JP2005085146A - Content reproducing device, content distribution system, content reproducing program and content reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently distribute a video content without being affected by equipment arrangement on a network. <P>SOLUTION: In this video distribution system, each client 4a-4c has a player 48 multicast-transmitting a distribution request of a desired content to a LAN, caching the received content into a primary cache 43 for the purpose of video reproduction when receiving the content streaming-distributed via the LAN in response to the multicast-transmitted distribution request, outputting the content to a decoder to sequentially reproduce it, and caching the received video content into a secondary cache 47 so as to distribute the received video content to the LAN. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a content reproduction apparatus, a content distribution system, a content reproduction program, and a content reproduction method applied to, for example, a video distribution service for streaming distribution of video content on the Internet.

In recent years, with the spread of broadband, video distribution services using streaming distribution technology are being performed on the Internet.
The video distribution service using the Internet is an on-demand type service in which the amount of video data transmitted to the information terminal operated by the viewer, that is, the client is large, and the client selects and browses the content that he / she wants to see. In realization, the load concentration on the video distribution server and the load on the network line become critical points of service quality.

As a prior art in the video distribution service, a technology of a data distribution system in which a cache server that caches content streamed from a content server that stores video distribution data is arranged in an xDSL accommodating device on a network is already known. (For example, refer to Patent Document 1).
However, in this case, a new capital investment is necessary because a dedicated server for the cache is added to the network, and the location of the cache server is fixed at the location of the xDSL accommodating device. Considering the above, there is a problem that it is difficult to obtain the caching effect unless the cache server is arranged in a place where the load is concentrated.
JP 2003-69639 A

  As described above, in the conventional data distribution system, the cache server is arranged for the purpose of reducing the load of the video distribution server. However, the cache server can be placed only at a fixed position on the network, and the number of clients dynamically increases and decreases. There was a problem that it was difficult to deal with when there was a bias.

  The present invention has been made to solve such a problem, and a content reproduction apparatus, a content distribution system, and a content reproduction program capable of efficiently streaming distributing content without being affected by the arrangement of devices on the network. The object is to provide a content reproduction method.

In order to solve the above-described problems, a content reproduction apparatus according to the present invention includes a transmission unit that multicasts a distribution request for a desired content to the network and a multicast transmission from the transmission unit in the content reproduction apparatus connected to the network. Receiving means for receiving the content distributed or distributed through the network in response to the distribution request, a first cache means for caching the content received by the receiving means for video reproduction, and the first cache means And a second cache unit that caches the content received by the receiving unit for distribution to the network.
In the content reproduction apparatus, when a content distribution request is received by the receiving means, a means for checking whether or not the corresponding content is cached in the second cache means, and the corresponding content is cached in the second cache means. If a response is received by the receiving means and a response means that can be delivered by the receiving means, an optimum device is selected from the received responses and a delivery start request is made. And a delivery start requesting means for performing streaming delivery of the contents cached in the second cache means to the request source when the delivery start request is received by the receiving means.
In the content reproduction apparatus, the reply means transmits the receivable response including its own IP address and content range information that can be distributed, or its own IP address and the current number of connections and the number of connectable items.
In the content reproduction apparatus, the distribution start request means includes means for selecting a device having the fastest time from the request to the response, or a device having the most connectable number among the received responses.
In the content reproduction apparatus, a receiving unit that receives content that is streamed on the network from the network regardless of a destination, and the content received by the receiving unit is cached in a secondary cache unit in preparation for a request from another. Cache control means.

The content distribution system according to the present invention includes a content reproduction apparatus that transmits a distribution request for a desired content to a network, and a video that is read out from the content storage unit in response to the distribution request and is streamed to the content reproduction apparatus through the network. In the content distribution system including a distribution server, the content reproduction device includes a transmission unit that multicasts a distribution request for a desired content to the network, and the video distribution server in response to the distribution request that is multicast transmission from the transmission unit Receiving means for receiving the content streamed from the network via the network, first cache means for caching the content received by the receiving means for video reproduction, and the first cache hand And a second cache unit that caches the content received by the receiving unit for secondary distribution to other content reproduction apparatuses on the network. It is characterized by that.
The content reproduction program of the present invention is a content reproduction program for causing a content reproduction device connected to a network to execute processing, and a transmission means for multicast transmission of a distribution request for the desired content to the network. Receiving means for receiving content or a request that has been distributed through the network in response to a distribution request transmitted by multicast from the transmitting means; and first cache means for caching the content received by the receiving means for video reproduction , Functioning as reproduction means for sequentially reproducing the contents cached in the first cache means, and second cache means for caching the contents received by the receiving means for delivery to the network. That.

