JP2009049487A - Content on demand type node device, on demand type content acquisition method and program - Google Patents

Abstract

In response to a request from a user promptly, the content requested by the user is downloaded from an overlay network and played back.
Prior to a content acquisition request from a user, the beginning portion data representing the beginning portion of the preselected content is downloaded and stored in its own node device. Further, in response to the user's content acquisition request, at least the remaining portion data excluding the beginning portion data among the content requested by the user is downloaded and stored in the own node device. Further, in response to the content acquisition request, the beginning portion data of the requested content is read and reproduced, and subsequently to the reproduction, the remaining portion data of the requested content is read and reproduced.
[Selection] Figure 3

Description

  The present invention relates to a node device that constructs an overlay network together with a plurality of other node devices, and retrieves and acquires content from among the plurality of other node devices in response to a request from a user of the node device. In particular, the present invention relates to a technique for quickly responding to a request from a user and acquiring and reproducing content requested by the user.

  With the advancement of computer technology and communication technology and the development of infrastructure such as networks, services for distributing content such as video and audio to a large number of users via networks are rapidly spreading.

  This type of content distribution service is provided, for example, in a communication environment in which a plurality of clients are connected to a server via a network. In this server-client communication environment, all clients must rely on the same server to obtain the requested content. Therefore, this server client method has a problem that there is a high possibility that access to the server will be concentrated and that a management cost is likely to rise.

  In contrast to the server-client communication environment, there exists a communication environment in which a plurality of node devices exchange contents with each other via a common overlay network. The above-described content distribution service can be realized even in this type of communication environment, and an example of this type of communication system is disclosed in Patent Document 1 as a peer-to-peer type content distribution system.

In a communication environment of an overlay network system, a plurality of node devices that are terminals that use or own content are connected to each other by a network, so that processing devices and storage devices possessed by the own node device can also be used by other node devices. Used. As a result, the burden for content search and transmission / reception is shared by all terminals, thereby reducing the problems of the server-client method described above.
JP 2006-197400 A

  In an example of a content distribution service provided in an overlay network communication environment, content requested by a user is reproduced in response to a request from the user. Prior to the reproduction, the requested content is downloaded and acquired.

  According to an example of the content acquisition method, when a user requests content, the entire requested content is searched for and downloaded on the overlay network. After the download is completed, the user starts playing the requested content. Therefore, in this example, even if the user requests the content, reproduction of the requested content is not started until the download of the requested content is completed. In particular, when a failure occurs in the network, a longer time than usual is consumed for downloading. As a result, the user may be frustrated with a time lag between the content request time and the playback start time of the requested content.

  According to another example of the content acquisition technique, prior to the user request, the entire content expected to be requested in the future is searched and downloaded on the overlay network, and the downloaded content is the user's node device. Saved in. In this case, when the user actually requests the content, the requested content is simply read from the own node device and reproduced without going through the download step. As a result, when the user requests content, reproduction of the requested content is started immediately, so that the user can view the requested content without irritation.

  However, in this case, content can be stored only within the storage capacity of the node device, and there is a limit to the number of content that can be stored together in the node device. If the user requests content not stored in the node device, it is necessary to download the requested content. In this case, the user requests the content request time and the requested content playback start time. There is a possibility of annoying the time lag between.

  In short, regardless of which method is employed, the user may be frustrated by the time lag between the content request time and the requested content playback start time.

  In the background described above, an object of the present invention is to promptly respond to a request from a user and acquire and reproduce the content requested by the user.

  According to one aspect of the present invention, prior to the user's content acquisition request, the beginning portion data representing the beginning portion of the preselected content is downloaded and stored in the own node device. Further, in response to the user's content acquisition request, at least the remaining portion data excluding the beginning portion data among the content requested by the user is downloaded and stored in the own node device. Further, in response to the content acquisition request, the beginning portion data of the requested content is read and reproduced, and following the reproduction, the remaining portion data of the requested content is read and reproduced.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as technical features of the present invention although they are not described in the following embodiments.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on the nature.

(1) A node device that constructs an overlay network with a plurality of other node devices, and searches for and downloads content from the plurality of other node devices in response to a request from a user of the node device. A content-on-demand node device to be acquired,
A request input means for inputting a content acquisition request from the user that the user wants to acquire content;
A search is made on the overlay network for a content holder that holds a pre-selected content from among the plurality of other node devices, and an initial portion of the pre-selected content from the searched content holder First data acquisition means for downloading the initial part data representing the data and storing the downloaded initial part data in the first storage means in a state that can be identified by the content ID;
In response to the content acquisition request, at least the beginning portion of the requested content already stored in the first storage means from at least one content holder holding the content requested by the user Second data acquisition means for downloading remaining part data excluding data and storing the downloaded at least remaining part data in a second storage means in a state that can be identified by a content ID;
In response to the content acquisition request, the beginning data of the requested content is read from the first storage unit and played back by a playback device. Following the playback, the request is sent from the second storage unit to the request. A content-on-demand type node device comprising: reproducing means for reading out the remaining partial data of the reproduced content and reproducing it by the reproducing device.

