JP2012249073A - Decoder, encoder, encoding/decoding system, descrambler, scrambler, and method of them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decoder for shortening channel switching time, an encoder, an encoding/decoding system, a descrambler, a scrambler, and a method of them.SOLUTION: The encoder decodes stream data obtained by scrambling an I picture, and a B picture, and a P picture, which refer to the I picture, and including them. The encoder includes: a key generation section for generating a descrambling key of a picture referring to the I picture on the basis of the I picture; and the descrambler for descrambling the I picture by the descrambling key of the I picture, which is previously prepared, and descrambling the picture referring to the I picture by the descrambling key generated by the key generation section.

Description

  The present invention relates to a decoding apparatus, an encoding apparatus, an encoding / decoding system, a descrambler, a scrambler, and methods thereof.

  In recent years, with the spread of digital broadcasting, digital contents such as moving images that require copyright protection have been distributed by transmission means such as broadcast waves and IP (Internet Protocol) networks. In general, in order to prevent unauthorized viewing and copying, digital content is encrypted (scrambled) and distributed. As an example, in digital broadcasting in Japan, digital content is scrambled called Multi2 to prevent viewing or recording by other than a valid receiver.

  The key information used for the decryption (descrambling) of the digital content encrypted in this manner is multiplexed as related data in a stream including the digital content at regular intervals. However, by doing so, since the key generation processing is performed after the key information is acquired when the channel is switched, the time until the output of the image and the sound is delayed. Therefore, it is desired to reduce the waiting time at the time of activation and the waiting time at the time of switching channels so that the viewer can watch without stress.

  Patent Documents 1 to 4 disclose techniques for shortening the waiting time when switching channels. Among them, Patent Document 1 aims to descramble a stream of a channel selected when switching a plurality of scrambled channels in a receiving apparatus in a short time.

  With reference to FIG. 10, the transmission apparatus 128 and the reception apparatus 110 of the conditional access system concerning patent document 4 are demonstrated. FIG. 10 is a block diagram illustrating configurations of the transmission device 128 and the reception device 110 of the conditional access system according to Patent Document 4.

  The transmission device 128 includes a key management device 11, a Kw encryption unit 12, a TS multiplexing unit 13, a Ks encryption unit 14, a scrambler 15, a content generation unit 16, a TS encoder 17, a 64QAM modulation unit 18, and a multiplexed information generation unit. 125 and a frequency multiplexing unit 126.

  The key management device 11 generates and manages a scramble key Ks, a work key Kw, and an individual key Kmi. The Kw encryption unit 12 encrypts the individual information EMM storing the work key Kw with Kmi. The TS multiplexing unit 13 multiplexes the individual information EMM, the common information ECM, the transport stream, and PSI (Program Specific Information) as defined in MPEG2 SYSTEMS (ISO / IEC 13818-1). The Ks encryption unit 14 encrypts the common information ECM storing the scramble key Ks with Kw. The scrambler 15 scrambles only the content stream from the data multiplexed by the TS multiplexing unit 13 with the scramble key Ks. The content generation unit 16 generates content such as video and data. The TS encoder 17 converts the content into a data format of an MPEG2 SYSTEM TS packet (Transport Stream Packet). The 64QAM modulator 18 performs 64Q modulation on transmission data. The multiplex information generation unit 125 generates MPEG2 SYSTEMS PSI in accordance with channel and program information. The frequency multiplexing unit 126 frequency-multiplexes the modulated signal.

  The receiving apparatus 110 includes a 64QAM demodulator 111, a TS separator 112, a control CPU 113, a descrambler 114, a special key decryption module 115, a general-purpose key decryption module 116, a TS decoder 123, an AV decoder 124, and a frequency separator 127. Yes.

  The 64QAM demodulator 111 demodulates the received signal by 64QAM. The TS separation unit 112 separates PSI, video stream, common information ECM, individual information EMM, and the like from the received signal. The control CPU 113 transmits the Program-ID to be filtered based on the PSI information to the TS separation unit 112, the descrambler 114, and the like. The descrambler 114 descrambles the video stream of the selected channel using Ks. The special key decryption module 115 decrypts Ks. The general-purpose key decryption module 116 is composed of an IC card. The general key decryption module 116 decrypts Ks. The TS decoder 123 converts the descrambled stream into a content stream format. The AV decoder 124 converts the content stream into a viewable analog signal. The frequency separation unit 127 performs frequency separation on the signal received from the transmission path 19.

  The special key decryption module 115 decrypts Ks when the transmission side uses Ks common to a plurality of channels. The special key decryption module 115 includes a Kw decryption unit 118 and a Ks decryption unit 119. The Kw decryption unit 118 decrypts the EMM with the individual key Kmi117 that is held in advance, and extracts Kw. The Ks decryption unit 119 decrypts the ECM with Kw and extracts Ks. The channel selected by the control CPU 113 is transmitted to the Ks decoding unit 119.

  The general-purpose key decryption module 116 configured with an IC card performs decryption of Ks when the transmission side does not use Ks common to a plurality of channels. The general-purpose key decryption module 116 configured with an IC card includes a Kw decryption unit 121 and a Ks decryption unit 122. Similar to the special key decryption module 115, the Kw decryption unit 121 decrypts the EMM with the individual key Kmi120 and extracts Kw. The Ks decoding unit 122 decodes the ECM with Kw and extracts Ks.

  Hereinafter, transmission / reception in this system will be described.

  On the sending side, the key management device 11 generates a work key Kw and stores it in the individual information EMM. Thereafter, the Kw encryption unit 12 encrypts the individual information EMM using Kmi received in advance from the key management apparatus 11 and sends the encrypted information to the TS multiplexing unit 13 as encrypted individual information.

  Further, the key management device 11 generates a scramble key Ks and stores it in the common information ECM. Thereafter, the Ks encryption unit 14 encrypts the common information ECM using Kw received from the key management apparatus 11 in advance, and sends it to the TS multiplexing unit 13 as encrypted common information.

  Content such as video and data is sent from the content generation unit 16 to the TS encoder 17 and converted into a data format of a TS packet in MPEG2 SYSTEMS. Content data such as video information converted to a TS is sent to the TS multiplexer 13. In the case of a multi-program configuration, content data is sent from each of a plurality of content generation units to each TS encoder. Then, the TS encoder 17 converts the content data into a TS packet and sends it to the TS multiplexer 13.

  In addition, the multiplex information generation unit 125 generates MPEG2 SYSTEMS PSI in accordance with channel and program information and sends the PSI to the TS multiplexing unit 13.

  The individual information EMM, common information ECM, content stream, and PSI sent to the TS multiplexing unit 13 are multiplexed as defined in MPEG2 SYSTEMS and sent to the scrambler 15. The scrambler 15 scrambles only the content stream using the scramble key Ks passed from the Ks encryption unit 14. The scrambler 15 sends the scrambled transport stream to the 64QAM modulation unit 18. The 64QAM modulator 18 performs 64QAM modulation on the transport stream. Further, the frequency multiplexing unit 126 performs frequency multiplexing with the other 64QAM modulated signal and sends it to the transmission line 19.

  On the other hand, in the receiving apparatus 110, the signal received from the transmission path 19 is frequency separated by the frequency separation unit 127, demodulated by the 64QAM demodulation unit 111, and the demodulated signal is separated by the TS separation unit 112.

  The control CPU 113 acquires the Program-ID to be filtered based on the PSI information of the channel selected by the receiving device operation unit, and transmits it to the TS separation unit 112. Accordingly, the TS separation unit 112 can separate the demodulated transport stream of the corresponding channel into related information (hereinafter, generic name of common information ECM and individual information EMM), a video stream, and the like. . Further, the control CPU 113 sets the Program-ID to be descrambled in the descrambler 114 and sets the selected channel in the Ks decoding unit 119.

