JP4821499B2 - Content distributed storage system, frame acquisition method, node device, etc. - Google Patents

Description

  The present invention relates to a technical field of a peer-to-peer (P2P) type communication system including a plurality of node devices that can communicate with each other via a network.

  In this kind of peer-to-peer communication system, there is known a distributed content storage system that distributes content data to multiple node devices (distributed storage), thereby improving fault tolerance and access dispersibility. It has been. The location of the content data distributed and stored in this way can be efficiently searched using a distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)) as disclosed in Patent Document 1, for example. The DHT is stored in each node device, and node information (for example, including IP addresses and port numbers) indicating a plurality of node devices to which various messages are to be transferred is registered in the DHT. .

When a node device participating in the distributed content storage system desires to acquire desired content data, the node device transmits a message (query) for searching (discovering) the location of the content data to other node devices. Thus, according to the DHT, the message is transferred to the managing node device where the content data is located by a plurality of relay node devices, and finally the message arrives at the managing node device. Node information is acquired from the node. Accordingly, the node device that has transmitted the message can request the content data from the node device that stores the content data related to the search, and can receive the content data.
JP 2006-197400 A

  By the way, a case where one unit of content data is divided into a plurality of pieces and the divided divided content data is distributed and stored across a plurality of node devices in the future can be considered. However, when special playback such as fast-forward playback, rewind playback, and seek playback is performed on the divided content data, the divided content data including frame image data to be sequentially played may extend over a plurality of node devices. As a result, it may be difficult to achieve smooth special playback.

The present invention has been made in view of the above points and the like, and is a case where one unit of content data is divided into a plurality of pieces, and the divided divided content data is distributed and stored across a plurality of node devices. even, and to provide a trick play to be able to run smoothly distributed storage system, frame acquisition process, and the node device or the like.

In order to solve the above problems, the invention described in claim 1 is a content distribution storage system in which divided content data obtained by dividing content data including a plurality of image frames into a plurality of nodes is distributed and stored in a plurality of node devices. Te, said node to each of the divided content data is assigned a unique identifier, before Symbol node device included in the divided distributed storage system content data was obtainable on the basis of the identification information The divided content data includes a key frame that has been compressed within the image frame, and difference data in which difference information between the image frames is compressed. One of said identification information of said contents data segments, the key frame in the prior SL divided content data Instructions for accepting the key frame information including information indicating a position from the beginning of said divided content data, storage means for previously storing the content catalog information is described, an indication of special playback before Symbol content data a reception unit, and said key frame information of said key frame to be reproduced in accordance with the instruction, before Symbol information acquisition for acquiring said identification information of said divided content data including key frame, from the content catalog information means, characterized in that it comprises a frame acquisition means for acquiring the key frames corresponding to the acquired said key frame information and the identification information.

According to the present invention, the node device, content and key frame information of said key frame to be reproduced in accordance with the indication of special playback data, the identification information of the divided content data including the key frames should be the reproduction Gets the, from the content catalog information, since it is configured to acquire the key frames corresponding to the acquired said key frame information and the identification information, content data is divided into a plurality of the division Even when the divided content data is distributed and stored across a plurality of node devices, special playback such as fast-forward playback, rewind playback, and seek playback can be executed smoothly. In addition, if the content catalog information is distributed to each node device in advance before the reproduction of the content data, the key frame information and the like can be extracted immediately, and the special reproduction is performed on the divided content data. Can be executed more efficiently.

According to a second aspect of the present invention, in the node device according to the first aspect, the instruction indicating the special reproduction is a reproduction instruction including any one of fast-forward reproduction, rewind reproduction, and seek reproduction. Features.

The invention according to claim 3, in the node device according to claim 1 or 2, in the content catalog information is described information indicating the data size of the divided content data to the al, the keyframe the information includes information further indicates the data size of the key frame, the information acquisition unit includes information indicating data size before Symbol divided content data, based on said key frame information, the reproduction and identifies the divided content data that contains should do the key frame.

According to the present invention, includes a key frame information of key frames, the identification information of the divided content data containing the keyframes, the keyframe relationship to be reproduced without defined in the content catalog information It is possible to determine divided content data.

According to a fourth aspect of the present invention, in the node device according to the first or second aspect, in the content catalog information , the identification information of the divided content data and the key frame information are associated with each other. Features.

According to the present invention, it is not necessary for the node device to determine which divided content data each key frame is included in by calculation, and it can be identified more quickly.

According to a fifth aspect of the present invention, in the node device according to the first or second aspect, the identification information is assigned to the divided content data according to a predetermined rule, and the content catalog information includes the first divided content data. wherein has the identification information, the information acquisition means, the identification information of the contents data segments other than the beginning of the divided content data, the identification information of the contents data segments of the head according to the predetermined rule of It is characterized by calculating from.

  According to the present invention, since the identification information of all the divided content data does not have to be included in the content catalog information, the data amount of the content catalog information can be reduced.

  A node processing program according to a sixth aspect causes a computer to function as the node device according to any one of the first to fifth aspects.

The invention according to claim 7 is a content distributed storage system in which divided content data obtained by dividing content data including a plurality of image frames into a plurality of nodes is distributed and stored in a plurality of node devices. It is assigned a unique identifier, before Symbol node apparatus, a frame acquisition method in can and the content distributed storage system obtains the divided content data on the basis of the identification information, the divided content The data includes a key frame that is completely compressed in the image frame and difference data in which difference information between the image frames is compressed, and the node device identifies the at least one piece of divided content data. information and, the divided content data of the key frame in the previous Symbol divided content data And key frame information including information indicating a position from the beginning of the inner, comprising a storage unit for previously storing a content catalog information described is, the frame acquisition method, the node device, special playback before Symbol content data a step of receiving an indication of the node device, wherein said key frame information of said key frame to be reproduced in response to the instruction, and the identification information of the divided content data including said key frame, the a step of acquiring from the content catalog information, the node device, characterized in that it comprises a, a step of acquiring the key frames corresponding to the acquired said key frame information and the identification information.

