JPH09282247A - Method for distributing multimedia data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high-quality and inexpensive multimedia service even in the case where there are many terminals, by holding a table of correspondence between respective data names and repeaters for holding data and a table of correspondence between exchanges and repeaters at a server. SOLUTION: A data server 16 holds a table 163 of correspondence between the data names of respective data and repeaters 12 for holding these data and a table 165 of correspondence between exchanges 14 and the repeaters 12 connected to them. Then, when there is a distribution request designating the data name from a terminal 10, it is discriminated whether the requested data are held in the connected repeater 12 or not and when they are held, the requested data held in that repeater 12 are distributed to the terminal 10. Besides, when these data are not held, the repeater 12 receives the report of the repeater 12, where the requested data are held, from the server 16 through the connected data exchange 14 and the report of the exchange 14 connected to that repeater 12. Then, the request source repeater 12 receives the data from the data holding repeater 12 through the exchange 14 and distributes them to the terminal 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of delivering multimedia data in a multimedia service such as a CATV system.

[0002]

2. Description of the Related Art In a current CATV system, a cable television station called a headend and terminals in each home or office are connected by a tree-shaped network with the headend as the apex. On such a system, the headend unilaterally broadcasts a news program or a video program using several channels, and the terminal selects a program to watch from a limited number of channels. However, recent video information compression technology (Moving Picture Experts Group:
Due to improvements in network transmission capacity such as MPEG2) and optical fibers, bidirectional communication and provision of services using multiple channels have begun even in the system having such a configuration.

Among such services, a service for providing multimedia data, which is a combination of large data such as moving images, still images, voices and character data, has been attracting attention. For example, a video-on-demand service, which allows users to watch their favorite movies when they want, is expected as a new business to replace rental video.

The multimedia data providing service in the current CATV system has a multimedia data server that centrally stores and manages multimedia data at the headend, and receives the data from a terminal connected via a network. It is done by delivering. Usually, hundreds of terminals are connected to a data repeater by a low speed line such as a coaxial cable, dozens of data repeaters are connected to a data switch by a high speed line such as an optical fiber, and dozens of data switches are high speed. , Is connected to the head-end multimedia data server by a large capacity communication line (main line). In addition, data exchanges are connected in a ring by high-speed lines in case the trunk line becomes unusable due to an accident.

[0005] In such a conventional system, when delivering a large amount of multimedia data from a data server to a terminal, the performance of the entire system depends on the data transmission capability of the multimedia data server and the transmission capability of the network trunk line. Since it manages multimedia data in one place, data delivery requests from terminals concentrate on the data server, and the requested data is always transmitted to the terminal using one of several trunk lines. This is because.

Therefore, if the number of terminals is large, the multimedia data server needs to be large-scale, complicated and expensive, and the network trunk line also needs to have a large capacity and high speed. Also, every time the number of terminals changes, it is necessary to replace the server and the main line, which is very costly. As a method of responding with cheap capital investment when there are many terminals, near
Video-on-demand system (JP-A-5-41858)
"Cable broadcasting system") has been reported. According to this method, the data of the same movie is repeatedly delivered at a short time interval from the beginning so that a user who wants to see the movie can watch the movie from the beginning without waiting a certain time. However, in this method, there is a waiting time from when the user requests movie data until the actual delivery. Also, since multiple channels are used to deliver one movie, it is effective for delivering popular movies, but is less effective for delivering movies that are rarely requested.

[0007]

For the above reasons, it is an object of the present invention to provide a high-quality, inexpensive multimedia service even when the number of terminals is large.

[0008]

In order to solve the above problems, the present invention has two methods of delivering multimedia data.