  The related information separated by the TS separation unit 112 is sent to either the special key decryption module 115 or the general-purpose key decryption module 116, where a scramble key Ks for descrambling the content is extracted. Distribution to either the special key decryption module 115 or the general-purpose key decryption module 116 is performed according to the module identification flag of the related information. When the related information is distributed to the special key decryption module 115, the special key decryption module 115 is used.

  For example, when the special key decryption module 115 is used, the individual information EMM separated by the TS separation unit 112 is decrypted by the Kw decryption unit 118 using the individual key Kmi117 previously held. The work key Kw stored in the individual information EMM is taken out and set in the Ks decryption unit 119. Further, the common information ECM separated by the TS separation unit 112 is decrypted by the Ks decryption unit 119 using the work key Kw previously extracted. Ks stored in the common information ECM is extracted and set in the descrambler 114.

  The content stream such as video separated by the TS separation unit 112 is descrambled by the descrambler 114 using the set scramble key Ks, and sent to the TS decoder 123 to be converted into a content stream format. Further, the video is converted into an analog signal that can be viewed by the AV decoder 124.

  Here, the MPEG2-TS format will be described with reference to FIG. FIG. 11 is a diagram showing a format of MPEG2-TS.

  In MPEG2-TS, video, audio, and other data are multiplexed and transmitted. Video (video) and audio (audio) data captured by a video camera or the like is converted into compression-coded digital data called an elementary stream (ES) by a coding device called an encoder. These video ES and audio ES are divided into appropriate sizes called PES (Packetized Elementary Stream) packets. Further, in the case of MPEG2-TS, the PES packet is further divided to generate a 188-byte TS (Transport Stream) packet (for example, Non-Patent Document 1 and Non-Patent Document 2).

  Also, each piece of key information for descrambling content such as video, audio, and other data is included in data called PSI (Program Specific Information) or SI (Service Information) extended from PSI. . PSI or SI is stored in an MPEG2-TS packet different from video or audio and transmitted.

  FIG. 11 shows a process from converting an elementary stream of video and audio and an ECM (Entity Control Message), which is one of PSI, into an MPEG2-TS packet and multiplexing it into an MPEG2-TS stream. It is a thing. The ECM stores key information for scrambling content that requires copyright.

  The video ES 200 is converted into PES and converted into video PES packets 202 and 203, and the audio ES 201 is converted into PES and converted into audio PES packets 204 and 205. Further, the video PES packet 202 is converted into a TS and converted into video TS packets 206, 207, 208, and 209, and the audio PES packet 204 is converted into a TS and converted into audio TS packets 210, 211, 212, and 213. . The TS packets of the video PES packet 203 and the audio PES packet 205 are not shown. The ECM 219 is converted to a TS and converted into ECM packets 215, 216, 217, and 218. The video TS packets 206 to 209, the audio TS packets 210 to 213, and the ECM packets 215 to 218 are multiplexed with the MPEG2-TS stream 214 and transmitted.

  Next, an example of the relationship of pictures in the video ES will be described with reference to FIG. FIG. 12 illustrates an example of the relationship between pictures arranged on the time axis in a video ES compressed and encoded by MPEG.

  In MPEG, a video signal is composed of a plurality of compressed image data. The compressed image data is called a frame. Frames are classified into three types: I pictures, P pictures, and B pictures.

  An I picture (Intra-picture) can independently obtain one image regardless of the preceding and following frames. In addition, a P picture (Predictive-picture) can be obtained as a single image by performing inter-frame prediction from an I picture or P picture existing in the past on the time axis. Further, a B picture (Bi-directional Predictive-Picture) can obtain a single image by performing inter-frame prediction from pictures existing in the past, future, or both on the time axis (for example, non-patent literature). 3).

  Referring to FIG. 12, the B picture 300 can obtain a single image by performing inter-frame prediction from the I picture 302 existing in the future on the time axis. The B picture 301 can obtain one image by performing inter-frame prediction from the I picture 302 existing in the future on the time axis.

  The I picture 302 can obtain a single image by itself. The B picture 303 can obtain one image by performing inter-frame prediction from the I picture 302 existing in the past on the time axis and the P picture 304 existing in the future on the time axis. The P picture 304 can obtain one image by performing inter-frame prediction from the I picture 302 existing in the past on the time axis. Each of the B picture 305 and the B picture 306 obtains one image by performing inter-frame prediction from the P picture 304 existing in the past on the time axis and the P picture 307 existing in the future on the time axis. The P picture 307 can obtain one image by performing inter-frame prediction from the P picture 304 existing in the past on the time axis.

  In this example, each of the B picture 300 and the B picture 301 exists before the I picture 302 on the time axis. However, in order to obtain one image, the I picture existing in the future on the time axis is obtained. A picture 302 is required.

  Next, a general MPEG2-TS packet configuration will be described with reference to FIG. FIG. 13 is a configuration diagram of a general MPEG2-TS packet.

  The MPEG2-TS packet F1 has a TS header F2, an adaptation field F3, and a data byte F4. In general, every MPEG2-TS packet has a TS header F2.

  The TS header F2 includes 2-bit data called adaptation field control. When the value of the adaptation field control is “10” or “11”, the adaptation field F3 is included in the MPEG2-TS packet F1.

  When the value of the adaptation field control is “01” or “11”, the data byte F4 is included in the MPEG2-TS packet F1. The data byte F4 stores video or audio PES data or PSI / SI data.

JP 2000-295202 A JP 2010-154349 A JP 2007-215069 A JP 2009-284283 A

Sony Corporation, “Features of Blu-ray Discs”, [online], Sony Corporation website, [Search February 14, 2011], Internet <URL: http://www.sony.jp/bd/products_archive/BDZ -S77 / technology / blu.html> Nikkei Business Publications, “Introducing new technologies such as VOD collaboration using 1Seg and mass data distribution”, [online], ITpro, [Search February 18, 2011], <URL: http: //itpro.nikkeibp. co.jp/article/COLUMN/20080417/299449/> JPO, "Digital Video Compression Technology", [online], JPO homepage, [Search February 16, 2011], Internet <URL: http://www.jpo.go.jp/shiryou/s_sonota/map /denki14/4/4-3-6.htm>

  In order to obtain a normal image, the technique disclosed in Patent Document 1 described above must wait for an I picture that arrives after receiving an ECM, and only waits for an I picture that arrives after receiving an ECM. There is a problem of slow switching.

  The reason for this is that by using a module called a special key decryption module that can be decrypted with a common key that does not depend on the channel, channel switching speed has been increased, but whether or not descrambling with a common key is possible. This is because it is necessary to wait for the reception of ECM in order to determine the above. This is because, as described above, whether or not to use the special decoding module is determined by the module identification flag of the ECM.

  Specifically, with the technique disclosed in Patent Document 1, if an I picture arrives earlier than the ECM after channel switching, it cannot be determined whether the I picture can be descrambled with a common key. Therefore, in this case, the I picture cannot be descrambled.

  In addition, in order to output a normal image, it is necessary to descramble and decode the I picture before the decoding of the B picture and P picture is started, so that the I picture can be used for inter-frame prediction of the B picture and P picture. There is. However, as described above, when the I picture arrives earlier than the ECM after the channel switching, the I picture cannot be descrambled. Therefore, the inter picture prediction of the B picture and the P picture may be performed using the I picture. It becomes impossible.

