Multi-point video conference system wherein each terminal comprises a shared frame memory to store information from other terminals

• US 5,446,491 A
• Filed: 12/21/1993
• Issued: 08/29/1995
• Est. Priority Date: 12/21/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shibata, Koichi, Kinoshita, Taizo
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): GRANT, CHRISTOPHER C
• Application Number:
  US08/170,750
• Time in Patent Office: 616 Days
• Field of Search: 348/15, 348/14, 348/16, 348/17
• US Class Current: 348/14.09
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 7/15 Conference systems
• CPC Class Codes: H04N 7/152 Multipoint control units therefor
• CPC Class Codes: Y10S 370/902 Packet switching

Abstract

A multi-point video conference system includes a plurality of terminals and a network. Each terminal includes a coder to code and to packetize at least a motion picture in a block unit and a multi-point video decoder to sequentially receive and to decode packets sent from decoders at other points. The decoder includes a video processor to process video information in a time sharing manner, a channel selection controller to decide a transmission source of a received packet according to information of the packet and to notify the source to the video processor, a shared frame memory to store therein video information from the plural terminals, and a display frame memory to output therefrom the video information in a synchronous fashion.

Claims

1. A multi-point video conference system including a plurality of terminals connected to each other via a network, wherein each terminal of said plurality of terminals comprises:

a coding means for packetizing video data inputted from a video camera and outputting packetized data to said network;

a decoder for receiving in a time sharing manner a plurality of packets transmitted from other terminals via said network, decoding received packets in an order of reception thereof, and outputting decoded video information;

a plurality of storage means for storing therein said decoded video information in a frame unit;

a display means for displaying thereon contents stored in said storage means; and

a switch for changing over the contents of said storage means to supply said display means.

2. A system according to claim 1, wherein the coding means comprises:

a means for coding the video data through compression thereof; and

a means for adding information identifying a video to the coded data and forming a packet thereof, thereby outputting the packet.

3. A multi-point video conference system according to claim 1,wherein in each of said plurality of storage means, there are independently reserved areas to respectively store therein decoded images of respective channels of transmitting terminals.

4. A multi-point video conference system according to claim 1, wherein in each of said plurality of storage means, write operations are independently carried out for respective channels or transmitting terminals.

5. A multi-point video conference system including a plurality of terminals connected to each other along connection channels via a network, wherein each terminal of said plurality of terminals comprises:

a coding means for packetizing video data inputted from a video camera and outputting packetized data to said network;

a decoder for receiving in a time sharing manner a plurality of packets transmitted from other terminals via said network, decoding received packets in an order of reception thereof, and outputting decoded video information;

a plurality of storage means for storing therein said decoded video information in a frame unit;

a display means for displaying thereon contents stored in said storage means; and

a code processor, wherein said code processor comprises;

a means for separating from a received packet, information identifying a transmission terminal of a transmission source and video information;

a decoding means for decoding said video information; and

a work register disposed for each connection channel between said each terminal and said other terminals, said work register being used by said decoding means according to said information identifying the transmission source terminal.

6. A system according to claim 5, wherein the decoder further comprises:

a storage means for storing the decoded video information in mutually different areas disposed for transmission sources, respectively; and

a table for receiving said information identifying the transmission sources and establishing correspondences between the areas and the transmission sources of the decoded video information.

7. A system according to claim 5, wherein the decoding means for decoding the video information comprises:

a keeping means operative, when there is obtained a left over number of code bits in a coding operation, for keeping the left over number of code bits for each of the transmission sources of the video information; and

a buffer for keeping therein, according to the video information kept in the keeping means, information of the transmission source of the video information.

8. A multi-point video conference system including a plurality of terminals connected to each other along connection channels via a network, wherein each terminal of said plurality of terminals comprises:

a coding means for packetizing video data inputted from a video camera and outputting packetized data to said network;

a decoder for receiving in a time sharing manner a plurality of packets transmitted from other terminals via said network, decoding received packets in an order of reception thereof, and outputting decoded video information;

a plurality of storage means for storing therein said decoded video information in a frame unit; and

a display means for displaying thereon contents stored in said storage means; and

wherein the storage means stores therein, for each connection channel for which a video conference is to be conducted at least three frames of decoded images to be outputted therefrom; and

wherein the display means includes means for each said connection channel for keeping therein information related to a frame currently conducting an output operation, information related to a frame currently available for a write operation, and information related to a frame to undergo a next output operation.