According to a first multimedia data delivery method of the present invention, a server, an exchange, a repeater and a terminal for holding multimedia data are connected in a tree structure, and each exchange is connected to each other in a system. A method of delivering multimedia data to a terminal, wherein the server holds a correspondence table of data names of respective data and relays holding the data, and a correspondence table of exchanges and relays connected thereto, In response to a data delivery request specifying a data name from, the data relay device connected to the terminal determines whether the corresponding data is held, and when the determination is affirmative, the relay device The corresponding data to be held is delivered to the terminal, and when the determination is negative, the relay holds the data from the data server via the connected data exchange. A data repeater receives a notification of the exchange to which the repeater is connected to receive the relevant data to which the repeater via the switch holds, characterized in that delivery to the terminal.

A second multimedia data delivery method of the present invention is a server, an exchange, a repeater and a terminal for holding multimedia data are connected in a tree structure, and each exchange is a terminal in a system connected to each other. A method of delivering multimedia data to a user, wherein the server holds a correspondence table of data names of respective data and terminals holding the data, and a correspondence table of exchanges and relays connected to the exchanges. In response to a data request specifying a data name from the terminal, it is determined whether the corresponding data is held in the terminal, and when the determination is positive, the corresponding data held by the terminal is provided to the user. When the determination is negative, the terminal is connected to the terminal that holds the data from the data server via the connected data relay or data exchange, and the terminal is connected. Repeater being receives a notification of the exchange receives the relevant data which the terminal via the exchange and the relay is held, and providing to the user.

[0011]

Embodiments of the present invention will be described with reference to the drawings.

First, an embodiment of the first multimedia data delivery method of the present invention will be described with reference to FIGS.
FIG. 1 shows the first multimedia data delivery method of the present invention, and FIG. 2 shows the flow of processing performed by the control unit 121 of the data repeater 12. FIG. 3 shows the contents of the correspondence table 123, FIG.
Shows the contents of the correspondence table 163, and FIG. 5 shows the contents of the correspondence table 165.

In FIG. 1, a multimedia data server 16 includes a wide area communication trunk line 15-1 and a plurality of data exchanges 1.
4, the correspondence table 163 of the data relays 12 and the multimedia data 1221 stored in the relays 12 and the correspondence between the data exchanges 14 and the data relays 12 connected to the exchanges. I have a table 165. The data exchange 14 is connected to the plurality of data relays 12 by the local communication trunk line 13 and is connected to another data switch 14 by the wide area communication trunk line 15-2. Data relay 12
Has a control unit 121, a storage device 122, multimedia data 1221 and a correspondence table 123 of stored data 1221. Further, the data repeater 12 is the terminal line 11
Is connected to the terminal 10. The terminal has a display device 104.

The procedure for requesting and delivering multimedia data is as follows. When the user of the multimedia service makes a service request to the terminal 10, the terminal 10 notifies the control unit 121 of the data repeater 12 of the multimedia data delivery request via the terminal line 11. When the control unit 121 receives the notification (step 202), the request is sent to the terminal 10
From the other data relay device 12 or not (step 204). In this case, the terminal 10
Since it was notified from the storage device 1 of the own data repeater 12
The correspondence table 123 of the multimedia data 1221 stored in 22 is searched (step 206). Repeater 1
2 in the correspondence table 123, as shown in FIG.
All multimedia data 122 stored in 2
The name of 1 is retained. There is the name of the requested multimedia data in the correspondence table 123, that is, the requested multimedia data 1221 is the own data relay device 12.
If it is stored in the storage device 122 (step 208), it is delivered from the own data relay 12 to the terminal 10 (step 2).
10). As a result of the search, if the requested multimedia data 1221 is not in the storage device 122 of the own data relay device 12 (step 208), it will be described later which data relay device stores the requested multimedia data 1221. (Step 212). Control unit 1
21 notifies the control unit 121 of the data relay device 12 storing the requested multimedia data 1221 of the data delivery request (step 214). Upon receiving the notification (step 202), the control unit 121 checks whether the request has been notified from the terminal 10 or another data relay device 12 (step 204). In this case, since the other data relay device 12 has notified, the requested multimedia data 1221 is taken out from the storage device 122 and delivered to the data exchange 14 via the local communication trunk line 13.
The data exchange 14 sends the request to the data relay 12
The wide area communication trunk line 15 is connected to the data exchange 14 connected to the
The multimedia data 1221 is delivered via -2. The data exchange 14 delivers the data to the data relay 12 via the local communication trunk line 13 (step 218). Data repeater 12 that has received multimedia data 1221
Delivers to the terminal 10 via the terminal line 11 (step 216). The terminal 10 displays the received multimedia data 1421 on the display device 104. This multimedia data 1221 is delivered as in the data stream 17.

