Multimedia-data transmission system, apparatus and method

• US 7,587,735 B2
• Filed: 09/26/2001
• Issued: 09/08/2009
• Est. Priority Date: 10/03/2000
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ando, Tsutomu
• Primary Examiner(s): Kelley; Christopher
• Assistant Examiner(s): BROWN, RUEBEN M
• Application Number:
  US09/962,108
• Publication Number:
  US 20020040478A1
• Time in Patent Office: 2,904 Days
• Field of Search: 725/87, 725/115, 725/117, 725 93- 95
• US Class Current: 725/93
• CPC Class Codes: H04N 21/2181 comprising remotely distributed storage units, e.g. when movies are replicated over a plurality of video servers distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: H04N 21/23103 using load balancing strategies, e.g. by placing or distributing content on different disks, different memories or different servers storage management G06F3/0604; allocation of resources considering the load in multiprogramming arrangements G06F9/505; techniques for rebalancing the load in a distributed system G06F9/5083; access to distributed or replicated servers, e.g. load balancing, in data networks H04L67/1001
• CPC Class Codes: H04N 21/242 Synchronization processes, e.g. processing of PCR [Program Clock References] arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/6125 involving transmission via Internet transmission by internet of broadcast information H04H60/82
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

In a system for transmitting multimedia data including video data, audio data, graphic data, text data and the like via a network, sets of media data are stored in a plurality of servers in a distributed state. When requested multimedia data is assigned from a transmitter, necessary sets of data from among media data stored in the servers in a distributed state are acquired by corresponding receivers in accordance with the assignment. A synchronization control unit and a multiplexer multiplex the acquired media data based on time stamps of the data, and transmit multimedia data after the multiplexing to a client which has assigned the multimedia data. According to such a configuration, distributed multimedia servers can be constructed without taking into consideration of influence by the effective rates of transmission channels from the respective servers.

Claims

1. A multimedia-data transmission system for transmitting multimedia data via a network, said system comprising:

a plurality of clients, each of which assign via the network multimedia data to be transmitted;

a first multimedia data storage server which stores a first type of multimedia data to be reproduced in synchronization with a corresponding second type of multimedia data and transmits via the network the stored first type of multimedia data to a proxy server upon receiving a request for the multimedia data from the proxy server;

a second multimedia data storage server which stores the second type of multimedia data, corresponding to the first type of multimedia data, to be reproduced in synchronization with the corresponding first type of multimedia data and transmits via the network the stored second type of multimedia data to the proxy server upon receiving a request for the multimedia data from the proxy server; and

a proxy server that receives the first type of multimedia data to be reproduced in synchronization transmitted from the first multimedia data storage server, receives the corresponding second type of multimedia data to be reproduced in synchronization transmitted from the second multimedia data storage server, multiplexes the received first type of multimedia data and the corresponding second type of multimedia data, and transmits the multiplexed multimedia data to at least one of the clients which assign the multimedia data to be transmitted,

wherein the proxy server comprises;

a first receiver that receives from one of the plurality of clients an assignment of multimedia data to be transmitted to the client;

a determiner for determining, based on multimedia data assigned by the one of the plurality of clients, the first multimedia data storage server storing the first type of multimedia data and the second multimedia data storage server storing the second type of multimedia data;

a requester for requesting that the first multimedia data storage server provide the first type of multimedia data to be reproduced in synchronization and for requesting that the second multimedia data storage server provide the corresponding second type of multimedia data to be reproduced in synchronization, based on the determination by the determiner;

a second receiver for receiving via the network the first type of multimedia data to be reproduced in synchronization transmitted from the first multimedia data storage server and for receiving via the network the corresponding second type of multimedia data to be reproduced in synchronization transmitted from the second multimedia data storage server in accordance with the request by the requestor;

a parser for analyzing a multimedia description language describing a mutual relationship among the first type of multimedia data and the second type of multimedia data, transmitted from said client;

a reproducing-information memory for storing reproducing information for the first type of multimedia data and the second type of multimedia data output from said parser;

a multiplexer for multiplexing the received first type of multimedia data and the corresponding second type of multimedia data based on a timestamp added to the received first type of multimedia data and the second type of multimedia data and the reproducing information stored in said reproducing-information memory; and

transmission means for transmitting via the network the multiplexed multimedia data obtained as a result of the multiplexing to said one client which assigned the multimedia data to be transmitted.

2. A system according to claim 1, wherein the first type and second type of multimedia data includes at least one of video data, audio data, graphic data and text data to be reproduced in synchronization.

3. A system according to claim 1, wherein said second receiver further comprises a cache memory for temporarily storing the received first type and second type of multimedia data, in order to absorb a difference between speeds of transmission from the first and second multimedia data storage servers.

