摘要:
A method of and system for facilitating synthetic stereo audio conferencing of a plurality of users over a local or wide area network (LAN/WAN). The disclosure describes a system architecture using a LAN/WAN to support synthetic audio conferencing thus allowing, at a receiving user location, for the spatially distinct virtual “placement” of the other parties involved in a conference call. This enables the user to differentiate between the various other parties and to discern which one or more of the parties are talking at any given time. In a first embodiment of the invention, both stereo synthesis and conferencing are client-based functions. In a second embodiment of the invention, both stereo synthesis and conferencing are server-based functions. In a third embodiment of the invention, stereo synthesis is a server-based function and conferencing is a hybrid client/server function using multicast.
摘要:
A method of and system for conferencing a plurality of clients over a local or wide area network using multicasting where the conferencing function is distributed between a server and the clients. The invention takes advantage of certain capabilities of existing client equipment and multicasting capabilities of the server to distribute the conference function between the server and the clients in a conference call over a LAN/WAN in a way that reduces network congestion and protocol complexity. The system of the present invention for providing conferencing over a local or wide area network, includes: a plurality of clients connected to the network for transmitting signals to and receiving signals from the network; and a server connected to the network for receiving a plurality of signals transmitted from the plurality of clients, mixing the received signals to create a single multicast signal, and transmitting the multicast signal to each of the clients. Each of the plurality of received signals is made up of data packets of a defined length. The server includes: a jitter buffer for synchronizing the data packets received from the plurality of clients; an adjustable gain/loss controller for applying adjustable gain/loss to the synchronized data packets—according to speech activity and average level at each client signal; a mixer for mixing the data packets of the plurality of signals to create the single multicast signal for transmission to each of the clients. An individual client receiving the multicast signal transmitted from the server includes an echo controller for estimating and removing, from the multicast signal, a signal component corresponding to a signal transmitted from that client.
摘要:
The present invention provides a method of and system for controlling and effectively reducing the echo introduced in telephone connections over variable delay networks such as LAN/WAN networks. The invention includes estimation of the round-trip user-to-user delay in the telephone connection. This estimation can be made in a number of different ways, including using timestamps in existing data packets according to a Real-Time Protocol (RTP) or a Real-Time Control Protocol (RTCP) and by sending timestamps in data packets according to an Internet Control Message Protocol (ICMP). The invention further includes determination of an echo control target for the telephone connection based upon the estimated user-to-user delay. This target represents the total amount of echo control required to limit the probability of objectionable echo to less than a predetermined threshold. The amount of echo control required increases as the length of the estimated user-to-user delay increases. The invention further includes determination of the minimum amount of signal-dependent loss required to supplement the acoustic echo cancellation in order to reach the determined echo control target. Then, in the invention, the determined amount of signal-dependent loss is applied to the telephone connection to effectively reduce echo based upon the estimated user-to-user delay.