There are two methods by which the control unit 121 of the data relay device 12 which receives the multimedia data delivery request checks which data relay device 12 stores the multimedia data 1221. The first method is a correspondence table 163 showing which multimedia data 1221 is stored in which data repeater 12, and a correspondence table 1 of each data repeater 12 and the data exchange 14 connected to it.
This is a method that the multimedia data server 16 has 65. In this case, the control unit 121 inquires of the multimedia data server 16 about the data relay device 12 storing the requested multimedia data 1221 (inquiry notification 18). Upon receiving the inquiry, the multimedia data server 16 searches the correspondence table 163. As shown in FIG. 4, the correspondence table 163 holds the names of the data relays 12 and the names of all the multimedia data 1221 stored in the storage device 122. The data server 16 searches the correspondence table 163 for the name of the requested multimedia data 1221 and obtains the name of the data relay 12 storing the requested multimedia data 1221. Further correspondence table 165
(FIG. 5) is searched, and the name of the exchange 14 to which the repeater 12 is connected is obtained from the obtained name of the repeater 12.
The data server 16 notifies the obtained names of the relay 12 and the exchange 14 to the data relay 12 that has transmitted the inquiry. The requesting data repeater 12 sends the notified exchange 14 to the data repeater 12 notified by the data server.
A multimedia data delivery request is notified via.

In the second method, the control unit 121 has a correspondence table 165 and makes an inquiry to all the data relays 12 via the data switch 14. Upon receipt of the inquiry, the control unit 121 refers to the correspondence table 123 and, if there is the requested multimedia data 1221, notifies the response to the control unit 121 that has issued the inquiry. The control unit 121 that has received the response to the inquiry notifies the data relay device 12 that has transmitted the response of the data delivery request, and receives the delivered multimedia data 1221. When multiple responses are received, the data delivery request is notified to the sender of the first response received.

The merits obtained by the first multimedia data delivery method of the present invention will be described. In the multimedia data delivery system according to the prior art, all data delivery requests from terminals are concentrated on the multimedia data server 16, so that the multimedia data server 16 must deliver data to all terminals at the same time when the load is maximum. . Therefore, the multimedia data server 16 must use an expensive computer. On the other hand, in the first multimedia data delivery method of the present invention in FIG. 1, assuming that there are n data relays 12 in the entire system, the number of terminals per data relay 12 is 1 / n. Even when the load is maximum, it is sufficient to simultaneously deliver data to about 1 / n of all terminals. Therefore, an inexpensive computer can be used for the control unit 121 of the data repeater 12. In addition, the storage device 122 of the data repeater 12
However, since it is not necessary to store all of the necessary multimedia data 1221, it is possible to procure it at low cost, as compared with the storage device 162 of the multimedia data server 16 of the related art, which has much lower performance and smaller capacity. You can Further, since the multimedia data server 16 does not deliver data, the communication amount of the wide area communication trunk line 15-1 is reduced, so that a low performance and inexpensive communication line can be used for the wide area communication trunk line 15-1. Further, even if the total number of terminals changes, the number of corresponding data exchanges and data repeaters may be increased or decreased, and it is not necessary to replace an expensive multimedia data server, so a more efficient system configuration can be taken. be able to.

