JP5208491B2 - Playback apparatus and playback method - Google Patents

Description

  The present invention relates to a playback apparatus and a playback method for receiving and playing back content data.

  2. Description of the Related Art Conventionally, a reproducing apparatus that receives and reproduces content including moving images and audio is known. For example, a personal computer connected to the Internet and a mobile communication terminal represented by a mobile phone play the role of such a playback device. When reproducing content (network content) provided via a network, the communication status of the network through which the content is transmitted cannot be ignored.

Regarding grasping the communication status, Patent Literature 1 below discloses a radio wave environment information processing server that notifies a radio wave environment of a region where a mobile terminal will move in the future. This processing server first receives position information, destination information, terminal type information, and the like related to the terminal from the portable terminal. Subsequently, the processing server calculates the required time to the point where communication is predicted to be impossible based on the received information, the map data and the radio wave environment data (data regarding the reception quality) held in advance, The calculation result is transmitted to the mobile terminal.
JP 2005-236818 A

  Even in content reproduction, it is considered that the communication status can be grasped by applying the prediction processing described in Patent Document 1. However, in content reproduction, it is necessary to consider the convenience. For example, the convenience of network content, such as playing content that is currently being viewed to the end without interruption, acquiring content that may be viewed in the future, and smoothly starting playback of the content when a user selects it Improvement is desired.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a playback device and a playback method capable of improving the convenience of content playback.

The playback apparatus according to the present invention includes a communication status detection unit that detects a communication status of a network, a determination unit that determines content data to be received based on the communication status detected by the communication status detection unit, and a determination unit that determines Receiving means for receiving the received content data via the network, storage means for storing the content data received by the receiving means, and playback means for playing back the content data stored in the storage means, and determining means Calculates the downloadable amount in a predetermined time based on the communication status and the playback status, calculates the download remaining amount of the content data being played back, and compares the downloadable amount and the download remaining amount It characterized that you determine the content data to be received.

The playback method of the present invention is a playback method in a playback device for playing back content data, wherein the playback device detects a communication status of the network, and the playback device detects in the communication status detection step. A determination step of determining content data to be received based on the determined communication status, a reception step in which the playback device receives the content data determined in the determination step via the network, and a playback device in the reception step A storage step for storing the received content data, a playback step for the playback device to play back the content data stored in the storage step, and a playback status detection step for the playback device to detect the playback status of the content data in the playback step and, only including, in the determining step, The downloadable amount at a predetermined time is calculated based on the communication status and the playback status, the remaining download amount of the content data being played back is calculated, and the downloadable amount is compared with the remaining download amount to be received The content data is determined .

According to such a playback apparatus and playback method, first, the communication status of the network is detected, and the content data to be received is determined based on the detection result. Subsequently, the determined content data is received and stored, and the stored content data is reproduced. As described above, since the content data is received in consideration of the network environment, it is possible to execute optimal content reception (download) and content reproduction. In addition, by storing the received content data, it is possible to reproduce the content data without being affected by subsequent changes in the communication environment. Therefore, the convenience of content reproduction is improved.
Further, the content data to be received is determined based not only on the communication status of the network but also on the playback status of the content data. Thus, by receiving content data in consideration of the operating status of the playback device, it is possible to execute optimal content reception (download) and content playback.
Furthermore, the content data to be received is determined by comparing the downloadable amount in a predetermined time with the remaining download amount of the content data being reproduced. In this way, by considering the reception status of the content data being played back, more optimal content reception and content playback can be realized.

  In the playback apparatus of the present invention, it is preferable that the determining unit determines that the content data being played back and content data different from the content data are received when the downloadable amount is greater than the remaining download amount. .

  In this case, when the downloadable amount in the predetermined time is larger than the remaining download amount of the content data being reproduced, the content data being reproduced and content data different from the content data are received. As a result, it is possible to receive the content data without affecting the viewing of the content data being reproduced, and to receive in advance another content data that may be viewed in the future.

In the playback apparatus of the present invention, it is preferable that the determining means determines to receive an undiagnosed portion of the content data being played back when the downloadable amount is less than or equal to the download remaining amount .

  The playback apparatus of the present invention further includes priority setting means for setting the priority of reception of content data, and the determining means is based on the communication status, the playback status, and the priority set by the priority setting means. Thus, it is preferable to determine the content data to be received.

