JP2004013440A - Data distribution system, data relay device and method therefor, and program for implementing data relay method by computer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To distribute separate contents in compliance with individual conditions to a maximally large number of clients without putting a great load to a server side in a content distribution system. <P>SOLUTION: In this data distribution system, client terminals are grouped, and contents are distributed to each group via a specific data relay device. In the data relay device, a part, to which a receipt packet belongs, is determined by a data selection part 13, and if the part is the one to be replaced, the receipt packet is discarded while a packet of replacement requiring data is formed by a data packet formation part 15. The formed replacement packet is transmitted to a client terminal T. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data relay device that relays data between a data distribution source and a user in a data distribution system that distributes multimedia data to a user via a network such as the Internet.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the development of communication technology, services for distributing multimedia contents (hereinafter, “contents”) such as still images, moving images, and audio on a network have been provided. Behind the background is the fact that broadband networks have enabled high-speed transmission of digital data. The content data is distributed in small packets and is transmitted according to a protocol called a real-time transport protocol (RTP) when real-time performance is important such as streaming.
[0003]
The content distribution mode is to transmit the content from the server that holds the content to the terminal of the client (user). One server is called “unicast” that sends individual content from the server to each client. From "multicast" that sends the same content to multiple clients.
[0004]
In the case of multicast, since the data sent from the server is the same for all clients, it is not necessary to increase the capacity (rate) of the line for sending data from the server regardless of the number of clients, and the number of clients that can respond Is theoretically infinite. However, it is not suitable for a service that sends out contents having different contents for each user. On the other hand, in the case of unicast, different contents can be delivered to each client in accordance with the request, but since the server sends out multiple types of contents at the same time, even if the line capacity is increased, the client can respond simultaneously. The number is limited and it is not suitable for services that deliver data to many clients at the same time.
[0005]
[Problems to be solved by the invention]
However, in the content distribution service, it may be necessary to simultaneously distribute contents having different contents to a large number of clients. For example, in the case of a service that adds a commercial or regional information (such as a weather forecast) to a certain program (such as a movie or live sports broadcast) to create one content and distributes it to clients nationwide, the program portion is common but the commercial and regional information Since the portion differs depending on the location (region) and taste of the client, the content of the content differs for each client. In such a case, it is necessary to edit and produce a plurality of types of contents that differ only in commercials and regional information, and hold the edited contents on a server. Furthermore, if these plural types of contents are to be distributed simultaneously, a very large line capacity is required for the data transmission from the server.
[0006]
The present invention has been made in view of the above problems, and in a content distribution system, it is possible to adjust as many clients as possible to each client's individual conditions such as locations and preferences without imposing a load such as management of a large amount of data on a server side. It is an object of the present invention to provide a data distribution system and a data relay device capable of distributing contents having the above contents.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, a data distribution system of the present invention is a data distribution system that distributes distribution data from a server to a plurality of client terminals via one or more data relay devices, wherein the client A data distribution system that is divided into a plurality of groups, and the distribution data distributed by the server is composed of a plurality of parts, wherein the one or more data relay devices correspond to any of the plurality of groups. A data receiving unit for receiving distribution data from the server; a necessity determining unit for determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received by the data receiving unit; The post-replacement distribution data in the form of replacing the part determined to be required by the rejection determination unit with the replacement part unique to the part, And having a replacement transmitting means for transmitting to the clients belonging to the group to respond, the.
[0008]
According to the system having this configuration, the single content transmitted by the server is partially updated by the one or more data relay devices and transmitted to the client terminals. Content with different contents can be distributed.
Further, in order to solve the above-mentioned problem, a data relay device of the present invention is directed to a distribution system that distributes distribution data from a server to a plurality of client terminals, wherein the data relay device is arranged between the server and a part of the plurality of client terminals. What is claimed is: 1. A data relay device for relaying distribution data, comprising: data receiving means for receiving distribution data composed of a plurality of parts from the server; and replacing each of the plurality of parts constituting the distribution data received by the data receiving means. And a replacement transmitting unit that transmits to the client terminal the post-replacement distribution data in which the part determined to be required for replacement is replaced with unique replacement data. It shall be.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a data distribution system and a data relay device of the present invention will be described with reference to the drawings.
(Overview of data distribution system)
FIG. 1 is a diagram showing an outline of a data relay device 1 and a data distribution system A including the same. The data distribution system A performs a service of distributing multimedia content data (hereinafter, referred to as “content data”) held by a server to a client (user) via a data relay device. In this distribution, the content data is distributed to the client according to a predetermined time table, and is close to the image of the current television broadcasting service. Since the real-time property is emphasized due to the nature of the service, the content data is transmitted according to RTP.
