JP2007019689A - Vod system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To introduce VOD service having a limited reception function into a digital broadcasting station at low cost. <P>SOLUTION: Sending-out systems for broadcasting are each given an HE identification number for discriminating the sending-out system for broadcasting, and HE identification numbers and work keys are received from the respective sending-out systems for broadcasting. When VOD contents are scrambled, scramble keys are fixed in content units or made common to all the sending-out systems for broadcasting, but common information to be sent out accompanying contents is generated by using the work keys individually for the respective sending-out systems for broadcasting. A plurality of pieces of common information generated by scrambled contents and HE identification numbers are stored on a VOD server, and at a request from a recipient, common information and scrambled contents corresponding to a broadcasting system that the identified recipient (receiver) belongs to are multiplexed and sent out. Consequently, different broadcasting companies which employ the same limited reception system can share the VOD system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a VOD (Video on Demand) system that transmits content in response to a request from a viewer, and more particularly to a system that scrambles and transmits content.

  In the field of digital video distribution, VOD (Video on Demand) service is attracting attention as a powerful service, coupled with the recent price reduction of servers, as a service that enables viewers to watch programs they want to watch when they want to watch. Yes. In particular, in digital CATV, VOD is easy to introduce because two-way communication is possible and the number of subscribers is within a certain range, and it is attracting a lot of attention because it is a differentiated service from other digital satellite broadcasting. .

  When this service is realized, the VOD requested content is sent from the center side to the receiver, but only the receiver that sent the request should be able to view and other receivers should not be able to view. For this reason, currently, the content to be transmitted is scrambled with a key, and this key is sent only to a valid receiver. This mechanism is called limited reception and is widely introduced in general digital broadcasting services.

  As described above, it is necessary to introduce a limited reception function (see Non-Patent Reference 1) equivalent to a normal broadcast service in the VOD service. Therefore, until now, a plurality of limited reception functions for broadcasting service and VOD service have been implemented on the transmission side and the receiver side, respectively, but this has been a factor that makes the apparatus large and expensive.

  In addition, even if multiple broadcasting stations or CATV stations that provide broadcasting services have introduced the same conditional access system, they have a different work key for each system in order to eliminate receivers of other systems. Since the VOD system cannot be shared, it is necessary to separately introduce a VOD system and a limited reception facility associated therewith, which is also a high cost factor.

  In the limited reception system in a normal broadcasting service, a function is realized by individual information that gives a viewing permission condition for each receiver and common information that gives a viewing condition for each program. On the receiver side, whether or not viewing is possible is determined by referring to and comparing these pieces of information. Therefore, devices such as an individual information generation unit, a common information generation unit, and a control unit that performs overall control of the individual information generation unit are required on the transmission side.

The individual information stores a work key that is unique for each system and viewing permission condition data, and the entire individual information is encrypted with a master key that is unique for each receiver. On the other hand, the common information stores a scramble key that actually scrambles the program and viewing condition data for each program, and the entire common information is encrypted with the work key. That is, exclusion for each system is realized by the work key.
Radio Industry Association “Access Control System Standards for Digital Broadcasting” ARIB STD-B25 4.1 Edition 15 pages, pages 20-25

  The problem to be solved by the present invention is that it cannot be introduced at low cost when the conditional access function is introduced into the VOD system.

  In the present invention, in order to introduce the limited reception function in the VOD service at a low cost, the scramble control unit creates the common information in the same format as the common information used in the normal broadcasting service different from the VOD service. Further, it is encrypted with the same work key, and is sent together with the content from the VOD server in response to a request from the receiver. Thus, the receiver side has a common conditional access decryption unit for extracting the descrambling key from the common information.

  Also, the scramble control unit receives common work keys and numbers identifying broadcast stations from different broadcast service conditional access systems when creating common information, and scrambles necessary for descrambling on the receiver side. A plurality of pieces of common information encrypted with each work key is created for the same information including the key. The VOD control unit identifies which head end the receiver that has transmitted the request belongs to, and sends common information corresponding to the head end together with the content.

  In the VOD system of the present invention, when the conditional access function is introduced into the VOD service, a part of the conditional access facility is adopted by adopting the same method as the conditional access for broadcast service that has already been introduced and sharing the work key. Can be shared with the broadcasting service and can be introduced at low cost. In addition, since the VOD system and the limited reception facility can be shared among a plurality of different broadcasting stations, the effect is further enhanced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram when the VOD system of the present invention is applied to a digital CATV system. First, its components will be described.