The content reproduction method of the present invention is a content reproduction method in a content reproduction apparatus connected to a network, wherein the content reproduction apparatus multicasts a distribution request for a desired content to the network; A step of receiving the content streamed through the network by the content playback device; and the content playback device temporarily caches the received content for video playback and sequentially plays back the content. And secondarily caching for delivery.
In the present invention, when the content playback apparatus receives a content that has been stream-distributed through the network in response to the distribution request, the content playback apparatus multicasts a distribution request for the desired content to the network. The cache is temporarily cached for playback and sequentially played back, and the received content is cached secondarily for distribution to the network, so the cache is available from the next, and the content server responds to requests from others. Content can be distributed as As a result, cache information on the network, that is, content can be shared and distributed, and content can be efficiently streamed without being affected by the arrangement of devices on the network.

  As described above, according to the present invention, by incorporating a cooperative caching mechanism into a content playback apparatus (at least a client and a server) on a network, cache information can be shared and distributed. The content can be efficiently streamed without being affected by the above device arrangement.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing the configuration of a video distribution system according to an embodiment of the present invention.
As shown in the figure, this video distribution system connects a plurality of computers such as a video distribution server 1 as a video distribution source and clients 4a to 4c as content reproduction apparatuses via the Internet 3, a router 3 and a LAN. It is configured. The router 3 is a routing device having a multicast distribution function. Note that the video distribution server 1 can also be a content reproduction device by mounting the functions of the clients 4a to 4c.

The video distribution server 1 and the clients 4a to 4c are computers including a CPU, a memory, a hard disk device, a monitor, a keyboard, a mouse, and the like. The hard disk device stores an operating system (hereinafter referred to as OS), an application program, and the like. When the computer is started, the OS is read into the memory and the application program operates in the environment of the OS. That is, the application program realizes various functions of this system in cooperation with the OS.
The video distribution server 1 includes a video database 11 that stores video content, a client list 12, and a management unit 13 that manages the video database 11 and controls content distribution based on the client list 12. The video database 11 is constructed on a hard disk device. The client list 12 is stored in a memory or a hard disk device.

The management unit 13 receives a content distribution request from each of the clients 4a to 4c, reads out the corresponding video content stored in the video database 11 in response to the received content distribution request, and performs streaming distribution to the request source. Reading the video content stored in the video database 11 and streaming it is called primary distribution.
The clients 4a to 4c are user terminals that receive video content and cache the received video content. The video content is content compressed in a format such as MPEG-2 or MPEG-4, for example.
The clients 4a to 4c include an input unit 40, a client list storage unit 41, a reproduction list storage unit 42, a primary cache 43 as a first cache means, a decoder 44, a video / audio reproduction device 45, a video content output such as a display and a speaker. , A secondary cache 47 as a second cache means, a player application 48 (hereinafter referred to as a player 48), and the like. The input unit 40 inputs a corresponding command to the player 48 for an operation for starting the player 48 performed by the user, a video content distribution request operation, and the like.

  In the primary cache 43, the distributed video content is cached. The decoder 44 decodes the video content cached in the primary cache 43 so as to be reproducible. The video / audio reproduction device 45 outputs the video and audio decoded by the decoder 44 in different systems. The display of the video content output unit 46 displays the video output from the video / audio playback device 45 in a separate system on the screen. The speaker of the video content output unit 46 generates audio output from the video / audio playback device 45 in a separate system. The decoder 44, the video / audio playback device 45, and the video content output unit 46 are referred to as video playback means. The player 48 is an application program having functions for joining and leaving a multicast group, cash control function, video content and various list requests, transmission / reception, management and playback functions, and the like, and is installed in the hard disk devices of the clients 4a to 4c. Yes.

The received client list 12 is registered in the client list storage unit 41. The client list 12 is set with the IP addresses of the computers in the same group and the computers that are one-to-one with itself. The client list 12 is used by the player 48 when distributing video content.
A playlist is set in the playlist storage unit 42. Corresponding to the computer ID, the reproduction list stores the name of the requested or distributed content, the presence or absence of its own cache, the presence or absence of a response from another computer to the request, the time when there is a response, and the like. The client list storage unit 41 and the reproduction list storage unit 42 are generated in the memories of the clients 4a to 4c.
In the memories or heart disk devices of the clients 4a to 4c, cache areas such as the primary cache 43 and the secondary cache 47 are secured by the player 48, and the received video content is cached (temporarily stored).