  In this node device, the content selected in advance is downloaded prior to the content acquisition request. However, the entire content is not downloaded, but a portion having a smaller amount of data, that is, of the content, The beginning part is downloaded and stored in the node device. Therefore, a smaller storage capacity is required than when all of the preselected contents must be stored in the node device.

  Further, in this node device, in response to the content acquisition request, at least the remaining partial data of the requested content excluding the first stored partial data is downloaded and stored in the node device.

  That is, according to this node device, the same content is divided into a beginning portion and a remaining portion, and the beginning portion is downloaded at a time preceding the content acquisition request and stored in the node device. The remaining portion is downloaded in response to the content acquisition request and stored in the node device. Therefore, the remaining portion of the content that will not be requested in the future is not wasted and the storage capacity of the node device is not wasted.

  Further, in this node device, in response to the content acquisition request, the beginning part data of the requested content is read from the node device and reproduced. Since the beginning portion data is stored in the node device prior to the content acquisition request, playback of the beginning portion of the requested content starts immediately in response to the content acquisition request. become.

  Furthermore, in this node device, when the reproduction of the beginning portion data of the requested content is completed, the remaining portion data of the same content is subsequently read from the node device and reproduced. Therefore, for the same content, the remaining partial data can be downloaded and acquired during the reproduction of the initial partial data.

(2) The first data acquisition unit includes an opening portion of a plurality of types of content substantially matching a plurality of types of content held by the plurality of other node devices as the preselected content. The content-on-demand type node device according to item (1), wherein the beginning portion data representing the information is stored in the first storage means.

(3) The first data acquisition unit may include the node device or the plurality of other node devices among the plurality of types of content held by the other node devices as the preselected content. First portion data representing the beginning portion of a plurality of types of content substantially matching the frequency acquired in the past by at least one of them being equal to or higher than a reference value is stored in the first storage means (1 The content on-demand type node device according to the item).

  According to this node device, the beginning portion data is downloaded prior to the content acquisition request for only the content that is expected to be requested in the future by the user in view of the past statistics regarding the usage frequency by content. And stored in the node device. As a result, it becomes easy to reduce the possibility that the beginning portion data of the content that will not be requested in the future is unnecessarily downloaded and the load on the node device is unnecessarily increased.

(4) The content-on-demand type node according to any one of (1) to (3), further including an opening portion data size determining unit that variably determines the size of the opening portion data based on the size of the content apparatus.

  In the node device according to any one of (1) to (3), for example, the remaining partial data of the same content may be downloaded and acquired during the reproduction of the initial partial data of the content. In this case, it is desirable to increase the reproduction time of the first partial data as the size of the remaining partial data is larger, that is, as the size of the content is larger. On the other hand, the larger the size of the beginning portion data, the longer the reproduction time of the beginning portion data.

  As in this example, there is a case where there is a certain relationship between the size of the beginning part data and the size of the content. In such a case, the size of the beginning part data in the node device according to this section Is variably determined based on the size of the content.

(5) The content-on-demand node device according to (4), wherein the opening part data size determining unit determines the size of the opening part data so that the size of the opening part data increases as the content size increases.

  According to this node device, the larger the content size, the longer the time required to reproduce the beginning part data. Therefore, it is possible to reliably download and store the remaining part data of the content during the reproduction. It becomes.

(6) Data representing the entire content is divided into multiple segments,
The node device downloads content data from the corresponding content holder in segment units,
The first data acquisition means stores, in the first storage means, the whole of the head segment located at the head of the plurality of segments or the head portion of the head segment as the head data. The content on demand type node device according to any one of (5).

(7) The first data obtaining unit obtains the first partial data of the preselected content in the first stage after the node device is activated and before a first content obtaining request is issued from the user. The content on-demand type node device according to any one of (1) to (6), which is stored in one storage means.

(8) content list receiving means for receiving a content list indicating the preselected content;
Receiving a new content list, and determining means for determining the presence or absence of new content,
The first data acquisition means stores the first partial data of the new content in the first storage means when the determination means determines that there is new content (paragraphs (1) to (7)). The content on demand type node device according to any one of the above.

(9) The second data acquisition unit is configured to receive the requested content while the opening portion data is read from the first storage unit and reproduced by the reproduction device in response to the content acquisition request. The content-on-demand type node device according to any one of (1) to (8), wherein at least the remaining portion data is stored in the second storage unit.

  In this node device, for the same content, the remaining partial data is downloaded in parallel with the reproduction of the initial partial data.