According to an eighth aspect of the present invention, there is provided a distributed content storage system in which content data including a plurality of image frames is divided and stored in a plurality of node devices. is assigned a unique identifier, before Symbol node device, the divided content data a distributed storage system which enables acquires based on the identification information, the divided content data, the image frame includes a key frame compression is completed at the inner, and the difference data difference information is compressed between said image frame, said node device includes: the identification information of at least one of the divided content data, before Symbol divided shows the position from the beginning of said divided content data of the key frames in the content data Storage means for storing the key frame information, the content catalog information is written in advance containing information, an instruction receiving means for receiving an instruction indicating the special playback of the previous SL content data, said to be reproduced in accordance with the instruction and said key frame information of key frames, and information obtaining means for obtaining said identification information of said divided content data containing the key frame, from the content catalog information, the obtained said key frame information and the identification a frame acquisition means for acquiring the key frames corresponding to the information, characterized in that it comprises a.

  According to the present invention, even when one unit of content data is divided into a plurality of pieces and the divided divided content data is distributed and stored across a plurality of node devices, for example, fast-forward playback and rewind playback are performed. And special playback such as seek playback can be executed smoothly. In addition, if the content catalog information is distributed to each node device in advance before the reproduction of the content data, the key frame information and the like can be extracted immediately, and the special reproduction is performed on the divided content data. Can be executed more efficiently.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings.

[ 1. Configuration of distributed content storage system ]
First, with reference to FIG. 1 and the like, a schematic configuration and the like of a content distributed storage system communication system according to an embodiment of the present invention will be described.

  FIG. 1 is a diagram illustrating an example of a connection mode of each node device in the distributed content storage system according to the present embodiment.

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4a, 4b, DSL (Digital Subscriber Line) line operators (devices) 5a, 5b, FTTH (Fiber To A network (which is a real-world communication network) 8 such as the Internet is constructed by a line provider (device) 6 and a communication line (for example, a telephone line or an optical cable) 7. A router for transferring data (packets) is appropriately inserted in the network (communication network) 8 in the example of FIG.

  A plurality of node devices (hereinafter referred to as “nodes”) Nn (n = 1, 2, 3,...) Are connected to such a network 8. Each node Nn is assigned a unique manufacturing number and an IP (Internet Protocol) address. Such serial numbers and IP addresses are not duplicated among a plurality of nodes.

  The content distributed storage system S according to the present embodiment is a peer-to-peer network system formed by participation of any of a plurality of nodes Nn, as shown in the upper frame 100 of FIG. It has become. A network 9 shown in the upper frame 100 of FIG. 1 is an overlay network 9 (logical network) that forms a virtual link formed using the existing network 8.

  Such a content distributed storage system S is realized by a specific algorithm, for example, an algorithm using DHT (Distributed Hash Table). Each node Nn participating in the distributed content storage system S is assigned a node ID, which is unique node identification information. The node ID is, for example, an IP assigned individually to each node Nn. It is a value (for example, the bit length is 160 bits) obtained by hashing the address or serial number with a common hash function (for example, SHA-1), and is distributed and distributed in one ID space without any deviation.

  In addition, participation in the content distributed storage system S is performed by any node Nn (for example, the node N8) that has not participated in any node Nn (for example, a contact node that always participates in the system S) that has not participated. This is done by sending a participation message indicating a participation request.

  As described above, the node ID obtained (hashed) by the common hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. The node ID needs to have a number of bits that can accommodate the maximum number of nodes that can be operated. For example, if a 128-bit number is used, 2 ^ 128 = 340 × 10 ^ 36 nodes can be operated. Since the hash function is publicly known, detailed description thereof is omitted.

  Each node Nn holds a DHT. This DHT defines the transfer destinations of various messages on the content distributed storage system S. Specifically, the node information includes the node ID, IP address, and port number of the node Nn that is moderately separated in the ID space. A plurality of (destination node information) are registered.

  One node Nn participating in the content distributed storage system S registers the minimum necessary node information of the nodes Nn among all the nodes Nn participating in the system S in the routing table, With respect to the node Nn that does not know (store) the node information, various messages are transferred between the nodes Nn to be delivered.

[ 1.1 Routing table using DHT ]
Here, the routing table using DHT will be described in detail with reference to FIGS.

  FIG. 2 is a diagram illustrating an example of a routing table using the DHT held by the node N2, and FIG. 3 is a conceptual diagram illustrating an example of an ID space of the DHT.

  2 and 3, for convenience of explanation, the bit length of the node ID is 2 bits × 3 digits = 6 bits, and each digit is represented by a quaternary number (an integer from 0 to 3) (actually, A longer bit length is used, and each digit is also divided into, for example, 4 bits and expressed by a hexadecimal number of 0 to f).

  In the example of FIG. 2, the routing table using DHT is composed of level 1 to level 3 tables (divided into a plurality of levels), and each level table entry includes node information for each area. The node ID is registered in association with the IP address and port number of the node Nn corresponding to the node ID. Each area in the table of each level is an area obtained by dividing the DHT node ID space. For example, as shown in FIG. 3, in the level 1, the entire ID space of the DHT is divided into four, and the area where the node IDs “000” to “033” are present is the 0XX area, “100” to “133” The area where the node ID exists is the 1XX area, the area where the node IDs "200" to "233" exist is the 2XX area, and the area where the node ID "300" to "333" exists is the 3XX area. . In level 2, the area of level 1 (that is, the area from 0XX to 3XX) is further divided into four, for example, the area of 1XX is divided into four, and the area where the node IDs “100” to “103” exist is 10X. Area, an area where node IDs “110” to “113” exist are 11X areas, an area where node IDs “120” to “123” exist are 12X areas, and node IDs “130” to “133” exist The area in which is present is defined as a 13X area.

