JP2003044398A - Method and device for reproducing contents, method and device for instructing reproduction of contents, contents reproducing program and recording medium for the program, and contents reproduction instructing program and recording medium for the program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new contents reproduction technology for preventing the interruption of the reproduction of contents on a terminal side even if congestion occurs on a server side when the contents are reproduced by distributing a decoding key to a terminal by a distribution server. SOLUTION: A center reproduces a ciphered content by distributing the decoding key to the terminal connected through a network. The center predicts future congestion and gives an instruction to reproduce a non-ciphered content which does not require the decoding key to the terminal before the congestion is started. Thus, the terminal can continue the reproduction of the contents even during a congestion period of the server by reproducing the non-ciphered contents such as advertisement contents without obtaining the decoding key in the congestion period which is caused later.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a content reproducing method executed by a terminal connected to a center which provides a decryption key via a network, a content reproducing apparatus for realizing the content reproducing method, and a network. Content reproduction instructing method executed in a center for instructing reproduction of content to a connected terminal, a content reproduction instructing device for realizing the content reproduction instructing method, and content reproduction used for realizing the content reproducing method A program and a recording medium for the program,
The present invention relates to a content reproduction instruction program used for realizing the content reproduction instruction method and a recording medium of the program.

[0002]

2. Description of the Related Art A distribution server distributes encrypted video data in advance to a terminal connected via a network, and when a user wants to reproduce this video data, the terminal displays the reproduction position. In accordance with the above, a decryption key is periodically acquired from the distribution server, and the corresponding part of the video data is decrypted and reproduced.

At this time, the video data cannot be decrypted with a single decryption key, and is encrypted so that the decryption key changes for each part of the video data.

In such a method of reproducing video data by key distribution, a large number of terminals issue decryption key transmission requests, and when congestion occurs on the distribution server side, transmission of the decryption key is stopped and reproduced. There is a problem that the image may be interrupted.

To solve this congestion problem, it has been proposed to distribute a decryption key using a telepolling communication system.

When this telepoling communication system is used, the timing of the next access is calculated according to the number of users who are reproducing the video, and the result is notified to each terminal, so that each terminal is notified. Controls the timing of the next request for a decryption key to avoid congestion.

Regarding the telepolling communication system, "Internet access traffic control technology"
TellePolling-Application interface for system construction, Kishida et al., Proc. Of the 58th Annual Conference of IPSJ, 3rd Volume, 3P-4, 1999 ".

[0008]

Certainly, if the decryption key is distributed by using the tele-polling communication system, congestion at the distribution server is avoided, so that the problem on the distribution server side is solved. Will be done.

However, since the terminal cannot access the distribution server until the time instructed by the distribution server, the decryption key cannot be acquired at a necessary timing, and thus the terminal can be obtained. There is a problem that the reproduction of the video data in the is interrupted. Then, there is a problem that the reproduction of the video data on the terminal is interrupted due to the failure of reception of the decryption key.

The present invention has been made in view of such circumstances, and there is a case where a distribution server distributes a decryption key to a terminal to reproduce content, and congestion occurs on the server side. An object of the present invention is to provide a new content reproduction technique that enables the terminal side to prevent interruption of content reproduction even if it occurs.

[0011]

To achieve this object, the present invention provides a configuration in which a center distributes a decryption key to terminals connected via a network to reproduce encrypted content. When I pick it up, (i)
The terminal includes an encrypted content storage unit that stores encrypted content distributed from a center and the like, and an encrypted content output unit that decrypts the encrypted content stored in this encrypted content storage unit and outputs the decrypted content to a playback device. A non-encrypted content storage unit for storing non-encrypted content distributed from the center and the like, and a non-encrypted content output unit for outputting the non-encrypted content stored in the non-encrypted content storage unit to the playback device. , Requesting the decryption key of the encrypted content from the center, and controlling the encrypted content output unit according to the response to the request,
And a reproduction control unit for reproducing the non-encrypted content by decrypting and reproducing the encrypted content or controlling the non-encrypted content output unit, and (ii)
The center manages the past access frequency of the decryption key request for the encrypted content issued from the terminal, and the prediction that predicts the future access frequency based on the past access frequency managed by this management unit. And a command unit for returning the decryption key or instructing the playback of the non-encrypted content to the terminal which is the source of the decryption key request according to the prediction result.