4. A transmission method implemented in a proxy server for controlling the proxy server which receives a first type of multimedia data to be reproduced in synchronization transmitted from a first multimedia data storage server, and receives a corresponding second type of multimedia data to be reproduced in synchronization transmitted from a second multimedia data storage server, and transmits via a network, multiplexed multimedia data to at least one of a plurality of clients which assign multimedia data to be transmitted, said method comprising:

a first receiving step of receiving, from one of the plurality of clients, an assignment of multimedia data to be transmitted to the client;

a determining step of determining, based on multimedia data assigned by the one of the plurality of clients, the first multimedia data storage server storing the first type of multimedia data and the second multimedia data storage server storing the second type of multimedia data;

a requesting step of requesting that the first multimedia data storage server provide the first type of multimedia data to be reproduced in synchronization and requesting that the second multimedia data storage server provide the corresponding second type of multimedia data to be reproduced in synchronization, based on the determination in the determining step;

a second receiving step of receiving via the network the first type of multimedia data to be reproduced in synchronization transmitted from the first multimedia data storage server and receiving via the network the corresponding second type of multimedia data to be reproduced in synchronization transmitted from the second multimedia data storage server in accordance with the request by the requesting step;

a parsing step of a parser analyzing a multimedia description language describing a mutual relationship among the first type of multimedia data and the second type of multimedia data, transmitted from said client;

a storing step of storing reproducing information, in a reproducing-information memory, for the first type of multimedia data and the second type of multimedia data output from said parser;

a multiplexing step of obtaining multiplexed multimedia data by multiplexing the received first type of multimedia data and the corresponding second type of multimedia data based on a timestamp added to the received first type of multimedia data and the second type of multimedia data and the reproducing information stored in said reproducing-information memory; and

a transmission step of transmitting via the network the multiplexed multimedia data obtained as a result of the multiplexing to the one client which transmitted the assignment.

5. A method according to claim 4, wherein the first type and second type of multimedia data includes at least one of video data, audio data, graphic data and text data to be reproduced in synchronization.

6. A method according to claim 4, further comprising temporarily storing the first type of multimedia data and the second type of multimedia data received in said second receiving step to a cache memory, and wherein a difference between speeds of transmission of multimedia data from the first type and second type of servers is absorbed in said storing step.

7. A computer-executable program stored in a computer-readable storage medium, the program for controlling a proxy server which receives a first type of multimedia data to be reproduced in synchronization transmitted from a first multimedia data storage server, and receives a corresponding second type of multimedia data to be reproduced in synchronization transmitted from a second multimedia data storage server, and transmits via a network multiplexed multimedia data to at least one of a plurality of clients which assign multimedia data to be transmitted, said computer program comprising:

code for a first receiving step for receiving, from one of the plurality of clients, an assignment of multimedia data to be transmitted to the client;

code for determining, based on the multimedia data assigned by the one of the plurality of clients, the first multimedia data storage server storing the first type of multimedia data and the second multimedia data storage server storing the second type of multimedia data;

code for requesting that the first multimedia data storage server provide the first type of multimedia data to be reproduced in synchronization and for requesting that the second multimedia data storage server provide the corresponding second type of multimedia data to be reproduced in synchronization, based on the determination of the determining code;

code for a second receiving step for receiving via the network the first type of multimedia data to be reproduced in synchronization transmitted from the first multimedia data storage server and for receiving via the network the corresponding second type of multimedia data to be reproduced in synchronization transmitted from the second multimedia data storage server in accordance with the request by the requesting code;

code for a parsing step of a parser for analyzing a multimedia description language describing a mutual relationship among the first type of multimedia data and the second type of multimedia data, transmitted from said client;

code for a storing step of storing, in a reproducing-information memory, reproducing information for the first type of multimedia data and the second type of multimedia data output from said parser;

code for a multiplexing step for obtaining multiplexed multimedia data by multiplexing the received first type of multimedia data and the corresponding second type of multimedia data based on a timestamp added to the received first type and second type of multimedia data and the reproducing information stored in said reproducing-information memory; and

code for transmitting via the network the multiplexed multimedia data obtained as a result of the multiplexing to the one client which transmitted the assignment.

8. A proxy server for receiving a first type of multimedia data to be reproduced in synchronization transmitted from a first multimedia data storage server and for receiving a corresponding second type of multimedia data to be reproduced in synchronization transmitted from a second multimedia data storage server, and for transmitting via a network, multiplexed multimedia data to at least one of a plurality of clients which assign multimedia data to be transmitted, said proxy server comprising:

a first receiver for receiving from one of the plurality of clients an assignment of multimedia data to be transmitted to the client;

a determiner for determining, based on multimedia data assigned by the one of the plurality of clients, the first multimedia data storage server storing the first type of multimedia data and the second multimedia data storage server storing the second type of multimedia data;

a requester for requesting that the first multimedia data storage server provide the first type of multimedia data to be reproduced in synchronization and for requesting that the second multimedia data storage server provide the corresponding second type of multimedia data to be reproduced in synchronization, based on the determination by the determiner;

a second receiver for receiving via the network the first type of multimedia data to be reproduced in synchronization transmitted from the first multimedia data storage server and for receiving via the network the corresponding second type of multimedia data to be reproduced in synchronization transmitted from the second multimedia data storage server in accordance with the request by the requestor;

a parser for analyzing a multimedia description language describing a mutual relationship among the first type of multimedia data and the second type of multimedia data, transmitted from said client;

a reproducing-information memory for storing reproducing information for the first type of multimedia data and the second type of multimedia data output from said parser;

a multiplexer for obtaining multiplexed multimedia data by multiplexing the received first type of multimedia data and the corresponding second type of multimedia data based on a timestamp added to the received first and second type of multimedia data and the reproducing information stored in said reproducing-information memory; and

a transmitter for transmitting via the network the multiplexed multimedia data obtained as a result of the multiplexing to the one client which transmitted the assignment.