  For example, if the node ID of the node N2 is “122”, as shown in FIG. 2, the table of the 1XX area at the level 1 of the node N2 (the area where the self (that is, the own node) exists) The area where the self node ID and IP address (the IP address is own, so it is not necessary to register it in the routing table) etc. is registered and does not exist (that is, 0XX area, 2XX area) , And 3XX area), node IDs and IP addresses of other arbitrary nodes Nn are registered.

  Further, in the table of the 12X area (the area where the self exists) in the level 2 of the node N1, as shown in FIG. 2, the own node ID and the IP address (the IP address is own) In the areas where the self does not exist (that is, the 10X area, the 11X area, and the 13X area), etc., nodes of other arbitrary nodes Nn, respectively, are registered. ID, IP address, etc. are registered.

  Further, in the level 3 of the node N2, as shown in FIG. 2, the node IDs and IP addresses having node IDs “120” to “122” are registered in the routing table. Is not necessary).

  In the example of FIGS. 2 and 3, since the bit length of the node ID is 3 digits × 2 bits, it can be covered by a table of three levels of levels 1 to 3, but if the bit length of the node ID increases, (For example, if the bit length of the node ID is 16 digits × 4 bits, a table for 16 levels is required).

  Thus, in the routing table using DHT in the present embodiment, the area becomes narrower as the level increases.

  In addition, such DHT is given, for example, when a non-participating node participates in the content distributed storage system S.

[ 1.2 Content data storage and discovery method ]
Next, a method for storing and finding content data that can be acquired in the content distributed storage system S will be described.

  In the content distributed storage system S, various content (for example, movies, music, etc.) data is distributed and stored (stored) in a plurality of nodes Nn (in other words, the content data is duplicated and the duplicate information thereof). Replicas are distributed).

  In the present embodiment, one unit of content data having a plurality of frame image data (video data) (for example, content data having a large data size (data capacity) such as a movie or a TV program) is divided into a plurality of pieces ( For example, the divided content data (which may be divided by the same data size or may be divided by different data sizes) is divided into a plurality of nodes Nn (hereinafter referred to as “content holding nodes”). ) Are distributed and stored (stored).

  For example, if the content data A of a movie whose title is XXX is divided into four pieces of divided content data A1 to A4, the divided content data A1 is stored in the nodes N1 and N5, and the divided content data A2 is stored in the node N3. Thus, the divided content data A3 is stored in the node N7, and the divided content data A4 is stored in the nodes N8 and N10. Note that content data of other movies with different titles are similarly divided and stored in a plurality of nodes Nn.

  Each of these divided content data A1 to A4 is assigned a content ID (CID) (identification information unique to each divided content data). This content ID is, for example, a content name (different for each content data) + an arbitrary value (or may be the first few bytes of the divided content data) hashed with a hash function common to the node ID To be generated (arranged in the same ID space as the node ID). The arbitrary value is a value that is different between the divided content data A1 to A4. For example, A1 is “1”, A2 is “2”, A3 “3”, and A4 is “4”. The system operator may give a unique ID value (same bit length as the node ID) for each content.

  Further, the location of the divided content data A1 that is distributed and stored in this way, that is, the node information (for example, including the IP address and port number) of the node Nn that stores the divided content data A1, and the divided content data A1. Index information including a set of content IDs corresponding to the node Nn (hereinafter referred to as “root node” or “root node of content (content ID)”) as the management source of the location of the divided content data A1 Or the like (stored in the index cache) and managed (the same applies to the divided content data A2 to A4).

  For example, the index information of the divided content data A1 is managed by the node N4 that is the root node of the content (content ID), and the index information of the divided content data A2 is the node N6 that is the root node of the content (content ID). It is managed by.

  In other words, since the root node is divided for each divided content data, the load is distributed, and the same divided content data A1 (content ID is the same) is stored in a plurality of content holding nodes. Even in such a case, the index information of the divided content data A1 can be managed by one root node. Further, such a root node is determined to be, for example, a node Nn having a node ID closest to the content ID (for example, the higher-order digits match more).

  When a user of a certain node Nn wants to acquire desired content data, a node Nn (hereinafter referred to as a “user node”) from which the content data is desired to be acquired is selected by the user (for example, to all the nodes Nn). A content location inquiry (search) message (query) including, for example, the content ID of the divided content data A1 and its own node information constituting the content data A selected from the distributed content catalog information (also referred to as a content list). It is generated and sent to other nodes Nn according to the routing table using its own DHT. That is, the user node sends a content location inquiry (search) message toward the root node. As a result, the content location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key.

  The content ID included in the content location inquiry (search) message may be generated by the user node by hashing the content name with the common hash function.

  FIG. 4 is a conceptual diagram showing an example of the flow of a content location inquiry (search) message sent from a user node in the ID space of the DHT.

  In the example of FIG. 4, for example, the node N2, which is a user node, refers to a DHT level 1 table (regardless of the routing table using the DHT shown in FIG. 2), and a content location inquiry (search) Obtain the IP address and port number included in the node information of, for example, the node N3 having the node ID closest to the content ID included in the message (for example, the higher digit matches more), and address the IP address and port number. The content location inquiry (search) message is transmitted.

  On the other hand, the node N3 receives the content location inquiry (search) message, refers to the DHT level 2 table, and is closest to the content ID included in the content location inquiry (search) message. The IP address and port number included in the node information of, for example, the node N4 having a node ID (for example, the higher digit matches more) are acquired, and the content location inquiry (search) message is addressed to the IP address and port number. Forward.

  On the other hand, the node N4 receives the content location inquiry (search) message, refers to the table of the level 3 of its own DHT, and is closest to the content ID included in the content location inquiry (search) message. If the node ID (for example, the higher-order digits match more) is itself, that is, if it recognizes that it is the root node of the content ID, it corresponds to the content ID included in the content location inquiry (search) message The index information to be acquired is acquired from the index cache, and the index information is returned to the user node that is the transmission source of the content location inquiry message. As a result, the user node transmits a content transmission request message to, for example, the node N5 that is the content holding node storing the divided content data A1 constituting the desired content data A, and the divided content is transmitted therefrom. The data A1 is provided (that is, the user node can acquire the divided content data A1 based on the content ID). For example, the content holding node performs streaming distribution of the packet data of the divided content data A1 in response to a request from the user node, and the user node receives and reproduces (normal reproduction) the distributed packet data of the divided content data A1. become.

