WO1997003522A1 - Videoconferencing - Google Patents

Videoconferencing Download PDF

Info

Publication number
WO1997003522A1
WO1997003522A1 PCT/GB1996/001640 GB9601640W WO9703522A1 WO 1997003522 A1 WO1997003522 A1 WO 1997003522A1 GB 9601640 W GB9601640 W GB 9601640W WO 9703522 A1 WO9703522 A1 WO 9703522A1
Authority
WO
WIPO (PCT)
Prior art keywords
network
mpeg
units
videoconferencing
desktop
Prior art date
Application number
PCT/GB1996/001640
Other languages
French (fr)
Inventor
David Connolly
Original Assignee
Hong Kong Telecommunications Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GBGB9514004.2A priority Critical patent/GB9514004D0/en
Priority to GB9514004.2 priority
Application filed by Hong Kong Telecommunications Limited filed Critical Hong Kong Telecommunications Limited
Publication of WO1997003522A1 publication Critical patent/WO1997003522A1/en

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00Television systems
    • H04N7/14Systems for two-way working
    • H04N7/141Systems for two-way working between two video terminals, e.g. videophone
    • H04N7/148Interfacing a video terminal to a particular transmission medium, e.g. ISDN
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00Television systems
    • H04N7/14Systems for two-way working
    • H04N7/15Conference systems

Abstract

A videoconferencing network comprises a plurality of desktop (PC) units (16) each having a small video camera (18) to provide simple video analogue signals. The units each have an MPEG decoder (17). A central controller or exchange (10) for the network includes an MPEG (10A) coder which is shared by all the desktop units and used for compressing signals for transmission to other networks. This means that each desktop unit user may be provided with a relatively low cost MPEG decoder and effectively share the relatively high cost of the MPEG coder with other users in the network.

Description

VIDEOCONFERENCING

The invention relates to videoconferencing.

In a personal videoconferencing service, the user typically has a small video camera placed above or near the screen of a personal computer (PC) , the PC screen being used to receive moving pictures form the distant party.

To minimize the transmission costs of the video pictures, it is desirable to use standard forms of telecom transmission in digital form. The most common of these is currently the H.320 standard, operating over the Integrated Services Digital Network (ISDN) using circuit switching at 64 or 128 Kbps which includes the audio channel. In this arrangement, both the video compression of the camera signal and the decompression of the transmitted signal for display are carried out in the desktop (PC) unit. In order to achieve minimum digital transmission capacity and cost, the H.320 system provides picture quality lower than normally expected in a TV programme.

A second facility which is emerging is the Motion Picture Exports Group (MPEG) coding standard for video pictures. The digital compression is complex but the decompression for display is simple and low cost. This asymmetric coding arrangement is ideal for pre-recorded material stored in digital form, for example in a Video on Demand (VOD) service or on Compact Disc (CD-ROM) for use in a PC. MPEG transmission is at rates of 1.5 to 6 Megabits/second, significantly higher than for H.320 compression, but with quality comparable with a normal TV picture.

The MPEG system is becoming popular for PC use, particularly to replay video from an internal CD-ROM source. The PC with CD ROM and MPEG decoding will therefore become commonplace at the desktop. However the complexity and cost of a realtime coder for MPEG compression prevents its use in a desktop unit for videoconferencing, despite the benefit of improved picture quality.

It is an object of the invention to at least reduce this problem.

According to the invention, there is provided a videoconferencing system including a number of personal computers in a network, each computer having an MPEG decoder, and a video camera for generating video analogue signals, in which a MPEG coder is provided for the network to compress the analogue signals of the personal computers in the network for transmission to other networks.

The invention also provides a personal computer for a videoconferencing network having a MPEG decoder and a video camera for generating video analogue signals for transmission to other personal computers in the network.

A videoconferencing network according to the invention will now be described by way of example with reference to the accompanying schematic drawings in which:

Figure 1 shows the network; and

Figure 2 shows the arrangement of each communicating unit of the network.