According to the present invention configured as described above, when each terminal requests the distribution of the decryption key to the center in response to the reproduction of the encrypted content, the center issues the decryption key issued by each terminal. Based on the request's past access frequency,
Predict future access frequency.

According to the prediction result, the center judges the prediction of the congestion when the predicted value of the future access frequency exceeds a certain value, and returns the decryption key to the terminal requesting the decryption key. Instruct to play the non-encrypted content without doing so.

Upon receiving the instruction of the non-encrypted content, the terminal suspends the reproduction of the encrypted content and starts the reproduction of the non-encrypted content such as the advertisement content which does not require the decryption key.

As described above, according to the present invention, when the center adopts a configuration in which the encrypted content is reproduced by distributing the decryption key to the terminals connected via the network, the center is Predicting future congestion (overload) and performing processing to instruct the terminal to play unencrypted content that does not require a decryption key such as advertisement content before the congestion starts. From
The terminal can continue playing the content during the congestion period of the server by playing the unencrypted content such as the advertising content without acquiring the decryption key during the congestion period that occurs thereafter. Like

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail according to embodiments.

FIG. 1 illustrates an embodiment of the present invention.

In the figure, 1 is a terminal for reproducing video data (program data, advertisement data), 2 is a distribution server for distributing video data and a decryption key to the terminal 1, and 3 is a terminal 1 and a distribution server 2. It is a network that connects the two.

The terminal 1 has a program data storage section 10 for storing and storing encrypted program data which is encrypted program data.
And a program output unit 11 that decrypts the encrypted program data and outputs the decrypted program data to the playback device, and advertisement data (not encrypted)
An advertisement data storage unit 12 that stores and stores the advertisement data, an advertisement output unit 13 that outputs the advertisement data to the playback device, a communication playback control unit 14 that communicates with the distribution server 2 and controls playback of the program data and the advertisement data, Program data acquisition unit 15 that acquires encrypted program data from distribution server 2 and stores it in program data storage unit 10, and acquisition of advertisement data that acquires advertisement data from distribution server 2 and stores it in advertisement data storage unit 12 And a section 16.

Here, the program output unit 11, the advertisement output unit 13, the communication reproduction control unit 14, the program data acquisition unit 15, and the advertisement data acquisition unit 16 included in the terminal 1 are specifically realized by a computer program. These computer programs can be stored in a computer-readable semiconductor memory or other suitable recording medium and provided.

On the other hand, the distribution server 2 encrypts the program data and distributes it to the terminal 1, a program data distribution unit 20, a program data storage unit 21 which stores the distributed unencrypted program data, and an advertisement. An advertisement data distribution unit 22 that distributes data to the terminal 1, an advertisement data storage unit 23 that stores the distributed advertisement data, a user profile database 24 that manages the program data reproduction status and password for each user, and program data. In response to the access requesting the decryption key, the process of transmitting the decryption key of the program data and the instruction of reproducing the advertisement data to the terminal 1 of the access request source, and performing the program for each user. Based on the reproduction instruction distribution unit 25 that performs a process of storing the data reproduction status in the user profile database 24 and the past access frequency It includes an access frequency prediction unit 26 for predicting a future access frequency and an access frequency management unit 27 that manages the past access frequencies to be aggregated by the access frequency prediction portion 26.

This user profile database 24
Is a password table 30 (shown in FIG. 1) for managing the password of each user and having a data structure as shown in FIG. 2, and the reproduction status of the program data for each user (request time of the decryption key and reproduction). The ID of the program data being played,
A reproduction status table 31 having a data structure as shown in FIG. 3 for managing the information on the reproduction portion of the program data being reproduced) (used for accounting processing, etc. shown in FIG. 1).
By including the above, the program data reproduction status and password for each user are managed.

