In the h . 323 video conference system , it transmits the media with multicast instead of unicast . in order to achieve real time and interaction goal of the system , it controls the quality of media transmission with qos technologies and strategies 323型系统，会议中视音频的传输不再采用单播，而采用组播技术实现，并利用qos策略和机制实现对媒体流的服务质量进行控制，以达到视频会议所需的实时和交互要求。
Education : video conference system can help college , academy and education organizations to realize large scale on - line courses and trainings to satisfy the learning request from different locations and student levels . with a simple network camera and internet connection , courses can be held at any time and any place 当前高校教学改革的主要目标之一是构建一种既能发挥教师主导作用，又能充分体现学生认知主体作用的新型教学模式，鼎视通视讯系统就成了中国高校的首选载体。
Shenzhen derenxin culture and technology industrial co . , ltd , registered with the governmental industrial and commercial administration , is a comprehensive corporation with independent legal person status , which is engaged in the design and making of picturesc and texts , planning for cultural exchange activities , the landscape design , art upholstering and construction for public facilities , the design and installation of stage lights and the video conference system , the consulting of technological information , business and the supply and sales of material 深圳市得人心文化科技产业有限公司是经政府工商行政管理部门登记注册的一家具有独立法人资格的集图文设计、制作，文化交流活动策划，公共设施的景观设计、艺术装满、施工，舞台灯光、视像会议系统设计、安装：技术信息咨询，商业，物资供销业等综合性企业。
Government : in order to cut administration cost and increase the work efficiency of government , the video conference system has more and more widely used nowadays . video conference systems can help government to increase remote communication , so that to cut meeting and travel cost , improve the decision - making process 政府机关：为了加快信息交流速度，保证政令畅谈，同时提高办公会议质量和效率，召开电视电话会议已经成为各级政府机关普遍推崇的方式，语音图像数据可同时交互，使沟通及时有效，鼎视通的一系列先进技术更保障了会议的安全保密。
An introduction of sony china professional solutions business ： as the international leading broadcasting & professional system solutions provider , sony corp . has successfully developed various kinds of tailor - made system solutions such as hd and sd systems for tv and film production , media asset management system , video server system , professional display products , video conference system , network monitor and audio equipments , some of which are broadband capable system solutions 索尼广播电视及专业业务自1978年进入中国，目前其针对中国各行业专业领域客户的包括高清及标清电影电视节目制作系统、媒体资产管理系统、专业显示设备、视频通讯、网络监控和数字展示等系统解决方案，已被广泛应用于包括节目制作、网络通信、政府机构、工矿企业、医疗和教育等各行各业。
As the information era proceeds , highly developed digital image processing technique and communication technique make multimedia communication possible , and it is now on the way of progress . video conference have received more attention as an example of multimedia . in this paper we first describe the construction and characteristic of the video conference system and analyze the theory of protocol with itu - t h . 323 recommendation which inculde video and audio codec standard , communication control protocol h . 245 . call signalling protocol h . 225 , as well as procedures within these protocols define how these components communicate . also an experimental video conferencing system is designed and some relating key technologies are studied , which include multithread programming , transmission technology , mcu technology , qos mechanism and so on . especially , a video codec based on h . 263 recommendation with high fram rate as well as high compression ratio is researched and implemented because of importance of video application , which solves the bad image reconstrction quality problem existed in the most present video systems that adopt h . 261 video compression algorithm . by using these technologies . a video conferencing system is implemented based on lan . the system that the paper provides is easy to implement and the results of exmperiment is good . such system can be widely used in the fields such as business conference , distance education etc . and it is of good practical value 随着信息时代的前进，数字图像处理技术和通信技术的高度发展，多媒体通信已成为可能并已初具规模，视频会议作为它的一个具体应用实例受到普遍关注。本文首先对国际电信联盟itu - t制定的基于分组交换的多媒体通信h . 323系列建议进行了阐述，其中包括ip网络视频会议系统的结构组成、视频传输标准、音频传输标准、系统的信息码流、通信控制协议h . 245和呼叫信令协议h . 225以及会议系统的进行过程。在此基础上给出了ip视频会议的实现的整体框架，为系统的软件实现进行了模块的划分和整体设计，分析了各个模块的功能、作用。
Enterprise : video conference system can help small , middle and large enterprises to deal with all kinds of business meetings including board meeting , shareholder meeting , departmental meeting , investor meeting , as well as employee training to branches and subsidiaries all over the world 企业集团：由于市场讯息瞬息万变，越来越多的公司意识到必须迅速反应，才可能全面地把握市场。为了快速反馈决策提升服务品质降低运营成本提高办公效率，已有众多集团高层构建了dstmedia视频会议系统，协助他们在竞争中立于不败之地。
Hands - free speech communication is indispensable in audio and video conference systems , hot - line telephones and videophones , mobile radio terminals , digital isdn network etc . however , the control ( cancellation ) of the acoustic echo has always had a strong impact on the transmission quality in hands - free telecommunication ~ [ 1 - 3 ] conventional methods of acoustic echo control ( cancellation ) , such as echo suppression or gain control , may lead to the degradations in speech quality or make the speakers feel uncomfortable 免提式话音通信在移动电话、热线电话、车载电话及isdn网的电视电话会议等多种领域正得到日益广泛的应用。但至今的免提式话音通信中，仍免不了受回声引起的话音失真、甚至啸叫等干扰，大大降低了免提话音通信的质量。由于声回波对消问题尚未得到圆满解决，实现高质量的免提式话音通信仍是一个极赋挑战性的课题。