  Reference numeral 1 denotes a VOD system. Although the VOD system has a more detailed configuration than shown in the drawings, only the part related to the present invention will be described, and only the outline of the other components will be described.

  The content supply unit 11 receives and accumulates content sent through the distribution network 10. Next, in the case of a VOD service that does not perform normal limited reception, the content is directly sent from the content supply unit 11 to the VOD server 12. However, in the present invention, the content is sent to the scrambler 20 for scrambling.

  The scrambler 20 scrambles content in units of predetermined data blocks. A scrambling key for scrambling is sent from the scrambling control unit 21. In addition, the scrambler 20 also multiplexes the common information sent from the scramble control unit 21 to the content as necessary.

  The VOD server 12 receives the scrambled content from the scrambler 20 and accumulates the content.

  The VOD control unit 13 controls the entire VOD system. The VOD control unit 13 sends a server storage instruction or the like to each device in order to perform a series of control until the content supplied from the VOD content supply unit 11 is stored in the VOD server 12. Further, the VOD control unit 13 accepts a request from a receiver that wants to receive the VOD service, determines whether viewing is permitted, and if viewing is possible, instructs the VOD server 12 to send the content and sets the sending condition to the VOD sending unit. Set to 14.

  In accordance with an instruction from the VOD control unit 13, the VOD transmission unit 14 modulates the content to be transmitted to a predetermined transmission frequency and transmits it to the receiver 15 via the transmission path.

  The receiver 15 receives and descrambles a broadcast service and a VOD service, and transmits a video signal to a video display device such as a television. In the VOD service, a request from a viewer is received from a remote controller or the like, and a request signal is transmitted to the VOD control unit 13.

  The decryption unit 16 is attached to or built in the receiver, extracts the scramble key from the common information, and returns it to the receiver 15.

  The limited reception control unit 2 includes a scramble control unit 21 and a common information generation unit 22.

  The scramble control unit 21 controls the entire scramble process. The work key for the limited reception is received from the limited reception facility of the broadcast transmission system 30, and the work key, the scramble key generated internally for each content unit, and preset VOD program information are sent to the common information generation unit 22. . Thereafter, the common information is received from the common information generation unit 22 as a response, and the common information and the scramble key are sent to the scrambler 20.

  The common information generation unit 22 generates common information based on the work key, scramble key, and VOD program information set from the scramble control unit 21. In the generation method, a scramble key and VOD program information are integrated and encrypted with a work key. The common information generated in this way is returned to the scramble control unit 21.

  The broadcast transmission system 30 is a facility for performing a normal digital broadcast service, and also has a limited reception function. The broadcast transmission system has a more detailed structure than shown in the drawings, but only the parts related to the present invention will be described, and only the outline of the other components will be described.

  Next, processing contents of the VOD system of the present invention will be described with reference to FIG.

  First, VOD content is sent to the content supply unit 11 through the distribution network 10.

  When the content supply unit 11 finishes receiving the content, the content supply unit 11 temporarily stores the content and then sends the content to the scrambler 20.

  Since the scrambler 20 needs a key for scrambling after receiving the content, it sends a key request signal to the scramble control unit 21.

  The scramble control unit 21 receives a work key from the limited reception facility of the broadcast transmission system 30 in advance. Upon receiving the key request signal, the scramble control unit 21 sets the work key in the common information generation unit 22. Next, a scramble key for scrambling the content is generated. The content of the scramble key is not particularly limited, and may be a random number or generated from a PN code string. Next, the scramble control unit 21 sends the generated scramble key and VOD program information set in metadata separately indicating GUI or the like to the common information generation unit 22.

  The common information generation unit 22 generates plaintext common information from the scramble key and VOD program information, encrypts the common information with a preset work key, and returns the encrypted common information to the scramble control unit 21.

  Here, the common information will be described with reference to FIG.

  The common information is data attached to the content and gives viewing permission conditions for each program. Common broadcast common information includes a scramble key for scrambling the content and a viewing permission number, as shown at 50. The viewing permission number is assigned on the limited reception facility installed in the broadcast transmission system 30 for each charging unit such as each channel or each program.