Here, the program data distribution unit 20, the advertisement data distribution unit 22, and the reproduction instruction distribution unit 2 included in the distribution server 2 are provided.
5 and the access frequency prediction unit 26 are specifically realized by computer programs, and these computer programs may be provided by being stored in an appropriate recording medium such as a computer-readable semiconductor memory. it can.

In the present embodiment, the program data and the advertisement data are assumed as the video data to be reproduced, but the present invention is not limited to this, and can be applied as it is to audio and the like.

In order for the present invention to exert its effect, the point is that the content is encrypted and thus requires a decryption key for reproduction (program data in the case of this embodiment).
Then, content (advertisement data in the case of the present embodiment) that can be played back without a decryption key as long as it is not encrypted may be prepared.

Next, the present invention having such a configuration will be described. The distribution server 2 first executes a process of downloading the video data to each terminal 1 as a preparation process before starting the reproduction of the video data (program data, advertisement data). That is, in the distribution server 2, the program data distribution unit 20 reads the program data from the program data storage unit 21, encrypts the program data, and distributes it to each terminal 1, as a preparatory process before starting the reproduction of the video data. The advertisement data distribution unit 22 reads the advertisement data from the advertisement data storage unit 23 and processes it so as to distribute it to each terminal 1.

Upon receiving the distribution of this video data,
In the terminal 1, the program data acquisition unit 15 receives the encrypted program data distributed from the distribution server 2, stores the encrypted program data in the program data storage unit 10, and at the same time, the advertisement data acquisition unit 1
6 receives the advertisement data distributed from the distribution server 2 and processes it so as to store it in the advertisement data storage unit 12. Here, the encryption method executed by the program data distribution unit 20 is not limited to a specific one, and any method can be used as long as the reproduction instruction distribution unit 25 can generate a decryption key. It may be.

The above-mentioned preparation process has only to be completed before the reproduction of the video data on the terminal 1, and it is not necessary to perform it in synchronization with the process such as the acquisition of the decryption key. In addition to this, as a preparation process, the password table 3 included in the user profile database 24 included in the distribution server 2 is also included.
In 0, the correspondence relationship between the user ID of the user and the password will be registered.

Next, the processing at the time of reproducing the program is performed by the distribution server 2.
Side, the terminal 1 side will be described.

(1) Processing of distribution server 2 When the communication reproduction control unit 14 included in the terminal 1 issues a key distribution request message, the reproduction instruction distribution unit 25 included in the distribution server 2 follows the processing flow shown in FIG. , A process of transmitting a decryption key of program data or a reproduction instruction of advertisement data to the terminal 1 that issued the message.

The key distribution request message issued at this time is a user ID (character string for identifying the user).
And password (password assigned to the user)
And the ID of the program data to be reproduced (a character string for identifying the program data) and the information of the reproduction position of the program data to be reproduced (information specifying which part of the program data is to be reproduced. Information about the elapsed time) and).

A reproduction instruction distribution unit 25 provided in the distribution server 2.
When a key distribution request message is issued from the terminal 1,
As shown in the process flow of FIG. 4, first, in step 1, the key distribution request message is received, and then the user ID, password, program data ID, and reproduction portion are acquired.

Subsequently, in step 2, it is determined whether or not the acquired paired data of the user ID and the password is registered in the password table 30. The password is information known only to the user, and by determining whether or not the acquired paired data of the user ID and the password is registered in the password table 30, the user of the terminal 1 who has accessed the password. Confirms whether the user is the user himself.

User ID acquired by this determination processing
When it is determined that the paired data of the password and the password is not registered in the password table 30, it is determined that the message is not a key distribution request message from a legitimate user,
Waits for the next access without performing any processing.

On the other hand, when it is judged that the paired data of the acquired user ID and password is registered in the password table 30, that is, when it is judged that the message is a key distribution request message from a legitimate user, a step is carried out. In step 3, the access frequency predicted by the access frequency predicting unit 26 is acquired, and it is determined whether or not the acquired predicted access frequency exceeds a predetermined value.

When it is determined by this determination process that the predicted access frequency has exceeded the predetermined value, it is determined that congestion will be predicted, and the process proceeds to step 4 where the issuer of the key distribution request message is issued. A reproduction instruction of the advertisement data is returned to the terminal 1 and the processing ends.

