JP2008182563A - Content distribution server and content distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To store PMT data into PMT packets so as not to increase the number of the PMT packets when DTCP descriptors are inserted into the PMT packets. <P>SOLUTION: A content distribution server of the present invention, when size of a padding area of a PMT packet is smaller than size of a DTCP descriptor, repeats an operation of deleting an ES descriptor of data for data broadcast of a second loop until the size of the padding area becomes equal to or above the size of the DTCP descriptor and after that, inserts the DTCP descriptor into the PMT packet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a content distribution server and a content distribution system for distributing terrestrial / BS / CS digital broadcast program content.

  Standards for receiving terrestrial / BS / CS digital broadcast program content are defined by ARIB (Association of Radio Industries and Businesses) (see Non-Patent Documents 1 and 2).

  Hereinafter, the data structure of the stream data of the program content defined by ARIB will be described with reference to FIG.

  As shown in FIG. 6, the stream data of the program content is before the ES packet storing ES (Elementary Stream) data of video (Video), audio (Audio), subtitles, and data for data broadcasting constituting the program content. A PMT (Program Map Table) packet storing a PID (packet ID) for identifying these ES packets is arranged, and a PAT (Program Association Table) packet storing the PID of the PMT packet is arranged before the PMT packet. It has a structured.

  The PMT packet is a payload portion having a fixed length of 184 bytes, and has a structure for designating the PID of each ES.

  The payload includes a program information length indicating the size of a first loop (1st loop), a first loop, a second loop (ES loop), and a CRC (Cyclic Redundancy Check). The calculation results are described in the sections in order, and a section length (Section length) indicating the size of the section is described before the section. In FIG. 6, since the payload size is less than the fixed length of 184 bytes, a padding area (empty area) exists.

  Further, the first loop includes a digital copy control descriptor including control information related to program content copying (for example, information designating whether copying is permitted, the number of times of copying), and control information related to program content storage and output (for example, whether output is possible). , Content use descriptors including information specifying resolution at the time of output) are described.

  In the second loop, an ES descriptor for storing the PID of the ES packet is described. Each ES descriptor may include the above-described digital copy control descriptor.

  Incidentally, DTCP (Digital Transmission Content Protection) -IP is defined as a standard for transmitting terrestrial / BS / CS digital broadcast program content within an IP network (see Non-Patent Documents 3 and 4). According to the DTCP-IP, it is defined that a DTCP descriptor (DTCP_descriptor) is inserted into a PMT packet when program content stream data is transmitted in an IP network.

  The DTCP descriptor is generated using the digital copy control descriptor and the content usage descriptor of the first loop. In this case, the DTCP descriptor covers the entire program content. In addition, when a digital copy control descriptor is included in each ES descriptor of the second loop, the DTCP descriptor is generated using the digital copy control descriptor. In this case, only the corresponding ES data is targeted for the DTCP descriptor. In FIG. 6, only the former DTCP descriptor exists, and its size is a fixed length of 6 bytes.

  Hereinafter, a general content distribution operation for distributing stream data of program content from a content distribution server to a client terminal via an IP network will be described with reference to FIG. In FIG. 7, description will be made assuming that the stream data of the program content is already encrypted and stored in the HDD in the content distribution server.

  As shown in FIG. 7, the content distribution server first provides a program list to the client terminal via the IP network (step 701).

  Next, the client terminal makes a distribution request for the program content selected by the client to the content distribution server via the IP network (step 702).

  When the content distribution server recognizes that the program distribution request is a request from a client terminal via the IP network, the following operation is performed.

  The content distribution server and the client terminal authenticate each other and perform key exchange (steps 703 and 704). As a result, the key used for encryption / decryption is shared between the content distribution server and the client terminal.

  Next, the content distribution server decrypts the stream data of the program content that is already encrypted and stored in the HDD (step 705), generates a DTCP descriptor, and inserts it into the decrypted stream data ( Step 706), the stream data is encrypted by an encryption method (AES encryption) defined by DTCP-IP (Step 707), and distributed to the client terminal via the IP network (Step 708).