[0010]
As shown in FIG. 1, a data distribution system A includes a plurality of data relay devices 1 connected to one multimedia content server S (hereinafter, simply referred to as “server S”) via a network N. Are connected to one or more client terminals via a network. The client terminals are divided into several groups, and each group corresponds to a specific data relay device. Since the configurations of a plurality of data relay devices and client terminals are the same, they are assigned a single reference number, and are hereinafter referred to as “data relay device 1” and “client terminal T”.
[0011]
The server S sends the content data to the data relay device 1 in packet units according to RTP. The transmission of the content data from the server S is performed by a multicast method, and the same content data is transmitted to all the data relay apparatuses 1.
Each data relay device 1 replaces a part of the content data received from the server S with the unique replacement data held in advance similarly in accordance with the unique replacement information held in advance, and connects each of them. To the client terminal T (at this point, the content data content to be transmitted differs for each data relay device). Transmission of content data from each data relay device to a plurality of corresponding client terminals is also performed by a multicast method. The entity of the data relay device 1 is a device (a concept including a program executed by a computer) incorporated in an existing relay device such as a router.
[0012]
The client terminal T receives the packet from the corresponding data relay device 1, takes out the content data therefrom, reproduces it, and presents it to the user.
That is, the data distribution system A is for grouping clients and distributing them via a specific data relay device for each group. Each data relay device separately replaces a part of the content data, and Content that has different contents.
(Content organization and replacement information)
Next, the organization of the content data distributed by the server S and the outline of the replacement information held by the data relay device 1 will be described.
[0013]
The content data distributed by the server S is obtained by inserting a commercial and regional information into the main program. The main program is common to all clients, but the content of the commercial and the regional information depends on the location of the client terminal T. Different. What is replaced in the data relay device 1 is the CM and the area information. The server S divides the content data into several parts, further divides each part into packet units, and distributes the data to the client terminal T via the data relay device 1. Further, the server S holds organization information indicating the configuration of each piece of content data, and sends the organization information to the data relay device 1 prior to content data distribution. At the time of this transmission, the server S adds identification information for identifying the content corresponding to each piece of organization information.
[0014]
FIG. 2 is a schematic diagram showing an example of the organization of the content data as described above. The content data 200 is composed of three main parts 211, 212, 213 forming a main part of a program, CM parts 221 and 222 corresponding to CMs, and a local information part 231 corresponding to regional information, and CM between the three main parts. In this configuration, parts 221 and 222 are inserted, and a regional information part 231 is added to the end.
[0015]
FIG. 3 is a diagram showing, in the form of a table, an example of the structure and content of the organization information using the content data 200 shown in FIG. 2 as an example. The composition information corresponds to each part. The knitting information 301 corresponds to the main part 211 shown in FIG. 2, and the knitting information 302 to 306 correspond to the CM part 221, the main part 212, the CM part 222, the main part 213, and the region information part 231. Each set information includes a part ID column 310 in which an ID for uniquely identifying each part is stored, and a timing column 320 in which information indicating a range in content data of each part by values of a reproduction start timing and a reproduction end timing is stored. The timing column 320 further includes a start timing column 321 and an end timing column 322. The value stored in the timing column 320 corresponds to the time stamp set for each packet at the time of data distribution. That is, the start of playback of the content data is set to "00: 00: 00: 00", and the start and end of playback of each part are represented by the elapsed time length (offset) from the start of playback. For example, the composition information 301 indicates that the main part 211 is to be reproduced in a range from “00: 00: 0” to “00:15:00” from the start of reproduction. Conversely, if the value of the time stamp stored in a certain packet is in the range of “00: 00: 0” or more and less than “00:15:00”, it means that the packet is included in the main part 211. .
[0016]
On the other hand, the data relay device 1 replaces a part of the content data on a part-by-part basis. For this purpose, the data relay device 1 retains replacement data, which is data after replacement, and replacement information indicating the content of replacement processing. The replacement data and replacement information are created in parallel with the production of the content, and are transmitted to each relay device via the network during a distribution service suspension period (such as midnight). The data relay device 1 stores the received replacement data and replacement information in an attached storage device. The replacement information is created for each content data and further for each data relay device.
[0017]
FIG. 4 shows an example of the configuration and contents of the replacement information held by the data relay device 1 in the case of the content data 200 shown in FIG. It is assumed that the replacement information 400 is added with content identification information indicating which content data corresponds to the content data (not shown). The replacement information 400 includes a part ID column 410 (corresponding to the part ID column 310 of the composition information shown in FIG. 3) in which the identification information of the replacement target part is stored, and a replacement data ID column in which the identification information of the replacement data is stored. 420.
