Method system and article of manufacture for multi-casting audio visual material

• US 5,862,329 A
• Filed: 04/18/1996
• Issued: 01/19/1999
• Est. Priority Date: 04/18/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Lebizay, Gerald, Shippy, Gary Roy, Onvural, Raif O., Guerin, Roch A., Tai, Ling-Ching Wang, Aras, Caglan M.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Barot, Bharat
• Application Number:
  US08/634,453
• Time in Patent Office: 1,006 Days
• Field of Search: 395/200, 395/200.01, 395/200.03, 395/200.04, 395/200.11, 395/500, 395/800, 395/200.34, 395/200.35, 395/200.49, 395/200.5, 395/200.51 , 395/200.57, 395/20.58, 395/200.3, 395/200.36, 395/200.81-200.82, 370/408, 370/256, 370/260, 370/466, 370/390, 370/388, 370/389, 370/396, 370/399, 379/96, 379/202, 379/93.21, 379/158, 348/7, 348/13, 348/15, 348/12-16, 348/585, 348/587, 380/7, 380/10, 380/14-15
• US Class Current: 709/204
• CPC Class Codes: H04N 7/152 Multipoint control units therefor

Abstract

A distance learning system consists of a plurality of multi-cast clients of various classes and priorities with one multi-cast client as a primary multi-cast client, a multi-cast server, arbitrator and a distance learning session coordinator. The primary multi-cast client provides the default or primary Audio-Visual Material (AVM) stream. The Multi-Cast Server (MCS) setups a multi-cast over a point to multi-point connection which connects all multi-cast clients that are to take part in a particular distance learning session, along with the Primary multi-cast client. Additionally, the primary multi-cast client is connected to the MCS via a point-to-point link. The multi-cast clients and the primary multi-cast client receive an AVM material stream from the multi-cast server via the point to multi-point connection. When a multi-cast client wishes to speak, a speaking request is sent to the arbitrator, the arbitrator determines whether to grant or deny the speaking request. If permission is granted then a point-to-point link is established between the requesting multi-cast client and the MCS. The requesting multi-cast client then provides an AVM stream to the multi-cast server over the newly established point-to-point connection and the multi-cast server switches or provides the AVM stream associated with the requesting multi-cast Client over the point to multi-point connection. When the requesting multi-cast client is through speaking the MCS switches the AVM stream associated with the primary multi-cast client onto the point to multi-point connection and the point-to-point link with the requesting multi-cast client is terminated.

Claims

1. An article of manufacture comprising a computer useable medium having a computer readable program embodied in said medium, wherein the computer readable program when executed on a multi-cast server causes the multi-cast server to:

set up a point to multi-point connection between a multi-cast server and a plurality of clients, said point to multi-point connection capable of transmitting an AVM stream from the multi-cast server to each of the plurality of clients;

receive a default AVM stream from a single one of the plurality of clients;

dynamically accept a point-to-point connection from any single other one of the plurality of clients;

receive an AVM stream originating with the single other one of the plurality of clients via the dynamically accepted point-to-point connection;

select either the default AVM stream or the AVM stream originating with the single other one of the plurality of clients over the dynamically accepted point-to-point connection; and

,

multi-cast the selected AVM stream wherein the source of the selected AVM stream is the default AVM stream unless the AVM stream is received from the dynamically accepted point-to-point connection.

2. A multi-cast server adapted for use in a video-conferencing system comprising:

a means for setting up a point to multi-point connection between a multi-cast server and a plurality of clients, said point to multi-point connection capable of transmitting an AVM stream from the multi-cast server to each of the plurality of clients;

a means for receiving a default AVM stream;

a means for dynamically accepting a point-to-point connection from any of the plurality of clients;

a means for receiving an AVM stream originating from a client via a dynamically accepted point-to-point connection;

a means for selecting either the default AVM stream or an AVM stream originating with one of the plurality of clients over the dynamically accepted point-to-point connection;

a means for multi-casting a selected AVM stream over the point to multi-point connection wherein the source of the selected AVM stream is switched between the default AVM stream and one or more AVM streams received from a dynamic point-to-point connection; and

an arbitrator for receiving speaking requests and granting speaking requests, wherein response to the arbitrator granting a speaking request, a point-to-point connection is dynamically established and the received AVM stream from the point-to-point connection is multi-cast as the selected AVM stream until the multi-cast server multi-casts the default AVM stream as the selected stream and terminates the point-to-point connection.