Further, when the demands for the multimedia data 1221 are biased and can be predicted by past statistical information or the like, optimum data arrangement can be performed. For example, the data of popular movies can be stored in all data exchanges 12
By storing the data in the storage device 122, the communication amount of the data wide area communication trunk line 15-2 can be reduced. In addition, since data that is rarely requested does not need to be stored in all the data exchanges 12, a small-capacity, inexpensive medium can be used as the storage device 122. For the above reasons, by using the first multimedia data delivery method of the present invention, it becomes possible to provide a higher quality and cheaper multimedia data service.

Next, a second multimedia data delivery method of the present invention will be described with reference to FIGS. FIG. 6 shows a second multimedia data delivery method of the present invention, and FIG. 7 shows a flow of processing performed by the control unit 101 of the terminal 10. 8 shows the contents of the correspondence table 103, and FIG. 9 shows the correspondence table 163.
, And FIG. 10 shows the contents of the correspondence table 165.

In FIG. 6, the multimedia data server 16 includes a plurality of data exchanges 1 through a wide area communication trunk line 15-1.
4, the correspondence table 163 of each terminal 10 and the multimedia data 1021 stored in the terminal 10,
It has a correspondence table 165 of each terminal 10, the data repeater 12 and the data switch 14 connected to the terminal 10. The data exchange 14 is connected to the plurality of data relays 12 by the local communication trunk line 13 and is connected to another data switch 14 by the wide area communication trunk line 15-2. Data relay 12
Is connected to the terminal 10 via a terminal line 11. The terminal has a correspondence table 10 of the control unit 101, the storage device 102, the multimedia data 1021, and the stored data 1021.
3 and the display device 104.

The procedure for requesting and delivering multimedia data is as follows. When the user of the multimedia service makes a service request to the terminal 10, the control unit 101 of the terminal 10 (step 702) determines whether the request is notified by the user or another terminal 10. Check (step 704). In this case, since the user is notified, the correspondence table 103 of the multimedia data 1021 stored in the storage device 102 of the own terminal 10 is searched (step 706). The correspondence table 103 holds the names of all the multimedia data 1021 stored in the storage device 102 as shown in FIG. 7. Correspondence table 1
If the requested multimedia data name exists in 03, that is, the requested multimedia data 1021 exists in the storage device 102 of the own terminal 10 (step 7
08), the multimedia data 1021 to the storage device 10
It is taken out from No. 2 and displayed on the display device 104 (step 710). As a result of the search, when the requested multimedia data 1021 is not in the storage device 102 of the terminal 10 (step 708), which terminal stores the requested multimedia data 1021 is checked by a method described later. (Step 712). The control unit 101 controls the terminal 10 that stores the requested multimedia data 1021.
The data delivery request is notified to the control unit 101 (step 714). Upon receiving the notification (step 702), the control unit 101 checks whether the request has been notified from the terminal 10 or another terminal 10 (step 704). In this case, since the notification is made from the other terminal 10, the requested multimedia data 1021 is taken out from the storage device 102 and delivered to the data exchange 14 via the terminal line 11, the data relay 12, and the local communication trunk 13. The data exchange 14 delivers the multimedia data 1221 to the data exchange 14 to which the terminal 10 which issued the request is connected, via the wide area communication trunk line 15-2. Data exchange 1
4 is delivered to the terminal 10 via the regional communication trunk line 13, the data relay device 12, and the terminal line 11 (step 718).
The terminal 10 that has received the multimedia data 1021
Displays the multimedia data 1021 on the display device 104 (step 716). This multimedia data 1021 is delivered as in the data stream 17.