  That is, the player 48 of each of the clients 4a to 4c multicasts a distribution request for a desired video content to the LAN, and receives the video content streamed from the video distribution server 1 through the LAN in response to the transmitted distribution request. . Then, the received video content is temporarily cached in the primary cache 43 for video playback and sequentially played back, and the secondary cache 47 is used to distribute the video content to the LAN in response to requests from others. Secondarily cache.

The basic operation (first operation example) of the video distribution system of this embodiment will be described below with reference to FIGS. This video distribution system has a function (cooperative caching mechanism) for realizing the following operations on the computer (the management unit 13 of the video distribution server 1 and the player 48 of each of the clients 4a to 4c) connected to the LAN. It has been incorporated.
In this video distribution system, for example, it is assumed that the clients 4a and 4b have already participated in the video distribution service, and the user of the client 4c newly starts the player 48.
When the player 48 is activated in the client 4c, the player 48 first connects to the video distribution server 1, acquires a multicast address for exchanging video distribution information and the like from the video distribution server 1, and enters the multicast group. Join (S101 in FIG. 3). Multicast is a function that enables transmission of IP packets to all members who receive a video distribution service participating in a group.
Subsequently, the player 48 of the client 4c transmits an IP address registration request (client registration request) to the client list 12 to the video distribution server 1 (S102). The client list 12 of the video distribution server 1 lists information on all clients managed by the video distribution server 1.

When the management unit 13 of the video distribution server 1 receives a client registration request from the client 4c (S103), the management unit 13 adds the IP address of the client 4c to the client list 12 and updates the client list 12 (S104).
When the client list 12 is updated, the management unit 13 periodically transmits update information to the clients 4a to 4c participating in the video distribution service using multicast (S105).
When the latest client list 12 is received by each of the clients 4a to 4c participating in the multicast group (S106), the clients 4a and 4b update the client list in the client list storage unit 41 with the received update information. In the newly participating client 4c, the player 48 registers the received client list 12 in the client list storage unit 41 (S107). Thereby, each client 4a-4c can recognize the connection condition of another client in substantially real time.

When the user of the client 4c wants to view the content A after joining the multicast group, the first case where the content A is not cached in the other clients 4a and 4b, and another client such as the client 4b, etc. Since there may be a second case where the content A is cached, each case will be described.
In the case of the first case, first, a desired content is selected by operating the input unit 40 on the screen of the player 48 of the client 4c and a confirmation operation is performed. Thereby, the player 48 generates a video distribution request for the content A, and transmits the generated video distribution request to the multicast group using a multicast packet (S201 in FIG. 4). At this time, the generated video distribution request includes the IP address of the client 4c and a unique ID (such as a URI) for identifying the requested content.

  In the clients 4a and 4b on the LAN, when the player 48 receives the video distribution request from the client 4c (S202), since the content A is not cached in the primary cache 43 at this time, the player 48 As a result of checking the cache state of A (S203), it is determined that there is no cache, and no response is returned to the client 4c without returning a response.

  On the other hand, when the video distribution server 1 receives a video distribution request from the client 4c (S203), the management unit 13 searches the video database 11. As a result of the search, the content A is stored and has a distribution capability, so the management unit 13 returns a response to the distribution request to the client 4c (S204). At this time, the IP address of the video distribution server 1 is inserted into the response.

When the client 4c receives a response from the video distribution server 1 (S205), the player 48 registers the IP address of the video distribution server 1 included in the response in the reproduction list of the reproduction list storage unit 42. Then, a distribution start request is transmitted to the video distribution server 1 registered in the reproduction list (S206).
When the video distribution server 1 receives the distribution start request from the client 4c (S207), the management unit 13 reads the content A stored in the video database 11 and performs streaming distribution (S208).
In the client 4c, when the content A streamed from the video distribution server 1 is received (S209), the player 48 caches the content A in the primary cache 43 and stores the data in the primary cache 43 as video reproduction means (decoder). 44), the data of the primary cache 43 is cached in the secondary cache 47 while reproducing the video and audio of the content A (S210).