  Alternatively, the node N4, which is the root node, sends a content transmission request message (including node information of the user node to the content holding node indicated in the node information included in the index information, and the divided content data to the user node. Request information indicating a transmission request of A1). As a result, the user node receives provision of the divided content data A1 from, for example, the node N5 that is the content holding node. The user node obtains the index information from the relay node that caches the same index information as the root node (for example, the cache node of the node N3) until the content location inquiry message reaches the root node. It can also be acquired (received).

  Then, at a predetermined timing when the distribution of the divided content data A1 is almost finished, the user node sends a content location inquiry (search) message including the content ID of the divided content data A2 following the divided content data A1 and its own node information. (Query) is generated and sent to another node Nn according to the routing table using its own DHT. As a result, the user node receives the provision of the divided content data A2 from the content holding node similarly to the divided content data A1 (the same applies to the divided content data A3 and A4).

[ 1.3 Content data special playback (trick play) method ]
Next, a special reproduction (trick play) method of content data that can be acquired in the content distributed storage system S will be described.

  In the present embodiment, special playback (trick play) such as fast-forward playback, rewind playback, or seek (jump) playback is smoothly performed on the content data divided into a plurality of pieces and stored in different nodes Nn as described above. In order to do so, the content ID of at least one divided content data, so that the node Nn can quickly identify which divided content data includes frame image data to be reproduced (hereinafter referred to as “key frame”), The offset position (for example, the position from the head) of each key frame in each divided content data and key frame information indicating the data size are described in the content catalog information.

  Here, in the image compression method such as MPEG, for example, the frame information is compressed every 1/30 seconds, but the frame image every second is compressed using only the frame information of one frame. This is called a key frame (compression is completed within the frame). In the other frames every 1/30 seconds, only the difference information from the key frame and the previous and subsequent frames is compressed and recorded. To perform special playback, for example, if every second frame is displayed at 1/10 second intervals, fast-forward playback at 10 times speed will be used. However, in the case of the compression method as described above, key frames are used here. Must be. This is because even if a frame of difference information is passed to the decoder, it cannot be decompressed with that frame alone. Therefore, in order to perform fast forward playback and rewind playback, it is important to accurately know the position and size of the key frame in the compressed data. In the case of seek reproduction, in order to display a frame immediately from the start of reproduction, it is preferable to start passing data from the key frame to the decoder, so it is good to know the position of the key frame.

  The content catalog information is managed (updated, etc.) by the node Nn or the server that manages the content catalog information, and distributed from the node Nn or the server to each node Nn that participates in the content distributed storage system S. It has come to be.

  FIGS. 5A to 5C are conceptual diagrams illustrating how content data is divided and key frame information of each key frame in each divided content data is described in the content catalog information.

  In the example of FIG. 5A, the content ID of each divided content data and key frame information (indicating an offset position (Offset) and a data size (Size)) corresponding to each key frame in each divided content data. Are described separately in the content catalog information. FIG. 6 shows a data structure example in the content catalog information (structure example 1) in the case of the example of FIG.

  The content catalog information (structure example 1) shown in FIG. 6 has unique information of each content data (A, B, C...) That can be acquired (available) by each node Nn in the content distributed storage system S. The unique information of each content data (A, B, C...) Includes a content title (content name), divided content information, and key frame information. The divided content information includes the number of content data divisions, and the content ID and data size of each divided content data from the first (first) to m (m is a natural number) divided. The key frame information includes the number of key frames (the number of key frames in the content data) and each key frame information from the first (first) to j (j is a natural number). The information includes the offset position of the key frame (the offset position from the beginning of the content data) and the data size of the key frame. According to the content catalog information (Structure Example 1), the node Nn determines which divided content data each key frame is included in by calculation. According to the content catalog information (Structure Example 1), the correspondence between the offset position and data size of the key frame and the content ID of the divided content data including the key frame is not defined in the content catalog information. However, it can be obtained by calculation.

  In the example of FIG. 5B, the content ID of each divided content data is in key frame information (indicating offset position (Offset) and data size (Size)) corresponding to each key frame in each divided content data. It is included and described in the content catalog information in association with the offset position. FIG. 7 shows an example of the data structure in the content catalog information (structure example 2) in the case of the example of FIG.

  The content catalog information (structure example 2) shown in FIG. 7 has the same basic structure as the content catalog information (structure example 1) shown in FIG. 6, but the divided content information includes the number of divisions of content data, and The content ID of each divided content data from the first (first) to m (m is a natural number) divided is included (data size is not included). Each key frame information includes the content ID of the divided content data including the key frame in association with the offset position of the key frame (offset position from the head of each divided content data) and the data size. ing. According to this content catalog information (structure example 2), it is not necessary for the node Nn to determine which divided content data each key frame is included in by calculation, and it is possible to specify more quickly.

  In the example of FIG. 5C, only the content ID of the first (first) divided content data and key frame information (offset position (Offset) and data size (Size) corresponding to each key frame in each divided content data) ) Is described in the content catalog information. FIG. 8 shows an example of the data structure in the content catalog information (structure example 3) in the case of the example of FIG.

  The content catalog information (structure example 3) shown in FIG. 8 has the same basic structure as the content catalog information (structure example 1) shown in FIG. 6, but the divided content information includes the number of divisions of content data, 1 The content ID of the second (first) divided content data and the divided data size are included. That is, the content catalog information (structure example 3) does not include the content IDs of all the divided content data, but includes only the content ID of the first (first) divided content data. Content IDs other than the first (first) divided content data are obtained by calculation from the content ID of the first (first) divided content data. The divided data size is information indicating in what data size the content data is divided (the data size of each divided content data is the same). According to the content catalog information (structure example 3), it is not necessary to include the content IDs of all the divided content data, so that the data amount can be reduced.

