Multipoint communications with speech mixing over IP network

✍ Scribed by Shutang Yang; Shengsheng Yu; Jingli Zhou; Qi Han

• Book ID: 104273781
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 255 KB
• Volume: 25
• Category: Article
• ISSN: 0140-3664
• DOI: 10.1016/s0140-3664(01)00333-4

✦ Synopsis

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 ¯ush 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 speci®cation.