Referring to the drawings, a network controller or exchange 10 is connected to a number of communication units 11 to 15 such as desk top (PC) units by unshielded twisted pair cables. The controller 10 is also connected to transmit to and receive transmissions from other like networks. The controller 10 includes an MPEG coder 10A and is controlled to receive signals from each of the units 11 to 15, one at a time and on demand, and to compress these signals for transmission to the other networks. The controller passes on any MPEG coded signals it receives from other networks for selected destinations at any of the units 11 to 15 in their compressed coded format. For communications within the network, that is between the units 11 to 15 however, the MPEG coder is not normally employed. In Figure 2, each unit includes a personal computer 16 and a MPEG decoder 17. The computer 16 is equipped to display visual images on its screen in the normal way based on MPEG coded signals received for the central controller 10. The computer 16 can also provide a display corresponding to analogue signals passed from other units in the same network. Each unit also has a video camera 18 and a convertor 19 that develops analogue signals which are passed to and via the central controller 10 and to other units in the network, as appropriate.

Thus, in the personal videoconferencing service, each PC is equipped with Video On Demand (VOD) service and a relatively low cost MPEG decoder. The PC may also have CD-ROM capability for local access to video material. The video camera at each PC is connected to a simple analogue transmission system which transmits a conventional analogue signal over a short distance and so can use conventional Unshielded Twisted Pair (UTP) cable to a central building for the network. At the central building, the analogue camera signals are converted to a compressed digital signal using the MPEG coder. However, this digital compression facility is shared among all the users of the network, and is occupied only while each call is in progress. In this way, the relatively high cost of the PEG compression can be allocated on a per call basis, rather than being dedicated to each PC in the network. As such. videoconference networks can be provided a reasonable individual cost, because the signifcantly high cost of each analogue MPEG coder can be in effect shared between a significant number of video work stations in each network. At the same time the encoding is carried out on original analogue signals, provided by video cameras, permitting conventional switching means to be used.

Videoconference calls are transmitted over a metropolitan area using the MPEG Coding Scheme for high picture quality, or over greater distances using the H.320 Coding Scheme. Each PC configuration for each user is the same for both coding standards, but for H.320 operation a digital transcoder H.320/MPEG will be required, which can be centrally located for the network.

Claims

AMENDED CLAIMS[received by the International Bureau on 18 December 1996 (18.12.96); original claims 1 and 2 amended (1 page)]
1. A videoconferencing network including a number of personal computers in the network, each computer having an MPEG decoder, and a video camera for generating video analogue signals, in which a MPEG coder is provided for the network to compress the analogue signals of each of the personal computers in the network one at a time and on demand for transmission to other networks.
2. A personal computer for the videoconferencing network of claim 1, arranged to transmit the video analogue signals to other personal computers in the network.
PCT/GB1996/001640 1995-07-10 1996-07-09 Videoconferencing WO1997003522A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GBGB9514004.2A GB9514004D0 (en) 1995-07-10 1995-07-10 Vidioconferencing
GB9514004.2 1995-07-10

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9800578A GB2318018A (en) 1995-07-10 1996-07-09 Videoconferencing
AU63662/96A AU6366296A (en) 1995-07-10 1996-07-09 Videoconferencing

Publications (1)

Publication Number Publication Date
WO1997003522A1 true WO1997003522A1 (en) 1997-01-30

Family

ID=10777384

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/001640 WO1997003522A1 (en) 1995-07-10 1996-07-09 Videoconferencing

Country Status (3)

Country Link
AU (1) AU6366296A (en)
GB (2) GB9514004D0 (en)
WO (1) WO1997003522A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2359437A (en) * 2000-02-16 2001-08-22 Stephen Albert Wilson Stand alone secure access web camera

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5375068A (en) * 1992-06-03 1994-12-20 Digital Equipment Corporation Video teleconferencing for networked workstations

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5375068A (en) * 1992-06-03 1994-12-20 Digital Equipment Corporation Video teleconferencing for networked workstations

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
GOLD E M: "PCS REWRITE THE RULES FOR VIDEOCONFERENCING LOW-COST PLATFORMS AND COLLABORATIVE SOFTWARE BRING DESKTOP VIDEOCONFERENCING CLOSER TO REALITY", DATA COMMUNICATIONS, vol. 23, no. 4, 1 March 1994 (1994-03-01), pages 95 - 98, 100, 102, 104, XP000432078 *
MOELLE S: "KOMPAKT UND FLEXIBEL", ELEKTRONIK, vol. 42, no. 19, 21 September 1993 (1993-09-21), pages 102 - 108, 114/115, XP000395519 *

Also Published As

Publication number Publication date
GB9514004D0 (en) 1995-09-06
AU6366296A (en) 1997-02-10
GB2318018A (en) 1998-04-08
GB9800578D0 (en) 1998-03-11

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