Next, the client terminal decodes the stream data of the program content distributed from the content distribution server (step 709), analyzes the control information included in the DTCP descriptor attached to the stream data, and outputs the resolution etc. Is recognized (step 710), and the program content is output on the screen (step 711).
Radio Industry Association, “Digital Terrestrial Television Broadcasting Operation Regulations”, ARIB TR-B14 2.9 Edition (Second Volume), Issued on September 28, 2006, Volume 4, PSI / SI Operation Regulations (4. 202-4.209, 4.216-4.218) Japan Radio Industry Association, “Digital Terrestrial Television Broadcasting Operation Regulations”, ARIB TR-B14 2.9 edition (third volume), published on September 28, 2006, Volume 8 Content Protection Regulations (8.10- 8.15) DTLA (Digital Transmission Licensing Administrator), “Digital Transmission Content Protection Specification Volume 1 (Informational Version)”, Revision 1.4, February 28, 2005, p. 67-70 DTLA, “DTCP Volume 1 Supplement E Mapping DTCP to IP (Informational Version)”, February 28, 2005, Revision 1.1, p. 10-12

  By the way, in the content distribution server, when the DTCP descriptor is inserted into the stream data according to the DTCP-IP standard, if the size of the padding area of the PMT packet is equal to or larger than the size of the DTCP descriptor, all or part of the padding area Can be used to insert a DTCP descriptor.

  However, as shown in FIG. 8, when the size of the padding area is smaller than the size of the DTCP descriptor, if the DTCP descriptor is simply inserted, the data protruding from the PMT packet (in FIG. 3, the last data broadcasting data Therefore, it is necessary to continuously provide new PMT packets in order to store the protruding data. In the case of this figure, two PMT packets are required to store the PMT data.

  As a result, the number of PMT packets for storing the PMT data increases to two, which increases the data size of the program content to be distributed and the positional deviation of the ES data, and the client terminal side during special playback (such as fast forward) Thus, even if the number of bytes is specified in order to reproduce ES data that is several bytes ahead of the current position, a data position different from the ES data desired by the client terminal side is specified.

  Therefore, as shown in FIG. 9, at the time of special playback, the client terminal inevitably designates ES data by time (time seek information) to the content distribution server (step 901).

  In this case, if the content distribution server adopts a so-called byte seek method that seeks the position of ES data in units of bytes, processing for converting the time specified by the client terminal into bytes is required (step 902). ). This time-byte conversion process increases the load on the content distribution server, and the load further increases as the number of client terminals increases. Note that steps 903 to 906 in FIG. 9 are the same as steps 705 to 708 in FIG. 7.

  As described above, when the change in the data size of the program content and the shift in the data position occur due to the increase in the PMT packet, the byte seek method cannot be used as the data designation method at the time of the special reproduction, so the PMT packet increases. It is desirable to store the PMT data so that it does not exist.

  Therefore, an object of the present invention is to provide a content distribution server and a content distribution system that can store PMT data so that PMT packets do not increase when a DTCP descriptor is inserted into a PMT packet.

In order to achieve the above object, the content distribution server of the present invention provides:
A content distribution server that inserts a DTCP descriptor into a PMT packet constituting stream data of terrestrial / BS / CS digital broadcast program content according to the DTCP-IP standard, and distributes the stream data via an IP network. And
A padding size calculator that calculates the size of the padding area of the PMT packet;
A DTCP descriptor generation unit that generates the DTCP descriptor using control information included in the PMT packet;
Until the size of the padding area of the PMT packet becomes equal to or larger than the size of the DTCP descriptor, the operation of deleting the ES descriptor of the data broadcasting data in the second loop of the PMT packet is repeated, and then the DTCP descriptor is changed. And a PMT packet constructing unit to be inserted into the PMT packet.

  In this case, the PMT packet configuration unit may delete the ES descriptor of the data broadcasting data of the second loop of the PMT packet in order from the tail.

