GB2306274A

GB2306274A - Video conference

Info

Publication number: GB2306274A
Application number: GB9520953A
Authority: GB
Inventors: Gilbert Cowie
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-13
Filing date: 1995-10-13
Publication date: 1997-04-30
Anticipated expiration: 2015-10-13
Also published as: GB2306274B; GB9520953D0

Abstract

A communication system usable to transfer compressed digital information representing audio and video images derived from different locations over digital quality telephone lines employs a central control station with a switching control unit (17) which brings together the information from the different locations and creates a montage display (15) for transfer back to the locations.

Description

ImDrovements in digital communication systems and in methods of transferring infornation The present invention relates in general to digital communication systems and more particularly to systems used for transferring information, including video and audio information, between different locations for conferences and teaching purposes for example.

In order to provide effective communication between remote sites it is desirable to have broadcast studio quality equipment to provide visual and audio information which is then transmitted to remote sites for reproduction on visual displays or monitors.

To provide two-way communication and to cope with three or more sites, additional equipment is needed with switching control facilities at a control station to direct the signals to the various sites. In order to utilise a public telephone network in order to convey the signals it is necessary to convert the analogue video and audio signals into digital signals and to compress the digital signal information with coding techniques to provide signals with bit rates suitable for transmission and reception and typically 2Mb/sec.. Codecs are specifically designed for this purpose and serve to encode and decode the digital signals transmitted over the telephone network.As techniques and components have improved it has become possible to provide multiple images on the visual displays so that a user can view a number of different sites at the same time as a montage.

A general object of the present invention is to provide an improved method of and system for enabling improved interactive communication between remote sites.

In one aspect the present invention provides a communications system for linking a plurality of sites over a telecommunications link, such as a telephone network, to permit information at least including real time video and audio information to be transferred between the sites wherein at least some of the sites each have a video camera, a microphone, a visual display unit with a loudspeaker, a codec which provides compressed coded digital signals as an input to said link and representing said video and audio information derived from the camera and the microphone at that site and another codec which serves to receive and decode digital signals received as an output from said link for reproduction by the local visual display unit and loudspeaker at that local site, the system also having a control station which serves to control the interconnections between the sites and employs means for receiving the coded signals from all or said some sites and for creating therefrom combined video and audio information which is then encoded and transferred back via said link to the other codecs at all of said at least some sites, whereby the combined video information can be reproduced on the display units as image components derived from all of said some sites.

In another aspect the invention provides a communications system for linking a plurality of sites over a telecommunication link, such as a telephone network to permit information at least including real time video and audio information to be transferred between the sites wherein the sites each have a video camera, a microphone, a visual display unit with a loudspeaker, a codec which provides compressed coded digital signals as an input to said link and representing said video and audio information derived from the camera and the microphone at that site and another codec which serves to receive and decode digital signals received as an output from said link for reproduction by the visual display unit and loudspeaker at that site the system also having a control station which serves to control the interconnections between the sites via the link and employs means for receiving the coded signals from all of the sites and for creating therefrom combined video and audio information which is then encoded and transferred back via said link to the other codec at at least one of the sites to permit the reproduction by the video display unit and the loudspeaker at the one site as images and sounds derived from all the other sites.

The present invention also provides a method of establishing communication between a plurality of sites via a telecommunications link, such as a telephone network, to permit information, including real time video and audio information to be transferred between the sites; said method comprising providing said information derived from a video camera and microphone at each site to a codec which produces compressed coded digital signals as an input to the telecommunications link, receiving at each site coded digital signals with another codec as an output from the telecommunications link, converting said received signals into information for reproduction by a video display unit and a loudspeaker at that site, controlling the interconnections between the sites via the telecommunications link and re-creating from the information inputted to the telecommunications link combined information which can be reproduced as multiple images and associated audio sounds by the video display unit and the loudspeaker at at least one of the sites.