(10) including content storage determination means for determining whether or not the requested content is stored in the second storage means;
The second data acquisition unit stores the requested content in the second storage unit when the content storage determination unit determines that the requested content is not stored in the second storage unit. The content on demand type node device according to any one of (1) to (9).

(11) In a node device that constructs an overlay network together with a plurality of other node devices, in response to a request from a user of the node device, the content is searched for and downloaded from the other node devices. An on-demand content acquisition method,
A request input step in which the user inputs a content acquisition request that the user wants to acquire content;
A search is made on the overlay network for a content holder that holds a pre-selected content from among the plurality of other node devices, and an initial portion of the pre-selected content from the searched content holder A first data acquisition step of downloading the first part data representing the first part and storing the downloaded first part data in a state that can be identified by the content ID;
In response to the content acquisition request, at least the beginning portion of the requested content already stored in the first storage means from at least one content holder holding the content requested by the user A second data acquisition step of downloading remaining part data excluding data and storing the downloaded at least remaining part data in a second storage means in a state that can be identified by a content ID;
In response to the content acquisition request, the beginning part data of the requested content is read from the first storage means and played back by a playback device, and subsequently to the playback, the request is sent from the second storage means to the request. A reproduction step of reading out the remaining partial data of the reproduced content and reproducing it by the reproduction device.

(12) A program executed for causing a computer to function as each means of the on-demand node device according to any one of (1) to (11).

  This program can be interpreted to include not only a combination of instructions executed by a computer to fulfill its function, but also files and data processed according to each instruction.

  In addition, this program may achieve its intended purpose by being executed by a computer alone, or may be intended to achieve its intended purpose by being executed by a computer together with other programs. it can. In the latter case, the program according to this section can be mainly composed of data.

(13) A recording medium on which the program according to item (12) is recorded so as to be readable by a computer.

  This recording medium can adopt various formats, for example, a magnetic recording medium such as a flexible disk, an optical recording medium such as a CD and a CD-ROM, a magneto-optical recording medium such as an MO, and an unremovable storage such as a ROM. Any of these may be adopted.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  An on-demand content acquisition method according to an embodiment of the present invention is implemented using a peer-to-peer (P2P) grid system (hereinafter abbreviated as “grid system”). As is well known, the grid system configures an overlay network using a distributed hash table DHT (Distributed Hash Table) so that contents and the like are shared among a plurality of terminal devices (also referred to as “node devices”). It enables peer-to-peer communication while sharing information.

  In this grid system, a plurality of logical positions on the overlay network are assigned to a plurality of terminal devices, respectively. A DHT is used to distribute and store a plurality of logical positions respectively assigned to a plurality of terminal apparatuses on the overlay network.

  Data for identifying a logical position of each terminal device on the overlay network is generally referred to as a node ID. For example, when the above-described DHT is used, a predetermined hash function is applied to information unique to each terminal device, and a value obtained as a result is adopted as a node ID.

  FIG. 1 conceptually shows a grid system 12 constructed by a plurality of terminal devices 10 connected to each other. These terminal devices 10 construct an overlay network 14 in cooperation with each other by using a common DHT. Each terminal device 10 is used for a user to specify content and download and view the specified content.

  A content input server 20 and a contact node introduction server 22 are added to the grid system 12. The content input server 20 is used to input content to the grid system 12. The content input server 20 stores a catalog list 30 in which content IDs are posted. Specifically, in the catalog list 30, names of a plurality of contents input to the grid system 12 are posted in association with respective contents IDs. On the other hand, the contact node introduction server 22 is used to introduce each terminal device 10 with the logical position of the terminal device 10 of the contact node to be contacted first in order for each terminal device 10 to participate in the grid system 12. . In response to an inquiry from each terminal device 10 that intends to participate in the grid system 12 from now on, the contact node introduction server 22 introduces a contact node to each terminal device 10 in response thereto.

  In FIG. 2, the hardware configuration of each terminal apparatus 10 is conceptually represented by a functional block diagram. In each terminal device 10, the CPU 40 and the main storage device 42 are connected to each other via a system bus 44.

  Further, a hard disk device (hereinafter referred to as “HDD”) 50 and an infrared port 52 as peripheral devices are connected to the system bus 44 via a peripheral device control chip 46. In the HDD 50, data is read from and written to the hard disk 60. As conceptually shown in FIG. 3, a plurality of areas including an initial partial data storage area 62 and a cache area 64 are allocated to the hard disk 60. On the other hand, the infrared port 52 is provided to enable wireless communication with a remote controller (an example of an input device) 70 that enables input by the user. The remote controller 70 allows the user to input a content acquisition request for requesting acquisition and reproduction of the content to the terminal device 10 after specifying the content.