  With reference to FIG. 14, the mechanism in which the problem occurs will be described in more detail. FIG. 14 is a diagram showing the relationship between the reception timing of MPEG2-TS packets on the time axis and pictures obtained from those MPEG2-TS packets.

  FIG. 14 shows a state where reception of MPEG2-TS packets 605 to 633 included in the stream after the channel switching is started from time 600. First, an MPEG2-TS packet 605 is received. Thereafter, MPEG2-TS packets 606 to 633 are sequentially received.

  In FIG. 14, each of the MPEG2-TS packets 611, 614, 615, 620, 628, and 630 indicates an audio TS packet, and each of the MPEG2-TS packets 610, 617, and 626 indicates an ECM packet. Each of the other MPEG2-TS packets represents a video TS packet.

  By receiving each video TS packet, various pictures shown in pictures 634 to 642 can be obtained. Various pictures are composed of a plurality of MPEG2-TS packets.

  Specifically, the MPEG2-TS stream shown in FIG. 14 includes a B picture 634 composed of MPEG2-TS packets 604 and 605 and a B picture 636 composed of MPEG2-TS packets 609 and 612 as pictures. B picture 637 composed of MPEG2-TS packets 613 and 616, B picture 640 composed of MPEG2-TS packets 624 and 625, B picture 641 composed of MPEG2-TS packets 627 and 629, and MPEG2 -An I picture 635 composed of TS packets 606, 607, 608, an I picture 639 composed of MPEG2-TS packets 621, 622, 623, and a P picture composed of MPEG2-TS packets 618, 619 A catcher 638, and P-picture 642 constituted by MPEG2-TS packets 631, 632, 633, are included.

  At time 601, all of the MPEG2-TS packets 606, 607, 608 constituting the I picture 635 are received. That is, a scrambled I picture 635 can be obtained at time 601. However, the ECM packet 610 is not obtained at the time 601. Therefore, the I picture 635 cannot be descrambled, and a normal image cannot be obtained from the I picture 635.

  On the other hand, after the ECM packet is acquired at the time 602 when the ECM packet 610 is first received after the stream reception is started, the B picture 636, the B picture 637, and the P picture 638 can be descrambled. . However, each of the B picture 636, the B picture 637, and the P picture 638 has a dependency relationship between the I picture 635 and inter-frame prediction. However, the B picture 636, the B picture 637, and the P picture 638 cannot be decoded using the undescrambled I picture 635. Therefore, a normal image cannot be obtained from the B picture 636, the B picture 637, and the P picture 638 as is the case with the I picture 635.

  As described above, in the stream reception relationship as shown in FIG. 14, after starting the reception of the stream after channel switching, all the pictures can be obtained correctly after receiving the ECM packet. It is after time 603 when the I picture 639 is first obtained. In other words, the time at which the receiving side can obtain a normal image after switching the channel is greatly delayed from the start of stream reception at time 600 to time 603.

  As described above, the technique disclosed in Patent Document 1 has a problem that the channel switching time from when the channel is switched to when a normal image can be obtained becomes long.

  A decoding apparatus according to a first aspect of the present invention is a decoding apparatus that decodes stream data including an I picture and a B picture and a P picture that respectively refer to the I picture. Based on the I picture, the I picture is descrambled by a key generation unit that generates a descrambling key of a picture that refers to the I picture, and a descrambling key of the I picture prepared in advance. A descrambler that descrambles a picture that refers to the I picture with a descrambling key generated by the generation unit.

  The encoding apparatus according to the second aspect of the present invention encodes moving image data to generate stream data including an I picture and a B picture and a P picture that refer to the I picture, respectively. An encoding device that scrambles the I picture by a key generation unit that generates a scramble key of a picture that refers to the I picture based on the I picture, and a scramble key of the I picture prepared in advance And a scrambler that scrambles a picture that refers to the I picture with the scramble key generated by the key generation unit.

  The encoding / decoding system according to the third aspect of the present invention encodes moving image data, and includes stream data including an I picture and a B picture and a P picture that respectively refer to the I picture. And a decoding device that decodes stream data generated by the encoding device, wherein the encoding device is based on the I picture. A scramble key generation unit that generates a scramble key for a picture that refers to the I picture, and a scramble key generated by the scramble key generation unit and a scramble key for the I picture prepared in advance. Scrambling a picture that references the I picture with a key A decrypting key generation unit configured to generate a descrambling key identical to the scramble key based on the I picture, and a scramble key for the I picture prepared in advance. A descrambler that descrambles the I picture with the same descrambling key and descrambles the picture that refers to the I picture with the descrambling key generated by the descrambling key generation unit. is there.

  A descrambler according to a fourth aspect of the present invention is a descrambler that descrambles stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures. The I picture is descrambled with the prepared descrambling key of the I picture, and the picture that refers to the I picture is descrambled with the descrambling key generated based on the I picture.

  A scrambler according to a fifth aspect of the present invention is a scrambler that scrambles an I picture, and a B picture and a P picture that respectively refer to the I picture, and a scramble key for the I picture prepared in advance. Thus, the I picture is scrambled, and a picture that refers to the I picture is scrambled by a scramble key generated based on the I picture.

  A decoding method according to a sixth aspect of the present invention is a decoding method for decoding stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures, The I picture is descrambled with a prepared descrambling key of the I picture, a descrambling key of a picture referring to the I picture is generated based on the I picture, and the generated descrambling key is generated. Thus, the picture that refers to the I picture is descrambled.

  The encoding method according to the seventh aspect of the present invention encodes moving image data to generate stream data including an I picture and a B picture and a P picture that refer to the I picture, respectively. A coding method for scrambling the I picture with a scramble key for the I picture prepared in advance, generating a scramble key for a picture referring to the I picture based on the I picture, and generating the scramble key The scrambled key is used to scramble a picture that references the I picture.

  The encoding / decoding method according to the eighth aspect of the present invention encodes moving image data, and includes stream data including an I picture and a B picture and a P picture that respectively refer to the I picture. And decoding the generated stream data, wherein the I picture is scrambled with a scramble key of the I picture prepared in advance, and the I picture is based on the I picture. A scramble key of a picture that refers to the I picture is generated, a picture that references the I picture is scrambled with the generated scramble key, and the scramble key that is the same as the scramble key of the I picture prepared in advance is used to Descramble the picture and based on the I picture, To produce the same descrambling key and tumble key, by the generated descramble key, it is to descramble the picture that refers to the I picture.

  A descrambling method according to a ninth aspect of the present invention is a descrambling method for descrambling stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures. The I picture is descrambled using a prepared descrambling key of the I picture, and a picture that refers to the I picture is descrambled using a descrambling key generated based on the I picture. .

  A scrambling method according to a tenth aspect of the present invention is a scrambling method for scrambling an I picture and a B picture and a P picture that respectively refer to the I picture, and the scrambling key for the I picture prepared in advance is provided. Thus, the I picture is scrambled, and a picture that refers to the I picture is scrambled with a scramble key generated based on the I picture.

  According to each aspect of the present invention described above, a normal image can be output from the time when an I picture is received regardless of the reception timing of other data such as ECM.

  According to each aspect of the present invention described above, it is possible to provide a decoding device, an encoding device, an encoding / decoding system, a descrambler, a scrambler, and a method thereof that can shorten the channel switching time. .