In a preferred multiple image there are components from six or more sites. The control station preferably also employs a multi-point control unit which can provide auxiliary communication between a single site equipped with a camera and a microphone and a plurality of the sites which simply reproduce the image and sounds derived from the single site. Where more than six sites are interconnected then means can be provided to select the sites for display.

The multi-point control unit can be fed with signals from a splitter which also provides the signals for decoding to provide the multiple image or montage display.

Where the system is used for teaching or lecturing purposes one site is equipped as aforesaid so the tutor can see, view and hear all students at the remote teaching sites with the multiple image display while the remote teaching sites simply receive the single image of the tutor. These teaching sites then require a simple codec for receiving and decoding the information emanating from the tutor site.

In a further modified system further control means can be provided for controlling the data rate of the codecs. This control can be automatic or user initiated depending on the conditions.

In another modified system the video cameras can be controlled remotely so that in the case of teaching applications the camera can pan and zoom so that each image in the multiple image can vary from an individual close-up to a wide angle view of all members in the teaching site. The necessary control signals to enable the system to operate and for the purposes just mentioned are best transferred in a separate communications channel although such control signals can be combined as by mulitplexing techniques with the other signals representing video and audio information.

In another modification the video camera can be controlled automatically and locally to follow the source of sounds so that the image inputted to the link corresponds to that of a person speaking at the time. Such control would adopt measures to inhibit the camera from moving where sounds are coming from different directions. One such measure would be to have the tutor control the microphones at the sites to ensure only one person can speak at a time.

In the application of the system to conferences in particular there is a need to blank out at least audio signals associated with the part of the multiple image associated with the origination of those audio signals. Otherwise a participant will hear his own voice at the same time as he is speaking. This technique is known in itself in radio broadcasting where sources are mixed together. In accordance with a further feature of the invention the presence of local audio signals is used to generate a control signal which blanks out the local image from the local display as well. This can be done by generating a black image to replace the normal image when the local audio signal is present. In this way participants in a conference will all see and hear one another but each time someone speaks the display local to the speaker will inhibit this local audio and visual information from being displayed while all other remote sites will still reliably receive the audio and visual information from that site. The necessary sensing and switching means to provide this facility can be provided in the central control station and can act on the multi point control unit.

The various components of the system can be packaged for transportation to different locations with suitable generators if necessary. Where site locations do not have the necessary buildings suitable for the equipment then portable temporary buildings can be employed provided these have access to the necessary telecommunication link.

The invention may be understood more readily, and various aspects and features of the invention may become apparent, from consideration of the following description.

Embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings wherein: Figure 1 is a block schematic diagram of part of a communications system for installation in one location; Figure 2 is a block schematic diagram of another part of the communications system for installation in another location; Figure 3 is a block schematic diagram of a central control station of the communications system partly represented in Figures 1 and 2; Figure 4 is a block schematic diagram of another central control station for the communications system partly represented in Figures 1 and 2; Figure 5 is a block schematic diagram of part of another communications system for installation in one location and Figure 6 is a block schematic diagram of a central control station of the system partly represented in Figure 4.

Figure 1 depicts part of a communications system for transmitting and receiving coded digital signals representing video and audio information and particularly for use in conferences or for remote teaching. As shown a main codec 12 is connected to a main communication network 10 and an auxiliary codec 13 is connected to an auxiliary communication network 11. The networks 10,11 can be digital quality telephone lines transferring coded digital signals to and from the codecs 12, 13. The auxiliary codec 13 is also connected to a multi-view camera 16 with a microphone for providing audio signals. The codec 13 converts analogue video and audio signals into coded digital signals for transmission over the network 11.The coded digital signals received by the codecs 12,13 from the networks 10,11 are decoded and analogue signals representing video and audio information are fed to a visual audio display unit 15 For convenience separate display units 15 are depicted but it can of course be the same unit operating in different modes. In one mode of operation associated with the main codec 12 the display unit 15 displays video images and audio derived from a remote tutor only and in another mode of operation associated with the auxiliary codec 13 the display unit 15 is divided into separate regions 1 to 6 each displaying a different video image derived from a different source. This montage display would thus typically be composed of a representation of the remote tutor together with representations of other tutorees in other remote sites equipped with the same set up as depicted in Figure 1.