  As shown in FIG. 2, a built-in display (an example of an image output device as a playback device) 74 is further connected to the system bus 44 via a video chip 72 for controlling video signals. Further, a built-in speaker (an example of an audio output device as a playback device) 78 is connected to the system bus 44 via a sound source chip 76 for controlling an audio signal. The system bus 44 is further connected to a router 82 as an external device via a network interface 80. The router 82 is provided to connect the corresponding at least one terminal device 10 and the overlay network 14 to each other.

  As shown in FIG. 2, the main storage device 42 stores in advance an operating system, a content control program, a screen control program, and a decoder (program). The content control program is a program necessary for understanding the contents of the present invention, while the other program is a general program necessary for the user to download and view the content. Only the control program will be described in detail, and detailed description of other programs will be omitted.

  First, the operation content of the content control program will be schematically described with reference to FIGS. 3 and 4. The content control program is activated when the terminal device 10 is powered on. When the content control program is started, first, when the terminal device 10 is powered on, the beginning portion data representing the beginning portion of the content corresponding to the content ID recorded in the catalog list 30 (obtained from the content input server 20) is displayed. It is checked whether or not a file (hereinafter referred to as “first partial data file”) already exists in the first partial data storage area 62 of the hard disk 60. In the example shown in FIG. 3, for convenience of explanation, an alphabet “a” is added to the end of the content ID to describe the beginning data file name corresponding to the content ID. Therefore, in the example shown in FIG. 3, it is understood that there is an initial data file for the content whose content ID is “10001” and the content whose content ID is “10002”.

  As a result of the further execution of the content control program, content whose initial part data file does not exist on the hard disk 60, for example, the initial part data file of the content whose content ID is “10003” is another terminal device 10 on the overlay network 14. The contents are then downloaded to the own terminal device 10 from the one holding the contents.

  By further execution of the content control program, for example, a reference value that can define the size of the initial data file to be downloaded is acquired from the setting file 90 stored in the hard disk 60 or the main storage device 42. This reference value can be defined as a common fixed value or variable value for all of a plurality of contents to be downloaded, or can be defined as a variable value that varies depending on the size of each content.

  In order to define the reference value as a variable value that changes according to the size of each content, for example, information on the overall size of the content to be downloaded from now on is stored in an external device (for example, the content input server 20 or other terminal). The size of the opening portion data file corresponding to the current content is determined based on the information obtained from the apparatus 10) and a predetermined relationship between the size of the content and the size of the opening portion data file. Also good. FIG. 5 is a graph showing an upward proportional relationship, which is an example of a relationship in which the size of the initial partial data file increases according to the size of the content to be downloaded of all the data.

  In the example shown in FIG. 4, the reference value is recorded in the setting file 90 as a common fixed value (for example, 10 MB) for all of the plurality of contents to be downloaded. In this example, by further execution of the content control program, for example, for the content whose content ID is “10003”, the beginning portion of the content data having a size of 10 MB is the overlay network 14. Downloaded from. The downloaded beginning part data is filed and stored in the beginning part data storage area 62 of the hard disk 60.

  In the example shown in FIG. 3, all other unacquired contents, that is, six contents whose content IDs are “20001”, “20002”, “20003”, “30001”, “30002”, and “30003”, respectively. Each initial part data is downloaded and stored in the initial part data storage area 62 as an initial part data file.

  FIG. 6 conceptually shows the content control program in a flowchart. When the terminal device 10 is powered on, the content control program is activated. When this content control program is activated, first, in step S1, the content control program is initialized. Next, in step S2, processing necessary for the terminal device 10 to participate in the grid system 12 is performed.

  In FIG. 7, the details of step S2 are conceptually represented by a flowchart as a participation processing subroutine. In this participation processing subroutine, first, in step S101, the terminal device 10 requests contact node information (for example, the node ID of the contact node) from the contact node introduction server 22. Next, in step S <b> 102, the terminal device 10 receives contact node information from the contact node introduction server 22.

  Subsequently, in step S103, a participation message indicating a participation request indicating that the user wants to participate in the grid system 12 is transmitted to the contact node (corresponding other terminal device 10) defined by the received contact node information. Thereafter, in step S104, the terminal device 10 receives the table information from the contact node. The table information includes the node IDs of other terminal devices 10 corresponding to the area designation information (information for designating the level of the routing table) included in the participation message in the routing table already stored in the contact node. Is included. Subsequently, in step S3, by using the received table information, its own routing table is created or updated.

  Thereafter, in step S <b> 106, the terminal device 10 requests the catalog list 30 from the content input server 20. Subsequently, in step S <b> 107, the terminal device 10 receives the catalog list 30 from the content input server 20. This completes the execution of the participation process subroutine, and the process proceeds to step S3 shown in FIG. In step S3, a process for acquiring the beginning data of the content by downloading is performed.

  In FIG. 8, the details of the step S3 are conceptually represented by a flowchart as an opening portion data acquisition processing subroutine. In this initial part data acquisition processing subroutine, first, in step S201, the initial part data corresponding to all the content IDs listed in the catalog list 30 already exists in the initial part data storage area 62 of the hard disk 60. Is determined. In this case, assuming that the beginning part data exists for all contents, the determination is YES, and the execution of the beginning part data acquisition processing subroutine is completed.