  The viewing permission number is also sent as individual information 51 for each receiver separately from the common information. The viewing permission number is sent as individual information within the receiver, and is sent accompanying the program and the viewing permission number held internally. If the viewing permission numbers of the common information match, the program can be descrambled and viewed. As described above, in order to realize the limited reception function, individual information for giving a viewing permission for each receiver and common information for giving a viewing permission condition for each program together with the program are necessary.

  The individual information and the common information are multiplexed with a video signal or the like as a digital broadcast transport stream packet defined in ISO-13818-1 (MPEG2-Systems) and sent from the broadcast station side to the receiver side. On the receiver side, it is stored in the decoding unit 16 associated with the receiver 15 shown in FIG. 1, and the viewing permission number stored here is compared with the viewing permission number sent in the common information.

  The individual information 51 includes a receiver number uniquely assigned to the receiver, a work key, and a viewing permission number that permits viewing of the receiver. In FIG. 2, the receiver can view the viewing permission numbers (1), (3), (100), and (101), and the common information 50 includes the viewing permission number (1). The machine can view the program accompanied by this common information 50.

  In this way, the individual information and the broadcast common information 50 are sent for broadcasting, and this is referred to in the case of general broadcasting.

  At this time, the individual information in the VOD service is not sent exclusively for the VOD system, but is shared with the individual information sent for broadcasting from the broadcasting transmission system. For example, in the individual information 51, a viewing permission number (1) (3) for broadcasting service and a viewing permission number (100) (101) for VOD service are sent together.

  When the viewing permission number (100) is sent using the VOD common information 52, the receiver that receives the VOD / broadcast shared individual information 51 can view the program accompanied by the VOD common information 52.

  Thus, by sharing the individual information for broadcasting, the individual information transmission facility for the VOD system becomes unnecessary and the effect is great.

  For this purpose, it is necessary to assign a viewing permission number so that it does not overlap between broadcasting and VOD. In this embodiment, (100) or more are assigned to VOD programs.

  Receiving the encrypted common information, the scramble control unit 21 sends the common information and the scramble key to the scrambler 20.

  The scrambler 20 scrambles the content in units of a certain data block using the sent scramble key. At this time, if the common information is multiplexed with the content together with the scramble processing, the VOD server 12 does not need to process the common information separately from the content data, and the VOD system only needs to manage the content data. There is.

  When the common information is multiplexed on the content, it is normally multiplexed at a fixed period in order to facilitate the extraction of the scramble key at the time of content reception on the receiver side. However, if the common information is multiplexed at a fixed period, the time information needs to be corrected and the scrambler processing increases. On the other hand, if the common information is multiplexed only on a specific part such that the time error can be ignored, such as the beginning part of the content, the time correction process becomes unnecessary. In this case, by fixing the scramble key with the content, once the descrambling key is extracted on the receiver side, the subsequent extraction process becomes unnecessary, and the same effect as that of periodically multiplexing the common information is obtained.

  The scrambled content is sent from the scrambler 20 to the VOD server 12 and stored.

  The above is the flow up to content storage for the VOD service.

  Next, a flow until the receiver 15 can view the VOD content will be described.

  In the receiver 15, the viewer operates a remote controller or the like to select VOD content to be viewed, and the request signal is sent to the VOD control unit 13 through the transmission path.

  The VOD control unit 13 confirms the receiver number, the vacant transmission band, and the like. If the receiver determines that the VOD service viewing right is available and can be transmitted, the content is specified and a transmission instruction is sent to the VOD server 12. . At the same time, the VOD sending unit 14 is instructed to send conditions such as the identification of the stream to be sent and the frequency band, and the VOD sending unit 14 sends the VOD content to the transmission path under the designated conditions.

  In addition, the VOD control unit 13 notifies the receiver 15 of the transmission conditions set in the VOD transmission unit 14, and the receiver 15 receives the content transmitted based on the transmission conditions.

  Receiving the transmission instruction from the VOD control unit 13, the VOD server 12 reproduces the instructed content and transmits it from the VOD transmission unit 14 to the receiver 15 via the transmission path.

  The receiver 15 receives a signal sent from the VOD sending unit 14 according to sending conditions instructed from the VOD control unit 13. Then, common information is extracted from the signal and sent to the limited reception decoding unit 16 attached to or built in the receiver 15. The conditional access decryption unit 16 decrypts the common information with the work key that is sent in advance and stored in the individual information, and compares it with the individual information written in advance. If there is, it is determined that viewing is possible, and the scramble key described in the common information is returned to the receiver 15. The receiver 15 uses this scramble key to descramble the content that is sent and allows normal video to be viewed.