There are two methods by which the control unit 101 of the terminal 10 which receives the multimedia data delivery request checks which terminal 10 stores the multimedia data 1021. The first method is a correspondence table 163 indicating which multimedia data 1021 is stored in which terminal 10, each terminal and a data relay device connected thereto,
This is a method in which the multimedia data server 16 has a correspondence table 165 with the data exchange 14. in this case,
The control unit 101 inquires of the multimedia data server 16 about the terminal 10 storing the requested multimedia data 1021 (inquiry notification 18). The multimedia data server 16 that received the inquiry
Searches the correspondence table 163. The correspondence table 163 is shown in FIG.
The name of each terminal 10 and its storage device 102
All multimedia data 1021 stored in
Holds the name of. The data server 16 maps the name of the requested multimedia data 1021 to the correspondence table 163.
, And obtains the name of the terminal 10 storing the requested multimedia data 1021. Correspondence table 16
5 (FIG. 5), the names of the intermediate device 12 and the exchange 14 to which the terminal 10 is connected are obtained from the obtained name of the terminal 10. The data server 16 notifies the terminal 10, which has sent the inquiry, of the obtained names of the terminal 10, the relay 12, and the exchange 14. The requesting terminal 10 notifies the terminal 10 notified from the data server of the multimedia data delivery request via the notified relay 12 and exchange 14.

In the second method, the control unit 101 uses the correspondence table 1
65, having a repeater 12 and an exchange 14 for all terminals 10.
Make an inquiry via. Upon receiving the inquiry, the control unit 101 refers to the correspondence table 103 and, if there is the requested multimedia data 1021, notifies the control unit 101 that has issued the inquiry of a response. The control unit 101 that has received the inquiry response sends the response to the terminal 10
To the data delivery request, and receives the delivered multimedia data 1021. When multiple responses are received, the data delivery request is notified to the sender of the first response received.

The merit obtained by the second multimedia data delivery method of the present invention will be described. In the multimedia data delivery system according to the prior art, all data delivery requests from terminals are concentrated on the multimedia data server 16, so that the multimedia data server 16 must deliver data to all terminals at the same time when the load is maximum. . Therefore, the multimedia data server 16 must use an expensive computer. On the other hand, in the second multimedia data delivery method of the present invention shown in FIG. 6, the terminal 1 that delivers data per terminal 10
There will be one 0. Therefore, since the data delivery capability of the terminal 10 does not have to be high, the control unit 101 of the terminal 10
You can use a cheap calculator for. Also, the terminal 10
The storage device 102 of the present invention does not have much multimedia data 1021 that needs to be stored (about 10 is sufficient), so the multimedia data server 1 of the related art is not required.
Compared with the storage device 162 of No. 6, it is sufficient that it has a low performance and a small capacity, and can be procured at a low cost. Further, since the multimedia data server 16 does not deliver data, the communication amount of the wide area communication trunk line 15-1 is reduced, so that a low performance and inexpensive communication line can be used for the wide area communication trunk line 15-1. Furthermore, even if the total number of terminals changes, the number of corresponding data exchanges and data repeaters may be increased or decreased.
Since it is not necessary to replace the expensive multimedia data server, a more efficient system configuration can be taken.

Further, when the demands for the multimedia data 1021 are biased and can be predicted by past statistical information or the like, the optimum data arrangement can be made. For example, by saving the data of a popular movie in the storage device 102 of many terminals 10, the communication amount of the data wide area communication trunk line 15-2 and the regional communication trunk line 13 can be reduced, and inexpensive communication is possible. You can use lines. For the above reasons, by using the second multimedia data delivery method of the present invention, it becomes possible to provide a higher quality and cheaper multimedia data service.

[0026]

According to the multimedia data delivery method of the present invention, it is possible to provide a high quality and inexpensive multimedia data service even if the number of terminals is large.

[Brief description of drawings]

FIG. 1 is a diagram showing a first multimedia data delivery method of the present invention.

FIG. 2 is a flow chart of a process performed by a control unit of the data relay device for illustrating the first multimedia data delivery method of the present invention.

FIG. 3 is a diagram showing contents of a correspondence table of a data relay device for showing a first multimedia data delivery method of the present invention.

FIG. 4 is a diagram showing the contents of a correspondence table of a multimedia data server for showing the first multimedia data delivery method of the present invention.