  Here, an outline when fast-forward playback is performed using content catalog information will be described with reference to FIGS. 9 to 11.

  FIG. 9 is a diagram showing a state in which fast-forward playback is performed using the content catalog information (structure example 1) shown in FIG. 6, and FIG. 10 is the content catalog information (structure example) shown in FIG. 2) is a diagram showing a situation when fast-forward playback is performed, and FIG. 11 shows a situation when fast-forward playback is performed using the content catalog information (structure example 3) shown in FIG. FIG.

  In any of the examples of FIGS. 9 to 11, the user node performs key frame information corresponding to a key frame to be reproduced according to a fast-forward reproduction instruction (an example of an instruction for reproduction) of content data from the user, and the reproduction. The content ID of the divided content data including the key frame to be determined is specified based on the content catalog information, and the key frame corresponding to the specified key frame information and the content ID is set to the content holding node (the content holding node is The user node stores the divided content data corresponding to the specified content ID, and is obtained from the root node by DHT routing using the content ID as a key) and reproduced (fast forward reproduction) It is supposed to be.

  Here, as shown in FIG. 9, when the content catalog information (Structure Example 1) is used, the divided content data (content ID) including the key frame to be reproduced includes the data size of the divided content data and the reproduced content data. It is determined by calculation based on the key frame information (indicating the offset position and data size) of the power key frame. On the other hand, as shown in FIG. 10, when content catalog information (structure example 2) is used, divided content data (content ID) including a key frame to be reproduced is specified from the key frame information. As shown in FIG. 11, when content catalog information (structure example 3) is used, content IDs other than the first (first) divided content data are calculated from the content IDs of the first (first) divided content data. Sought by.

[ 2. Configuration and function of node Nn ]
Next, the configuration and function of the node Nn will be described with reference to FIG.

  FIG. 12 is a diagram illustrating a schematic configuration example of the node Nn.

  As shown in FIG. 12, each node Nn includes a control unit 11 as a computer including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, and various data (for example, divided contents). Data, index information, DHT, etc.) and various programs, etc., and a storage unit 12 as storage means configured to store (store) a buffer, and a buffer memory 13 for temporarily storing the received divided content data and the like A decoder unit 14 for decoding (data expansion, decoding, etc.) encoded video data (video information) and audio data (audio information) included in the divided content data, and for the decoded video data, etc. A video processing unit 15 that performs a predetermined drawing process and outputs a video signal; After a display unit 16 such as a CRT or a liquid crystal display for displaying video based on the video signal output from the video processing unit 15 and D (Digital) / A (Analog) conversion of the decoded audio data into an analog audio signal Communication of information between the audio processing unit 17 that amplifies this with an amplifier and outputs it, the speaker 18 that outputs the audio signal output from the audio processing unit 17 as a sound wave, and other nodes Nn and the like through the network 8 A communication unit 20 for performing control, and an input unit 21 (for example, a keyboard, a mouse, or an operation panel) that receives an instruction from a user and provides an instruction signal corresponding to the instruction to the control unit 11; The control unit 11, the storage unit 12, the buffer memory 13, the decoder unit 14, and the communication unit 20 are connected via a bus 22. Are connected to each other. As the node Nn, a personal computer, an STB (Set Top Box), a TV receiver, or the like can be applied.

  In such a configuration, the control unit 11 performs overall control by reading and executing a program stored in the storage unit 12 or the like by the CPU, and the above-described user node by participating in the content distributed storage system S. The relay node, the root node, the cache node, and the content holding node are processed as at least one of the nodes.

  Further, the control unit 11 in the node Nn participating in the content distributed storage system S reads and executes a program (including the node processing program of the present invention) stored in the storage unit 12 or the like by the CPU. It functions as an instruction receiving means, a specifying means, a frame acquisition means, etc. according to the present invention, and performs the processing described later. The node processing program may be downloaded from a predetermined server on the network 8, for example, or recorded on a recording medium such as a CD-ROM and read via the drive of the recording medium. You may be made to do.

[ 3. Processing during special playback at node Nn ]
Next, the special reproduction process at the node Nn will be described with reference to FIGS.

  FIG. 13 is a flowchart showing fast forward playback or rewind playback processing in the control unit 11 of the node Nn. FIG. 14 is a flowchart showing seek (jump) reproduction processing in the control unit 11 of the node Nn. FIG. 15 is a flowchart showing key frame information and content ID specifying processing when the content catalog information (structure example 1) shown in FIG. 6 is used, and FIG. 16 is a content catalog shown in FIG. FIG. 17 is a flowchart showing key frame information and content ID identification processing when information (structure example 2) is used, and FIG. 17 shows a key when content catalog information (structure example 3) shown in FIG. 8 is used. It is a flowchart which shows frame information and content ID specific processing.

  First, in the node Nn (user node) participating in the distributed content storage system S, the control unit 11 stores the above-described content catalog information when receiving a content list display instruction from the user via the input unit 21. The content is read from the unit 12 into the RAM, and a content list in which a plurality of content names (content titles) included in the content catalog information is described is displayed on the display unit 16. When one content name is selected by the user via the input unit 21 from the content names in the displayed content list, the control unit 11 configures content data A corresponding to the content name. A content location inquiry (search) message (query) including the content ID of the divided content data A1 and its own node information is generated and sent to other nodes Nn according to the routing table using its own DHT. Thereby, the content location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key, and the user node acquires node information of the content holding node from the root node. Then, the control unit 11 of the user node makes a content transmission request to the content holding node that stores the divided content data A1 according to the acquired node information, and for example, packet data of the divided content data A1 that has been distributed by streaming. And is reproduced (normally reproduced) through the decoder unit 14, the video processing unit 15, the audio processing unit 17, and the like. Thus, as described above, the target of streaming distribution is switched in the order of the divided content data A1, the divided content data A2, the divided content data A3, and so on.