On the other hand, when it is determined by this determination process that the predicted access frequency does not exceed the predetermined value, it is determined that the occurrence of congestion is not predicted, the process proceeds to step 5, and the reproduction status table 31 is displayed. In contrast, the current time, the acquired user ID, and the acquired program data ID
And the acquired playback part are registered.

The reproduction status table 31 created in this manner is used not only when charging for pay program data, but also when confirming the reproduction status of the program data for each user.

Then, in step 6, a decryption key required for reproducing the program data portion designated at the reproduction position is generated, and is sent to the terminal 1 which issued the key distribution request message.
The generated decryption key is returned and the processing ends.

The decryption key generated at this time is generated according to the agreement at the time of encryption. For example,
Depending on the user ID, program data ID and playback location,
If the program data downloaded to the terminal 1 is encrypted and the encryption key and the decryption key are the same, if the function for generating the encryption key is K, then the decryption key also uses the function K to obtain K. (User ID, program data ID, reproduction location).

In this way, when the key distribution request message is issued from the terminal 1, the reproduction instruction distribution unit 25 included in the distribution server 2 obtains the access frequency predicted by the access frequency prediction unit 26 and obtains it. By determining whether the predicted access frequency exceeds a predetermined value, it is determined whether the occurrence of congestion is predicted. If the occurrence of congestion is not predicted, the decryption key of the program data is determined. Is generated and returned, and when the occurrence of congestion is predicted, the reproduction instruction of the advertisement data that can be reproduced without the decryption key is processed to be returned.

Here, the access frequency predicting section 26 performs a process of predicting the future access frequency from the past access frequency, and any prediction method may be used.

For example, the access frequency for each unit time is calculated (the result is managed by the access frequency management unit 27), and the access frequency one unit time after the present is calculated by using the linear prediction method. By predicting, the processing for predicting future access frequency is performed. The linear prediction method used at this time is a weighted linear sum of the access frequencies from the present to the past n cycles and the access frequencies up to the past n cycles (sum of values obtained by multiplying each access frequency by a prediction coefficient). Is a method of estimating a future value by setting the value to a future value.

That is, the mean value 0 is obtained by using the linear prediction method.
And the value f of the stationary signal f (t) with variance σ ² at time t = t _0
0, the value f _1, f ₂ past f (t), if predicted using .... f _n (stored in the register constitutes the access frequency management unit 27 1 to n), this <F
>, And the prediction error is e ₀ , e ₀ = f ₀ − <f><f> = Σa _i f _i However, Σ is the sum of i = 1 to n.

The prediction error a _i (i = 1 to n) that minimizes the prediction error by the root mean square is R _0i = Σa _j R _ij where i = 1 to n and Σ is j = 1 to n.
It is obtained by solving the sum of n. Here, R _ij is the covariance of f _i and f _j , and the variance σ _e ² of e ₀ is σ _e ² = R ₀₀ −Σa _i R _0i where Σ is i = 1 to n. It is given as the sum.

(2) Processing of the terminal 1 The communication reproduction control unit 14 provided in the terminal 1 receives the decryption key from the program output unit 11 which decrypts and reproduces the encrypted program data stored in the program data storage unit 10. When the acquisition request is issued, the distribution server 2 follows the processing flow shown in FIG.
A key distribution request message is issued to, and a reply to the issuance is received, so that the decryption key is passed to the program output unit 11 or stored in the advertisement data storage unit 12 for the advertisement output unit 13. Process to instruct the reproduction of the advertisement data.

That is, when the decryption key acquisition request is issued from the program output unit 11, the communication reproduction control unit 14 included in the terminal 1 first, as shown in the processing flow of FIG.
In step 1, a key distribution request message is transmitted to the distribution server 2.

The key distribution request message is, as described above, the user ID (character string for identifying the user).
And password (password assigned to the user)
And the ID of the program data to be reproduced (a character string for identifying the program data) and the information of the reproduction position of the program data to be reproduced (information specifying which part of the program data is to be reproduced. Information about the elapsed time) and).

