Instant Messaging Software Midrange Video Data Transmission On The Internet And Research

IM is a technic that users can Recognite other users who is online and communicate with them.IM software has very wilder Application and very big market.The trend of IM software is to combine with the technic of Multimedia.This papers research the key technology of im software on the background of "national blood resource management platform".The main research works are as follow:(1)This paper introduce some knowledge of MPEG-4,P2P,NAT which IM software will used.(2)when we communicate with others on P2P by using IM,for many users connect to Internet by NAT,that make many users cannt straightly communicate with others on p2p.This article analyses the types of NAT that on p2p,and put forward some projects to solve these problems.The Details as the follows:With the other third server can makes users communication on P2P:for another type of Symmetric NAT,users cannt communite on p2p with the other third server also,so,I put forward a Interchange Communition Model to solve the Trouble(3)And we know that audio frequency is more important than video frequency,so we put forward an precept of audio frequency first,and using the different channel to respectively transmit audio frequency and video frequency.But it will carry a new problem which audio frequency and video frequency is no synchronization.And for solving this problem,we make use of the time stamp of RTP/RTCP protocol.(4)For convenience,I put up a system which is like qq—ACM(ang call me) to examination and realize.The Coding of audio and video frequency is use MPEG—4, the communication of audio and video frequency is use UDP protocol,the control of communication is use TCP protocal.And also list the Introduction of some class which used in the ACM,and the code of them realized on the IDE of Delphi.