  In this case, the content data to be received is determined based not only on the network communication status but also on the content data playback status and content data reception priority. This makes it possible to execute optimal content reception (download) and content reproduction, and the convenience of content reproduction is further improved.

  In the playback device of the present invention, it is preferable that the priority setting means sets the priority based on at least one of a user's viewing tendency, content data attributes, and content data being played back.

  In this case, since the download priority is set based on at least one of the viewing tendency of the user, the attribute of the content data, and the content of the content data being played back, the content data that matches the user's preference is given priority. Can be received. As a result, the convenience of content reproduction is further improved.

  According to such a playback apparatus and playback method, content data to be received is determined based on the communication status of the network, and the content data is received and stored, so that the convenience of content playback can be improved. become.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  First, the configuration of the content reproduction system 1 including the reproduction device 20 according to the embodiment will be described with reference to FIGS. FIG. 1 is a diagram illustrating an overall configuration of the content reproduction system 1 and functional configurations of the distribution server 10 and the reproduction device 20. FIG. 2 is a diagram illustrating a hardware configuration of the distribution server 10 illustrated in FIG. 1. FIG. 3 is a diagram showing a configuration of content data. FIG. 4 is a diagram showing a hardware configuration of the playback apparatus 20 shown in FIG.

  The content reproduction system 1 includes a distribution server 10, a network N, and a reproduction device 20. The distribution server 10 and the playback device 20 can communicate with each other via the network N. In FIG. 1, only one playback device 20 is shown for simplicity of explanation, but a plurality of playback devices 20 may exist in the content playback system 1.

  The distribution server 10 is a computer system that distributes content data including moving image data and audio data to the playback device 20. The distribution server 10 includes a content storage unit 11 and a communication unit 12 as functional components.

  As shown in FIG. 2, the distribution server 10 includes a CPU 101 that executes an operating system, application programs, and the like, a main storage unit 102 that includes ROM and RAM, an auxiliary storage unit 103 that includes a hard disk, a network card, and the like. Communication control unit 104, input unit 105 including a keyboard and mouse, and output unit 106 including a monitor and a printer. Each function shown in FIG. 1 reads predetermined software on the CPU 101 and the main storage unit 102 shown in FIG. 2 and operates the communication control unit 104 under the control of the CPU 101, This is realized by reading and writing data in the storage unit 103.

  The content storage unit 11 is means (database) for storing content data. Each content data is encrypted and is identified by a content ID.

As shown in FIG. 3, the content data C includes an initial key s used for decryption, validity verification information used to verify whether the initial key s is authentic, and content. And a plurality of encrypted block data c _i (i = 1 to n). Each encrypted block data c _i, tag information that indicates the attribute of the block data (attribute information) is associated. The specific configuration of the tag information is not limited. For example, tag information including a block number may be set, or tag information including an attribute of a scene indicated by block data and an attribute of content data including block data may be set. As such an attribute, for example, development of a story in a character or scene can be considered.

  The communication unit 12 is means for distributing the content data stored in the content storage unit 11 to the playback device 20. Specifically, the communication unit 12 receives a request signal from the playback device 20, and extracts a device ID for identifying the playback device 20 and a content ID for identifying content data from the request signal. Subsequently, the communication unit 12 reads content data corresponding to the content ID from the content storage unit 11 and transmits the content data to the playback device 20 corresponding to the device ID.

  The network N includes a mobile communication network. However, the configuration of the network N is not limited, and the network N may be configured by other types of wireless communication networks or wired communication networks.

  The playback device 20 is a device that receives and plays back content data. Specifically, the playback device 20 is a mobile communication terminal such as a mobile phone or a portable information terminal (PDA: Personal Digital Assistant). However, the playback device 20 is not limited to a mobile communication terminal, and may be a fixed device such as a hard disk recorder.

  The playback device 20 includes, as functional components, a communication status detection unit (communication status detection unit) 21, a playback status detection unit (playback status detection unit) 22, a priority setting unit (priority setting unit) 23, and a determination unit (determination). Means) 24, a transmission unit 25, a reception unit 26, a content storage unit (storage unit) 27, an IC card key storage unit 28, and a reproduction unit (reproduction unit) 29. The playback unit 29 includes a content key generation unit 29a, a block key generation unit 29b, and a decryption unit 29c.