1 is a system configuration diagram including a transmission device and a reception device according to an embodiment of the present invention. It is a block diagram of the TS encoder part concerning embodiment of this invention. It is a packet block diagram of MPEG2-TS concerning an embodiment of the invention. It is a block diagram of the AV decoder part concerning embodiment of this invention. It is a control flowchart of the transmitter concerning embodiment of this invention. It is a control flowchart of the TS encoder part concerning embodiment of this invention. It is a control flowchart of the receiver concerning embodiment of this invention. It is a control flowchart of the AV decoder part concerning embodiment of this invention. It is a receiving relation figure at the time of the channel switching concerning embodiment of this invention. It is a block diagram which shows the structure of the transmitter of the conditional access system concerning patent document 1, and a receiver. It is a figure which shows the format of MPEG2-TS. It is a figure which shows the relationship of the picture in MPEG2. FIG. 2 is a general MPEG2-TS packet configuration diagram. It is a receiving relation figure at the time of the channel switching concerning patent documents 1.

  With reference to FIG. 1, the structure of the transmission / reception system concerning embodiment of this invention is demonstrated. FIG. 1 is a system configuration diagram including a transmission apparatus and a reception apparatus according to an embodiment of the present invention.

  The transmission / reception system includes a transmission device 41 and a reception device 410. The transmission device 41 and the reception device 410 are connected to each other by a transmission line 49. The transmission device 41 converts the moving image data into an MPEG2-TS stream and transmits it to the reception device 410. The receiving device 410 converts the MPEG2-TS stream received from the transmitting device 41 via the transmission path 49 into reproducible data and outputs it to an output device (not shown). Here, in the present embodiment, the case where the moving image data is television program data is exemplified. Therefore, the transmission device 41 is, for example, a digital broadcast transmission device, and the reception device 410 and the output device are devices included in the digital television receiver.

  The transmission apparatus 41 includes a content generation unit 42, a TS encoder unit 43, an initial value management unit 44, a TS multiplexing unit 45, a multiplexed information generation unit 46, a 64QAM modulation unit 47, and a frequency multiplexing unit 48.

  The content generation unit 42 generates content such as image data, audio data, caption data, and BML (Broadcast Markup Language) data. The TV program data includes a plurality of these contents. The moving image data is not limited to such television program data, and any moving image data may be used as long as it includes at least a plurality of image data among these contents. The content generation unit 42 stores and manages moving image data composed of the generated content. That is, the content generation unit 42 includes an arbitrary storage device that stores moving image data. The storage device is, for example, a memory or a hard disk. The content generation unit 42 outputs the moving image data to the TS encoder unit 43.

  Here, when the transmission device 41 is a multi-channel digital broadcast transmission device, the transmission device 41 includes a plurality of content generation units 42, and each of the content generation units 42 has contents of television program data of different channels. Is generated.

  The TS encoder unit 43 receives moving image data from the content generation unit 42 and receives an initial value from the initial value management unit 44. The TS encoder unit 43 encodes (encodes) and scrambles each of image data and audio data among the contents included in the moving image data, and converts the encoded data into the MPEG2-TS packet format. Note that the initial value functions as an initial key for a scramble key of image data. The TS encoder unit 43 outputs the generated MPEG2-TS packet to the TS multiplexing unit 45. Hereinafter, the MPEG2-TS packet of image data is also referred to as “video TS packet”, and the MPEG2-TS packet of audio data is also referred to as “audio TS packet”.

  Here, when the transmission device 41 is a multi-channel digital broadcast transmission device, the transmission device 41 includes a plurality of TS encoder units 43, and each TS encoder unit 43 includes a plurality of content generation units 42. The content of the generated television program data is converted into the MPEG2-TS packet format.

  The initial value management unit 44 manages initial values used when image data is scrambled. That is, the initial value management unit 44 has an arbitrary storage device in which the initial value is stored. Here, in this embodiment, the case where an IC card is used as a storage device in which initial values are stored is illustrated. Therefore, the initial value management unit 44 includes an IC card reader that inserts an IC (Integrated Circuit) card and reads an initial value stored in the inserted IC card. The same applies to an initial value management unit 417 described later. The initial value management unit 44 outputs the initial value to the TS encoder unit 43.

  The TS multiplexing unit 45 receives an MPEG2-TS packet of content from the TS encoder unit 43, and receives a PSI / SI (Service Information) packet from the multiplexed information generation unit 46. The TS multiplexing unit 45 multiplexes the MPEG2-TS packet and the PSI packet of the content to generate an MPEG2-TS stream. The TS multiplexing unit 45 outputs the generated MPEG2-TS stream to the 64QAM modulation unit 47.

  The multiple information generation unit 46 generates a PSI / SI packet in the MPEG2 system in accordance with the data of the television program and the channel of the data. The multiplexed information generation unit 46 outputs the generated PSI / SI packet to the TS multiplexing unit 45.

  The 64QAM modulation unit 47 performs 64Q modulation on the MPEG2-TS stream output from the TS multiplexing unit 45. The 64QAM modulation unit 47 outputs the 64-QAM modulated MPEG2-TS stream to the frequency multiplexing unit 48.

  The frequency multiplexing unit 48 frequency multiplexes the MPEG2-TS stream output from the 64QAM modulation unit 47 to generate a transmission wave. The frequency multiplexing unit 48 transmits the generated transmission wave to the reception device 410 via the transmission path 49.

  The receiving apparatus 410 includes a frequency separation unit 411, a 64QAM demodulation unit 412, a TS separation unit 413, a control CPU unit 414, a TS decoder unit 415, an AV decoder unit 416, and an initial value management unit 417.

  The frequency separation unit 411 separates the MPEG2-TS stream from the transmission wave received from the transmission device 41 via the transmission line 49. The frequency separation unit 411 outputs the separated MPEG2-TS stream to the 64QAM demodulation unit 412.

  The 64QAM demodulator 412 demodulates the MPEG2-TS packet output from the frequency separator 411 by 64QAM. The 64QAM demodulator 412 outputs the MPEG2-TS packet demodulated by 64QAM to the TS separator 413.

  The TS separation unit 413 separates the MPEG2-TS packet output from the 64QAM demodulation unit 412. The TS separation unit 413 acquires MPEG2-TS packet filtering control information from the control CPU unit 414. The filtering control information will be described later. Then, the TS separation unit 413 classifies the separated MPEG2-TS packets according to the type in accordance with the acquired filtering control information, and outputs them to the TS decoder unit 415.

  The control CPU unit 414 controls MPEG2-TS packet filtering and descrambling. The control CPU unit 414 acquires filtering control information and descrambling control information from the MPEG2-TS packet acquired from the TS separation unit 413. The control CPU unit 414 outputs the acquired filtering control information to the TS separation unit 413. Further, the control CPU unit 414 outputs the acquired descrambling control information to the AV decoder unit 416. The descrambling control information will be described later.

  The TS decoder unit 415 converts the video TS packet and the audio TS packet in the MPEG2-TS packet output from the TS separation unit 413 into an elementary stream format that can be processed by the AV decoder unit 416. The TS decoder unit 415 outputs the generated elementary stream to the AV decoder unit 416. Hereinafter, an elementary stream of a video TS packet is also referred to as “video ES”, and an elementary stream of an audio TS packet is also referred to as “audio ES”.

  The AV decoder unit 416 receives descrambling control information from the control CPU unit 414, receives an initial value from the initial value management unit 417, and receives an elementary stream from the TS decoder unit 415. The AV decoder unit 416 descrambles and decodes (decodes) the elementary stream. The initial value functions as an initial key that is a descrambling key of the video ES. The AV decoder unit 416 decodes the video ES to generate picture data in a format that can display an image. The AV decoder unit 416 decodes the audio ES and generates audio data in a format that can output sound. The AV decoder unit 416 outputs the generated picture data and audio data to an output device connected to the outside of the receiving device 410.