  On the other hand, in the second case, first, a desired content is selected from the screen of the player 48 of the client 4c by operating the input unit 40 and a confirmation operation is performed. Thereby, the player 48 generates a video distribution request for the content A, and transmits the generated video distribution request to the multicast group using a multicast packet (S301 in FIG. 5). At this time, the generated video distribution request includes the IP address of the client 4c and a unique ID (such as a URI) for identifying the requested content.

When the client 4a, 4b on the LAN receives the video distribution request from the client 4c (S302), the content A is not cached in the primary cache 43 of the client 4a among the clients 4a, 4b at this time. As a result of checking the cache state of the content A (S303), the player 48 of the client 4a determines that there is no cache, and returns no response to the client 4c without returning a response.
Since the content A is cached in the primary cache 43 of the client 4b, the player 48 of the client 4b checks the cache status of the content A (S303), determines that there is a cache, and sends it to the client 4c. A response is returned (S304). At this time, the IP address of the client 4b is inserted into the response.

  On the other hand, when the video distribution server 1 receives a video distribution request from the client 4c (S303), the management unit 13 searches the video database 11. As a result of the search, the content A is stored and has a distribution capability, so the management unit 13 returns a response to the distribution request to the client 4c (S304). At this time, the IP address of the video distribution server 1 is inserted into the response.

The client 4c receives the response from the client 4b and the response from the video distribution server 1 in order (S305).
Then, the player 48 of the client 4c stores the IP address and reception time of the client 4b and the IP address and reception time of the video distribution server 1 included in each received response in the playlist of the playlist storage unit 42, respectively. register.
When a predetermined time elapses from the time when the distribution request is transmitted, the player 48 of the client 4c has the IP address with the earliest time at which the response is received in the playlist stored in the playlist storage unit 42. In this case, the client 4b is selected and a distribution start request is transmitted to the client 4b (S306).

When the client 4b receives the distribution start request from the client 4c (S307), the player 48 reads the content A cached in the secondary cache 47 and distributes it to the client 4c (S308).
In the client 4c, when the content A stream-distributed from the client 4b is received (S309), the player 48 caches the content A in the primary cache 43 and the data in the primary cache 43 is a video reproduction means (decoder 44, etc.). ), The data of the primary cache 43 is cached in the secondary cache 47 while reproducing the video and audio of the content A (S310).

  In the client 4 c, when the viewer ends the player 48, when the viewer performs an end operation of the player 48 from the input unit 40, the player 48 sends the client list of the client list storage unit 41 to the video distribution server 1. A request for deletion of the own IP address registered in is sent, and then the multicast group is left.

As described above, according to the video distribution system of this embodiment, a cache sharing network is constructed between the plurality of clients 4a to 4c receiving the video distribution service, and the video distribution information is shared among the clients 4a to 4c. On-demand video distribution using the content caches of the clients 4a to 4c can be realized.
Further, the load on the video distribution server 1 can be reduced by using the caches of the clients 4a to 4c. Further, when there is a client 4b that caches video content at a position closer than the network distance from the requesting client 4c to the video distribution server 1 or at a position where transmission is fast, the line load can be reduced more than usual. .

Subsequently, a second operation example of the video distribution system of this embodiment will be described.
Normally, content transmitted over a network is handled as one file. Content is also performed in file units for caching in a computer. Among content transmitted over a network, video content has a length in the time axis direction, and one file may become very large. In addition, depending on the request or operation at the time of browsing, there may be a demand for browsing only a specific range (separated by the start time / end time) in the content.

Therefore, in the second operation example, the video contents to be cached in each of the clients 4a to 4c are managed by dividing them in time units. The operation sequence in this case is as follows. In this case, it is assumed that the contents are cached in the clients 4a and 4b, and the client 4c issues a request.
That is, when a viewer who is a user of the client 4c wants to view the video content, first, as in the first operation example, first, a video distribution request for the desired content is transmitted from the player 48 of the client 4c to the multicast group by multicast. To do. At this time, the player 48 of the client 4c includes a video distribution request including its own IP address, a unique ID (URI, etc.) for identifying the requested content, a playback range (start time / end time) of the requested content, and the like. Send.
When the computer other than the client 4c that transmitted the request, that is, the clients 4a and 4b, the video distribution server 1, etc. receives the video distribution request from the client 4c, it checks whether or not the corresponding content is cached in the secondary cache 47. If the corresponding content is cached in the secondary cache 47, a response indicating that distribution is possible is returned to the requesting client 4c. At this time, the player 48 of each of the clients 4a and 4b and the management unit 13 of the video distribution server 1 respond to the response with range information (start time) that can be distributed within its own IP address, cache, or stored content A. -Reply including the end time).