  Further, when the content catalog information (structure example 3) shown in FIG. 8 is used, since only the content ID of the first divided content data is included, the content ID of the other divided content data is, for example, the divided content data. The calculation is performed by substituting the order from the head and the content ID of the head divided content data into a predetermined function.

(Fast forward playback or rewind playback)
When such a normal reproduction, the control unit 11 receives a start instruction from the user via the input unit 21 for fast-forward reproduction or rewind reproduction (an example of an instruction related to reproduction of content data), the process illustrated in FIG. First, the key frame number (in order from the top) corresponding to the reproduction position of the current divided content data is acquired, and this is set to “J” (step S1).

  Next, the control unit 11 increases J by 1 in the case of fast-forward playback, and decreases J by 1 in the case of rewind playback (step S2).

  Next, the control unit 11 determines whether J has reached a predetermined value (step S3). Specifically, in the case of fast-forward playback, the control unit 11 refers to the content catalog information to determine whether J has reached the number of key frames, and has reached the number of key frames (J = key frame). (Step S3: Y), since the key frame corresponding to the reproduction position is the last key frame, the process is terminated, while the number of key frames is not reached (J <key In the case of (the number of frames) (step S3: N), the process proceeds to step S4.

  On the other hand, in the case of rewind playback, the control unit 11 refers to the content catalog information to determine whether J has become “1”, and when it has become “1” (J = 1) ( Step S3: Y) Since the key frame corresponding to the reproduction position is the first key frame, the process is terminated. On the other hand, if it is not “1” (J> 1) (Step S3: N), the process proceeds to step S4.

  In step S4, the control unit 11 determines the key frame information corresponding to the J-th key frame and the content ID of the divided content data corresponding to the J-th key frame (that is, the divided content data including the key frame). And specify. Note that the identification processing of the content ID and key frame information differs depending on the structure examples 1 to 3 of the content catalog information, and details will be described later.

  Next, the control unit 11 acquires a J-th key frame included in the divided content data corresponding to the specified content ID (step S5). More specifically, the control unit 11 determines whether or not the divided content data corresponding to the specified content ID is stored, and if it is stored, the specified key frame is determined from the divided content data. Get keyframe corresponding to information. On the other hand, when the divided content data corresponding to the specified content ID is not stored, the control unit 11 generates a key frame location inquiry (search) message (query) including the content ID and its own node information. Then, this is transmitted to other nodes Nn according to the routing table using its own DHT. Thereby, the key frame location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key, and the control unit 11 of the user node receives the node information of the content holding node from the root node. To get. Then, the control unit 11 makes a key frame transmission request by designating the specified key frame information to the content holding node that stores the divided content data in accordance with the acquired node information, and responds accordingly. To get the keyframe sent.

  Next, the control unit 11 reproduces the acquired key frame through the decoder unit 14 and the video processing unit 15 (step S6).

  Next, the control unit 11 determines whether or not a fast forward playback or rewind playback end instruction is received from the user via the input unit 21 (step S7), and if received (step S7: Y), When the process is completed and not accepted (step S7: N), the process returns to step S2 and the same process as described above is performed. Thus, fast forward playback or rewind playback is performed until J reaches a predetermined value or a fast forward playback or rewind playback end instruction is accepted.

(Seek (jump) playback)
On the other hand, if the control unit 11 receives a start instruction for seek (jump) playback (an example of an instruction related to playback of content data) via the input unit 21 during normal playback, the control unit 11 starts the process illustrated in FIG. First, the key frame number (in order from the top) corresponding to the reproduction position of the divided content data to be seeked (jumped) is acquired, and this is set to “J” (step S11).

  Next, the control unit 11 specifies the key frame information corresponding to the Jth key frame and the content ID of the divided content data corresponding to the Jth key frame (step S12). Note that the content ID and key frame information specifying process is the same as step S4 in the fast forward playback or rewind playback process, and details will be described later.

  Next, the control unit 11 acquires the J-th key frame included in the divided content data corresponding to the specified content ID (step S13), and starts reproduction (jump reproduction) from the key frame (step 14). Then, the process ends (returns to normal playback thereafter).

  More specifically, the control unit 11 determines whether or not the divided content data corresponding to the specified content ID is stored, and if it is stored, the specified key frame is determined from the divided content data. A key frame corresponding to the information is acquired, and reproduction is started from the key frame. On the other hand, when the divided content data corresponding to the specified content ID is not stored, the control unit 11 generates a key frame location inquiry (search) message (query) including the content ID and its own node information. Then, this is transmitted to other nodes Nn according to the routing table using its own DHT. Thereby, the key frame location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key, and the control unit 11 of the user node receives the node information of the content holding node from the root node. To get. Then, the control unit 11 makes a transmission request from the key frame by designating the specified key frame information to the content holding node storing the divided content data according to the acquired node information. The key frame transmitted in response to the key frame is acquired, and playback is started from the key frame. Thereafter, normal playback is performed in response to streaming distribution of data following the key frame.

  Next, the details of the identification processing of the content ID and key frame information in step S4 and step S12 when each content catalog information of the structural examples 1 to 3 is used will be described.

(When the content catalog information of Structure Example 1 is used)
In this case, as shown in FIG. 15, first, the control unit 11 refers to the content catalog information shown in FIG. 6 and determines the offset position F0_OFFSET (content data of the J-th key frame from the J-th key frame information). The offset position from the head) and the data size F_SIZE of the key frame are acquired (step S51).

  Next, the control unit 11 sets the variable “M” to “1” (step S52), refers to the content catalog information shown in FIG. 6, and is the Mth (first in the case of M = 1) from the divided content information. The data size C_SIZE and content ID of the divided content data are acquired, and the offset position C_OFFSET (“0” when M = 1) of the M-th divided content data is calculated (step S53).