  Here, the output device includes a display device (not shown) and a sound output device (not shown). Examples of the display device include a CRT (Cathode Ray Tube) display, a plasma display, a liquid crystal display, and an organic EL (Electro Luminescence) display. The sound output device is, for example, a speaker. The display device displays an image based on the picture data output from the receiving device 410. The sound output device outputs sound based on the audio data output from the reception device 410.

  The initial value management unit 417 manages the initial value used when the elementary stream is descrambled. That is, the initial value management unit 417 includes an arbitrary storage device that stores initial values. Note that the initial value management unit 417 manages the initial value shared with the transmission device 41. That is, the initial value management unit 417 stores the same initial value as the initial value stored in the initial value management unit 44. The initial value management unit 417 outputs the initial value to the AV decoder unit 416.

  Next, the configuration of the TS encoder unit 43 according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram of the TS encoder unit 43 according to the embodiment of the present invention.

  The TS encoder unit 43 includes a video encoder 22, a video decoder 23, a hash generator 24, a buffer 25, a scrambler 26, and a TS processing unit 27.

  The video encoder 22 converts the image data output from the content generation unit 42 into an elementary stream format. An elementary stream is data in which image data is encoded. Therefore, the elementary stream is data of any one of I picture, B picture, and P picture. The video encoder 22 outputs the generated elementary stream to the video decoder 23 and the scrambler 26.

  The video decoder 23 decodes the elementary stream output from the video encoder 22. The video decoder 23 outputs the picture data generated by decoding the elementary stream to the hash generator 24. In addition, the video decoder 23 generates a reset flag that is descrambling control information and outputs the reset flag to the TS processing unit 27.

  The hash generator 24 performs a hash operation on the picture data output from the video decoder 23 to generate a hash of a unique value. The hash generator 24 outputs the generated hash to the buffer 25.

  The buffer 25 holds the hash output from the hash generator 24 or the initial value output from the initial value management unit 44. That is, the buffer 25 is an arbitrary storage device that stores a hash or an initial value. The buffer 25 outputs the held hash or initial value to the scrambler 26 as a scramble key.

  The scrambler 26 scrambles the elementary stream output from the video encoder 22 using the scramble key output from the buffer 25. The scrambler 26 outputs the scrambled elementary stream to the TS processing unit 27.

  The TS processing unit 27 converts the elementary stream output from the scrambler 26 into the MPEG2-TS packet format. The TS processing unit 27 embeds the reset flag output from the video decoder 23 in the adaptation field included in the MPEG2-TS packet. Then, the TS processing unit 27 outputs the generated MPEG2-TS packet to the TS multiplexing unit 45.

  In this embodiment, the case of conversion to the MPEG2-TS format is exemplified as described above. However, any format that can embed information necessary for descrambling in the reception device 410, such as a reset flag, is used. For example, the format is not limited.

  Next, the configuration of the MPEG2-TS packet according to the embodiment of the present invention will be described. FIG. 3 is a configuration diagram of an MPEG2-TS packet according to the embodiment of the present invention. Here, differences from the MPEG2-TS packet described with reference to FIG. 13 will be described.

  The MPEG2-TS packet according to the present embodiment is provided with an area in which the reset flag F6 is stored in the adaptation field F3. The area in which the reset flag F6 is stored may be provided at an arbitrary bit position in the adaptation field F3.

  Next, the configuration of the AV decoder unit 416 according to the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of the AV decoder unit 416 according to the embodiment of the present invention.

  The AV decoder unit 416 includes a video decoder 37, a descrambler 38, a buffer 39, and a hash generator 310.

  The video decoder 37 decodes the elementary stream output from the descrambler 38. The video decoder 37 outputs the picture data generated by decoding the elementary stream to the outside of the receiving apparatus 410 and the hash generator 310. Here, the video decoder 37 decodes the elementary stream according to the same decoding rule as that of the video decoder 23 of the transmission device 41. That is, the video decoder 23 and the video decoder 37 generate the same picture data when the same elementary stream is decoded.

  The descrambler 38 descrambles the elementary stream output from the TS decoder unit 415 using the descrambling key output from the buffer 39. The descrambler 38 outputs the descrambled elementary stream to the video decoder 37.

  The buffer 39 holds the initial value output from the initial value management unit 417 or the hash output from the hash generator 310. That is, the buffer 39 is an arbitrary storage device that stores a hash or an initial value. The buffer 39 outputs the stored initial value or hash to the descrambler 38 as a descrambling key.

  The hash generator 310 performs a hash operation on the picture data output from the video decoder 37 to generate a hash of a unique value. The hash generator 310 outputs the generated hash to the buffer 39. Here, the hash generator 310 generates a hash with the same calculation rule as the hash generator 24 of the transmission device 41. That is, the hash generator 24 and the hash generator 310 generate the same hash when calculating the same picture data.

  Then, with reference to FIG. 5, operation | movement of the transmitter 41 concerning embodiment of this invention is demonstrated. FIG. 5 is a control flowchart of the transmission apparatus 41 according to the embodiment of the present invention.

  The content generation unit 42 generates content such as image data, audio data, caption data, and BML data. That is, moving image data constituted by each content is generated. The content generation unit 42 outputs the generated moving image data to the TS encoder unit 43 (S101).

  The TS encoder unit 43 scrambles the buffer 25 after converting the moving image data output from the content generation unit 42 into data that needs to be protected by scrambling, such as image data and audio data, into an elementary stream. It is scrambled using the key and converted into an MPEG2-TS packet (S102). The TS encoder unit 43 outputs the generated MPEG2-TS packet to the TS multiplexing unit 45.

  The TS multiplexing unit 45 includes an MPEG2-TS packet output from the TS encoder unit 43, a PSI / SI packet output from the multiplexing information generation unit 46, a NULL packet for adjusting the bit rate of the entire stream, Are multiplexed into one MPEG2-TS stream (S103). The TS multiplexing unit 45 outputs the generated PEG2-TS stream to the 64QAM modulation unit 47.

  Here, Japanese terrestrial digital broadcasting is modulated by a 64QAM (Quadrature Amplitude Modulation) system in order to transmit broadcast waves. Also, in Japanese digital broadcasting, broadcasting called one-segment broadcasting is also performed for mobile bodies such as portable devices. One-segment broadcasting, unlike terrestrial digital broadcasting, is modulated by QPSK (Quadrature Phase Shift Keying). The terrestrial digital broadcast radio waves modulated by the 64QAM modulation scheme and the one-segment broadcast radio waves modulated by the QPSK modulation scheme are multiplexed and transmitted by a scheme called OFDM (Orthogonal Frequency-Division Multiplexing).

  The 64QAM modulation unit 47 performs 64QAM modulation on the MPEG2-TS stream output from the TS multiplexing unit 45 (S104). The 64QAM modulation unit 47 outputs the 64-QAM modulated MPEG2-TS stream to the frequency multiplexing unit 48.

  The frequency multiplexing unit 48 multiplexes the MPEG2-TS stream output from the 64QAM modulation unit 47 as an OFDM subcarrier (S105). The transmission device 41 transmits the OFDM wave generated by multiplexing the MPEG2-TS stream to the reception device 410 (S106). That is, in this embodiment, the case where the transmission path 49 is a free space that transmits an OFDM wave that is a radio wave is illustrated.

  In the present invention, the method for transmitting and receiving streams between the transmission device 41 and the reception device 410 is not limited to the method described above. For example, the transmission path 49 is not limited to a wireless one such as a free space, and may be a wired one such as an IP network. Further, the presence / absence of modulation and the method thereof are not limited to those described above. That is, the MPEG2-TS stream may be transmitted without performing 64QAM modulation. Further, for example, the MPEG2-TS stream may be modulated by the QPSK method and transmitted. That is, the moving image data is not limited to the television program data in terrestrial digital broadcasting, but may be television program data in one-segment broadcasting.