  As shown in FIG. 4, the playback device 20 includes a CPU 201 that executes an operating system, application programs, and the like, a main storage unit 202 that includes a ROM and a RAM, an auxiliary storage unit 203 that includes a hard disk, The communication control unit 204 performs data communication via the network N, an operation unit 205 such as operation buttons, and an output unit 206 such as a liquid crystal monitor. Each function shown in FIG. 1 reads predetermined software on the CPU 201 and the main storage unit 202 shown in FIG. 4 and operates the communication control unit 204 under the control of the CPU 201. This is realized by reading and writing data in the storage unit 203.

  The communication status detection unit 21 is a means for detecting the communication status of the network N. Specifically, the communication status detection unit 21 detects a communication amount per unit time of the network N (hereinafter referred to as “download efficiency”). For this purpose, the communication status detection unit 21 measures a communication speed and a communication amount in a predetermined time (for example, 5 minutes or 10 minutes), and calculates download efficiency based on the measurement result. The download efficiency can be expressed in units such as blocks / second and bytes / second, for example. The communication status detection unit 21 may calculate the download efficiency based on the communication specification (theoretical value) of the network N. The communication status detection unit 21 outputs the calculated (detected) download efficiency to the determination unit 24.

  The playback status detection unit 22 is means for detecting the playback status of content data in the playback unit 29. Specifically, the remaining time (remaining reproduction time) until the reproduction of the content data that has been received and is being reproduced is detected. For example, when the data for 45 minutes out of the content A for 60 minutes has been received and the content A has been played for 30 minutes, the playback status detection unit 22 sets 45-30 = 15 (minutes). Detected as remaining playback time. The reproduction status detection unit 22 outputs the detected remaining reproduction time to the determination unit 24.

  The priority setting unit 23 is a means for setting the reception priority (download priority) of content data. The content data with high priority is more likely to be received before the content data with low priority. Several priority setting methods in the priority setting unit 23 are conceivable.

  For example, the priority setting unit 23 sets the priority based on the viewing log (viewing history) and the content data attribute. Specifically, the priority setting unit 23 analyzes the viewing log to derive the viewing tendency of the user and acquires tag information of receivable content data. Note that the priority setting unit 23 may receive the tag information of the content data when setting the priority, or may receive and store the tag information in advance. Subsequently, the priority setting unit 23 sets a priority for receivable content data by comparing the derived viewing tendency with the attribute of the content data included in the tag information. Then, the priority setting unit 23 outputs the set priority to the determination unit 24.

  The viewing tendency includes, for example, viewing time, number of times of viewing, presence / absence of access to latest works and fashionable items. Further, the content data attributes include, for example, content genre, story development, characters, authors, recommendation level, statistical information indicating viewing tendency of other users, information indicating relation (such as order relationship) between contents, and the like. .

  For example, the receivable content data is a sports program “contents A”, a variety program “contents B”, and a news program “contents C”. When the viewing time is long in the order of the programs, the priority setting unit 23 sets the priorities of the contents A, B, and C to the first, third, and second positions, respectively.

  Further, the priority setting unit 23 may set the priority by weighting the content (tag information) of the content data being reproduced rather than the derived viewing tendency. For example, it is assumed that the receivable content data is “drama A second episode” and “drama B second episode”. At this time, even if the result that the user prefers “drama B second episode” over “drama A second episode” is derived from the viewing tendency, the content data being reproduced is “drama A first episode”. If so, the priority setting unit 23 sets the priority of the “second drama A” following the “first drama A” to the first. Note that such a relation (for example, order relation) between contents is included in the tag information as an attribute of the contents data as described above.

  The priority setting unit 23 may set the priority using only one of the user viewing tendency, the content data attribute, and the content data being reproduced. For example, the priority setting unit 23 can set the priority based only on the recommended level of content.

  The priority setting unit 23 may receive the priority input by the user and set the priority according to the input content. In this case, the content data is received in the order selected by the user.

  The determination unit 24 determines the reception target based on the communication status detected by the communication status detection unit 21, the playback status detected by the playback status detection unit 22, and the priority set by the priority setting unit 23. It is a means for determining content data.

