论文部分内容阅读
视频应用一直是高质量通信的试金石,从80年代初期CCITT提出最早的基于电路交换的会议电视标准至今,视频应用一直是萦绕在通信技术人员心头的一个难解的情结。这不仅是因为视频应用对网络带宽和终端设备的要求比较苛刻,造成视频应用的价格昂贵,还因为可以满足大众需要的视频应用的价格又必须低廉,两者的矛盾让视频应用多年的发展一直处于非常尴尬的境地。今天,宽带网络和NGN的高速发展为视频应用带来了重新发展的契机,为此我刊特组织本期专题,邀请信息产业部IP及多媒体研究组组长蒋林涛担任总策划,就国内正在开始的视频应用(特别是基于IP的会议电视技术)进行一些介绍。从严格意义上讲,真正适用于公众的视频应用网络在国内屈指可数且都基本处于前期预研阶段,因此,本期专题主要侧重于用何种标准技术体系构建电信级的视频网络,网络整体如何组织,视频应用如何实现,视频设备的构成如何去适应新型网络的结构,以及一些比较成功的视频应用的案例。正如某位业内人事所言:“视频应用将为过剩的网络带宽带来充足的业务,但如何组织这样一个有别于传统电话和IP业务的网络仍将是一个艰巨的任务”。
Video applications have been the litmus test for high-quality communications. Since the early CCIT standards for circuit switched televisions were presented by CCITT in the early 1980s, video applications have been a mystery lingering in the hearts of communications technologists. This is not only because video applications have harsh demands on network bandwidth and terminal equipment, which makes video applications expensive, but also because the price of video applications that meet the needs of the general public has to be low. The contradiction between the two has led to the development of video applications for many years In a very awkward position. Today, the rapid development of broadband networks and NGNs bring a chance for redevelopment of video applications. To this end, we have organized this special issue and invited Jiang Lintao, head of the IP and multimedia research group of the Ministry of Information Industry, as the chief planner. The beginning of video applications (especially IP-based video conferencing technology) for some introduction. In a strict sense, the number of video application networks that really apply to the public is one of the few in the country and are basically in the pre-research stage. Therefore, this issue mainly focuses on what kind of standard technology system is used to build carrier-grade video networks and networks How to organize the whole, how to realize the video application, how to make the video equipment adapt to the structure of the new network, and some more successful video applications. As one person in the industry put it: “Video applications will bring enough business to excess network bandwidth, but how to organize such a network that is different from traditional phone and IP services will still be a daunting task.”