  Next, the operation of the TS encoder unit 43 according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a control flowchart of the TS encoder unit 43 according to the embodiment of the present invention.

  The video encoder 22 encodes the image data output from the TS encoder unit 43 into an elementary stream (S201). Here, the encoding method of the image data is, for example, H.264. Any encoding method may be used as long as the decoding results obtained by the video decoders on the transmitting device side and the receiving device side are the same as in H.264 / AVC. For example, in the MPEG2 format used in current Japanese digital broadcasting, a decimal operation is required for the decoding operation, and therefore the decoding operation result may differ depending on the accuracy of the decimal operation of the decoder and the mounting method. That is, when such an encoding method is employed, the decoding calculation result in the transmission device 41 may be different from the decoding calculation result in the reception device 410. In this case, since the scramble key and the descramble key generated from the respective decoding calculation results are different from each other, the receiving device 410 cannot be normally descrambled.

  In contrast, H.C. In H.264 / AVC, decoding operations can be performed using only integers, so that the decoding operation results match regardless of the decimal arithmetic accuracy and mounting method. Therefore, H.264 is used as an encoding method. By adopting H.264 / AVC, the same scramble key and descrambling key can be generated from the decoding calculation result in the transmission device 41 and the decoding calculation result in the reception device 410, and the descrambling can be normally performed. It becomes possible to do.

  The video decoder 23 decodes the elementary stream output from the video encoder 22 (S202). The video decoder 23 outputs the picture data generated by decoding the elementary stream to the hash generator 24 and the TS processing unit 27. Here, in the general image decoding method, if the I picture cannot be decoded, it is impossible to decode the B picture existing before and after the I picture and the P picture existing after the I picture. Therefore, in this embodiment, the time until descrambling and decoding by the receiving apparatus 410 is minimized by setting the I picture as the scramble / descramble key reset timing. Therefore, in order to set the I picture as the scramble / descramble key reset timing, it is necessary for the transmission apparatus 41 to determine the type of the elementary stream picture to be scrambled.

  Therefore, in the decoding, the video decoder 23 determines whether or not the decoded elementary stream is an I picture (S203). Whether it is an I picture is determined by, for example, PCT (Picture Start Code) included in the elementary stream.

  When it is determined that the decoded elementary stream is an I picture (S203: Yes), the TS encoder unit 43 acquires an initial value from the initial value management unit 44 and stores it in the buffer 25. Further, the video decoder 23 sets the reset flag to “1” and outputs it to the TS processing unit 27 (S205). Then, the process proceeds to step S207.

  When it is determined that the decoded elementary stream is not an I picture (S203: No), the video decoder 23 sets the reset flag to “0” and outputs it to the TS processing unit 27 (S206). Then, the process proceeds to step S207. In this case, the buffer 25 stores a hash generated by hashing the picture data previously decoded by the video decoder 23. This hash is stored in step S209 described later.

  The scrambler 26 scrambles the elementary stream output from the video encoder 22 using the value stored in the buffer 25 as a scramble key. Therefore, the scrambler 26 descrambles the elementary stream of the I picture with the initial value, and the elementary stream of the B picture and the P picture that refer to the I picture by the hash of the previously decoded picture. It will be descrambled. The scrambler 26 outputs the scrambled elementary stream to the TS processing unit 27 (S207). Here, any algorithm may be adopted as a scramble algorithm in the scrambler 26.

  The TS processing unit 27 converts the elementary stream output from the scrambler 26 into an MPEG2-TS packet. Then, the TS processing unit 27 stores the reset flag F6 output from the video decoder 23 in the adaptation field F3 of the MPEG2-TS packet. As a result, the reset flag is stored as “1” in the adaptation field F3 of the MPEG2-TS packet generated from the elementary stream of the I picture, and the MPEG2-TS generated from the elementary stream of the B picture and the P picture. A reset flag of “0” is stored in the adaptation field F3 of the TS packet.

  The hash generator 24 generates a hash from the picture data decoded by the video decoder 23 (step S208). Here, the hash generator 24 may employ any algorithm as an algorithm for generating a hash. For example, an algorithm such as SHA-1 or MD5 is adopted. Further, as long as it is a unique value that can be generated from a picture, a value other than a hash may be generated. The hash generator 24 stores the generated hash in the buffer 25 (S209). The hash stored in the buffer 25 is used as a scramble key in step S207 when the elementary stream to be decoded next is a B picture or a P picture.

  Next, with reference to FIG. 7, the operation of the receiving apparatus 410 according to the embodiment of the present invention will be described. FIG. 7 is a control flowchart of the receiving apparatus 410 according to the embodiment of the present invention.

  The receiving device 410 receives an OFDM wave from the transmitting device 41 through the transmission path 49 (S301). The OFDM wave received by the receiving apparatus 410 is input to the frequency separation unit 411. The frequency separation unit 411 separates the MPEG2-TS stream from the input OFDM wave (S302). The frequency separation unit 411 outputs the separated MPEG2-TS stream to the 64QAM demodulation unit 412. At this point, the MPEG2-TS stream is in a state of being 64QAM modulated.

  The 64QAM demodulator 412 demodulates the MPEG2-TS stream separated by the frequency separator 411 (S303). The 64QAM demodulation unit 412 outputs the 64-QAM demodulated MPEG2-TS stream to the TS separation unit 413.

  The TS separation unit 413 separates the MPEG2-TS stream output from the 64QAM demodulation unit 412 into MPEG2-TS packets (S304). The TS separation unit 413 outputs a copy of the separated MPEG2-TS packet to the control CPU unit 414. Here, the TS header portion of the MPEG2-TS packet includes an identifier for identifying what type of data is stored in the MPEG2-TS packet. This identifier is called a PID (Packet Identifier). The control CPU unit 414 acquires a PID from the MPEG2-TS packet output from the TS separation unit 413, and outputs the acquired PID to the TS separation unit 413 as filtering control information. The TS separation unit 413 determines the type of copy source MPEG2-TS packet based on the PID output from the control CPU unit 414. The TS separation unit 413 classifies MPEG2-TS packets according to types such as image, sound, and PSI / SI according to the determination result. The TS separation unit 413 outputs the classified MPEG2-TS packet to the TS decoder unit 415.

  In addition, the control CPU unit 414 analyzes the MPEG2-TS packet output from the TS separation unit 413, and acquires a reset flag that is descrambling control information from the analyzed MPEG2-TS packet (S305). The control CPU unit 414 output from the TS separation unit 413 outputs the acquired reset flag to the AV decoder unit 416.

  The TS decoder unit 415 converts the video TS packet and the audio TS packet among the MPEG2-TS packets separated by the TS separation unit 413 into elementary streams, and converts the PSI / SI packet into a section format (S306). . The TS decoder unit 415 outputs the PSI / SI converted into the elementary stream and the section format to the AV decoder unit 416. At this point, the elementary stream is in a scrambled state.

  The AV decoder unit 416 is based on the elementary stream output from the TS decoder unit 415, the reset flag F6 output from the control CPU unit 414, and the initial value output from the initial value management unit 417. The stream is descrambled (S307). Further, the AV decoder unit 416 decodes the descrambled elementary stream to generate picture data and audio data. The AV decoder unit 416 outputs the generated picture data and audio data to an output device connected outside the reception device 410 (S308).

  Next, the operation of the AV decoder unit 416 according to the embodiment of the present invention will be described with reference to FIG. FIG. 8 is a control flowchart of the AV decoder unit 416 according to the embodiment of the present invention.