  First, the determination unit 24 multiplies the download efficiency input from the communication status detection unit 21 and the remaining playback time input from the playback status detection unit 22 to complete the playback of the content data that has been received and is being played back. The amount of data that can be downloaded before download (downloadable amount) is calculated. Subsequently, the determination unit 24 calculates the data amount (download remaining amount) of the portion of the content data being reproduced that has not yet been received. Subsequently, the determination unit 24 derives a magnitude relationship between the downloadable amount and the remaining download amount, and determines content data to be received next based on the derived result and the priority of the content data. Finally, the determination unit 24 outputs the determination result to the transmission unit 25.

  For example, assuming that the content data being reproduced is “content A” and the downloadable amount is 3 megabytes and the download remaining amount of content A is 2 megabytes, the determination unit 24 finishes reproducing the received content A. It is determined that the unreceived part (data of 2 megabytes) of content A can be received by the time. Then, the determination unit 24 determines to receive an unreceived portion of the content A and to receive content data (content C in the above example) having the second highest priority after the content A.

  On the other hand, when the downloadable amount is 1.5 megabytes and the remaining download amount of the content A is 2 megabytes, the determination unit 24 does not receive the content A before receiving the received content A. It is determined that all (2 megabytes of data) cannot be received. In this case, the determination unit 24 determines to receive only the unreceived portion of the content A. This is to prevent the reproduction of the content A from being interrupted.

  The determination unit 24 can also determine the content data to be received by a method different from such a determination method. For example, the determination unit 24 may calculate the downloadable amount not based on the remaining reproduction time but based on a predetermined fixed time (for example, 3 minutes or 10 minutes) or an average reproduction time per user. . In this case, the determination unit 24 multiplies the download efficiency and the fixed time, or multiplies the download efficiency and the predicted playback time (difference between the average playback time and the current playback time) to download. Calculate the possible amount. In addition, the determination unit 24 corrects those values by multiplying or adding a predetermined coefficient to at least one of the downloadable amount and the download remaining amount, and then compares the downloadable amount and the download remaining amount. May be.

  Note that, depending on the measurement by the communication status detection unit 21, since the playback device 20 has moved out of the communication range or has been outside the communication range for a long time, the download efficiency is 0 or a very low value (for example, 10 kilobytes / second). As a result, the downloadable amount may be 0 or a very low value. Therefore, the determination unit 24 may determine not to receive the content data when the download efficiency is a predetermined threshold (for example, 0 or 10 kilobytes / second). Further, the determination unit 24 may determine not to receive the content data when the downloadable amount is equal to or less than a predetermined threshold (for example, 0 or 500 kilobytes). As a result, it is possible to suppress a load on the network N and to avoid useless reception processing in which an increase in content reproduction time can hardly be expected.

  The transmission unit 25 generates a request signal for requesting the distribution server 10 to distribute the content data based on the determination result input from the determination unit 24, and transmits the generated request signal. For example, when the determination result indicates that the contents A and B have been received, the transmission unit 25 generates and transmits a request signal including the content IDs of the contents A and B and the device ID of the playback device 20.

  The receiving unit 26 is means for receiving content data distributed from the distribution server 10 in response to the request signal transmitted from the transmitting unit 25. That is, the receiving unit 26 receives the content data determined by the determining unit 24. The receiving unit 26 outputs the received content data to the content storage unit 27. Since the content data is divided into one or more block data, the receiving unit 26 sequentially receives the data in units of blocks and outputs the data to the content storage unit 27.

  The content storage unit 27 is means for storing content data (encrypted content data) input from the reception unit 26. Since the content data is sequentially input to the receiving unit 26 in units of blocks, the content storage unit 27 stores content data for one or a plurality of continuous blocks.

  The data stored in the content storage unit 27 is not limited to the content data input from the reception unit 26. For example, the content storage unit 27 can store the read content data in the optical disc, or can store content data received from a communication terminal other than the distribution server 10 (for example, a personal computer of another user). Some of the content data stored in the content storage unit 27 may be acquired in advance from another communication terminal or an optical disc, and the remaining portion (shortage) may be acquired from the distribution server 10.