The DTCP descriptor generation unit generates the DTCP descriptor using control information included in the first loop of the PMT packet, and the video, audio, caption, and data broadcast of the second loop of the PMT packet. Generating the DTCP descriptor using control information included in each ES descriptor of the data for use,
Priorities are assigned to each of the DTCP descriptors in advance,
The PMT packet configuration unit performs data broadcasting of the second loop of the PMT packet until the size of the padding area of the PMT packet is equal to or larger than the total size of DTCP descriptors having a certain priority among the DTCP descriptors. It is also possible to repeat the operation of deleting the ES descriptor of the business data, and then insert the DTCP descriptor having the certain priority into the PMT packet.

  Further, the DTCP descriptor having the certain priority may be a DTCP descriptor generated using control information included in a first loop of the PMT packet.

  In addition, the DTCP descriptor having the predetermined priority includes a DTCP descriptor generated using control information included in the first loop of the PMT packet, and a video, audio of the second loop of the PMT packet, It may be a DTCP descriptor generated using control information included in each ES descriptor of the caption.

In order to achieve the above object, the content distribution system of the present invention provides:
Content that distributes the stream data to the terminal via the IP network after inserting the DTCP descriptor into the PMT packet constituting the stream data of the terrestrial digital broadcast program content according to the DTCP-IP standard A content distribution system comprising a distribution server,
The content distribution server is
A padding size calculator that calculates the size of the padding area of the PMT packet;
A DTCP descriptor generation unit that generates the DTCP descriptor using control information included in the PMT packet;
Until the size of the padding area of the PMT packet becomes equal to or larger than the size of the DTCP descriptor, the operation of deleting the ES descriptor of the data broadcasting data in the second loop of the PMT packet is repeated, and then the DTCP descriptor is changed. And a PMT packet constructing unit to be inserted into the PMT packet.

  According to the present invention configured as described above, the content distribution server deletes the ES descriptor of the data broadcasting data for the second loop until the size of the padding area of the PMT packet is equal to or larger than the size of the DTCP descriptor. Since the DTCP descriptor is inserted into the PMT packet after that, the PMT packet is not increased, and the data size of the program content can be maintained.

  Further, as a result, a terminal that makes a program distribution request to the content distribution server can designate data by byte designation at the time of special reproduction. Therefore, the content distribution server performs time-byte conversion processing as in the prior art. There is no need to perform the process, and an increase in load due to the time-byte conversion process can be avoided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the content distribution system according to the present embodiment distributes the client terminal 10 and stream data of terrestrial / BS / CS digital broadcast program content to the client terminal 10 via the IP network 30. Distribution server 20.

  The content distribution server 20 includes a control unit 21, a stream data receiving unit 22, an HDD 23, an encryption / decryption processing unit 24, and a network I / F 25.

  The control unit 21 controls the entire processing performed in the content distribution server 20, for example, processing for analyzing control information (digital copy control descriptor, content usage descriptor, etc.) included in the stream data, client terminal Processing for performing authentication and key exchange with 10 and processing for generating a DTCP descriptor and inserting it into a PMT packet.

  The stream data receiving unit 22 receives stream data of digital terrestrial broadcast program content as shown in FIG. 6 in an encrypted state. Note that the present invention is not limited to this, and a broadcast wave of terrestrial / BS / CS digital broadcasting can be directly received and converted into stream data. In that case, a means for converting broadcast waves into stream data is required.

  The HDD 23 stores the encrypted stream data received by the stream data receiving unit 22.

  The encryption / decryption processing unit 24 performs encryption / decryption processing of stream data using a key exchanged with the client terminal 10. For example, before the DTCP descriptor generation / insertion process, the stream data that has already been encrypted and stored in the HDD 23 is decrypted, and after the process, the stream data into which the DTCP descriptor is inserted is encrypted again.

  The network I / F 25 is an interface part with the IP network 30. For example, in the network I / F 25, program content stream data is transmitted to the client terminal 10 via the IP network 30, and a program distribution request from the client terminal 10 is received via the IP network 30.