  The control CPU unit 414 searches for a video TS packet from the MPEG2-TS packet output from the TS separation unit 413. The control CPU unit 414 analyzes the adaptation field F3 of the MPEG2-TS packet searched for as a video TS packet, and acquires the reset flag F6 (S401). The control CPU unit 414 outputs the acquired reset flag F6 to the AV decoder unit 416. Further, the TS decoder unit 415 converts the MPEG2-TS packet output from the TS separation unit 413 into an elementary stream format. The TS decoder unit 415 outputs the generated elementary stream to the AV decoder unit 416.

  The AV decoder unit 416 acquires the reset flag F6 output from the control CPU unit 414 (S402). Here, when a video TS packet is output from the TS decoder unit 415 to the AV decoder unit 416, the reset flag F6 in the adaptation field F3 of the video TS packet is output from the control CPU unit 414 to the AV decoder unit 416. As described above, the respective output timings are synchronized.

  The AV decoder unit 416 determines whether or not the acquired reset flag F6 is “1” (S403). That is, the AV decoder unit 416 determines whether or not the video TS packet output from the TS decoder unit 415 is an I picture.

  When the reset flag F6 is “1”, the AV decoder unit 416 reads the initial value stored in the IC card inserted in the IC card reader of the initial value management unit 417 and stores it in the buffer 39 (S404). ). Then, the process proceeds to step S405.

  If the reset flag F6 is not “1”, the process proceeds to step S405. In this case, the buffer 39 stores a hash generated from the picture data previously decoded by the video decoder 37. This hash is stored in step S408 described later.

  Thus, in the present embodiment, sharing using an IC card is performed as an example of means for sharing the initial value of the scramble / descramble key between the transmission device 41 and the reception device 410. Specifically, the content manager distributes the IC card in which the initial value is recorded to the user of the receiving device 410, and inserts the IC card in which the user is distributed into the receiving device 410, thereby sharing the initial value. Is done.

  However, the method of sharing the initial value is not limited to this. For example, it may be shared by an external storage medium other than the IC card. As the external storage medium, for example, a USB (Universal Serial Bus) memory, an external hard disk, an optical disk, or the like may be used, and the initial value management units 44 and 417 may be able to read the initial value therefrom. Further, the transmission apparatus 41 and the reception apparatus 410 have input devices so that the content manager or user inputs the same initial value to the initial value management units 44 and 417 via the input device. Also good. For example, a keyboard and a mouse may be used as the input device.

  The descrambler 38 descrambles the elementary stream output from the TS decoder unit 415 using the value stored in the buffer 39 as a descrambling key (S405). Therefore, as with the scrambler 26 of the transmission device 41, the descrambler 38 descrambles the elementary stream of the I picture according to the initial value, and the elementary stream of the B picture and the P picture that refer to the I picture. Is descrambled with the hash of the previously decoded picture. The descrambler 38 outputs the descrambled elementary stream to the video decoder 37.

  The video decoder 37 decodes the elementary stream output from the descrambler 38 to generate picture data (S406). The video decoder 23 outputs the generated picture data to the hash generator 310.

  The hash generator 310 generates a hash from the picture data output from the video decoder 37 (S407). The hash generator 24 stores the generated hash in the buffer 39 (S408).

  In addition, the video decoder 37 outputs the picture data that is the result of decoding the elementary stream to an output device (not shown) connected to the outside of the receiving device 410 (S409).

  Next, the mechanism and effect according to the present embodiment will be described with reference to FIG. FIG. 9 is a diagram showing the relationship between the reception timing of MPEG2-TS packets on the time axis and pictures obtained from those MPEG2-TS packets.

  FIG. 9 shows that reception of MPEG2-TS packets 704 to 733 included in the stream after channel switching is started from time 700. First, an MPEG2-TS packet 704 is received. Thereafter, MPEG2-TS packets 705 to 633 are sequentially received.

  In FIG. 9, MPEG2-TS packets 710, 713, 714, 719, 727, and 729 each indicate an audio TS packet, and MPEG2-TS packets 709, 716, and 725 each indicate an ECM packet. Each of the other MPEG2-TS packets represents a video TS packet.

  By receiving each video TS packet, various pictures shown in pictures 733 to 741 can be obtained. Various pictures are composed of a plurality of MPEG2-TS packets.

  Specifically, the MPEG2-TS stream shown in FIG. 9 includes, as pictures, a B picture 733 composed of MPEG2-TS packets 703 and 704, and a B picture 735 composed of MPEG2-TS packets 708 and 711. B picture 737 composed of MPEG2-TS packets 712 and 715, B picture 739 composed of MPEG2-TS packets 723 and 724, B picture 740 composed of MPEG2-TS packets 726 and 728, and MPEG2 -An I picture 734 composed of TS packets 705, 706, 707, an I picture 738 composed of MPEG2-TS packets 720, 721, 722, and a P picture composed of MPEG2-TS packets 717, 718 And 737, a P-picture 741 constituted by MPEG2-TS packets 730,731,732, are included.

  After channel switching, MPEG2-TS packet 704 is obtained at time 700 when reception of the stream is started. The MPEG2-TS packet 704 is a packet that constitutes the B picture 733. However, since the MPEG2-TS packet 703 cannot be received at the reception start time 700, the B picture 733 cannot be obtained.

  At time 701, all MPEG2-TS packets 705, 706, and 707 constituting the I picture 734 are received. In step S401, the control CPU 414 analyzes the adaptation field F3 of the MPEG2-TS packet 705, and obtains a reset flag F6 in step S402. In step S306, the TS decoder unit 415 converts the MPEG2-TS packet including the I picture 734 into an elementary stream.

  In step S403, the AV decoder unit 416 determines whether the reset flag F6 is “1” or “0”. In the processes of steps S203, S204, and S205, “1” is stored in the reset flag F6 in the MPEG2-TS packets 705, 706, and 707 constituting the I picture 734. Therefore, the process proceeds to step S404, and the AV decoder unit 416 reads the initial value from the initial value management unit 417 and stores it in the buffer 39. In step S405, the descrambler 38 descrambles the elementary stream in which the I picture 734 is stored by using the initial value stored in the buffer 39 as a descrambling key, thereby descrambling the I descrambled at time 701. A picture 734 can be obtained (S406).

  In steps S407 and S408, the hash generator 310 generates a hash from the I picture 734 obtained at time 701, and stores the generated hash in the buffer 39.

  After time 701, only the reset flag F6 in which “0” is stored in the adaptation field of the MPEG2-TS packet obtained until the I picture 738 is detected at time 702 can be obtained. Therefore, when the elementary stream storing the B picture 735 is descrambled, it is descrambled using the hash of the I picture 734 stored in the buffer 39 in step S408. Similarly, the elementary stream storing the B picture 736 is descrambled using the hash of the B picture 735 stored in the buffer 39 in step S408, and the elementary stream storing the P picture 737 is In S408, the data is descrambled using the hash of the B picture 736 stored in the buffer 39.

  As described above, in this embodiment, the time at which a normal image can be output can be shortened from time 702 corresponding to time 603 shown in FIG. 14 to time 701. That is, in this embodiment, even an I picture received before receiving an ECM can be descrambled and a normal image can be obtained. Therefore, since it is not necessary to wait for an I picture that arrives after receiving the ECM, the channel switching time can be shortened compared to the technique disclosed in Patent Document 1.

  As described above, in the present embodiment, the I picture is descrambled by using the I picture descrambling key prepared in advance. Then, based on the I picture, a descrambling key for the picture that refers to the I picture is generated, and the picture that refers to the I picture is descrambled using the generated descrambling key.