  On the other hand, this time, assuming that the beginning part data does not exist for all the contents, the determination in step S201 is NO, and in step S202, any one of the at least one contents for which the beginning part data does not exist is determined. Is selected as the current target content. Subsequently, in step S203, the above-described reference value is acquired from the setting file 90. Thereafter, in step S204, it is determined whether or not a metafile corresponding to the current target content already exists in the cache area 64 of the hard disk 60. Here, the “meta file” is a file indicating a content ID corresponding to the current target content, and segment file information for identifying all segment files constituting the corresponding content (for example, the corresponding segment file is Content ID).

  At present, since the metafile corresponding to the current target content does not normally exist in the cache area 64, the determination in step S204 is NO. Subsequently, in step S205, the metafile corresponding to the current target content is overlaid on the overlay network. 14 is searched and downloaded. Thereafter, even when the determination in step S204 is YES, in step S206, segment file information of all segment files constituting the current target content is extracted from the existing metafile.

  Subsequently, in step S207, it is determined whether or not the first segment file corresponding to the current target content already exists in the cache area 64 of the hard disk 60. At present, since the first segment file corresponding to the current target content does not exist in the cache area 64 at this time, the determination in step S207 is NO, and in step S208, based on the extracted segment file information, this time The first segment file corresponding to the target content is retrieved on the overlay network 14 and downloaded.

  After that, even if the determination in step S207 is YES, in the same way, in step S209, the mode in which only the first part data is extracted as the first part data from the first segment file corresponding to the current target content is the setting file (basically the user It is determined whether or not it is selected. If it is assumed that the head partial data extraction mode is selected this time, the determination in step S209 is YES, and then in step S210, the acquired reference is obtained from the head segment file corresponding to the current target content. Content data corresponding to the same size as the value is filed and saved as the beginning portion data in the beginning portion data storage area 62 of the hard disk 60. The beginning portion data is stored in the beginning portion data storage area 62 in a state where it can be identified by the corresponding content ID. Thereafter, the process returns to step S201.

  On the other hand, if it is assumed that the head partial data extraction mode is not selected this time, the determination in step S209 is NO, and then, in step S211, the entire head segment file corresponding to the current target content starts. The data is copied as partial data, and the copied initial partial data is stored in the initial partial data storage area 62 of the hard disk 60. The beginning portion data is stored in the beginning portion data storage area 62 in a state where it can be identified by the corresponding content ID. Thereafter, the process returns to step S201.

  The execution of steps S202 to S211 is repeated until the determination in step S201 becomes YES. When the determination in step S201 is YES, the execution of this initial part data acquisition processing subroutine is terminated.

  By the way, the content control program is activated after the terminal device 10 is activated and before the time when the user can issue a content reproduction request (that is, music selection described later). Therefore, this content control program is activated after the terminal device 10 is activated and before the user first issues a content reproduction request. As a result, the beginning portion data acquisition processing subroutine is also started before the user first selects the music, so that all the contents posted in the catalog list 30 prior to the first music selection operation by the user, Only the beginning part data is downloaded and acquired by the terminal device 10.

  Thereafter, in step S4 shown in FIG. 6, it is determined whether or not the user has selected a music piece that is specific content, that is, whether or not music selection has been performed. In order to select a song, the user operates the remote controller 70 to specify content to be reproduced and transmits a signal requesting reproduction of the content to the terminal device 10. If it is assumed that music selection has been performed by the user this time, the determination in step S4 is YES, and music selection processing is performed in step S5.

  FIG. 9 conceptually shows the details of step S5 as a music selection processing subroutine in a flowchart. In this music selection processing subroutine, first, segment acquisition thread processing is performed in step S301. FIG. 10 conceptually shows the details of step S301 as a segment acquisition thread processing program in a flowchart.

  This segment acquisition thread processing program is executed substantially in parallel with the content control program shown in FIG. When this segment acquisition thread processing program is executed, first, in step S401, it is determined whether or not the above-mentioned metafile corresponding to the music selection target content exists in the cache area 64. The metafile normally exists in the cache area 64, but the CPU 40 automatically performs a process of erasing data stored in the cache area 64 that has a long unused period, Therefore, even if a necessary metafile is once stored in the cache area 64, it may not exist in the cache area 64 when the metafile is actually used. Therefore, this step S401 exists in this segment acquisition thread processing program.

  If the metafile corresponding to the current target content does not exist in the cache area 64, the metafile corresponding to the current target content is searched on the overlay network 14 and downloaded in step S402, and then to step S403. However, if the metafile corresponding to the current target content exists in the cache area 64, the process immediately proceeds to step S403. In any case, in step S403, the segment file information of all the segment files constituting the current target content is extracted from the existing metafile.