  The client terminal 10 includes a control unit 11, a network I / F 12, a decryption processing unit 13, and an output unit 14.

  The control unit 11 controls the entire processing performed in the client terminal 10, for example, processing for analyzing control information included in stream data, processing for performing authentication and key exchange with the content distribution server 20, and the like. I do.

  The network I / F 12 is an interface part with the IP network 30. For example, in the network I / F 12, a program distribution request is transmitted to the content distribution server 20 via the IP network 30, and stream data of the program content from the content distribution server 20 is received via the IP network 30.

  The decryption processing unit 13 decrypts the stream data distributed from the content distribution server 20 using the key exchanged with the content distribution server 20.

  The output unit 14 displays the program content on the screen or the like according to the analysis result of the control information by the control unit 11 (for example, the output resolution obtained by analyzing the DTCP descriptor).

  Here, among the constituent elements constituting the control unit 21, constituent elements relating to the DTCP descriptor generation / insertion processing will be described with reference to FIG.

  As illustrated in FIG. 2, the control unit 21 includes a PMT packet control unit 210, a padding size calculation unit 211, a DTCP descriptor generation unit 212, and a PMT packet as components related to DTCP descriptor generation / insertion processing. A configuration unit 213, a program information length calculation unit 214, a section length calculation unit 215, and a CRC calculation unit 216 are included.

  The PMT packet control unit 210 controls the entire process related to the DTCP descriptor generation / insertion process.

  The padding size calculation unit 211 calculates the size of the padding area of the PMT packet.

  The DTCP descriptor generation unit 212 generates a DTCP descriptor using the digital copy control descriptor and the content use descriptor of the first loop. If each ES descriptor in the second loop includes a digital copy control descriptor, a DTCP descriptor is also generated using the digital copy control descriptor.

  The PMT packet configuration unit 213 reconfigures each data of the PMT packet, and inserts a DTCP descriptor into the PMT packet.

  Further, as a characteristic operation of the present invention, as shown in FIG. 3, the PMT packet configuration unit 213 sets the ES descriptor of data for data broadcasting when the size of the padding area is smaller than the size of the DTCP descriptor. delete. By repeating this deletion process, a DTCP descriptor is inserted after a padding area for inserting the DTCP descriptor is secured. Note that the PMT data deleted from the PMT packet is not the data broadcast data itself, but merely an ES descriptor for storing the PID of the ES packet of the data broadcast data, and therefore, the program content is reproduced on the client terminal 10 side ( (Video, audio, subtitles) is not particularly affected.

  The program information length calculation unit 214 calculates the program information length after insertion of the DTCP descriptor, the section length calculation unit 215 calculates the section length after insertion of the DTCP descriptor, and the CRC calculation unit 216 calculates the DTCP description. CRC after child insertion is calculated. These calculation results are described in the corresponding part of the PMT packet by the PMT packet configuration unit 213.

  Hereinafter, an operation of the content distribution system shown in FIGS. 1 and 2 will be described. Since the overall flow of the content distribution operation of the present invention is the same as that in FIG. 7, hereinafter, refer to FIG. 4 for the DTCP descriptor generation / insertion operation, which is a characteristic operation of the present invention. To explain. The operation in FIG. 4 corresponds to step 706 in FIG.

  As shown in FIG. 4, the padding size calculation unit 211 first calculates the size of the padding area of the PMT packet based on the section length (step 401).

  Next, the DTCP descriptor generation unit 212 generates a DTCP descriptor using the digital copy control descriptor and the content use descriptor of the first loop (step 402). If each ES descriptor of the second loop includes a digital copy control descriptor, a DTCP descriptor is further generated using the digital copy control descriptor.

  Next, the PMT control unit 210 determines whether or not the size of the padding area is smaller than the size of the DTCP descriptor (step 403).