The IC card key storage unit 28 is a means for storing in advance an IC card key K ₀ necessary for decrypting encrypted content data.

  The playback unit 29 is means for decrypting and playing back the encrypted content data stored in the content storage unit 27. The playback unit 29 receives a playback instruction from a user of the playback device 20 or a playback instruction based on a preset playback reservation, and reads predetermined encrypted content data from the content storage unit 27 based on the playback instruction. Subsequently, the playback unit 29 decrypts and plays back the read encrypted content data. Note that the reproducing unit 29 can directly read out and reproduce not only the content data stored in the content storage unit 27 but also the content data in the optical disc.

  The reproduction unit 29 can reproduce not only the content data received from the distribution server 10 but also content data received from a communication terminal other than the distribution server 10, content data provided by a recording medium such as an optical disk, and the like. Therefore, the user of the playback device 20 can view not only the content data collected by himself / herself, but also content data provided by others.

  The reproduction of the content data is realized by the cooperation of the content key generation unit 29a, the block key generation unit 29b, and the decryption unit 29c that constitute the reproduction unit 29. Below, each part is demonstrated on the assumption that the reproduction | regeneration part 29 reproduce | regenerates the encryption content data C shown in FIG.

The content key generation unit 29a is a means for generating a content key necessary for decrypting the encrypted content data C. First, the content key generation unit 29a reads the encrypted content data C from the content storage unit 27, and verifies whether or not the initial key s is authentic by MAC authentication. Subsequently, the content key generation unit 29 a reads the IC card key K ₀ from the IC card key storage unit 28. Subsequently, the content key generating unit 29a generates a content key K by applying an initial key s and IC card key K ₀ to the content key generation algorithm stored in advance. Subsequently, the content key generation unit 29a outputs the encrypted content data C and the content key K to the block key generation unit 29b.

The block key generation unit 29b is a unit that generates a block key necessary for decrypting the encrypted block data constituting the encrypted content data. First, the block key generating unit 29b gives the content key K and the block number t _i corresponding to the encrypted block data c _i in the encrypted content data C to the block key generation algorithm stored in advance. in, it generates a block key k _i corresponding to the encrypted block data c _i. Subsequently, the block key generation unit 29b outputs the generated block key k _i and the encrypted block data c _i to the decryption unit 29c. The block-key generation unit 29b, when generating the block key k _i, and generates the viewing log indicating that encryption block data c _i corresponding to the block key k _i is viewed to the user is playing Remember. This viewing log includes block key generation time, tag information, and the like.

The decryption unit 29c is means for decrypting and reproducing the encrypted content. Specifically, the decoding unit 29c reads out the decoding application stored in advance, to derive the decoded block data m _i by giving the block key k _i in the application and the encrypted block data c _i. Then the decoding unit 29c reproduces the decoded block data m _i derived. Note that the block key generation unit 29b and the decryption unit 29c perform the above-described processing on block data for one or a plurality of continuous blocks. Thereby, the user of the playback device 20 can view the content (program).

  Next, with reference to FIGS. 5 to 7, the processing of the playback device 20 shown in FIG. 1 will be described and the playback method according to the present embodiment will be described. FIG. 5 is a flowchart showing a process when content data is received. FIG. 6 is a flowchart showing details of the content data determination process shown in FIG. FIG. 7 is a flowchart showing processing at the time of content data reproduction.

  The processing at the time of content data reception will be described with reference to FIG. In this process, first, the communication status detection unit 21 measures the communication speed and the communication amount at a predetermined time, and calculates the download efficiency based on the measurement result, thereby detecting the communication status (step S11, communication status). Detection step). Subsequently, the playback status detection unit 22 detects the remaining time until the end of playback of the content data that has been received and being played back, that is, the playback status (step S12). Subsequently, the priority setting unit 23 sets the reception priority of the content data based on the viewing tendency derived from the viewing log and the attribute of the content data (step S13).

  Subsequently, the determination unit 24 determines the content data to be received based on the detected communication status and reproduction status and the set priority (step S14, determination step). Details of this determination process will be described with reference to FIG.

  The determination unit 24 first calculates the downloadable amount by multiplying the download efficiency detected by the communication status detection unit 21 and the remaining playback time detected by the playback status detection unit 22 (step S141). Subsequently, the determination unit 24 calculates the remaining download amount of the content data being reproduced (step S142). Subsequently, the determination unit 24 derives a magnitude relationship between the downloadable amount and the download remaining amount (step S143).