  In addition, when the scrambler 20 performs the scramble process, it is possible to leave a specific data block unscrambled. This is because the VOD server 12 needs to create a special playback file such as fast forward / rewind in response to a request from the viewer. For this purpose, the index data block in the content needs to be unscrambled. As a result, a special playback file can be created from the main content that has been scrambled, and both the conditional access function and the special playback function in the VOD service can be realized.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIG.

  Also in the second embodiment, since the configuration is the same as that in FIG. 1, a detailed description of the device is omitted. The second embodiment is different from the first embodiment in that there are a plurality of broadcasting stations or CATV stations using this for one VOD system 1, and the broadcasting system 30 starts from 30-1. There are a plurality of up to 30-n.

  Each of the broadcasting systems 30-1 to 30-n employs a limited reception system of the same system, and a work key used for limited reception is different.

  In the second embodiment, the common information is not multiplexed to the content by the scrambler 20, but is sent from the scramble control unit 21 to the VOD control unit 13 and multiplexed at the time of content transmission on the VOD system side.

  A sequence for scrambling the VOD content will be described with reference to FIG.

  First, prior to scrambling, each of the broadcasting systems 30-1 to 30-n notifies the scramble control unit 21 of the uniquely assigned HE identification number (HE-ID) and work key (Kw) <S1>.

  The scramble control unit 21 stores a set of HE identification numbers (HE-ID) and work keys (Kw) for the broadcasting system. In this embodiment, the number is n.

  Next, when the content is sent to the scrambler 20, a key request signal is sent from the scrambler 20 to the scramble control unit 21 <S2>.

  The scramble control unit 21 extracts the work key (Kw1) of the first broadcast transmission system from the held work keys and sends it to the common information generation unit 22. Subsequently, the generated common scramble key (Ks) and VOD program information (AC) are sent to the common information generation unit 22.

  Upon receiving this, the common information generating unit 22 generates common information (ECM1) for viewing and sends it back to the scramble control unit 21. <S3-1>.

  As a result, the scramble control unit 21 obtains common information (ECM1) for the first broadcast transmission system.

  This procedure is repeated for all the broadcast transmission systems that are held, and VOD common information (ECM1 to n) corresponding to all the broadcast transmission systems is obtained <S3-2> to <S3-n>. .

  Thereafter, the scramble control unit 21 sends the scramble key (Ks) to the scrambler 20 <S4>.

  The scrambler 20 scrambles the content with the scramble key (Ks) sent to all HEs.

  On the other hand, a set of common information (VOD common information (ECM1 to n)) and HE identification number (HE-ID) for each broadcasting transmission system is sent from the scramble control unit 21 via the VOD control unit 13 to the VOD server 12. Sent to.

  The VOD server 12 accumulates a set of content separately sent from the scrambler 20, a HE identification number (HE-ID) corresponding to the content, and VOD common information (ECM1 to n).

  At this time, all sets of HE identification numbers (HE-ID) and VOD common information (ECM1-n) sent from the scramble control unit 21 to the VOD control unit 13 are normally sent. However, the scramble control unit 21 sets in advance to which broadcast station each content is distributed, creates only the set VOD common information (ECM1 to n) for the broadcast station, and sends it to the VOD control unit 13. By doing so, it becomes possible to operate contents by broadcasting station.

  Furthermore, instead of setting the distribution broadcast station by the scramble control unit 21, it is possible to describe in the metadata indicating the content attribute transmitted along with the content through the distribution network 10. The scramble control unit 21 creates only the VOD common information (ECM) for the broadcasting station described in the metadata. In this way, the content supplier can determine the content operation of which broadcast station to distribute.

  The VOD control unit 13 individually manages the subordinate receiver number and which broadcast transmission system the receiver is subordinate to.

  When a VOD viewing request is received from the receiver 15, it is determined to which broadcasting transmission system the receiver belongs and whether the requested content viewing right is available. 12 is notified of the content number and the HE identification number (HE-ID).

  Information managed by the VOD control unit 13 will be described with reference to FIG.