FIG. 5 is a diagram showing contents of a correspondence table of the multimedia data server for showing the first multimedia data delivery method of the present invention.

FIG. 6 is a diagram showing a second multimedia data delivery method of the present invention.

FIG. 7 is a flow chart of a process performed by a control unit of a terminal to show a second multimedia data delivery method of the present invention.

FIG. 8 is a diagram showing contents of a correspondence table of terminals for showing a second multimedia data delivery method of the present invention.

FIG. 9 is a diagram showing contents of a correspondence table of a multimedia data server for showing a second multimedia data delivery method of the present invention.

FIG. 10 is a diagram showing contents of a correspondence table of a multimedia data server for showing a second multimedia data delivery method of the present invention.

[Explanation of symbols]

10 ... Terminal, 11 ... Terminal line, 12 ... Data repeater, 1
3 ... Regional communication trunk line, 14 ... Data exchange, 15 ... Wide area communication trunk line, 16 ... Multimedia data server, 17 ... Multimedia data flow, 18 ... Notification of inquiry.

Claims (4)

[Claims] 1. A method of delivering multimedia data to each terminal in a system in which a server, an exchange, a repeater holding multimedia data and a terminal are connected in a tree structure, and each exchange is connected to each other. There was a data delivery request from the terminal, which holds the correspondence table of the data name of each data and the repeater holding the data, and the correspondence table of the exchange and the repeaters connected to it, in the server. Accordingly, it is determined whether the corresponding data is held in the data relay device connected to the terminal, and when the determination is affirmative, the corresponding data held by the relay device is delivered to the terminal, When the determination is negative, the repeater is a data repeater that holds the data from the data server via the connected data exchanger, and the repeater to which the repeater is connected. A method for delivering multimedia data, comprising receiving a notice of exchange, receiving corresponding data held by the repeater via the exchange, and delivering the data to the terminal. 2. A method of delivering multimedia data to each terminal in a system in which a server, an exchange, a repeater holding multimedia data and a terminal are connected in a tree structure, and each exchange is connected to each other, The server holds a correspondence table of the data name of each data and the repeater holding the data, and the data relay connected to the terminal in response to the data delivery request specifying the data name from the terminal. Whether the corresponding data is held in the device, when the determination is affirmative, the corresponding data held by the relay is delivered to the terminal, and when the determination is negative, the relay is connected All data relays are inquired about the existence of the relevant data via the data exchange, and the corresponding data is received from the repeater holding the relevant data via the exchange. A method of delivering multimedia data, characterized by taking and delivering to the terminal. 3. A method of delivering multimedia data to each terminal in a system in which a server, an exchange, a repeater for holding multimedia data and a terminal are connected in a tree structure, and each exchange is connected to each other, The server holds a correspondence table of the data name of each data and the terminal holding the data, and a correspondence table of the exchange and the repeater connected to it, and there is a data request from the user specifying the data name. According to, it determines whether the corresponding data is held in the terminal, when the determination is affirmative, provides the user with the corresponding data held by the terminal, when the determination is negative, the terminal, A terminal that retains the data from a data server via a connected data relay or data switch, a relay to which the terminal is connected, a notification of the switch, and the relay A method of delivering multimedia data, characterized in that the corresponding data held by the terminal is received via a container and the exchange and provided to the user. 4. A method of delivering multimedia data to each terminal in a system in which a server, an exchange, a repeater holding multimedia data and a terminal are connected in a tree structure, and each exchange is a system connected to each other. The server holds a correspondence table of the data name of each data and the terminal holding the data, and whether the terminal holds the corresponding data in response to a data request specifying the data name from the user. When the determination is affirmative, the corresponding data held by the terminal is provided to the user, and when the determination is negative, the terminal passes through the connected data repeater and data switch. Inquires all terminals of the existence of relevant data, receives the relevant data from the terminal holding the relevant data via the repeater and the exchange, and provides it to the user. The delivery method of multi-media data, characterized in that.