When the player 48 of the client 4c receives a response from each computer (other clients 4a, 4b, video distribution server 1), each computer (other clients 4a, 4b, video distribution server 1) is received from the received response information. ) Analyze the range that can be distributed, and create a playlist to perform the necessary playback. The created playlist is a list in which information of each computer (the IP addresses of the other clients 4a and 4b and the video distribution server 1) is arranged in the order of the content time axis. The player 48 of the client 4c is sequentially connected to the corresponding computer based on this reproduction list, and receives distribution of video content in the corresponding range.
In other words, when a response that can be distributed is received, the player 48 of the client 4c selects an optimal device from the received response and makes a distribution start request, thereby distributing video content for each range from the other. Therefore, the player 48 of the client 4c receives and reproduces the video, so that the video of the desired range is displayed on the screen of the client 4c. Therefore, the viewer of the client 4c views and views the video of the desired range. can do.

Next, a third operation example of the video distribution system of this embodiment will be described. In the above operation example, the server (client 4b) that has the fastest response to the video distribution request from the client 4c is preferentially selected as the connection target server, but this may cause the distribution load to concentrate on a specific computer (client 4b). There is sex.
Therefore, in the third operation example, for example, when a video distribution request is received from the client 4c, the player of the computer (client 4a, 4b or video distribution server 1) that can respond within the other computer that has received the request. 48 returns the response to the request source including its own IP address, the current number of connections, and the number of connectable connections.

In the client 4c that has sent the video distribution request, the framer 48 selects the distribution server in response to the information on the communication margin included in the response (the number of connections currently distributing content and the maximum number of connections). A computer (client or video distribution server) that sends a distribution start request is selected as a condition. As a result, load distribution is achieved.
The maximum number of connections set as a distribution server selection condition in the memory of each client 4a-4c is a value (number) determined in advance from the machine performance of each client 4a-4c.
The client that has transmitted the video distribution request, for example, the player 48 of the client 4c, determines the communication margin included in the response from the computers (IP addresses) that have received the response within a predetermined time from when the request is issued until the timeout occurs. From the information, a computer having the largest number of connections (maximum number of connections-current number of connections) is preferentially selected as a connection target server.
Thereby, the load of the client connected to the video distribution service can be smoothed as much as possible.

Next, a fourth operation example of the video distribution system of this embodiment will be described.
In this case, the player 48 functions as a cache control unit that receives video content streamed over the LAN regardless of the destination and caches it in the secondary cache 47 for future requests.
That is, in the above operation example, the client 4c that has received the video distribution from the client 4b caches the target content in the primary cache and the secondary cache 47. In this fourth operation example, the client 4c other than the client 4c that has received the video distribution. Even when a client that has not issued a video distribution request, for example, the client 4a does not reproduce content by itself, the content that is stream-distributed over the LAN in preparation for other requests is received from the LAN and stored in the secondary cache 47. Cache. As a result, the next time this client 4a receives a distribution request from another, it becomes possible to return a response as having a cache, and the cache can be more efficiently distributed.

Subsequently, a fifth operation example of the video distribution system of this embodiment will be described.
In this case, the thinking information (keywords, genres, etc.) of the user who is the viewer is set (stored) in the memories (preference information setting means) of the clients 4a to 4c. The player 48 caches the video content in the secondary cache 47 when the video content received in the fourth operation example matches the preference set in the memory.
That is, the fifth operation example includes preference information setting means in which the preference information of the user of the apparatus is set, and the cache control means changes the content received by the receiving means to the preference set in the preference information setting means. If it matches, it is cached in the secondary cache means.
That is, until the fourth operation example, the user of each of the clients 4a to 4c has performed an operation for requesting a desired content. However, in the fifth operation example, a keyword corresponding to the preference of the user, that is, the viewer in advance. The genre is set in the memory of each of the clients 4a to 4c, and when the player 48 caches the content from the network, the content that matches (adapts) the preference information set in the memory is preferentially cached. To do. Thereby, the video content suitable for the viewer's preference of each client 4a-4c can be cached. In addition, the cache distribution mechanism causes a cache of contents including the same type of keyword / genre to be accumulated in clients around the target client, thereby improving the cache hit rate.