[0018]
FIG. 4 shows that the parts whose identification information values are “CM1” and “DI01” (CM part 221 and regional information part 231) are to be replaced, and the identification information values are “R01” and “DI01”, respectively. It is information that the content is replaced with replacement data of “R02”. Each data relay device included in the data distribution system A has the same configuration as that shown in FIG. 4 and holds replacement information having different contents.
(Configuration of Data Relay Device 1)
Next, the configuration of the data relay device 1 according to the present embodiment will be described.
[0019]
FIG. 5 is a block diagram showing a detailed configuration of the data relay device 1 shown in FIG. The storage device 19 storing replacement data is connected to the data relay device 1.
The data relay device 1 includes a data receiving unit 11 that receives, via the network N, content data transmitted from the content server S in RTP packet units, organization information (see FIG. 3), replacement information (see FIG. 4), and replacement data. The composition information acquisition unit 12 that receives data, the data selection unit 13 that determines the necessity of replacement for each part of the content data received by the data reception unit 11 with reference to the composition information and replacement information, and the data selection unit 13 replaces the content data. The data reading unit 14 reads the replacement data corresponding to the part determined to be necessary from the storage device 19, and creates a data packet that divides the read replacement data for one part into RTP packets for transmission. Unit 15, a part of the header information as needed regarding the packet to be transmitted to the client. Packet information changing unit 16 for changing, with the data sending unit 17 for sending the packets over the network N 'to the client terminal T.
[0020]
The storage device 19 stores the replacement data received by the composition information acquisition unit 12. In the following description, for convenience, the packet received by the data receiving unit 11 from the server S is distinguished from the received packet, and the packet created by the data packet creating unit 15 from the replacement data is distinguished from the replaced packet.
Hereinafter, the main components of the components will be described in more detail.
(Data selector 13)
When receiving the received packet from the data receiving unit 11, the data selecting unit 13 refers to the content and determines whether or not the received packet is the first packet of the part. When the first packet of the part is detected, it is determined whether or not the part is a part to be replaced. If it is a replacement target part, the received packet sent from the data receiving unit 11 is discarded until the head packet of the next part is detected. On the other hand, it instructs the data packet creation unit 15 to create a replacement packet from the replacement data corresponding to the replacement target part, and outputs the replacement packet to the packet information change unit 16.
[0021]
The data selection unit 13 detects the first packet of each part and determines whether the part is a replacement target part with reference to the time stamp information, the organization information, and the replacement information of the received packet. This is because information directly indicating the part to which the packet belongs is not stored. The time stamp is stored in a header or a payload of a received packet (RTP packet), and indicates an offset from the head of the content data at a timing. The data selection unit 13 obtains the organization information and the replacement information from the organization information receiving unit 12 in advance and holds the information.
[0022]
When receiving a new received packet from the data receiving unit 11, the data selecting unit 13 reads the time stamp of the received packet. Then, the time stamp is referred to the timing column 320 (see FIG. 3) of the composition information to obtain the part ID of the part to which the packet belongs (the value of the part ID column 310). With the part ID of As a result of the comparison, if the part ID of the packet is different from the part ID of a previously received part, the packet is known as a part change, that is, a leading packet of a new part. Since the “part ID of the received part” does not exist (is a null value) for the first packet of the content, it is always recognized as the first packet of the part. If it is determined that the received packet is the head of the part, the data selection unit 13 further queries the part ID of the part to which the received packet belongs to the contents of the part ID column 410 (see FIG. 4) of the replacement information. Then, it is determined whether the part is to be replaced.
[0023]
When the data selection unit 13 detects the first packet of the part and determines whether the part is a replacement target, the data selection unit 13 performs the following processing according to the determination result.
First, if it is not the replacement target part, the data selection unit 13 outputs the received packet sent from the data reception unit 11 to the packet information change unit 16 as it is until the head packet of the next part is detected.
[0024]
On the other hand, if the part is a replacement target part, the data selection unit 13 then performs a process of discarding a subsequent received packet included in the part, causes the data packet creation unit 15 to create a replacement packet, and outputs the replacement packet to the packet information update unit 16 Is performed in parallel.
In the discarding process, first, when it is determined that the detected first packet is the replacement target part, the discard flag is set to ON, and the first packet is discarded. The data selection unit 13 discards the received packet when “the part to which the received packet sent from the data receiving unit 11 belongs is the same as the previous part” and the condition that “discard flag = ON” is satisfied. If the received packet and the previous packet belong to different parts with the discard flag = ON (when the first packet of the next part is detected), the data selection unit 13 returns the discard flag to OFF, Thus, the determination whether the next part is a replacement target and the subsequent processing are performed.