In response to the transmission of the key distribution request message, as described above, the reproduction instruction distribution unit 25 included in the distribution server 2 returns the decryption key of the program data or the reproduction instruction of the advertisement data. Come on.

Then, subsequently, in step 2, the reply from the distribution server 2 is waited, and when there is a reply from the distribution server 2, the process proceeds to step 3 to judge whether or not the decryption key has been returned. When it is determined that the decryption key has been returned, the process proceeds to step 4, and the program output unit 11 is instructed to output the program data by passing the returned decryption key.

In response to this instruction, the program output section 11
By using the decryption key passed from the communication reproduction control unit 14, the relevant portion of the encrypted program data being reproduced is decrypted and output to the reproducing device, so that the program data is reproduced.

On the other hand, when it is determined in step 3 that the decryption key has not been returned from the distribution server 2,
That is, when determining that the reproduction instruction of the advertisement data is returned from the distribution server 2, the process proceeds to step 5 and the advertisement output unit 13 is instructed to output the advertisement data.

In response to the advertisement data output instruction, the advertisement output unit 13 reads the advertisement data from the advertisement data storage unit 12 and outputs the advertisement data to the reproducing device so that the advertisement data is reproduced.

When the time that can be reproduced by one decryption key is constant, the next decryption key is required after the reproduction for the constant time is completed.

Then, the program output unit 11 issues a request for acquiring the next decryption key to the communication reproduction control unit 14 before the next decryption key is needed, and in response thereto, the communication reproduction control unit The unit 14 performs processing so as to transmit the next key distribution request message to the distribution server 2.

Further, when the prescribed time has elapsed since the reproduction of the advertisement data was started, the communication reproduction control unit 14 determines whether or not the state where the decryption key can be obtained (the state where the congestion is eliminated) is restored. In order to check, a key distribution request message instructing acquisition of a decryption key that failed in acquisition is sent again to the distribution server 2, and if the decryption key is returned in response to this transmission, the program output By passing the decryption key to the unit 11, the instruction to output the program data whose reproduction is interrupted, and when the decryption key is not returned, the advertisement output unit 13 is notified of the advertisement data. Will continue to output.

Then, when the advertisement data that has started to be reproduced is completed, the communication reproduction controller 14 checks whether or not the state has returned to the state in which the decryption key can be obtained (the state in which the congestion is eliminated), and the distribution server. 2, the key distribution request message instructing the acquisition of the decryption key that failed in acquisition is transmitted again, and when the decryption key is returned in response to this transmission, the decryption key is sent to the program output unit 11. By instructing to output the program data whose reproduction is interrupted, and when the decryption key is not returned, the advertisement output unit 1
3 will be instructed to start output of new advertisement data.

In the embodiment described above, when the occurrence of the congestion state of the distribution server 2 is detected, even when there are a plurality of programs being reproduced, they are detected without distinguishing them. The occurrence of a congestion state may be detected for each program in the program.

That is, the program A is permitted to access 100 times, and the program B is permitted to access 200 times. For example, it is used to judge whether or not a congestion state has occurred for each program being reproduced. The threshold value may be set.

By using this configuration, the distribution server 2
Predicts that the program A will enter the congestion state, instructs the terminal 1 requesting the decryption key for the program A to reproduce advertisement data, and predicts that the program B will not enter the congestion state. Then, it becomes possible to realize a delicate service such as returning the decryption key to the terminal 1 requesting the decryption key for the program B.

Although the present invention has been described according to the illustrated embodiment, the present invention is not limited to this. For example, in the embodiment, the distribution server 2 that provides the decryption key has a configuration that distributes the program data and the advertisement data to the terminal 1. However, a server other than the distribution server 2 that provides the decryption key The present invention can be applied as it is even when the program data and the advertisement data are distributed to the terminal 1.

Further, in the embodiment, the configuration is adopted in which the program data and the advertisement data which are the video data are distributed. However, when distributing the encrypted content and the non-encrypted content other than the video data, However, the present invention can be applied as it is.

Although not particularly described in the embodiment, any communication method may be used between the terminal 1 and the distribution server 2. The telepolling communication system may be used, or another communication system may be used.