  Next, the control unit 11 determines whether or not the J-th key frame is included in the M-th divided content data (step S54). Specifically, whether F0_OFFSET <C_OFFSET + C_SIZE is satisfied (that is, the position indicated by C_OFFSET + C_SIZE (the end position of the M-th divided content data) is larger than the offset position F0_OFFSET of the J-th key frame ( Whether it is later)) or not is determined.

  When the J-th key frame is not included in the M-th divided content data (that is, when F0_OFFSET <C_OFFSET + C_SIZE is not satisfied) (step S54: N), the control unit 11 sets “M”. "1" is added (step S55), the process returns to step S53, the offset position C_OFFSET of the Mth divided content data is calculated, the data size C_SIZE and the content ID of the Mth divided content data are obtained, and the same as above Perform the process. Thus, the divided content data including the Jth key frame is determined based on the data size C_SIZE of the divided content data, the offset position F0_OFFSET of the Jth key frame, and the like.

  When the J-th key frame is included in the M-th divided content data (that is, when F0_OFFSET <C_OFFSET + C_SIZE is satisfied) (step S54: Y), the control unit 11 performs the M-th division. The content ID of the content data (the content ID acquired last) is specified as the content ID of the divided content data corresponding to the J-th key frame (step S56).

  Next, the control unit 11 calculates the offset position F_OFFSET (offset position from the beginning of the Mth divided content data) of the Jth key frame (that is, F_OFFSET = F0_OFFSET−C_OFFSET) (step S57). Then, the calculated offset position F_OFFSET and the data size F_SIZE of the J-th key frame acquired in step S51 are specified as key frame information corresponding to the J-th key frame (step S58).

(When the content catalog information of Structure Example 2 is used)
In this case, as shown in FIG. 16, first, the control unit 11 refers to the content catalog information shown in FIG. 7 and determines the content ID of the divided content data, the J-th key frame from the J-th key frame information. Get the offset position F_OFFSET (offset position from the beginning of the divided content data) and the data size F_SIZE (step S61), specify the acquired content ID as the content ID of the divided content data corresponding to the Jth key frame, The offset position F_OFFSET and data size F_SIZE of the acquired Jth key frame are specified as key frame information corresponding to the Jth key frame (step S62).

(When using the content catalog information of Structure Example 3)
In this case, as shown in FIG. 17, first, the control unit 11 refers to the content catalog information shown in FIG. 8 and determines the offset position F0_OFFSET (content data of the J-th key frame from the J-th key frame information). The offset position from the head) and the data size F_SIZE of the key frame are acquired (step S71).

  Next, after setting the variable “M” to “1”, the control unit 11 refers to the content catalog information shown in FIG. 8 and determines the divided data size C_SIZE and the content ID of the first divided content data from the divided content information. Obtain (step S72).

  Next, the control unit 11 calculates an offset position C_OFFSET (“0” when M = 1) of the M-th (first when M = 1) divided content data (step S73).

  Next, the control unit 11 determines whether or not the J-th key frame is included in the M-th divided content data (step S74). As in step S54, specifically, it is determined whether or not F0_OFFSET <C_OFFSET + C_SIZE is satisfied.

  When the J-th key frame is not included in the M-th divided content data (that is, when F0_OFFSET <C_OFFSET + C_SIZE is not satisfied) (step S74: N), the control unit 11 sets “M”. After adding “1”, the content ID of the Mth divided content data is calculated from the content ID of the first divided content data according to a predetermined rule (step S75), and the process returns to step S73.

  Here, if the content IDs of a plurality of pieces of divided content data constituting one unit of content data are determined to have regularity, content IDs other than the first piece of divided content data are assigned from the beginning of the divided content data. Can be calculated by substituting the order M and the content ID of the first divided content data into a predetermined function (in a simple example, M × A value obtained by adding A (A is an arbitrary value) is the content ID of the Mth (M ≧ 2) divided content data).

  When the J-th key frame is included in the M-th divided content data (that is, when F0_OFFSET <C_OFFSET + C_SIZE is satisfied) (step S74: Y), the control unit 11 determines that the M-th divided content data. The content ID of the content data (the content ID acquired or calculated last) is specified as the content ID of the divided content data corresponding to the J-th key frame (step S76).

  Next, the control unit 11 calculates the offset position F_OFFSET (offset position from the beginning of the Mth divided content data) of the Jth key frame (that is, F_OFFSET = F0_OFFSET−C_OFFSET) (step S77). Then, the calculated offset position F_OFFSET and the data size F_SIZE of the J-th key frame acquired in step S71 are specified as key frame information corresponding to the J-th key frame (step S78).

  As described above, according to the above-described embodiment, in response to a special reproduction instruction for content data from a user, a user node and key frame information corresponding to a key frame to be reproduced, and divided content including the key frame The content ID of the data is specified based on the content catalog information, and the key frame is acquired from the content holding node storing the key frame based on the specified key frame information and the content ID, and played back. Therefore, even when one unit of content data is divided into a plurality of pieces and the divided divided content data is distributed and stored across a plurality of nodes Nn, special playback can be executed smoothly. .

  In addition, since the content catalog information is distributed to each node Nn in advance before the reproduction of the content data, the key frame information and the like can be extracted immediately, and the special reproduction is more efficiently performed on the divided content data. can do.

  In addition, although the content distributed storage system S in the said embodiment was demonstrated on the assumption that it was formed by the algorithm using DHT, this invention is not limited to this. For example, when special reproduction is performed, each node Nn has content IDs of all divided content data (whether or not it is determined by a hash function as described above) and node information corresponding to the content ID (that is, the content ID) The content ID specified from the content catalog information is transmitted to the management server that manages the IP address and port number of the content holding node that stores the content data corresponding to the content data, and the content ID is sent from the management server accordingly. It is also possible to obtain node information corresponding to, and to request a key frame from the content holding node.