[0025]
As a process for creating and outputting the replacement packet, the data selection unit 13 first sends identification information of the replacement data (the value of the replacement data ID column 420 of the replacement information) to the data packet creation unit 15 and converts the replacement data. Instruct creation of the stored RTP packet. Then, the replacement packets output from the data packet creating unit 15 in response to the instruction are sequentially output to the packet information changing unit 16.
[0026]
The data selection unit 13 sets the “creating flag” to ON at the time of instructing the packet creation unit 15 to create a packet of replacement data, and sends the last packet of the replacement data to be instructed from the packet creation unit 15 to the packet creation unit 15. Return to OFF when received. This flag is set when the data selection unit 13 receives the first packet of the next part from the data reception unit 11 during the process of receiving the replacement packet from the packet generation unit 15 and outputting the replacement packet to the packet information change unit 16. Referenced. That is, when the first packet of the next part is detected while the above-mentioned creation flag is ON, the data selection unit 13 receives the last replacement packet from the data packet creation unit 15 and outputs it to the packet information change unit 16. Until the creation flag is turned off, the received packet of the next part sent from the data receiving unit 11 is temporarily stored. Then, after sending the last packet of the replacement part to the packet information change unit 16, the received packet temporarily stored is discarded or output to the packet information change unit 16, depending on whether or not this next part is to be replaced. I do.
[0027]
The data selection unit 13 repeats the above processing until the processing of all parts of the content data is completed. Further, every time the data selection unit 13 outputs a packet to the packet information change unit 16, the data selection unit 13 outputs to the packet information change unit 16 information referred to when a part (sequence number) of the management information of the packet is changed. . The information is the total number of discarded packets from the start of the distribution of the content data and the total number of replacement packets from the start of the distribution. In order to obtain such information, the data selector 13 holds a counter for discarded packets and a counter for created packets.
(Data packet creation unit 15)
The data packet creation unit 15 creates a replacement packet according to the instruction from the data selection unit 13 and sends the replacement packet to the data selection unit 13. First, the identification information of the replacement data sent together with the instruction from the data selection unit 13 is sent to the data reading unit 14, and the replacement data corresponding to the identification information is read from the storage device 19. If there is information necessary for RTP packetization (such as HintTrack in the MP4 format), that part is also read by the data reading unit 14. Subsequently, the read replacement data is divided and stored in the RTP packet, and management information necessary for the packet is set and transmitted to the data selection unit 13. Further, when transmitting the final replacement packet of the replacement data to the data selection unit 13, the terminal device notifies the data selection unit 13 that the replacement data is final. For the created replacement packet, the sequence number, which is a part of the management information, is set to a null value.
(Packet information change unit 16)
The packet information changing unit 16 updates the sequence number of the packet sent to the client terminal T when necessary. The sequence number is a serial number of a packet constituting one piece of content data, and is set so that the receiving apparatus (here, the client terminal T) can detect “packet loss” or “reversal of packet order” occurring during transmission. Information. For example, when one piece of content data is divided into 100 packets and transmitted to a client terminal, a sequence number from 1 to 100 is set for each packet according to the transmission order. If the client terminal receives the packet of “sequence number: 12” after the packet of “sequence number: 12” after the packet of “sequence number: 10”, the packet of “sequence number: 11” is being transmitted on the client side. Can be recognized as lost (packet loss). In this case, when reproducing the received multimedia data, the client terminal performs adjustment in consideration of the lost packet.
[0028]
The inversion of the packet order is a phenomenon in which the transmission order and the reception order of the packets do not match. For example, three packets transmitted in the order of “sequence number: 10”, “sequence number: 11”, and “sequence number: 12” are sent to the client terminal as “sequence number: 10” and “sequence number: 12”. , "Sequence number: 11". In this case, the client side discards “sequence number: 11”.
[0029]
However, when data replacement is performed, the data amount after compression is not the same between the replacement target part and the replacement data even if the time length at the time of reproduction is the same, so that the data amount before and after the replacement is different. If the difference in the data amount is large, the number of packets will be different. For example, while the replacement target part has a data amount that can be accommodated in 10 packets (sequence numbers are “11” to “20”), if the replacement data is an amount that can be accommodated in 9 packets, the data Since the sequence number contained in the last replacement packet of the replacement data sent from the relay device 1 to the client terminal T is “19”, the sequence number of the next packet sent from the server is “21”. If the packet is directly transmitted to the client terminal T, it is erroneously recognized that the packet of “sequence number: 20” has been lost.
[0030]
On the other hand, if the replacement target part has a data amount that can be accommodated in 10 packets, while the replacement data has an amount that can be accommodated in 12 packets, the final replacement packet of the replacement data sent to the client terminal T is provided. Since the sequence number of the packet transmitted from the server is "21" while the sequence number of the packet transmitted next from the server is "21", the packet is transmitted to the client terminal without adjusting the sequence number. In this case, the packet is discarded by erroneously recognizing that the above-mentioned "reverse of the packet order" has occurred.