Figure 2 depicts the complementary equipment to Figure 1 and usable in remote receiving classrooms and/or for a remote tutor. Here the auxiliary codec 13 connected to the auxiliary network 11 simply acts as a decoder and the camera 16 is omitted.

Figure 3 depicts a central control station for use in the system. In this case there is multi-point switching control unit (MCV) 17 connected via the main network 10 to the main codecs 12 in the remote sites. The central control station employs a picture combiner 18 which provides the output to the individual codecs 121-125 via a splitter 9.

The outputs from the codecs 121-125 are connected to the auxiliary network 11 and the signals are routed to the remote sites for processing by the auxiliary codecs 13 and display.

Figure 4 depicts an alternative control station where like reference numerals denote like parts to Figure 3. In this case the picture combiner 18 has one output for driving the display 15 which is at the same site as the control station and further outputs which are connected via auxiliary codecs 134 to the auxiliary network 11. A splitter 19 between the MCU 17 and the main network 10 provides the inputs to the picture combiner 18 which co-operates with the codecs 134.

Figure 5 and 6 depict an alternative system.

Figure 5 represents a typical classroom where the main codec 126 is again connected to the main network 10 and provides a "stills" video channel 20 as well as a main video channel 21. The codec 126 is also connected to the camera 16. For convenience the auxiliary network is represented as networks 111-114 connected to a PC in the classroom. The network 111 is connected via a PC codec 127 to the montage display unit 15 and the codec 127 is also connected to the output from the camera 16.

In addition there is provided a group system controller 23 connected to the auxiliary network 112 to control the data and image view of the display 15. A response controller 24 connected to the auxiliary network 113 responds to a key pad 25 provided for the individual tutorees. The PC has a controller 26 connected to the auxiliary network 114 and to an auxiliary controller 27 for the camera 16 as well as to a system power controller 28.

Figure 6 depicts the central control station for the system partly represented in Figure 5. This control station employs the multi-point control unit (MCU) 17 connected via the main network 10 to the main codecs 126 in the remote classroom sites. A multiview controller 29 is connected via the auxiliary network 111 to the PC codecs 127. A group collaboration master control unit 30 is connected via the auxiliary network 112 to the controllers 23.

A response system controller 31 is connected via the auxiliary network 113 to the response controllers 24. A further controller 32 for controlling power and the cameras 16 as well as operating as a help line is connected via the auxiliary network 114 to the controllers 26,27.

In a filly operational system the following devices and units were employed: 12,126 (Main codec) CLI Rembrandt 2VP 16 (Figures 1 and 5) - (Camera) Parker Vision Cameraman 2 16 (Figure 5) - (Multiview camera) Procom+JVCor Procom-Chugai Boyeki 13, 127,134, 121-125 - (Auxiliary codec) Visitacom or V Con or Picture Tel 100 15 (VDU) Mitsubishi-monitor "37" & video & graphics/data display 18 (Picture combiner)-Chugai Boyeki-rgb or Spectrum or Kalcom 17 (MCU) CLI MCU2 or Video Server or Teleos 24,25,31,32 (Response Controller) One-Touch Systems 23 (P/C group system) - Standard '486' with Microsoft Windows running Future Labs 'Talkshow' or "Vis a Vis" software with modem connection to telephone line x25 or ISDN network 26,28,32 (P/C control) - specially designed '486' with Microsoft Windows running specially developed software for power and camera control with additional power switching modules and modem connection to telephone line x25 or ISDN 30 (Group Collaboration MCU) Future Labs "Vis a Vis".