It is a figure which shows an example of the connection aspect of each node apparatus in the content distributed storage system which concerns on this embodiment. It is a figure which shows an example of the routing table using DHT which node N2 hold | maintains. It is a conceptual diagram which shows an example of ID space of DHT. It is the conceptual diagram which showed an example of the flow of the content location inquiry (search) message sent from the user node in ID space of DHT. It is a conceptual diagram which shows a mode that content data is divided | segmented and the key frame information etc. of each key frame in each division | segmentation content data are described by content catalog information. FIG. 6 is a diagram illustrating a data structure example in content catalog information (structure example 1) in the case of the example of FIG. It is a figure which shows the data structural example in the content catalog information (structure example 2) in the case of the example of FIG. 5 (B). It is a figure which shows the example of a data structure in the content catalog information (structure example 3) in the case of the example of FIG.5 (C). It is a figure which shows a mode in case fast-forward reproduction | regeneration is performed using the content catalog information (structure example 1) shown in FIG. It is a figure which shows a mode in the case of fast-forward reproduction | regeneration using the content catalog information (structure example 2) shown in FIG. It is a figure which shows a mode in the case of fast-forward reproduction | regeneration using the content catalog information (structure example 3) shown in FIG. It is a figure which shows the example of an outline structure of the node Nn. It is a flowchart which shows the fast forward reproduction | regeneration or the rewind reproduction | regeneration processing in the control part 11 of the node Nn. It is a flowchart which shows the seek (jump) reproduction | regeneration processing in the control part 11 of the node Nn. FIG. 7 is a flowchart showing key frame information and content ID specifying processing when the content catalog information (structure example 1) shown in FIG. 6 is used. FIG. 8 is a flowchart showing key frame information and content ID specifying processing when the content catalog information (structure example 2) shown in FIG. 7 is used. FIG. 9 is a flowchart showing key frame information and content ID identification processing when the content catalog information (structure example 3) shown in FIG. 8 is used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 Network 9 Overlay network 10 Broadcast station apparatus 11 Control part 12 Memory | storage part 13 Buffer memory 14 Decoder part 15 Image | video processing part 16 Display part 17 Audio | voice processing part 18 Speaker 20 Communication part 21 Input part 22 Bus Nn node S Content distribution preservation | save system

Claims (8)

A content distributed storage system in which content data including a plurality of image frames is divided and stored in a plurality of node devices, and unique identification information is assigned to each of the divided content data and, before Symbol node device, a said node device included in the divided content distributed storage system in which data was capable of acquiring, based on the identification information,
The divided content data includes a key frame that is completely compressed in the image frame, and difference data in which difference information between the image frames is compressed,
The node device is
And the identification information of at least one of the divided content data, the content catalog and the key frame information including information indicating a position from the beginning of said divided content data of the key frame before Symbol in divided content data, it is described Storage means for storing information in advance ;
An instruction receiving means for receiving an indication of a special playback of pre-Symbol content data,
And said key frame information of said key frame to be reproduced in response to the instruction, the information obtaining means and the identification information of the divided content data that contains the pre-Symbol key frame, to get from the content catalog information,
A frame acquisition means for acquiring the key frames corresponding to the acquired said key frame information and the identification information,
A node device comprising: The node device according to claim 1,
The node device according to claim 1, wherein the instruction indicating the special reproduction is a reproduction instruction including any one of fast forward reproduction, rewind reproduction, and seek reproduction. The node device according to claim 1 or 2,
Wherein the content catalog information is described information indicating the data size of the divided content data to the al,
The key frame information further includes information indicating the data size of the key frame,
The information acquisition unit includes information indicating the data size of the divided content data, based on said key frame information, node and identifies the divided content data included the Keyframe said to be reproduced apparatus. The node device according to claim 1 or 2,
In the content catalog information , the identification information of the divided content data and the key frame information are associated with each other. The node device according to claim 1 or 2,
The identification information is assigned to the divided content data according to a predetermined rule,
The content catalog information has the identification information of the head the divided content data,
The node device characterized in that the information acquisition means calculates the identification information of divided content data other than the first divided content data from the identification information of the first divided content data according to the predetermined rule.   A node processing program for causing a computer to function as the node device according to any one of claims 1 to 5. A content distributed storage system in which content data including a plurality of image frames is divided and stored in a plurality of node devices, and unique identification information is assigned to each of the divided content data and, before Symbol node apparatus, a frame acquisition method in can and the content distributed storage system obtains the divided content data based on said identification information,
The divided content data includes a key frame that is completely compressed in the image frame, and difference data in which difference information between the image frames is compressed,
The node device is
And the identification information of at least one of the divided content data, the content catalog and the key frame information including information indicating a position from the beginning of said divided content data of the key frame before Symbol in divided content data, it is described Comprising storage means for storing information in advance ;
The frame acquisition method includes:
Said node apparatus, a step of receiving an indication of special playback before Symbol content data,
Said node apparatus, a step of acquiring and said key frame information of said key frame to be reproduced in response to the instruction, the identification information of the divided content data containing the key frame, from the content catalog information ,
A step of the node device acquires the key frames corresponding to the acquired said key frame information and the identification information,
Frame acquisition method characterized by comprising a. A content distributed storage system in which content data including a plurality of image frames is divided and stored in a plurality of node devices, and unique identification information is assigned to each of the divided content data and, before Symbol node device, the divided content data a distributed storage system which enables acquires based on the identification information,
The divided content data includes a key frame that is completely compressed in the image frame, and difference data in which difference information between the image frames is compressed,
The node device is
And the identification information of at least one of the divided content data, co and key frame information including information indicating a position from the beginning of said divided content data of the key frame in front Symbol divided content data, are described content Storage means for storing catalog information in advance ;
An instruction receiving means for receiving an indication of a special playback of pre-Symbol content data,
And said key frame information of said key frame to be reproduced in response to the instruction, the information acquiring means for acquiring said identification information of said divided content data containing the key frame, from the content catalog information,
A frame acquisition means for acquiring the key frames corresponding to the acquired said key frame information and the identification information,
A content distributed storage system comprising:

Images