[0031]
Therefore, the packet information change unit 16 changes the sequence number prior to transmission to the client terminal T in order to prevent such erroneous recognition regarding packet loss and inversion of the packet order.
The content of the sequence number changing process by the packet information changing unit 16 is that the packet output by the data selecting unit 13 is a received packet received by the data receiving unit 11 or a replacement packet created by the packet data creating unit 15. Divided by Which packet is determined by determining whether the sequence number is null (as described above, the sequence number of the replacement packet is null).
[0032]
When a packet received by the data receiving unit 11 (a packet whose sequence number is not null) is transmitted from the data selecting unit 13, the packet information changing unit 16 sends two types of information provided from the data selecting unit 13, ▲ The sequence number after change is calculated by referring to 1) the total number of discarded packets and 2) the total number of replacement packets. That is, an adjustment value obtained by subtracting the value of (1) from the value of (2) is added to the value of the sequence number before change of the packet.
[0033]
On the other hand, in the case of the replacement packet created by the data packet creation unit 15, the packet information change unit 16 counts up the sequence number of the packet sent by the packet information change unit 16 immediately before itself to the data send unit 17 by one. It is set as a sequence number and sent to the data sending unit 17. Note that the packet information change unit 16 stores the sequence number of the packet transmitted immediately before to the data transmission unit 17 and updates the sequence number each time the packet is transmitted so that the above processing can be performed.
[0034]
If the packet loss and the reversal of the packet order also occur in the data transmission from the server S to the data relay device 1, the detection and adjustment of these are performed before the data selection unit 13 determines whether the replacement is necessary. (For example, in the data receiving unit 11).
(motion)
Next, the operation of the data relay device 1 will be described with reference to the drawings.
[0035]
FIG. 6 is a flowchart showing a flow of processing performed by the data relay device 1 in the present embodiment in distributing one content data, focusing on processing for received packets sequentially received from the server S.
First, the data receiving unit 11 receives the notification of the distribution start from the server S, and the processing is started (S601: Yes), and the data selecting unit 13 initializes various counters and flags (the discarded packet counter and the replacement packet). Counter 0, discard flag and creation flag ← OFF). Then, the data receiving unit 11 receives the content to be distributed in packet units (S602).
[0036]
The received packet is sent to the data selecting unit 13, and the data selecting unit 13 checks the attribute of the received packet (whether or not it is the first packet of the part and whether or not the part to which the packet belongs is to be replaced) (S603). Hereinafter, the processing is divided depending on whether the received packet is the head of the part.
When the received packet is the head of the part (S604: Yes), the data selecting unit 13 refers to the identification information of the part to which the received packet belongs to the organization information (see FIG. 4) corresponding to the content to which the part belongs. It is determined whether or not the part is to be replaced.
[0037]
If the data is to be replaced (S605: Yes), the data selection unit 13 sets a discard flag indicating that a packet belonging to the same part among the received packets received by the data reception unit 11 should be discarded to ON. Further, the received packet is discarded, and the value of the discarded packet counter is incremented by "1" (S606, S607).
[0038]
Further, as the processing in step S608, processing of packetizing replacement data corresponding to the replacement target part and transmitting the replacement data to the client terminal T is performed. However, since this process is performed in parallel with the process (except for S608) for the received packet shown in FIG. 6, it will be described separately with reference to another drawing (FIG. 7).
On the other hand, in the determination processing of step S605, if the part to which the detected head packet belongs is not a replacement target (S605: No), the data selection unit 13 refers to the discard flag, and if it is ON, resets it to OFF. (S609), the received packet is sent to the packet information changing unit 16. At this time, the total number of discarded packets and the total number of created packets are sent to the packet information changing unit 16 together. The packet information changing unit 16 adjusts the sequence number of the received packet according to the information on the total number of discarded packets and the total number of created packets, and sends the adjusted packet number to the data sending unit 17. (S610).
[0039]
However, the data selection unit 13 refers to the in-progress flag before sending the received packet to the packet information change unit 16. If the creation flag is OFF, the received packet is sent to the packet information changing unit 16 as it is. If it is ON, the received packet is sent to the OFF state (until the last packet of the replacement data is sent to the packet information changing unit 16). After being held and turned OFF, the packet is sent to the packet information changing unit 16 or discarded according to the attribute of the received packet (whether or not the packet is to be replaced).
[0040]
Next, a case where the received packet is not the head of the part (S604: No) will be described. In this case, the data selection unit 13 further determines whether to discard the received packet based on the discard flag.