3. The multi-cast server of claim 2 further comprising:

an arbitrator for receiving speaking requests and granting speaking requests, wherein response to the arbitrator granting a speaking request, a point-to-point connection is dynamically established and the received AVM from the point-to-point connection is multi-cast as the selected AVM stream until the MC server multi-casts the default AVM stream as the selected stream and terminates the point-to-point connection.

4. The multi-cast server of claim 3 wherein the MC server combines the received AVM stream with the default AVM stream to form the selected AVM stream.

5. The multi-cast server of claim 3 further comprising:

a coordinator for joining and dropping clients from the point-to-multi point connection.

6. The multi-cast server of claim 3 wherein the multi-casting of the selected AVM stream is performed by virtual circuit re-routing.

7. The multi-cast server of claim 3 wherein the multi-cast server establishes the dynamic point-to-point connections.

8. The multi-cast server of claim 3 wherein the multi-cast server performs switching by virtual circuit re-routing.

9. The multi-cast server of claim 3 wherein the multi-cast server contains a codec for producing the default AVM stream.

10. The multi-cast server of claim 3 wherein the client dynamically establishes the point-to-point link.

11. The multi-cast server of claim 3 wherein at least one ATM adapter is used for receiving and multi-casting of AVM streams.

12. The multi-cast server of claim 11 wherein the multi-cast server performs switching by virtual circuit re-routing.

13. The multi-cast server of claim 11 wherein the multi-cast server contains a codec for producing the default AVM stream.

14. The multi-cast server of claim 12 wherein switching by virtual circuit re-routing is performed by the ATM adapter.

15. The multi-cast server of claim 3 wherein the point to multi-point connection is established using a multi-cast tree.

16. A multi-cast client for use in a video-conferencing system comprising:

means for receiving a multi-cast AVM stream from a point to multi-point connection;

means for generating a speaking request;

means for transmitting the generated speaking request;

means for generating a client AVM stream;

means for transmitting the client AVM stream;

means for dynamically setting up a point-to-point connection;

means for terminating the dynamically setup point-to-point connection;

wherein response to being granted permission to speak, the point-to-point connection is established and the client AVM stream is transmitted using the point-to-point connection while said multi-cast AVM stream is received, said client AVM stream being transmitted until permission to speak is otherwise terminated at which time the point-to-point connection is terminated but the multi-cast AVM stream continues to be received by the multi-cast client.

17. In a multi-cast client the method comprising:

receiving a multi-cast AVM stream during a video-conferencing session;

generating a speaking request;

transmitting the speaking request;

dynamically setting up a point-to-point connection and transmitting a client AVM stream in response to receiving permission to speak;

terminating the dynamically setup point-to-point connection when said permission to speak is otherwise ended; and

continuing to receive the multi-cast AVM stream after the point-to-point connection is terminated.

18. An article of manufacture comprising a computer useable medium having a computer readable program embodied in said medium, wherein the computer readable program when executed on a multi-cast client causes the multi-cast client to:

receive a multi-cast AVM stream during a video-conferencing session;

generate a speaking request;

transmit the speaking request;

dynamically set up a point-to-point connection and transmit a client AVM stream in response to receiving permission to speak;

terminate the dynamically setup point-to-point connection when said permission to speak is otherwise ended; and

continue to receive the multi-cast AVM stream after the point-to-point connection has been terminated.

19. In a multi-cast server the method comprising:

setting up a point to multi-point connection between a multi-cast server and a plurality of clients, said point to multi-point connection transmitting an AVM stream from the multi-cast server to each of the plurality of clients;

establishing a first point-to-point connection between the multi-cast server and a first one of the plurality of clients for receipt of a first AVM stream by the multi-cast server from the first one of the plurality of clients;

receiving the first AVM stream by the multi-cast server from the first one of the plurality of clients;

multi-casting the first AVM stream from the multi-cast server to each of the plurality of clients;

receiving, by the multi-cast server, a request from the second one of the plurality of clients to establish a second point-to-point connection between the multi-cast server and the second one of the plurality of clients;

establishing the second point-to-point connection between the multi-cast server and the second one of the plurality of clients;

receiving, by the multi-cast server, the second AVM stream from the second one of the plurality of clients via the second point-to-point connection;

terminating the multi-casting of the first AVM stream from the multi-cast server to the each of the plurality of clients;

multi-casting the second AVM stream from the multi-cast server to the each of the plurality of clients;

after a period of time, terminating the multi-casting of the second AVM stream from the multi-cast server to the each of the plurality of clients; and

again, multi-casting the first AVM stream from the multi-cast server to the each of the plurality of clients.