  According to this, for example, a normal image can be output from the time when the I picture is received regardless of the reception timing of other data such as ECM. Therefore, according to the present embodiment, the channel switching time can be shortened.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

  In the above-described embodiment, the case where the transmission apparatus 41 is applied to a digital broadcast transmission apparatus and the reception apparatus 410 is applied to a digital television receiver is illustrated, but the present invention is not limited to this. For example, the transmission device 41 is applied to a recorder that stores the generated MPEG2-TS stream in an external storage medium, and the reception device 410 is applied to a player that reproduces the MPEG2-TS stream stored in the external storage medium. May be.

  In the above-described embodiment, the case where the hash is generated based on the picture data generated by the video decoder 23 and the video decoder 37 is illustrated, but the present invention is not limited thereto. A hash may be generated based on an elementary stream before being decoded into picture data.

11 Key management device 12 Kw encryption unit 13, 45 TS multiplexing unit 14 Ks encryption unit 15, 26 Scrambler 16, 42 Content generation unit 17 TS encoder 18, 47 64QAM modulation unit 19, 49 Transmission path 22 Video encoder 23 37 Video decoder 24, 310 Hash generator 25, 39 Buffer 27 TS processing unit 38, 114 Descrambler 41, 128 Transmitting device 43 TS encoder unit 44, 417 Initial value management unit 46, 125 Multiplex information generation unit 48, 126 Frequency Multiplexer 110, 410 Receiver 111, 412, 64QAM demodulator 112, 413 TS separator 113 Control CPU
115 Special key decryption module 116 General-purpose key decryption modules 117 and 120 Individual key Kmi
118, 121 Kw decoding unit 119, 122 Ks decoding unit 123 TS decoder 124 AV decoder 127, 411 Frequency separation unit 128, 410 Transmission device 200 Video ES
201 Audio ES
202, 203 Video PES
204, 205 Audio PES
206, 207, 208, 209 Video TS packet 210, 211, 212, 213 Audio TS packet 214 MPEG2-TS stream 215, 216, 217, 218 ECM packet 219 ECM
300, 301, 303, 305, 306, 634, 636, 637, 640, 641, 733, 735, 736, 739, 740 B picture 302, 635, 639, 734, 738 I picture 304, 307, 638, 642, 737, 741 P picture 414 Control CPU unit 415 TS decoder unit 416 AV decoder unit F1 MPEG2-TS packet F2 TS header F3 Adaptation field F4 Data byte F6 Reset flag

Claims (18)

A decoding device for decoding stream data including an I picture and a B picture and a P picture that refer to the I picture, respectively,
A key generation unit that generates a descrambling key of a picture that refers to the I picture based on the I picture;
A descrambler that descrambles the I picture with a descrambling key of the I picture prepared in advance and descrambles a picture that references the I picture with a descrambling key generated by the key generation unit;
A decoding apparatus comprising: The key generation unit generates the descrambling key for the first picture following the I picture based on the I picture, and refers to the I picture than the first picture. For the subsequent second picture, a descrambling key is generated based on the first picture or the second picture before the second picture.
The decoding device according to claim 1. The key generation unit generates a descrambling key of the second picture based on the first picture or the second picture immediately before the second picture;
The decoding device according to claim 2. The key generation unit generates a hash value of the picture, and generates the descrambling key based on the generated hash value;
The decoding device according to any one of claims 1 to 3. The decoding apparatus includes a decoding unit that decodes a picture descrambled by the descrambler,
The key generation unit generates the descrambling key based on the picture decrypted by the decryption unit;
The decoding device according to any one of claims 1 to 4. An encoding device that encodes moving image data to generate stream data including an I picture and B and P pictures that respectively refer to the I picture.
A key generation unit that generates a scramble key of a picture that refers to the I picture based on the I picture;
A scrambler that scrambles the I picture with a scramble key of the I picture prepared in advance, and scrambles a picture that refers to the I picture with a scramble key generated by the key generation unit;
An encoding device comprising: The key generation unit generates the scramble key based on the I picture for the first picture following the I picture, and refers to the I picture and is subsequent to the first picture. For the second picture, a scramble key is generated based on the first picture or the second picture before the second picture.
The encoding device according to claim 6. The key generation unit generates a scramble key for the second picture based on the first picture or the second picture immediately before the second picture;
The encoding device according to claim 7. The key generation unit generates a hash value of the picture, and generates the scramble key based on the generated hash value.
The encoding device according to any one of claims 6 to 8. The encoding device includes a decoding unit that decodes a picture before being scrambled by the scrambler,
The key generation unit generates the scramble key based on the picture decoded by the decoding unit;
The encoding device according to any one of claims 6 to 9. An encoding device that encodes moving image data and generates scrambled stream data including an I picture and a B picture and a P picture that respectively refer to the I picture, and the encoding device A decoding apparatus comprising: a decoding device that decodes stream data;
The encoding device includes:
A scramble key generation unit that generates a scramble key of a picture that refers to the I picture based on the I picture;
A scrambler that scrambles the I picture with a scramble key of the I picture prepared in advance and scrambles a picture that refers to the I picture with a scramble key generated by the scramble key generation unit. ,
The decoding device
A descrambling key generation unit that generates the same descrambling key as the scramble key based on the I picture;
The I picture is descrambled with the same descramble key as the scramble key of the I picture prepared in advance, and a picture that refers to the I picture with the descramble key generated by the descramble key generation unit A descrambler for descrambling,
Encoding / decoding system. A descrambler that descrambles stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures,
Descrambling the I picture with a descrambling key of the I picture prepared in advance, and descrambling a picture referring to the I picture with a descrambling key generated based on the I picture;
Descrambler. A scrambler that scrambles an I picture and a B picture and a P picture that respectively refer to the I picture,
The I picture is scrambled with a scramble key of the I picture prepared in advance, and a picture that refers to the I picture is scrambled with a scramble key generated based on the I picture.
Scrambler. A decoding method for decoding stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures,
The I picture is descrambled with a previously prepared I picture descramble key,
Based on the I picture, a descrambling key for a picture that refers to the I picture is generated,
Using the generated descrambling key, descrambling a picture referring to the I picture;
Decryption method. An encoding method for encoding moving image data and generating stream data including scrambled I pictures and B pictures and P pictures respectively referring to the I pictures,
The I picture is scrambled by a scramble key of the I picture prepared in advance,
Based on the I picture, generate a scramble key for a picture that references the I picture,
Scramble a picture that references the I picture with the generated scramble key;
Encoding method. Coding and decoding that encodes moving image data, generates stream data including an I picture and B and P pictures that respectively refer to the I picture, and decodes the generated stream data A method,
The I picture is scrambled by a scramble key of the I picture prepared in advance,
Based on the I picture, generate a scramble key for a picture that references the I picture,
Scramble a picture referring to the I picture with the generated scramble key;
Descramble the I picture with the same descrambling key as the scramble key of the I picture prepared in advance,
Based on the I picture, a descramble key identical to the scramble key is generated,
Using the generated descrambling key, descrambling a picture referring to the I picture;
Encoding / decoding method. A descrambling method for descrambling stream data including scrambled I pictures and B pictures and P pictures that respectively refer to the I pictures,
The I picture is descrambled with a previously prepared I picture descramble key,
Descrambling a picture that references the I picture with a descrambling key generated based on the I picture;
Descramble method. A scrambling method for scrambling an I picture and a B picture and a P picture that respectively refer to the I picture,
The I picture is scrambled by a scramble key of the I picture prepared in advance,
Scramble a picture that references the I picture with a scramble key generated based on the I picture;
Scramble method.

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