When the discard flag is ON (when the received packet belongs to the replacement target part) (S611: Yes), the data selecting unit 13 discards the received packet and increments the value of the discarded packet counter by "1" (S612). ).
[0041]
When the discard flag is OFF (when the discard flag does not belong to the replacement target part) (S611: No), the data selecting unit 13 sends the received packet to the packet information changing unit 16 together with the values of the total number of discarded packets and the total number of created packets. The packet information changing unit 16 adjusts the sequence number of the received packet according to the information on the number of discarded packets and the number of created packets, and sends the adjusted packet to the data sending unit 17. The data sending unit 17 sends the received packet to the client terminal ( S613).
[0042]
However, the data selection unit 13 refers to the in-progress flag before sending the received packet to the packet information change unit 16. If the creation flag is OFF, the received packet is sent to the packet information changing unit 16 as it is. If it is ON, the received packet is turned OFF (until the last packet of the replacement data is sent to the packet information changing unit 16). Is held, and after being turned off, the packet is sent to the packet information changing unit 16 or discarded. In the case where a plurality of received packets are to be held while waiting for the OFF of the creation flag, the data selection unit 13 stores the order, and after the creation flag is set to OFF, the data reception unit 13 starts from the earliest reception order. The packet is sent to the packet information changing unit 16 (when the received packet does not belong to the replacement target part).
[0043]
The above processing is repeated until the last packet of the content data to be distributed is processed (S614: Yes).
Next, the flow of the packetization and transmission processing of the replacement data shown as step S608 in FIG. 6 will be described with reference to the drawings.
FIG. 7 is a flowchart showing the flow of packetization and transmission processing of replacement data.
[0044]
First, the data selection unit 13 instructs the data packet creation unit 15 to packetize replacement data, and sets a creation flag to ON (S701).
Thereafter, the data selection unit 13 sends the replacement data packets sequentially output from the data packet creation unit 15 to the packet information change unit 16 (S702). Further, the data selection unit 13 further counts up the value of the replacement packet counter by “1” each time one replacement data packet is sent from the data packet creation unit 15 (S703).
[0045]
Upon receiving the replacement packet from the data selection unit 13, the packet information change unit 16 sets a value obtained by adding “1” to the sequence number of the replacement packet transmitted immediately before as the sequence number of the packet, and then sets the value to the data transmission unit 17. (S704), and the replacement packet is sent to the client terminal by the data sending unit 17 (S705).
[0046]
Thereafter, when the final replacement packet is output from the data packet creation unit 15 (S706: Yes), the data selection unit 13 sets the creation flag to OFF, and completes the packetization and transmission processing of the replacement data. (S707).
The above-described processing relating to the creation, transmission, and creation of the replacement packet is performed in parallel with the processing relating to the received packet shown in FIG.
(Summary)
As described above, the data relay device according to the present embodiment separately replaces a part of the content data sent from the server S based on the replacement information. By arranging such a data relay device between the server and the client terminal, the content distribution system A can distribute content data having different contents according to the location to each client in the content distribution system A. Does not impose a load such as holding or distributing a plurality of patterns of content data that are only partially different.
(Other)
In the present embodiment, the distribution of broadcast image data in accordance with a time table has been described as an example of a content distribution form, but the distribution form to be invented is not limited to this. The present invention is effective as long as a situation occurs in which a server distributes contents having partially different contents to a plurality of user terminals. For example, it is conceivable that content with different CM contents is distributed, for example, on video-on-demand in which the content can be viewed free of charge on condition that the CM is viewed.
[0047]
A data distribution system in which the data relay device has a hierarchical structure is also conceivable. For example, in a system for distributing contents from one server to users all over Japan, a plurality of data relay devices are arranged as a first layer in each prefecture, and a second layer is provided under each of the first layer data relay devices. In this embodiment, a data relay device for each city and district is arranged as a hierarchy. The server sends standard-content to the first-tier data relay device, and each first-tier data relay device replaces a part of the content with unique data for each prefecture, and stores a plurality of second-tier data under its own. Send to relay device. Then, each second-tier data relay device further replaces a part of the content with unique data in units of city and district, and sends the data to the user. According to this, it is possible to distribute the contents after substituting the contents for each user finely without increasing the load on the server and the individual data relay devices.
[0048]
In the above embodiment, the distribution system has a plurality of data relay devices, and all the client terminals receive data distribution from the data server via any one of the data relay devices. There may be one device. In this case, the client terminal is divided into a standard group to which standard content data is distributed, and a replacement group to which some parts are to be replaced and distributed. The data relay device is located between the client terminal of the replacement group and the data server, and performs data replacement. The standard group receives the standard content data from the data server without passing through the data relay device. Specifically, a distribution system in which there are users who view only programs for a fee and users who watch programs with CM for free can be considered. The server sends only the program data by multicast, and the paid program receives the sent program data, while the free user receives the program data via the data relay device, and the data relay device adds a CM. Is to be done. Alternatively, a system in which a user in a specific area is set as a standard and a user in another area as a replacement target, and only content data distributed to a user in a non-standard area is passed through a data relay device is also conceivable.
