Videoconferencing can treat people as if they talked face to face with both images and sound propagation in real time. This article is designed to guide you through the various options to achieve the kind of system that best suits the purpose.
There are different types of videoconferencing, which is suitable for your application will depend on the information structure and what you actually want to achieve.
Videoconferencing has previouslyrelatively expensive, but prices are falling, and it is possible for anyone with an Internet connection fast enough to run a video-conference.
The systems are available for lease, rent or buy.
Systems that can handle some or all of the following installed: —
desktop
dedicated video conferencing suite
phone – for use in case of need.
Each has different advantages and limitations that may be crucial to your goal.
Paradoxically, this is by farcritical that the audio connections are met when the video. You can break away from a video signal, or it may be intermittent, but the conference will go further – if you lose the sound, can not get nothing (unless both parties are fluid in sign language!)
Fast video equipment, which often appear as frames per second, abbreviated as FPS.
In the United Kingdom the majority of video sources running with PAL is 25 frames per second – for example VHS nationalplayers. In the U.S. NTSC system running at 30 frames per second. Videoconferencing equipment is generally indicated as 15 fps or 30 fps. In simple terms it is clear – will be 15 fps biltong, shows a frame every second, 30 frames per second full motion video.
The higher the frame rate the larger the load of data, so before the connection settings required.
A minimum requirement for full motion video and audio between two points is 768 kbps.
It includes: – an encoding of 384Kbps (normally used) is selected. E 'divided into two parts —
64kbps for audio
320 Kbps for video.
The resulting stream of 384 kbps is compressed and sent (by you – the source) to the point of distance (the target). Similarly, a flow of 384 Kbps is received from a remote control for you. Bandwidth Kbps So two times in 384 is required.
If there is a great movement in the video, the compression is achieved very little. If there is little or nomotion in the video is, the savings can approach 50%. However, it would be foolish to design a system that relied on the participants are forced to remain static.
There are two types of video conferences, each sub-types.
Point to Point – a live video / audio communication between two places.
Multi-point – to connect three or more places
Point to Point (P2P)
Point to Point – a live video and audio communications linkbetween the two positions.
P2P – Application
Where is the need to communicate between the two points only at a particular moment —
Two offices of the same company
You and a business partner of companies such as yourself and a key supplier
Senior management teams in two divisions – such as research and production.
P2P – U.S.
Virtual meetings with a special
The project working group that coordinates the work of living adjustment data, drawings, documents orprototypes
Virtual board meeting between the two groups of people in some places – for example, in a 5 and 4 in another
P2P – Limitations
Required bandwidth increases in proportion to the amount of data to be exchanged.
Audit trail of actions taken by anyone with a calendar is often necessary.
Optional equipment is necessary to show the physical objects, a visulaiser said, parts of engineering
Point-to-point video conferencing
Consider two videoconferencingTerminals (VCT), which is connected to the Internet.
The VCT and associated peripheral allows the user to make a call to another client, sends the local audio / video stream to the remote client and listen / watch the video received audio stream or a local speaker / screen connected to the VCT.
Suppose a person (the local user) uses a FBC to create a user on a remote IP address of the VCT VCT outside. Customers call between stationsaccording to the specifications of the H.323 protocol. Once the call is set, clients exchange audio and video streams over the Internet. The point-to-point video conference continues until one of the users of "Hang up" call.
IP numbers are hard to remember, some users have dynamically assigned (DHCP) for IP numbers that change every time you boot the system and problems in the use of IP addresses when different system suppliers are used.
The Custodian
Toaddress the problem of IP numbers, H.323 standard specifies the use of a gatekeeper.
The keeper is a system that is connected to the Internet, the client terminal. IP address of the gatekeeper is configured for terminal clients, and when the customer "may", which communicate with the guardian and the transfer of information to the gatekeeper, describing LCS.
When customers register with the gatekeeper, had their IP numbers, aka H.323 and moveH.323 gatekeeper for the extension where it is stored. This allows a local user to dial a remote user via remote control with H.323 extension in the sense that their phone video.
The extension of local community VCT H.323 gatekeeper. The keeper then checks to see if the remote client is registered with the gatekeeper, then the conversation between the two clients.
Once the call is set, the audio and video streams directly between the flowcustomers via the Internet.
Multi Point
Live video and audio connections between three or more locations.
Addressing this situation, the H.323 standard, the concept of a Multipoint Control Unit (MCU). The MCU can be seen as a bridge "video." The MCU is connected to the Internet and register with the gatekeeper.
An MCU, depending on its design capacity to handle a certain number of simultaneous video conferencing with each eachlogically be separated from the others and each with a number of users.
When users want to participate in a special videoconference session, calling the service number / password combination. The gatekeeper checks to see if this service has been registered by a MCU. The gatekeeper terminates the call by connecting the client to the specified videoconferencing MCU.
When the call is connected, streaming audio and video reviews then transferred viaInternet from the client to the MCU. Other customers connected to the session and send their video and audio signals to the MCU. The MCU, select one of the audio and video conferencing and come back as audio / video stream to all clients (which are nothing but the power which the customer is selected).
There are several ways to stream audio / video. Switch sound control and the President are two alternatives. Typicalchosen method is sound MCU call where the active flow sound select (not talking or is the highest).
If the user (s) on a site, talk and keep user (s) on another site has started to talk, to take on the MCU. The process was repeated with the video 's newly elected office will now be sent to all the other places.
Streaming
To participate in a H.323 videoconference, the user must have adequate video conferencing client terminals and Internet connection with sufficient bandwidth to support video conferencing.
Some users of these facilities, but would still be able to participate, although this means that they could see and hear conference participants, but not be able to interact with them. (See and hear)
Users can receive power through a browser on a PC. Give the URL of the server, the server starts the audio /> Video streaming Internet on your computer.
Plugins for the reader who is able to decode both streams RealVideo and Windows Media. The user can see and hear the participants at the conference in near real-time video streaming.
Alternatively, a user can access the server at a later time and view the archived version of videoconferencing.