  Here, when the downloadable amount is larger than the remaining download amount (step S143; YES), the determination unit 24 receives the unreceived portion of the content data being reproduced and the content data having the next highest priority after the content data. It is decided to do (step S144). On the other hand, when the downloadable amount is equal to or less than the download remaining amount (step S143; NO), the determination unit 24 determines to receive only the unreceived portion of the content data being reproduced (step S145).

  Returning to FIG. 5, when the content data to be received is determined by the determination unit 24, the transmission unit 25 generates a request signal based on the determination result and transmits it to the distribution server 10 (step S15). Subsequently, the reception unit 26 receives the content data transmitted from the distribution server 10 in response to the request signal (Step S16, reception step), and the content storage unit 27 stores the content data (Step S17, storage). Step). As a result, the content can be played back on the playback device 20.

  Next, processing (reproduction step) at the time of reproducing content data will be described with reference to FIG. When the reproduction unit 29 receives a reproduction instruction, first, the content key generation unit 29a generates a content key from the IC card key stored in the IC card key storage unit 28 and the initial key in the encrypted content data. (Step S21). Subsequently, the block key generation unit 29b generates a block key from the generated content key and the block number of the encrypted block data to be decrypted (step S22). At this time, the block key generation unit 29b generates a viewing log corresponding to the encrypted block data to be decrypted (step S23). Subsequently, the decryption unit 29c decrypts the encrypted block data using the generated block key, and reproduces the decrypted block data (step S24). The processes in steps S21 to S24 are repeatedly executed until the playback unit 29 receives a stop instruction input by the user of the playback device 20 (step S25; NO). When the stop instruction is input, the reproduction process ends (step S25; YES).

  As described above, according to the present embodiment, content data is received in consideration of the communication status of the network N and the operating status of the playback device 20, so that optimal content reception and content playback can be executed. It becomes possible. In addition, since the received content data is stored in the playback device 20, the playback of the content is continued even if the communication status deteriorates (for example, even when the communication status is deteriorated or the communication quality is deteriorated). It becomes possible. Thereby, the user can continue to view the content even when the user moves out of the communication range, for example. Therefore, the convenience of content reproduction is improved.

  Further, according to the present embodiment, the content data to be received is determined by comparing the downloadable amount and the download remaining amount. In this way, by considering the reception status of the content data being played back, more optimal content reception and content playback can be realized.

  Further, according to the present embodiment, when the downloadable amount in a predetermined time is larger than the download remaining amount of the content data being reproduced, the content data being reproduced and the content data different from the content data are received. The As a result, the content data can be received without affecting the viewing of the content data being reproduced, and another content data that may be viewed in the future can be received in advance.

  Further, according to the present embodiment, the content data to be received is determined based on the download priority set based on any of the viewing tendency of the user, the attribute of the content data, and the content of the content data being played back. Is done. Therefore, it is possible to preferentially receive content data that is highly likely to be viewed by the user (matching the user's preference) in consideration of the viewing tendency of the user and the nature of the content. As a result, the convenience of content reproduction is further improved.

  Further, according to the present embodiment, the content data to be received is determined in consideration of the communication amount per unit time of the network and the remaining reproduction time of the content data being reproduced, so that the load on the network is suppressed. And the convenience of content playback can be achieved.

  Further, according to the present embodiment, reception, storage, and reproduction of content data are executed in units of blocks and without impairing the order relationship between the blocks. Therefore, the user waits until the entire content is downloaded or can view only a part of the content, such as when browsing a pre-read web page (for example, the user can view text but cannot view images). Without being in a state), the content data can be viewed from the downloaded part. Therefore, the convenience of content reproduction is further improved.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be modified in various ways as described below without departing from the scope of the invention.

  In the above embodiment, the determination unit 24 determines the content data to be received using the download priority, but based on only the communication status of the network N and the playback status in the playback device 20 without using this priority. A determination process may be executed. In this case, the content data to be received can be determined more easily.