[0049]
Further, in the above embodiment, the clients to receive the distribution are grouped by region, but the clients may be grouped by other criteria. For example, the genre of the content (movie, sports, music, etc.) can be considered.
Further, in the above embodiment, the replacement information is created unilaterally by the content provider who manages the server. However, the replacement information is created by each user in response to the request from the user or the result of the user questionnaire. It may be created to reflect your preferences.
[0050]
Further, in the above embodiment, the replacement data stored in the storage device is received and stored from the outside together with the organization information, but the storage mode is not limited to this. The data may be recorded on a medium, transported, and stored in a storage device.
In the above embodiment, the data relay device and the server, and the data relay device and the client terminal are all connected via the network, but the connection form is not limited to this. They may be directly connected without going through a network.
[0051]
In the composition information, the range of each part is defined by a combination of a start timing and an end timing, but may be defined by a combination of a start timing and a duration.
Further, in the above-described embodiment, the part to which each packet belongs is determined by the time stamp. However, the determination may be made by other information included in the packet. For example, the determination may be made with reference to an SSRC identifier (Synchronization Source identifier). The SSRC identifier is an identifier assigned so that a plurality of streams to be handled in combination, such as an audio stream and a video stream, share the same value. When transmitting the content from the server, if the value of the SSRC identifier is assigned to each packet so that the value differs for each part, the data relay device detects the first packet of the part based on the change in the SSRC identifier. it can.
[0052]
Further, in the above embodiment, different replacement data is held for each data relay device. However, the same replacement data is provided, and each data relay device has the same replacement data. It is also possible to pass information that can specify a necessary part. For example, all the data relay devices have CM replacement data in which replacement CMs are combined and regional replacement data in which regional information is combined, and the replacement information includes “replacement data” in addition to the information shown in FIG. Which range to use "is added. The range information may indicate the start position and the end position as offsets from the head of the data, similarly to the composition information in FIG. Therefore, when an instruction is issued from the data selecting unit to the data packet creating unit, the identification information of the replacement data and the range information are sent together with the instruction. For example, in the replacement data having the identification information “CM1”, a replacement packet should be created for a portion in the range of “00:01:00” to “00:03:00”.
[0053]
【The invention's effect】
As is apparent from the above description, the data distribution system of the present invention is a data distribution system that distributes distribution data from a server to a plurality of client terminals via one or more data relay devices. A data distribution system that is divided into a plurality of groups, and the distribution data distributed by the server is composed of a plurality of parts, wherein the one or more data relay devices correspond to any of the plurality of groups. A data receiving unit for receiving distribution data from the server; a necessity determining unit for determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received by the data receiving unit; The post-replacement distribution data in the form of replacing the part that the rejection determination means determined to require replacement with a unique replacement part It characterized the structure having a replacement transmitting means for transmitting to the clients belonging to the corresponding group, the.
[0054]
According to this configuration, the single data transmitted by the server is partially updated by the one or more data relay devices and transmitted to the client terminal, so that the content is stored for each user terminal corresponding to each data relay device. Different data can be distributed, and no load is imposed on the server, such as transmitting a plurality of patterns of data to many users at the same time.
[0055]
Further, in a distribution system for distributing distribution data from a server to a plurality of client terminals, a data relay device for relaying the distribution data between the server and a part of the plurality of client terminals, comprising a plurality of parts Data receiving means for receiving distribution data from the server, necessity determining means for determining whether or not replacement is necessary for each of a plurality of parts constituting the distribution data received by the data receiving means, and the necessity determining means The same effect can be obtained by a data relay device having a replacement transmitting unit for transmitting the post-replacement distribution data in a form in which the part determined to be required to be replaced is replaced with unique replacement data to the client terminal.
[0056]
In order to obtain the above effect, specifically, the parts constituting the distribution data are transmitted in packet units, the data receiving means receives the distribution data from the server in packet units, and the replacement transmitting means Alternatively, the packet belonging to the part that the necessity determining unit determines that replacement is necessary may be discarded, and the replacement part may be transmitted to the client terminal in packet units.