  Subsequently, in step S404, it is determined whether or not the first segment file corresponding to the current target content already exists in the cache area 64 of the hard disk 60. If the first segment file corresponding to the current target content does not exist in the cache area 64, the first segment file corresponding to the current target content is stored on the overlay network 14 based on the extracted segment file information in step S405. Searched and downloaded at. The head segment file is stored in the cache area 64 in a state where it can be identified by the corresponding content ID. Thereafter, the process proceeds to step S406. If the first segment file corresponding to the current target content exists in the cache area 64, the process immediately proceeds to step S406. In either case, in step S406, the music selection processing subroutine is notified that the download of the first segment file corresponding to the current target content has been completed.

  Thereafter, in step S407, it is determined whether or not all the segment files constituting the current target content have been checked. Assuming that this is not the case, in step S408, a segment file corresponding to the current target content and following the first segment file (hereinafter referred to as “subsequent segment file”) exists in the cache area 64. It is determined whether or not to do so. If it is assumed that it does not exist this time, the subsequent segment file is searched on the overlay network 14 and downloaded in step S409. The subsequent segment file is stored in the cache area 64 in a state where it can be identified by the corresponding content ID. Thereafter, in step S410, the music selection processing subroutine is notified that the download of the subsequent segment file corresponding to the current target content has been completed. On the other hand, assuming that the subsequent segment file corresponding to the current target content exists in the cache area 64, the process immediately proceeds to step S410.

  In either case, the process returns to step S407. The execution of steps S408 to S410 is repeated until the determination in step S407 is YES, and when the determination in step S407 is YES, the execution of this segment acquisition thread processing program ends.

  Returning to the description of the music selection processing subroutine shown in FIG. 9, it is determined in step S302 whether or not the current target content is being reproduced. If it is being reproduced, in step S303, it is waited for the download of all the segment files constituting the current target content to be completed. When completed, the music selection process subroutine is finished.

  On the other hand, assuming that the current target content is not being played back, in step S304, whether or not the metafile and the first segment file corresponding to the current target content exist in the cache area 64 of the hard disk 60 is determined. Is determined. Assuming that both the metafile and the head segment file are present this time, the determination in step S304 is YES, and then in step S305, the head segment file is read from the cache area 64 and read. The first segment file is played from the first position.

  After that, in step S306, among all the segment files constituting the current target content, there is a segment file that is currently being played back, that is, a segment file that has succeeded the first segment file (not yet downloaded). It is determined whether or not to do so. If there is a subsequent segment that has not yet been downloaded, in step S307, the subsequent segment file is downloaded based on the existing metafile and waits for completion. The downloaded subsequent segment file is stored in the cache area 64 in a state where it can be identified by the corresponding content ID. Subsequently, in step S308, the downloaded subsequent segment file is reproduced. Thereafter, the process returns to step S306. The execution of steps S306 to S308 is repeated until the determination in step S306 becomes NO. This completes the execution of the music selection processing subroutine.

  If both the metafile and the first segment file corresponding to the current target content are not present in the cache area 64 of the hard disk 60, the determination in step S304 is NO, and then step S309. , The beginning portion data of the selected content is read from the beginning portion data storage area 62 of the hard disk 60, and the read beginning portion data is reproduced. Thereafter, in step S310, the first segment file of the current target content is downloaded and waits for completion. The downloaded first segment file is stored in the cache area 64 in a state where it can be identified by the corresponding content ID. Subsequently, in step S311, non-starting part data following the starting part data is reproduced from the head segment file. Thereafter, the process proceeds to step S306.

  When the above-described segment acquisition thread processing program is executed during the reproduction of the initial part data of the current target content, as shown in the time chart of FIG. 11, in parallel with the reproduction of the initial part data, The first file segment of the content is downloaded, that is, the first segment is acquired. The first segment may be all beginning part data or only a part may be beginning part data. In the example shown in FIG. 11, in the example shown in FIG. It consists of partial data.

  Therefore, in the example shown in FIG. 11, during the reproduction of the beginning part data (before the reproduction start, the beginning part data is obtained and stored), the first segment is obtained, and as a result, The initial part data is acquired twice, but the non-initial part data is acquired for the first time.

  Furthermore, in the example shown in FIG. 11, when the reproduction of the beginning part data is finished, the reproduction of the non-beginning part data in the first segment is started. When the playback of the first segment ends, playback of the second segment following the first segment starts, and when playback of the second segment ends, playback of the third segment following the second segment starts. Is done.

