Implementation And Realization Of The Rtp Audio-based Real-time Transmission

The development of network technology and multimedia technology has greatly improved the communication technology of integration, digitalization, intellectualizati- -on and personalization, which makes it possible to realize integrated services of audio, data, video, and so on, on a single network platform. Therefore, under such a background, the network multimedia living broadcast, which integrates network technology and multimedia technology, has appeared and made fast development.Although the traditional PSTN telephone network based on TDM can provide the serviceat the rate of 64kb/s,However,although the technology may ensure good voice quality, its offer to new service need much longer period and cannot deal with increasing market. Compared with voice telecommunication, IP network communicat- -ion is increasing incredibly, whose bandwidth is increasing more rapid than voice communication. Advancing voice serviceover IP network may also reduce cost. At the same time,data service over IP is advancing much more rapidly than voice service. Packtized Audio is one of the most interested research areas in Internet which is typically represented by IP telephorley. Recent efforts mainly focus on two aspects, real-time transfer protocol and packtized audio control mechanism.Based on packtized audio control mechanism, there are five algorithms investigated in this thesis. Dealing with delay spikes occurring in talkspurt which is not noticed by former algorithems, an improved algorithm is propounded. As experiments suggested, it can function better than other algorithms in decreasing average playout delay and packet lost rate.H.323 is an ITU standard that specifies how terminals,equipment,and services for multimedia communicate over networks that do not provide a guaranteed quality of service (such as Internet),RTP/RTCP is one of the most important components of H.323.RTP/UDP/IP protocol stack is most frequently used in IP network which benefit from the high performance of UDP and is enhanced by RTP to provide real-time audio transfer. RTP basic concepts are referred here first. Then, by investigating RTP and RTCP packet format and related algorithms, RTP is implemented in Win32 environment.Applying times uimp and sequence number of RTP to packtized audio control mechanism, WATS(WAN Audio Transport System)provide better service for packtized audio transfer.