a bandwidth 4 times than ordinary telephone line.
Ethernet LAN's that provide a bandwidth of 10Mbps would seem to provide an ideal data channel for an office or building video conferencing systems. However the bursty nature of LAN's makes the problem more difficult. The bandwidth available to any particular application cannot be quarantined. On a busy network there is easy to ensure high priority video and audio data will arrive on time. With ether speed several video streams are certainly possible, but having hundreds or tens of video streams occurring simultaneously is not possible for that research and development is carried out to design and implement a network topology that allows for high speed access to each disk to device. Despite these difficulties several manufacturers have developed LAN video conferencing software that provides acceptable results. In some cases they have done this by using DEDICATED LAN VIDEO MANAGEMENT SOFTWARE. Video conferencing is also possible through Internet but this suffers from all problems associated with LANS.
POTS are another form of communical channel for connecting desktops for video conferencing system. The main advantage of POTS is its low cost of the standard analog phone line. The problem with POTS is its limited bandwidth. The modems with capacity 28.8kbps are fast enough to transmit a small image at around 10 frames/second. If there were fast modems on the horizon, this model is acceptable beginning. But 33.6kbps modems recently announced by manufacturers such as US ROBOTICS are coming very close to theoretical maximum amount of data that can be squeezed in the narrow pipe of analog telephone line.
Any further improvements in POTS will have to come from enhanced compression algorithms. The latency is defined as the delay between the time that is received. All networks have some latency. An audio latency of more than 0.02 seconds is notable and make conversation awkward. Higher latencies make conversation increasingly difficult. This is especially true when of conversation where a log of interruption take place, such as negations and brain storming secessions.