In addition, this invention is not limited only to the said embodiment.
In the above embodiment, the client server system form is the clients 4a to 4c and the video distribution server 1. However, these computers are regarded as equivalent (content playback devices), and the same request function and cache distribution function (original) Content chain sharing type network can be configured, and load distribution can be achieved no matter where the computer (client or video distribution server) is connected or arranged on the network. And additional hardware is available.

The figure which shows the structure of the video delivery system of this embodiment. The figure which shows the structure of the client of the video delivery system of FIG. The flowchart which shows operation | movement until a client participates in a video delivery service in the video delivery system of FIG. 2 is a flowchart showing a video distribution operation (no cache hit) in the video distribution system of FIG. 1. The flowchart which shows video delivery operation | movement (with a cache hit) in the video delivery system of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Video distribution server, 2 ... Internet, 3 ... Router, 4a-4c ... Client, 11 ... Video database, 12 ... Client list, 13 ... Management part, 40 ... Input part, 41 ... Client list storage part, 42 ... Playback List storage unit 43... Primary cache 44. Decoder 45. Video / audio playback device 46. Video content output unit 47. Secondary cache 48.

Claims (8)

In a content playback device connected to a network,
Transmission means for multicast transmission of a desired content distribution request to the network;
Receiving means for receiving a content or request that has been streamed and distributed through the network in response to a distribution request that has been multicast transmitted from the transmitting means;
First caching means for caching the content received by the receiving means for video playback;
Playback means for sequentially playing back the contents cached in the first cache means;
A content reproduction apparatus comprising: a second cache unit that caches the content received by the reception unit for distribution to the network. The content playback apparatus according to claim 1, wherein
Means for checking whether or not the content is cached in the second cache means when a content distribution request is received by the receiving means;
When the corresponding content is cached in the second cache means, a reply means for returning a deliverable response to the request source;
A delivery start requesting means for selecting an optimum device from the received responses and making a delivery start request when a response is received by the receiving means;
A content playback apparatus comprising: means for streaming distribution of content cached in the second cache means to a request source when a delivery start request is received by the receiving means. The content playback apparatus according to claim 2, wherein
The reply means is
A content playback apparatus comprising: a delivery response including an own IP address and range information of deliverable content, or an own IP address and a current connection number and a connectable number. The content playback apparatus according to claim 2, wherein
The distribution start request means includes
A content playback apparatus comprising means for selecting a device having the fastest time from a request to a response or a device having the most margin in the number of connections among received responses. The content playback apparatus according to claim 2, wherein
Receiving means for receiving the content to be streamed on the network from the network regardless of the destination;
A content playback apparatus comprising: cache control means for caching the content received by the receiving means in the secondary cache means in preparation for a request from another. Content distribution apparatus comprising: a content reproduction apparatus that transmits a distribution request for a desired content to a network; and a video distribution server that reads the corresponding content from a content storage unit in response to the distribution request and performs streaming distribution to the corresponding content reproduction apparatus through the network In the system,
The content playback device
Transmission means for multicast transmission of a desired content distribution request to the network;
Receiving means for receiving the content streamed from the video distribution server through the network in response to the distribution request transmitted by multicast from the transmitting means;
First caching means for caching the content received by the receiving means for video playback;
Playback means for sequentially playing back the contents cached in the first cache means;
A content distribution system comprising: a second cache unit that caches the content received by the reception unit for secondary distribution to other content reproduction apparatuses on the network. In a content playback program that causes a content playback device connected to a network to execute processing,
The content playback device;
Transmission means for multicast transmission of a desired content distribution request to the network;
Receiving means for receiving a content or request that has been streamed and distributed through the network in response to a distribution request that has been multicast transmitted from the transmitting means;
First caching means for caching the content received by the receiving means for video playback;
Playback means for sequentially playing back the contents cached in the first cache means;
A content reproduction program that functions as a second cache unit that caches the content received by the receiving unit for distribution to the network. In a content playback method in a content playback device connected to a network,
A step of multicast transmission of a request for distribution of desired content by the content reproduction device to the network;
The content playback device receiving the content that has been streamed and distributed over the network in response to the distribution request;
The content playback apparatus includes a step of temporarily caching the received content for video playback and sequentially playing the content, and secondarily caching the content for delivery to the network. Content playback method.

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