The Design And Realization Of Voice Over IP Software

The development of network technology and multimedia technology has greatly improved the communication technology of integration, digitalization, intellectualization and personalization, which makes it possible to realize integrated services of audio, data, view and so on, on a single network platform. Therefore, under such a background, the IP telephony technology, which integrates network technology and multimedia technology, has appeared and made fast development. Now it has become a strong competitor in the field of audio communication technology. Apart from those advantages of using packet switching, improving the efficiency of the channel and lowering the communication cost, using the IP telephony technology is easier to realize the expansive services and the integration with the multimedia technology, which makes it advantageous among telecommunication fields and prosperous in the future.Although the quality of IP telephony is not satisfactory at present, the orientations of its development have been highly valued by the telecommunication industry. Many international standardization organizations have been engaging in stipulating system standards and protocols that focus not merely on the IP telephony self but more on the IP multimedia multicast communication and the application of various enhanced services by IP telephony.In view of the domestic and international development of IP technology, the paper has considered the key techniques and designed a software which can realize visual IP telephony from PC TO PC in a LAN and studied the IP telephony technology systematically . The purpose is to analyse the working principles and deal with the key technology of IP telephony. At the same time, the software can be extended into a Video-Conference system, Web phone, voice E-mail and so on by appending some specific functions.The paper firstly describes protocol standards, key technology and working principles of IP telephony. Then it presents the software of PC TO PC visual IP telephony including system analysis, system design and system realization . And finally there are some tests on the software. The system realization mainly includes the realization of recording, playing, coding-decoding, compressing and RTP of the audio as well as video capturing, replaying, etc. Those problems of audio-compressing technology, audio-delaying, audio-jitter, echoing and voice activity detection which influence the audio quality have also been discussed and dealt with.