Claims

1. A communications system for linking a plurality of sites over a telecommunications link, such as a telephone network, to permit information at least including real time video and audio information to be transferred between the sites wherein at least some of the sites each have a video camera, a microphone, a visual display unit with a loudspeaker, a codec which provides compressed coded digital signals as an input to said link and representing said video and audio information derived from the camera and the microphone at that site and another codec which serves to receive and decode digital signals received as an output from said link for reproduction by the local visual display unit and loudspeaker at that local site, the system also having a control station which serves to control the interconnections between the sites and employs means for receiving the coded signals from all or said some sites and for creating therefrom combined video and audio information which is then encoded and transferred back via said link to the other codecs at all of said at least some sites, whereby the combined video information can be reproduced on the display units as image components derived from all of said some sites.

2 A communications system for linking a plurality of sites over a telecommunication link, such as a telephone network, to permit information at least including real time video and audio information to be transferred between the sites wherein the sites each have a video camera, a microphone, a visual display unit with a loudspeaker, a codec which provides compressed coded digital signals as an input to said link and representing said video and audio information derived from the camera and the microphone at that site and another codec which serves to receive and decode digital signals received as an output from said link for reproduction by the visual display unit and loudspeaker at that site the system also having a control station which serves to control the interconnections between the sites via the link and employs means for receiving the coded signals from all of the sites and for creating therefrom combined video and audio information which is then encoded and transferred back via said link to the other codec at at least one of the sites to permit the reproduction by the video display unit and the loudspeaker at the one site as images and sounds derived from all the other sites.

3 A system according to claim 1 or 2, wherein the control station employs a multipoint control unit which provides auxiliary communication between a single site equipped with a camera and a microphone and a plurality of the sites which simply reproduce the image and sounds derived from the single site.

4 A system according to claim 3, wherein the multi-point control unit is fed with signals from a splitter which also provides the signals for decoding to provide the multiple image.

5. A system according to claim 1, 2, 3 or 4, wherein the components in the combined information display are derived from six or more sites.

6 A system according to claim 5 and further comprising means for selecting sites for display.

7. A system according to any one of claims 1 to 6 and further comprising control means for controlling the data rate of the codecs.

8 A system according to any one of claims 1 to 7, and further comprising control means for controlling the video cameras so that the cameras can pan and zoom so that each image in the multiple image can vary from an individual close-up to a wide angle view.

9. A system according to any one of claims 1 to 8 wherein all control signals to enable the system to operate are transferred in a separate communications channel.

10. A signal according to any one of claims 1 to 8, wherein all control signals to enable the system to operate are combined with the other signals representing video and audio information.

11. A system according to any one of claims 1 to 10 and further comprising means for controlling at least one of the video cameras automatically and locally to follow the source of local sounds so that the associated image inputted to the link corresponds to that of a person speaking at the time and means to inhibit the camera from moving where sounds are coming from a number of different directions simultaneously.

12. A system according to any one of claims l to 11 and further comprising means to blank out at least audio signals associated with the part cf the multiple image associated with the local origination of those audio signals.

13 A system according to any one of claims 1 to i2, and further comprising means for sensing the presence of local audio signals and for generating a control signal which blanks out the local image from the local display aswell.

14. A method of establishing communication between a plurality of sites via a telecommunications link, such as a telephone network, to permit information, including real time video and audio information to be transferred between the sites; said method comprising providing said information derived from a video camera and microphone at each site to a codec which produces compressed coded digital signals as an input to the telecommunications link, receiving at each site coded digital signals with another codec as an output from the telecommunications link, converting said received signals into information for reproduction by a video display unit and a loudspeaker at that site, controlling the interconnections between the sites via the telecommunications link and re-creating from the information inputted to the telecommunications link combined information which can be reproduced as multiple images and associated audio sounds by the video display unit and the loudspeaker at at least one of the sites.

15. A method according to claim 14 and substituted as herein described with reference to the accompanying drawings.

16. A communication system substantially as described with reference to and as illustraled in any one or more of the Figures of the accompanying drawings