[0057]
Further, with regard to the data relay device, the replacement transmitting means may include a number of discarded packets, which is a total number of packets discarded in a process of distributing one distribution data, and a value of replacement data in a process of distributing one distribution data. The number of replacement packets, which is the total number of packets used for transmission, is counted, and when transmitting a packet to the client terminal, the sequence number of the packet to be transmitted is determined based on the number of discarded packets and the number of replacement packets at that time. By further providing a packet updating unit for adjusting, it is possible to prevent erroneous recognition regarding packet loss and inversion of the packet order, which may be caused by mismatching of packet sequence numbers which may be caused by data part replacement.
[0058]
The effects described above can also be realized by a data relay method for sequentially executing the processing performed by each of the above configurations, and further by a program for causing a computer to execute the data relay method.
[Brief description of the drawings]
FIG. 1 is a diagram showing a data distribution system including a data relay device according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of a configuration of content data according to the embodiment.
FIG. 3 is a diagram showing an example of the configuration and content of configuration information according to the embodiment.
FIG. 4 is a diagram showing an example of a configuration and contents of replacement information in the embodiment.
FIG. 5 is a block diagram showing a configuration of a data relay device according to the embodiment.
FIG. 6 is a flowchart showing a flow of a process performed by the data relay device in the embodiment for distributing one content data.
FIG. 7 is a flowchart showing a flow of processing when the data relay device in the embodiment performs packetization and transmission of replacement data.
[Explanation of symbols]
1 Data relay device
11 Data receiving unit
12 formation information acquisition section
13 Data selector
14 Data reading unit
15 Data packet generator
16 Packet information change unit
17 Data transmission unit
19 Storage device
S Multimedia content server
T client terminal
N, N 'network

Claims (7)

A data distribution system for distributing distribution data from a server to a plurality of client terminals via one or more data relay devices, wherein the clients are divided into a plurality of groups, and the distribution data distributed by the server is A data distribution system comprising a plurality of parts,
The one or more data relay devices are each
Corresponds to any of the plurality of groups,
Data receiving means for receiving distribution data from the server;
Necessity determining means for determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received by the data receiving means,
Replacement transmission means for transmitting post-replacement distribution data in a form in which the part required to be replaced by the necessity determination means is replaced with a unique replacement part, to a client belonging to a corresponding group. Data distribution system. In a distribution system that distributes distribution data from a server to a plurality of client terminals, a data relay device that relays the distribution data between the server and a part of the plurality of client terminals,
Data receiving means for receiving distribution data composed of a plurality of parts from the server;
Necessity determining means for determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received by the data receiving means,
Replacement transmitting means for transmitting to the client terminal the post-replacement distribution data in the form of replacing the part determined to be required by the necessity determination means with replacement data unique to the part,
A data relay device characterized by the following. The parts constituting the distribution data are transmitted in packet units, and the data receiving means receives the distribution data from the server in packet units,
The replacement transmission unit, discards a packet belonging to the part that the necessity determination unit has determined that replacement is necessary, and transmits the replacement part to the client terminal in packet units,
The data relay device according to claim 2, wherein: The replacement transmitting means is a total number of discarded packets, which is a total number of packets discarded in a process of distributing one distribution data, and a total number of packets used for transmitting replacement data in a process of distributing one distribution data. The number of replacement packets is counted,
In transmitting a packet to the client terminal, further comprising a packet updating unit that adjusts a sequence number of a transmission target packet based on the discarded packet number and the replacement packet number at that time,
The data relay device according to claim 3, wherein: In a data distribution system that distributes distribution data from a server to a plurality of client terminals via one or more data relay devices, a data relay method executed by the data relay device,
A data receiving step of receiving distribution data from the server;
A necessity determination step of determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received in the data reception step,
A replacement transmission step of transmitting the distribution data after replacement in a form where the necessity determination step is replaced with a unique replacement part to the part determined to be replacement, to the client,
A data relay method characterized by the following. In a distribution system for distributing distribution data from a server to a plurality of client terminals, a program for causing a computer to execute a data relay method of relaying the distribution data between the server and a part of the plurality of client terminals. ,
The data relay method,
A data receiving step of receiving distribution data from the server;
A necessity determination step of determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received in the data reception step,
A replacement transmission step of transmitting the distribution data after replacement in a form where the necessity determination step is replaced with a unique replacement part to the part determined to be replacement, to the client,
Program characterized by the following. In a distribution system for distributing distribution data from a server to a plurality of client terminals, a computer-readable recording program for executing a data relay process for relaying the distribution data between the server and a part of the plurality of client terminals A possible recording medium,
The program is
A data receiving step of receiving distribution data from the server;
A necessity determination step of determining whether replacement is necessary for each of a plurality of parts constituting the distribution data received in the data reception step,
A replacement transmission step of transmitting the distribution data after replacement in a form where the necessity determination step is replaced with a unique replacement part to the part determined to be replacement, to the client,
Recording medium characterized by the above-mentioned.

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