  The receiver information table 40 is information managed for each receiver. Each receiver includes a receiver number, a HE identification number (HE-ID) to which the receiver belongs, and a viewing permission number indicating a program that can be viewed.

  The content information table 41 is information managed for each content, and includes a content number and a viewing permission number for each content.

  A receiver number and a content number are sent from the receiver 15 as a VOD program viewing request.

  The VOD control unit 13 first obtains a viewing permission number related to the requested VOD content from the content information table 41. For example, it is assumed that the content number 1002 is requested from the receiver having the receiver number 0000002. It can be seen from the content information table 41 that the viewing permission number for the content number 1002 is 101.

  Next, the receiver information table 40 determines whether the receiver that has made the request has the right to view the content. In the above example, the receiver with the receiver number 000002 has the viewing permission number 101, and the requested content number 1002 can be viewed.

  Finally, when it is determined that viewing is possible, the VOD server 12 is notified of the content number and the broadcasting system number (HE identification number) to which the requesting receiver belongs. In this example, the content number 1002 and the HE identification number 01 are sent.

  The VOD server 12 multiplexes common information (ECM) corresponding to the content designated by the designated content number and HE identification number (HE-ID) and sends it to the VOD sending unit 14.

  As described above, the VOD system can be shared between broadcasting stations such as CATV stations having different broadcasting facilities.

  As described above, in the present invention, when a CATV station that has already introduced a conditional access system for digital broadcasting newly introduces a VOD service, a part of the conditional access system used for broadcasting is used as it is. It can also be applied to.

  Furthermore, it is possible to share the same VOD system between broadcasting transmission systems such as different digital CATV broadcasting stations.

The block diagram which shows the system configuration | structure in Embodiment 1 of this invention. Schematic diagram showing common information in the first embodiment The block diagram which shows the system configuration | structure in Embodiment 2 of this invention. The figure which showed the sequence in Embodiment 2. The figure which showed the information which the VOD control part in Embodiment 2 manages

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 VOD system 12 VOD server 13 VOD control part 20 Scrambler 21 Scramble control part 22 Common information generation part

Claims (7)

A VOD server that stores content made up of video information and audio information provided to the viewer, and an instruction to receive a request from the viewer and send the content in response to the request is received at the receiver side. A VOD control unit for notifying a receiver of necessary transmission conditions, a scramble unit for scrambling the content, and a common for generating common information necessary for descrambling on the receiver side when the content is scrambled A scramble control unit that generates a scramble process and a scramble key by controlling the information generation unit, the scramble unit, and the common information generation unit, receives a request from a viewer, and sends it to the VOD control unit and sends it from the server Receivers that receive and descramble received content, and In VOD system consisting of transmission line for connection,
The scramble control unit creates the common information in the same format as the common information used in a normal broadcasting service different from the VOD service, further encrypts the common information with the same work key, and sends it together with the content. The VOD system is characterized in that the conditional access decoding unit for extracting the descrambling key from the common information is shared between the broadcast service and the VOD service. When the scramble control unit creates common information, it receives necessary work keys and numbers for identifying different broadcast stations from broadcast service conditional access systems of different broadcast stations, and is necessary for descrambling on the receiver side. A plurality of common information encrypted with each work key is created for each piece of information, and the VOD control unit identifies which broadcast equipment the receiver that transmitted the request belongs to, and uses the work key corresponding to the broadcast equipment. 2. The VOD system according to claim 1, wherein the encrypted common information is transmitted together with the content. The scramble control unit creates common information for a specific broadcasting station preset for each content from a plurality of different broadcasting stations, and sends the previous period common information together with the VOD content from the VOD server. The VOD system according to claim 2. The scramble control unit creates common information for a broadcasting station specified by metadata indicating the attribute of the content transmitted together with the content from a plurality of different broadcasting stations, and the common information for the previous period is obtained from the VOD server as a VOD. The VOD system according to claim 2, wherein the VOD system is transmitted together with content. 5. The VOD according to claim 1, wherein the scramble control unit transmits the common information received from the common information generation unit to the scrambler, and the scrambler multiplexes the common information in a specific part in the content. system. The scramble control unit transmits the common information received from the common information generation unit to the VOD control unit, and the VOD control unit multiplexes the content and the common information with a VOD server when transmitting the content. Item 5. The VOD system according to Items 1 to 4. 7. The VOD system according to claim 1, wherein the scrambler makes a specific data block of content non-scrambled.

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