  In the above embodiment, the content data to be received is determined by comparing the downloadable amount and the remaining download amount, but the determination method by the determination unit 24 is not limited to this. For example, when the determination unit 24 determines whether or not the remaining download amount is equal to or less than a predetermined threshold and the remaining download amount is equal to or less than the threshold, only the content data being reproduced is received without performing the comparison process. You may decide. The predetermined threshold value can be defined by the amount of data (for example, 1 megabyte) or the ratio (for example, 20%) with respect to the entire content. By receiving only the content data being played when the remaining download amount is low in this way, the reception of the entire content data can be completed more quickly, and the situation where the content playback being executed is interrupted can be avoided more reliably. Is possible.

  The present invention is also applicable to a system that charges when content is reproduced. In this case, the billing table is further included in the encrypted content data. When the block key is generated, the block key generating unit 29b generates a viewing log and generates charging information based on the charging table. The generated billing information is transmitted to a billing management server (not shown), and the billing amount for the user is calculated in the billing management server.

  In the above embodiment, the playback device 20 decrypts and plays back the encrypted content data. However, the present invention also applies when the distribution server 10 delivers plaintext content data and the playback device 20 plays back the content data as it is. Can be applied.

It is a figure which shows the function structure of the reproducing | regenerating apparatus which concerns on embodiment. It is a figure which shows the hardware constitutions of the delivery server shown in FIG. It is a figure which shows the structure of content data. It is a figure which shows the hardware constitutions of the reproducing | regenerating apparatus shown in FIG. It is a flowchart which shows the process at the time of content data reception. It is a flowchart which shows the detail of the content data determination process shown in FIG. It is a flowchart which shows the process at the time of content data reproduction | regeneration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Content reproduction system, 10 ... Distribution server, 20 ... Reproduction apparatus, 21 ... Communication condition detection part (communication condition detection means), 22 ... Reproduction condition detection part (reproduction condition detection means), 23 ... Priority setting part (priority) Degree setting means), 24 ... determination section (determination means), 25 ... transmission section, 26 ... reception section (reception means), 27 ... content storage section (storage means), 28 ... IC card key storage section, 29 ... reproduction section (Reproducing means), 29a ... content key generation unit, 29b ... block key generation unit, 29c ... decryption unit

Claims (6)

A communication status detection means for detecting the communication status of the network;
A determination unit that determines content data to be received based on the communication status detected by the communication status detection unit;
Receiving means for receiving the content data determined by the determining means via the network;
Storage means for storing content data received by the receiving means;
Reproduction means for reproducing the content data stored in the storage means;
Playback status detection means for detecting the playback status of the content data in the playback means;
Equipped with a,
The determining means calculates a downloadable amount at a predetermined time based on the communication status and the playback status, calculates a download remaining amount of content data being played back, the downloadable amount and the download remaining amount, reproducing apparatus characterized that you determine the content data to be received by comparing the. The determination means determines that the content data being played and content data different from the content data are received when the downloadable amount is larger than the download remaining amount;
The reproducing apparatus according to claim 1 . The determining unit determines to receive an undiagnosed portion of the content data being played when the downloadable amount is equal to or less than the remaining download amount;
The reproducing apparatus according to claim 1 or 2, characterized in that It further comprises priority setting means for setting the priority of receiving the content data,
The determining unit determines content data to be received based on the communication status, the playback status, and the priority set by the priority setting unit;
The reproduction apparatus according to claim 1 , wherein the reproduction apparatus is a reproduction apparatus. The priority setting means sets the priority based on at least one of a user's viewing tendency, content data attributes, and content data being played back;
The playback apparatus according to claim 4 , wherein: A playback method in a playback device for playing back content data,
A communication status detection step in which the playback device detects a network communication status;
A determination step in which the playback device determines content data to be received based on the communication status detected in the communication status detection step;
A receiving step in which the playback device receives the content data determined in the determining step via the network;
A storage step in which the playback device stores the content data received in the reception step;
A playback step in which the playback device plays back the content data stored in the storage step;
A playback status detection step in which the playback device detects the playback status of the content data in the playback step;
Only including,
In the determining step, a downloadable amount at a predetermined time is calculated based on the communication status and the playback status, and a download remaining amount of the content data being played back is calculated, the downloadable amount and the download remaining amount, A reproduction method characterized in that content data to be received is determined by comparing .

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