  If the size of the padding area is smaller than the size of the DTCP descriptor, the PMT packet configuration unit 213 deletes the ES descriptor of the data for data broadcasting in order to secure a padding area for inserting the DTCP descriptor. (Step 404). At this time, it is preferable to delete the ES descriptor of the data broadcasting data from the tail end.

  Here, again in step 403, the PMT control unit 210 derives the size of the padding area increased by deleting the ES descriptor of the data broadcasting data, and determines again whether or not it is smaller than the size of the DTCP descriptor. . If it is still smaller than the size of the DTCP descriptor, in step 404, the PMT packet configuration unit 213 further deletes the ES descriptor of the data for data broadcasting. The operations in steps 403 and 404 are repeated until the size of the padding area becomes equal to or larger than the size of the DTCP descriptor.

  When the size of the padding area becomes equal to or larger than the size of the DTCP descriptor and the padding area for inserting the DTCP descriptor is secured, the PMT packet configuration unit 213 inserts the DTCP descriptor into the PMT packet (step 405). ).

  After inserting the DTCP descriptor, the program information length calculation unit 214 calculates the program information length, the section length calculation unit 215 calculates the section length, the CRC calculation unit 216 calculates the CRC, and the PMT packet configuration unit 213 The calculation result is described in the corresponding part of the PMT packet to replace the PMT data (step 406).

  In the present embodiment, the control information included in each ES descriptor of the DTCP descriptor created using the control information included in the first loop, the video, audio, caption, and data for data broadcasting in the second loop. Although all the DTCP descriptors created using the above are described as being inserted into the PMT packet, the present invention is not limited to this.

  That is, priority may be given to each DTCP descriptor, and only the DTCP descriptor having a certain priority may be inserted into the PMT packet.

  For example, as shown in Table 1, when priority levels “1” to “3” are assigned to each DTCP descriptor and the padding size is insufficient, data broadcasting including a DTCP descriptor with a priority level “3” is used. Either delete the data ES descriptor and insert only the DTCP descriptor with the priority “1”, or insert only the DTCP descriptors with the priority “1” and “2”. Also good.

  In Table 1, for example, when only DTCP descriptors with priorities of “1” and “2” are inserted, the controls included in the ES descriptors of the video, audio, and subtitles of the first loop and the second loop The operations of Steps 403 and 404 are repeated until a padding area for inserting the DTCP descriptor created using the information is secured. When the padding area is secured, these DTCP descriptors are inserted. If there is a margin in the padding area at this time, insert a DTCP descriptor with a priority “3” created using the control information included in the ES descriptor of the data broadcasting data in the second loop. Also good.

  As described above, according to the present embodiment, the operation of deleting the ES descriptor of the data broadcasting data in the second loop is repeated until the size of the padding area of the PMT packet becomes equal to or larger than the size of the DTCP descriptor, and thereafter Since the DTCP descriptor is inserted into the PMT packet, the PMT data can be stored without increasing the number of PMT packets.

  As a result, since the number of PMT packets does not increase on the content distribution server 20 side, when the number of bytes is specified on the client terminal 10 side during special playback, a different ES data position is specified as in the prior art. Can be avoided.

  Therefore, as shown in FIG. 5, even when the content distribution server 20 adopts the byte seek method, the client terminal 10 converts the time instructed by the client into bytes (step 501), and converts the converted bytes. ES data can be designated to the content distribution server 20 by the number (byte seek information) (step 502). Note that steps 503 to 506 in FIG. 5 are the same as steps 705 to 708 in FIG. 7.

  Therefore, the content distribution server 20 does not need to perform time-byte conversion processing as in the prior art, and can avoid an increase in load due to time-byte conversion processing.