  As described above, the case where the music selection is performed by the user has been described. However, when the music selection is not performed, the determination in step S4 shown in FIG. 6 is NO, and then the catalog list 30 enters the content in step S7. It is determined whether or not it has been updated by the server 20. If the catalog list 30 is updated, the determination in step S7 is YES, and in the step S8, the above-described initial portion data acquisition processing subroutine is executed again. As a result, the beginning part data of the content having the content ID that is listed in the updated catalog list 30 but not in the catalog list 30 before the update is downloaded and stored in the beginning part data storage area 62. Is done. Thereafter, the process proceeds to step S6.

  On the other hand, if the catalog list 30 has not been updated, the determination in step S7 is NO, and subsequently, in step S9, whether or not each terminal device 10 has received a message from another terminal device 10 is determined. Determined. If it is assumed that a message has not been received, the determination in step S9 is NO and the process immediately proceeds to step S6. However, if it is assumed that a message has been received, the determination in step S9 is YES, and then step S10. , The process corresponding to the received message is performed, and then the process proceeds to step S6.

  In step S6, it is determined whether or not the terminal device 10 is powered off. If it is assumed that it is not turned off, the determination in step S6 is NO and the process returns to step S4. However, if it is assumed that it is turned off, the determination in step S6 is YES, and the execution of this content control program ends.

  As is clear from the above description, in the present embodiment, for convenience of explanation, for example, each terminal device 10 constitutes an example of the “content on demand type node device” according to the item (1), and the remote controller 70 constitutes an example of “request input means” in the same paragraph, and a portion for executing steps S208 to S211 of each terminal device 10 constitutes an example of “first data acquisition means” in the same paragraph. In addition, it can be considered that the portion for executing steps S405 to S410 of each terminal device 10 constitutes an example of the “second data acquisition unit” in the same section.

  Further, in the present embodiment, for the sake of convenience of explanation, in the hard disk 60, the initial partial data storage area 62 constitutes an example of the “first storage means” in the above item (1), and the cache area 64 has the same item. It is considered that the “second storage means” in FIG. 1 is configured, and that the non-starting part data and the subsequent segment file in the head segment file respectively constitute an example of “remaining partial data” in the same section. It is possible.

  Further, in the present embodiment, for convenience of explanation, the portion for executing steps S305, S308, S309, and S311 of each terminal device 10 constitutes an example of the “reproducing means” in the above section (1). It can be considered that the built-in display 74 and the built-in speaker 78 constitute an example of the “reproducing device” in the same section.

  Furthermore, in the present embodiment, for convenience of explanation, the catalog list 30 constitutes an example of the “content list” in the above section (8), and a portion for executing steps S106 and S107 in each terminal device 10 Constitutes an example of “content list receiving means” in the same paragraph, and a portion for executing step S201 in each terminal device 10 constitutes an example of “determination means” in the same paragraph, and each terminal It can be considered that the part for executing steps S202 to S211 of the apparatus 10 constitutes an example of the “first data acquisition means” in the same section.

  Further, in the present embodiment, for convenience of explanation, the portion for executing steps S302, S303 and S407 to S410 of each terminal device 10 constitutes an example of the “second data acquisition means” in the above section (9). It is possible to think that

  Further, in the present embodiment, for convenience of explanation, the portion for executing step S306 in each terminal device 10 constitutes an example of the “content storage determination unit” in the above (10), and each terminal device It can be considered that the portion for executing steps S307 and S407 to S410 of 10 constitutes an example of “second data acquisition means” in the same section.

  Further, in the present embodiment, for convenience of explanation, the content control program constitutes an example of the “program” according to the item (12), and the main storage device 42 storing the content control program includes the ( It can be considered that it constitutes an example of a “recording medium” according to item 13).

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and are based on the knowledge of those skilled in the art including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

1 is a system diagram conceptually showing a peer-to-peer grid system 12 used for implementing an on-demand content acquisition method according to an embodiment of the present invention, together with a content input server 20 and a contact node introduction server 22. FIG. It is a functional block diagram which represents notionally the hardware constitutions of each terminal device 10 shown in FIG. FIG. 2 is a diagram conceptually showing a relationship between the contents of a hard disk 60 shown in FIG. 1 and the contents of a catalog list 30 in order to schematically explain the operation of the content control program shown in FIG. FIG. 2 is a diagram conceptually showing the relationship between the contents of a hard disk 60 shown in FIG. 1 and the contents of a setting file 90 in order to schematically explain the operation of the content control program shown in FIG. As a modification of the embodiment shown in FIG. 1, the relationship between the size of the content data referred to in order to variably determine the size of the beginning portion data of the content to be downloaded for each content and the size of the beginning portion data It is a graph which shows. 2 is a flowchart conceptually showing the content control program shown in FIG. 7 is a flowchart conceptually showing details of step S2 shown in FIG. 6 as a participation process subroutine. FIG. 7 is a flowchart conceptually showing details of step S <b> 3 shown in FIG. 6 as an initial partial data acquisition processing subroutine. 7 is a flowchart conceptually showing details of step S5 shown in FIG. 6 as a music selection processing subroutine. 10 is a flowchart conceptually showing details of step S301 shown in FIG. 9 as a segment acquisition thread processing program. It is a time chart for demonstrating an example of the operation content of the content control program shown in FIG.

