Video Conferencing System and Its Application

Source: Internet
Author: User
Tags password protection
Currently, video conferencing has been widely used, and our video conferencing system has been put into use. We have successfully held several major conferences, which play a very important role in daily office meetings. The following section briefly introduces the knowledge base of the video conferencing system. Then, we will take our company's video conferencing system as an example to introduce its application.
H.323 protocol standard
The video conferencing system complies with ITU's H.323 Video protocol. The H.323 standard covers audio, video, and data communication on the packet switching network. It solves problems such as call and session control, multimedia and bandwidth control in point-to-point and multi-point video conferences. H.323 references the t.120 protocol to process data exchange.
H.323 has the following advantages. The H.323 protocol is designed to run on a general network architecture and has network independence. The H.323 Protocol provides the network bandwidth management function, which can limit the number of concurrent H.323 connections in the network and the total amount of bandwidth that can be obtained by H.323 applications. H.323 provides a means to connect a video conference based on circuit switching or ISDN. H.323 supports multi-point conference and multi-point conference broadcast (Multicast. H.323 enables interoperability between multimedia products and applications of different vendors.
Composition of A Video Conferencing System
The H.323 Protocol defines four main components of a Video Conferencing System: A terminal (termial), a gateway (GATEWAY), a gateway (keeper), and a multi-point Controller (MCU ).
A client provides one-way or two-way real-time communication. All terminals support voice communication, and video and data communication are optional.
The gateway is used to connect to a non-H.323 terminal.
The gateway implements the function of protecting data network integrity, including address translation, access control, and bandwidth management.
A multi-point controller is used to support network meetings between three or more points. It consists of the necessary Multi-Point Controller (MC) and zero or multiple multi-point processors (MP. MC determines the audio and video processing capabilities of all terminals and controls conference resources. MP blends, exchanges, and processes audio, video, and data streams.
Multi-Point Meeting Mode
Multi-Point meetings are divided into three modes: centralized, distributed, and hybrid multi-point meetings.
MCU is required for centralized multi-point conferences. All terminals send audio, video, data, and control flow to MCU in a point-to-point manner. MC manages meetings in a centralized manner. MP is used for audio mixing, video mixing, and data distribution, and is sent back to the terminals attending the meeting. Centralized Multi-Point meeting allows all H.323 terminals from different vendors to join the meeting.
Distributed Multi-Point conferences use the multicast technology. The H.323 terminal that participates in the meeting broadcasts audio and video streams to other terminals that participate in the meeting. The control information is sent to MC in point-to-point mode. The receiving terminal is responsible for processing the received audio and video streams. Distributed Multi-Point conferencing reduces the usage of network resources and greatly reduces costs. It requires that network configurations support network broadcast.
Hybrid multi-point conferences combine the features of centralized and distributed multi-point meetings. The H.323 terminal that participates in the meeting sends one of the audio and video streams to MC in point-to-point mode, and the rest to all H.323 terminals in broadcast mode.
The MCU can be used to connect a centralized multi-point meeting with a hybrid multi-point meeting for greater flexibility.
In addition, H.323 defines "loose contact" meetings to support large-scale meetings. In this mode, participants are divided into active and passive participants, and active participants are divided into permanent and temporary members. Passive participants can only watch meetings. Allows more participants to express their opinions through role conversion between temporary members and passive participants.
System Selection
The company is headquartered in Fuzhou and Shanghai is an important business center. At present, there are more than 10 provincial branches distributed nationwide.
After comparison, we use the video conferencing terminal of the Israeli vcon company. In the video conferencing system field, vcon has a leading position in terms of technology and market share, with a high price-performance ratio. We use two sets of mediaconnect 8001 Conference terminals for Fuzhou and Shanghai respectively, and also select 10 sets of Desktop Conference terminal escort 25pro for branches outside the province.
The MCU of the conference system selects an ezenia multimedia communication server that supports 16 users at the same time. The encounter3000 integrates gateway, keeper, and MCU modules to provide a convenient Web-based management interface.
MCU-based conference applications
All terminals attending the meeting first set the Keeper address to the IP address of encounter3000, and register on the server. After the MCU starts a meeting, each terminal can join the meeting by inviting a server or calling a terminal.
This mode has the following advantages: centralized and automatic conference management is adopted to facilitate the use of end users; end users can speak freely; MCU supports automatic switching of voice-activated images and manual forced image switching; when the continuous attendance function is used, the terminal can display the pictures of the four users who spoke recently at the same time; the speech synthesis function can be used to hear the voices of multiple participants at the same time; microsoft NetMeeting terminal users can also join meetings to facilitate group meetings without complex network configurations. Disadvantages: high network bandwidth requirements; limited number of terminals supported by each meeting.
At present, the company's daily office meetings mainly adopt this mode.
IP-based Broadcast conference applications
Vcon video terminal products use interactive Multicast technology. This technology allows the vcon end users who participate in the conference to communicate with each other, and end users who use the Cisco IP/TV viewer software can watch broadcast meetings without password protection.
The Conference Chairman first initiated an interactive Broadcast Conference on a vcon terminal. Other terminals can join the meeting by inviting or calling the terminal. Participants can apply to the Chairman for a speech, and can make a speech with the approval of the Chairman. The speaker's audio and video signals are broadcast to all participating terminals. The Chairman may also set the meeting to a free discussion mode, and the system will automatically switch according to the requests received.
This mode has the following advantages: it supports up to 100 interactive Conference terminals, and the number of audience members is unlimited. It saves network bandwidth, and each terminal occupies about half of the bandwidth based on MCU, the bandwidth used has nothing to do with the number of terminals participating in the meeting. Disadvantage: you must use a vcon terminal to speak. You cannot use a Microsoft NetMeeting terminal. You must configure a vro to support IP broadcast and prevent bandwidth usage caused by improper broadcast; the management of the Meeting is relatively complex; the terminal can only display the current user.
This mode is applicable to conferences with large scale and low interaction requirements such as remote training and stock evaluation live broadcasting .,
Data Sharing Solution
As the video terminal software of vcon does not have a Chinese version, it brings some difficulties to the Conference data sharing. Because data is relatively independent from audio and video, and Microsoft NetMeeting's data sharing function is strong and easy to use, and it does not need to use MCU, NetMeeting is used to set up independent data meetings, solve the Data Sharing Problem of attendees. Users who are currently speaking can use PowerPoint, word, and so on to cooperate with their own speeches. At the same time, they can use the NetMeeting application sharing function to present relevant materials to other participants, in addition, the use of projectors, electronic whiteboards, and other devices can effectively improve the communication efficiency.
Notes during the meeting
During the meeting, you should pay attention to the venue discipline to keep the venue quiet and avoid frequent personnel access. The speech should be made in sequence in MCU-based meetings. The speaker should note that controlling the volume and speed will affect the listening effect if the volume is too large, too small, or too fast.
Using the functions provided by the video conferencing system and flexibly using different conference modes and different video terminals to hold meetings of different scales can improve the system usage efficiency and application scope, play a greater role in saving office money and improving work efficiency.

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