[0064]

As described above, according to the present invention, there is a case where the center reproduces the encrypted content by distributing the decryption key to the terminals connected via the network. , The center predicts future congestion (overload), and instructs the terminal to play unencrypted content that does not require a decryption key such as advertising content before the congestion starts. Because of the processing, the terminal plays unencrypted content such as advertising content without acquiring a decryption key during the congestion period that occurs thereafter, so that the content can be played even during the congestion period of the server. You will be able to continue.

[Brief description of drawings]

FIG. 1 is an example of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a password table.

FIG. 3 is an explanatory diagram of a reproduction status table.

FIG. 4 is an exemplary embodiment of a processing flow executed by a reproduction instruction distribution unit.

FIG. 5 is an exemplary embodiment of a processing flow executed by a communication reproduction control unit.

[Explanation of symbols]

1 terminal 2 distribution servers 3 network 10 Program data storage 11 Program output section 12 Advertising data storage 13 Advertising output section 14 Communication playback controller 15 Program data acquisition unit 16 Advertising data acquisition section 20 Program data distribution section 21 Program data storage 22 Advertising data distribution section 23 Advertising data storage 24 user profile database 25 Playback instruction distribution section 26 Access Frequency Prediction Unit 27 Access Frequency Management Department 30 password table 31 Playback status table

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaru Miyamoto             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Hiroto Inagaki             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 5B082 HA05                 5B085 AE13 AE29 BG07 CA04                 5J104 AA01 AA16 EA01 EA04 NA02    (54) [Title of Invention] Content reproduction method and apparatus, content reproduction instruction method and apparatus, and content reproduction program                     System and a recording medium of the program, a content reproduction instruction program and the recording of the program                     Medium

Claims (9)

[Claims] 1. A content reproduction method for reproducing content, comprising the steps of storing a plurality of contents, receiving a command indicating which content is to be reproduced from a center connected via a network, and said command. And a step of reproducing the content according to the method. 2. A content reproduction method for reproducing content, comprising: receiving and storing encrypted content; receiving and storing unencrypted content; and connecting via a network. A process of requesting the center for a decryption key of the encrypted content, a process of receiving a response from the center to the request, and whether or not the encrypted content is decrypted and reproduced according to the response. And a step of playing back the unencrypted content. 3. A content reproduction instructing method for instructing a terminal connected via a network to reproduce a content, comprising the steps of: decrypting a decryption key request for an encrypted content issued from the terminal; The method includes a step of predicting a future access frequency based on the access frequency, and a step of returning the decryption key to the terminal or instructing the terminal to reproduce unencrypted content according to the prediction result. This is a method of instructing content reproduction. 4. A content reproduction device for reproducing content, comprising: an encrypted content storage unit for storing encrypted content; and an encrypted content output for decrypting the encrypted content and outputting the decrypted content to a reproduction device. Section, an unencrypted content storage section that stores unencrypted content, an unencrypted content output section that outputs the unencrypted content to a playback device, and a center connected via a network. On the other hand, by requesting the decryption key of the encrypted content and controlling the encrypted content output unit according to the response to the request, the encrypted content is decrypted and reproduced, or By controlling the encrypted content output unit, a playback control unit that plays back the unencrypted content That obtaining content reproduction apparatus according to claim. 5. A content reproduction instructing device for instructing a terminal connected via a network to reproduce the content, wherein the decryption key request for the encrypted content issued from the terminal is in the past. A management unit that manages the access frequency, a prediction unit that predicts the future access frequency based on the managed past access frequency, and returns the decryption key to the terminal according to the prediction result, A content reproduction instruction device, comprising: an instruction unit for instructing reproduction of unencrypted content. 6. A content reproduction program for causing a computer to execute the process used to implement the content reproduction method according to claim 1. 7. A recording medium for a content reproduction program, which records a program for causing a computer to execute the process used to implement the content reproduction method according to claim 1. 8. A content reproduction instruction program for causing a computer to execute the process used to implement the content reproduction instruction method according to claim 3. 9. A recording medium of a content reproduction instruction program, which records a program for causing a computer to execute the process used to implement the content reproduction instruction method according to claim 3.