Multipoint communications with speech mixing over IP network

  • Authors:
  • Shutang Yang;Shengsheng Yu;Jingli Zhou;Qi Han

  • Affiliations:
  • National Storage System Lab, Department of Computer Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, People's Republic of China;National Storage System Lab, Department of Computer Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, People's Republic of China;National Storage System Lab, Department of Computer Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, People's Republic of China;Department of Information and Computer Science, University of California-Irvine, Los Angeles, CA, USA

  • Venue:
  • Computer Communications
  • Year:
  • 2002

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Abstract

Multipoint communications makes it possible to exchange information among a set of participants and also the key technique to realize a distributed multiparty collaboration communications system. In this paper, a multipoint communications strategy is discussed based on our H.323 multipoint conferencing system. A new architecture, Speech Scheduling and Mixing System (SSMS), is proposed for speech mixing, and its key techniques, such as the synchronous control of real time speeches, the pre-fetching mechanism of speech data, and the method of buffer flush are discussed in order to guarantee the continuity of the mixed speech in a limited complexity. Moreover, echo problem in the conferencing system is observed and a delayless subband AEC is used to cancel acoustic echo. Simulations show that our H.323 system sounds better in the multipoint conferencing mode than those video conferencing products available, such as Microsoft Netmeeting, which is based on the same H.323 specification.