Electrical computers and digital processing systems: multicomput – Multicomputer synchronizing
Reexamination Certificate
1998-03-11
2001-01-30
Rinehart, Mark H. (Department: 2756)
Electrical computers and digital processing systems: multicomput
Multicomputer synchronizing
C709S204000
Reexamination Certificate
active
06182150
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for A COMPUTER CONFERENCING SYSTEM WITH TRANSMISSION SIGNALS SYNCHRONIZING SCHEME earlier filed in the Korean Industrial Property Office on the 11
th
of March 1997 and there duly assigned Serial No. 8062/1997.
TECHNICAL FIELD
The present invention relates to a computer conferencing system, and more particularly to audio, video, and data conferencing between two computer systems in which a stream of multiplexed formatted data is transmitted over a communications link.
RELATED ART
There is known a computer conferencing system which provides real-time audio, video, and data conferencing between personal computer systems. Each personal computer system has a conferencing system, a camera, a microphone, a monitor, and a speaker. The conferencing systems communicate via a communications network.
In such conferencing systems, audio, video and data signals are typically multiplexed, and are then transmitted to a remote site asynchronously via the communications network. In certain cases, such as in the case of a PSTN network, many errors can occur due to characteristics of the transmission line. This can result in discrepancies between the original data and the data received after transmission, and after reconstruction of the compressed formatted data is performed at the remote site.
Therefore, there is a need in the art for development of a conferencing system which overcome the aforementioned problems, as well as other problems mentioned herein. That is to say, there is a need for the development of a computer conferencing system which can provide synchronization of audio, video and data signals transmitted over a communications link.
The following patents are considered to be representative of the prior art relative to the present invention, and are burdened by the disadvantage discussed above: U.S. Pat. No. 5,717,857 to Burkman et al., entitled System For Switching Data Connection To Use First Channel And Second Channel Without Substantial Interruption Of Transfer Of Audio Signals And Image Data Between Computers, U.S. Pat. No. 5,712,906 to Grady et al., entitled Communications Systems Supporting Shared Multimedia Session, U.S. Pat. No. 5,668,811 to Worsley et al., entitled Method Of Maintaining Frame Synchronization In A Communication Network, U.S. Pat. No. 5,625,404 to Grady et al., entitled Method And System For Accessing Multimedia Data Over Public Switched Telephone Network, U.S. Pat. No. 5,608,653 to Palmer et al., entitled Video Teleconferencing For Networked Workstations, U.S. Pat. No. 5,546,324 to Palmer et al., entitled Video Teleconferencing For Networked Workstations, U.S. Pat. No. 5,534,914 to Flohr et al., entitled Videoconferencing System, U.S. Pat. No. 5,524,110 to Danneels, entitled Conferencing Over Multiple Transports, U.S. Pat. No. 5,506,954 to Arshi et al., entitled PC-Based Conferencing System, U.S. Pat. No. 5,434,913 to Tung et al., entitled Audio Subsystem For Computer-Based Conferencing System, U.S. Pat. No. 5,410,343 to Coddington et al., entitled Video-On-Demand Services Using Public Switched Telephone Network, and U.S. Pat. No. 5,195,086 to Baumgartner et al., entitled Multiple Call Control Method In A Multimedia Conferencing System.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a computer conferencing system which can provide synchronization of audio, video and data signals transmitted over a communications link.
In accordance with the present invention, there is provided a computer conferencing system provided with a transmission signal synchronization scheme, which comprises an audio board; a video board; a host processor; and a communication board coupled to the audio board, video board and host processor via a bus and connected to the remote conferencing system via a communications network. Further, the conferencing system includes: a multiplexer/demultiplexer that multiplexes compressed and formatted audio/video/data generated by the audio board, video board and host processor with the communication board for transmission to and reception from the remote conferencing system; a synchronization (sync) signal generator coupled to the compressed signal output of the audio board by way of a mixer for generating a sync signal which the mixer adds to the audio signal frame generated by the audio board; and a synchronization control unit coupled to audio data input lines of the multiplexer/demultiplexer for enabling/disabling addition of the sync signal to the audio signal frame.
In the preferred embodiment of the present invention, the communications network comprises a public switched telephone network (PSTN) or an integrated services data network (ISDN). The audio sync signal is preferably interposed between the header signal and the audio data. In addition, the compressed formatted audio/video/data generated by the remote site is demultiplexed via the demultiplexer in synchronization with the sync signal included in the audio signal frame.
REFERENCES:
patent: 5195086 (1993-03-01), Baumgartner et al.
patent: 5231633 (1993-07-01), Hluchyj et al.
patent: 5410343 (1995-04-01), Coddington et al.
patent: 5434913 (1995-07-01), Tung et al.
patent: 5506954 (1996-04-01), Arshi et al.
patent: 5524110 (1996-06-01), Danneels et al.
patent: 5534914 (1996-07-01), Flohr et al.
patent: 5546324 (1996-08-01), Palmer et al.
patent: 5608653 (1997-03-01), Palmer et al.
patent: 5625404 (1997-04-01), Grady et al.
patent: 5668811 (1997-09-01), Worsley et al.
patent: 5712906 (1998-01-01), Grady et al.
patent: 5717857 (1998-02-01), Burkman et al.
Bushnell , Esq. Robert E.
Kang Paul
Rinehart Mark H.
Samsung Electronics Co,. Ltd.
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