It is a figure which shows the structure of the content delivery system of one Embodiment of this invention. It is a figure which extracts and shows the component which concerns on the production | generation / insertion process of a DTCP descriptor among the components of the control part in the content delivery server shown in FIG. It is a figure explaining the outline | summary of the production | generation / insertion process of a DTCP descriptor in the content delivery system shown in FIG. 3 is a flowchart for explaining a flow of DTCP descriptor generation / insertion processing in the content distribution system shown in FIG. 1. 2 is a flowchart for explaining a flow of special reproduction processing when the content distribution server adopts a byte seek method in the content distribution system shown in FIG. 1. It is a figure explaining the data structure of the stream data of the program content prescribed | regulated by ARIB. It is a flowchart explaining the flow of a general content delivery operation | movement. It is a figure explaining the outline | summary of the production | generation and insertion process of the conventional DTCP descriptor. It is a flowchart explaining the flow of the conventional special reproduction | regeneration processing in case a content delivery server employ | adopts a byte seek system.

Explanation of symbols

10 Client terminal 11 Control unit 12 Network I / F
13 Decoding Processing Unit 14 Output Unit 20 Content Distribution Server 21 Control Unit 22 Stream Data Receiving Unit 23 HDD
24 Encryption / Decryption Processing Unit 25 Network I / F
30 IP network 210 PMT packet control unit 211 Padding size calculation unit 212 DTCP descriptor generation unit 213 PMT packet configuration unit 214 Program information length calculation unit 215 Section length calculation unit 216 CRC calculation unit

Claims (6)

A content distribution server that inserts a DTCP descriptor into a PMT packet constituting stream data of terrestrial / BS / CS digital broadcast program content according to the DTCP-IP standard, and distributes the stream data via an IP network. And
A padding size calculator that calculates the size of the padding area of the PMT packet;
A DTCP descriptor generation unit that generates the DTCP descriptor using control information included in the PMT packet;
Until the size of the padding area of the PMT packet becomes equal to or larger than the size of the DTCP descriptor, the operation of deleting the ES descriptor of the data broadcasting data in the second loop of the PMT packet is repeated, and then the DTCP descriptor is changed. A content delivery server having a PMT packet constructing unit to be inserted into the PMT packet.   The content distribution server according to claim 1, wherein the PMT packet configuration unit deletes the ES descriptor of the data broadcasting data of the second loop of the PMT packet in order from the tail. The DTCP descriptor generation unit generates the DTCP descriptor using control information included in the first loop of the PMT packet, and the video, audio, caption, and data broadcasting data of the second loop of the PMT packet Generating the DTCP descriptor using control information included in each ES descriptor of
Priorities are assigned to each of the DTCP descriptors in advance,
The PMT packet configuration unit performs data broadcasting of the second loop of the PMT packet until the size of the padding area of the PMT packet is equal to or larger than the total size of DTCP descriptors having a certain priority among the DTCP descriptors. The content distribution server according to claim 1 or 2, wherein the operation of deleting the ES descriptor of the data for use is repeated, and then the DTCP descriptor having the certain priority is inserted into the PMT packet.   The content distribution server according to claim 3, wherein the DTCP descriptor having the certain priority is a DTCP descriptor generated using control information included in a first loop of the PMT packet.   The DTCP descriptor having the predetermined priority is a DTCP descriptor generated using control information included in the first loop of the PMT packet, and video, audio, and subtitles of the second loop of the PMT packet. The content distribution server according to claim 3, wherein the content distribution server is a DTCP descriptor generated using control information included in each ES descriptor. In accordance with the DTCP-IP standard, after inserting a DTCP descriptor into a PMT packet constituting stream data of terrestrial / BS / CS digital broadcast program content, the stream data is transmitted to the terminal via the IP network. A content distribution system that distributes the content distribution server,
The content distribution server is
A padding size calculator that calculates the size of the padding area of the PMT packet;
A DTCP descriptor generation unit that generates the DTCP descriptor using control information included in the PMT packet;
Until the size of the padding area of the PMT packet becomes equal to or larger than the size of the DTCP descriptor, the operation of deleting the ES descriptor of the data broadcasting data in the second loop of the PMT packet is repeated, and then the DTCP descriptor is changed. A content distribution system comprising: a PMT packet configuration unit to be inserted into the PMT packet.

Images