Explanation of symbols

10 Terminal device 12 Peer-to-peer grid system 14 Overlay network 30 Catalog list 50 Hard disk device 60 Hard disk 62 Initial data storage area 64 Cache area 70 Remote control 90 Setting file

Claims (12)

A node device that constructs an overlay network together with a plurality of other node devices, wherein the content is searched for and downloaded from the plurality of other node devices in response to a request from a user of the node device An on-demand node device,
A request input means for inputting a content acquisition request from the user that the user wants to acquire content;
A search is made on the overlay network for a content holder that holds a pre-selected content from among the plurality of other node devices, and an initial portion of the pre-selected content from the searched content holder First data acquisition means for downloading the initial part data representing the data and storing the downloaded initial part data in the first storage means in a state that can be identified by the content ID;
In response to the content acquisition request, at least the beginning portion of the requested content already stored in the first storage means from at least one content holder holding the content requested by the user Second data acquisition means for downloading remaining part data excluding data and storing the downloaded at least remaining part data in a second storage means in a state that can be identified by a content ID;
In response to the content acquisition request, the beginning part data of the requested content is read from the first storage means and played back by a playback device, and subsequently to the playback, the request is sent from the second storage means to the request. A content-on-demand type node device comprising: reproducing means for reading out the remaining partial data of the reproduced content and reproducing it by the reproducing device.   The first data acquisition means is an opening representing an opening portion of a plurality of types of content substantially matching a plurality of types of content held by the other plurality of node devices as the preselected content. The content on-demand type node device according to claim 1, wherein partial data is stored in the first storage means.   The first data acquisition means includes at least one of the plurality of types of content held by the other node devices as the preselected content, of the node device or the other node devices. 2. The initial storage data representing an initial portion of a plurality of types of contents substantially matching a frequency acquired in the past by a single reference value or more is stored in the first storage unit. Content on demand type node device.   4. The content-on-demand type node device according to claim 1, further comprising an opening portion data size determining unit that variably determines the size of the opening portion data based on the size of the content.   5. The content-on-demand type node device according to claim 4, wherein the start part data size determining means determines the size of the start part data so that the start part data size increases as the size of the content increases. The data representing the entire content is divided into multiple segments,
The node device downloads content data from the corresponding content holder in segment units,
The first data acquisition unit stores, as the initial part data, the entire first segment located at the beginning of the plurality of segments or the first part of the first segment in the first storage unit. The content on-demand type node device according to any one of 5.   The first data acquisition unit is configured to store the first partial data of the preselected content in the stage after the node device is activated and before a first content acquisition request is issued from a user. The content on demand type node device according to any one of claims 1 to 6, wherein the node device stores the content on demand. Content list receiving means for receiving a content list indicating the preselected content;
Receiving a new content list, and determining means for determining the presence or absence of new content,
The said 1st data acquisition means stores the said opening part data of the new content in the said 1st memory means, when it determines with the new content existing by the said determination means. The content on-demand type node device described in 1.   In response to the content acquisition request, the second data acquisition means reads at least the requested content while the initial partial data is read from the first storage means and reproduced by the reproduction device. The content on-demand type node device according to any one of claims 1 to 8, wherein storage of remaining partial data is started in the second storage means. Content storage determination means for determining whether or not the requested content is stored in the second storage means;
The second data acquisition unit stores the requested content in the second storage unit when the content storage determination unit determines that the requested content is not stored in the second storage unit. The content on-demand type node device according to any one of claims 1 to 9. In a node device that constructs an overlay network together with a plurality of other node devices, an on-demand type that searches for, downloads, and acquires content from among the plurality of other node devices in response to a user request of the node device A content acquisition method,
A request input step in which the user inputs a content acquisition request that the user wants to acquire content;
A search is made on the overlay network for a content holder that holds a pre-selected content from among the plurality of other node devices, and an initial portion of the pre-selected content from the searched content holder A first data acquisition step of downloading the beginning part data representing the information and storing the downloaded beginning part data in the first storage means in a state that can be identified by the content ID;
In response to the content acquisition request, at least the beginning portion of the requested content already stored in the first storage means from at least one content holder holding the content requested by the user A second data acquisition step of downloading remaining part data excluding data and storing the downloaded at least remaining part data in a second storage means in a state that can be identified by a content ID;
In response to the content acquisition request, the beginning part data of the requested content is read from the first storage means and played back by a playback device, and subsequently to the playback, the request is sent from the second storage means to the request. A reproduction step of reading out the remaining partial data of the reproduced content and reproducing it by the reproduction device.   A program executed to cause a computer to function as each means of the on-demand type node device according to any one of claims 1 to 11.

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