JP4466425B2 - MPEG stream processing method and MPEG stream processing apparatus - Google Patents

Description

The present invention relates to a processing method and processing apparatus for storing and reproducing an MPEG stream such as MPEG-TS (Moving Picture Experts Group-Transport Stream) used in a CS (Communication Satellite) digital broadcasting system, and more particularly to an MPEG stream. The present invention relates to a processing method and a processing apparatus in the case where the data is encrypted.

In the reproduction of the MPEG stream, in the case of normal reproduction, the received TS packets are stored in the TS accumulating means, sequentially transferred to the TS decoder, the elementary stream to be reproduced is extracted by the TS decoder, and the extracted elementary stream is extracted. The stream is decoded by an MPEG decoder, transferred to a television or the like, and a reproduced image is displayed.
On the other hand, for special playback such as fast-forward playback, reverse playback, cue playback, etc., processing such as thinning out unnecessary packets or rearranging packets is required when inputting a stream to the TS decoder. Become.
FIG. 1 is a diagram for explaining special reproduction processing performed in a conventional MPEG stream reproduction apparatus. FIG. 1A shows a TS packet group stored in the TS storage means, and 1 to 15 show TS packets. Here, the TS packet group corresponding to the I code is a TS packet including I picture information, the TS packet group corresponding to the P code is a TS packet including P picture information, and the TS corresponding to the B code. The packet group represents a TS packet including B picture information. FIG. 1B shows an elementary stream in the case of normal reproduction, in which TS packet groups accumulated in the TS accumulation means are sequentially output. FIG. 1 (c) shows an elementary stream when only fast forward playback is performed while displaying only I and P pictures. In this case, only the I picture and P picture are extracted from the TS packet group stored in the TS storage means, and the special playback elementary stream shown in FIG. 1C is created.
As described above, in the case of special reproduction, predetermined processing is required, and in order to perform efficient processing, index information is created in advance for TS packet positions of I pictures, P pictures, and B pictures in the stream. The present inventor has proposed a device that uses information to speed up detection of a picture header (see Patent Document 1).

Also, in MPEG-TS that handles content such as digital broadcasting, processing for scrambling (encrypting) in units of TS packets is required for content protection. In this case, the scramble key used for scrambling on the transmitter side is packetized, multiplexed with the scrambled content, and transmitted. The receiver side takes out the scramble key by sending a packet including the scramble key information to an IC card or the like, and uses it for descrambling (decoding) the content. Normally, this scramble key is updated periodically (for example, once every 3 seconds).
FIG. 2 is a diagram for explaining a scrambled TS packet stream. 2A shows TS packet groups stored in the TS storage means, K0, K1, K2, K3 are TS packets including scramble key information, and other C1, C2,... C10 are video and audio. A TS packet including content information such as Here, the C0 and C1 packets are scrambled with the scramble key included in K0, and the C2 to C4 packet K1 and the C5 to C8 packets are scrambled with the scramble key included in K2.
FIG. 2B shows the correspondence between the elementary stream and the scramble key information in the case where only the I picture and the P picture are displayed and the fast forward playback is performed. In this figure, the first I picture is scrambled with the scramble key information included in K0, and the next P picture is the part scrambled with the scramble key information included in K2 and the scramble key included in K3. It has a scrambled part with information. Further, the next P picture has a portion scrambled with the scramble key information included in K7 and a portion scrambled with the scramble key information included in K8.
When the scrambled TS packet stream is normally reproduced, even if the stream is input from an appropriate position, the scramble key can be extracted from the TS packets input in order and descrambled. However, in the case of special playback, etc., the necessary TS packets are thinned out and rearranged, so it is necessary to find a scramble key that scrambles each TS packet and descramble it accordingly. become.
Therefore, in order to facilitate the association between the TS packet and the scramble key, the present inventor has proposed a device for updating the scramble key at each timing of the I picture when scrambling the content. (See Patent Document 2). In this technique, the scramble key can be updated in units of GOP (Group Of Pictures: a screen group structure including at least one I picture to enable random access). Becomes easier.
JP 2002-165180 A JP 2003-324699 A

  However, in the conventional method, when specially reproducing a scrambled TS packet stream, it is still unknown which packet contains the necessary scramble key information, so that special reproduction processing is performed efficiently. There is no problem.

  In view of this point, the present invention is able to realize special reproduction with a light load without analyzing the accumulated TS packet even in a scrambled MPEG stream. An object is to provide a processing method and a processing apparatus.

Therefore, in the present invention, it is possible to efficiently reproduce by storing, as index information, in which position in the stream the scramble key information of the scrambled TS packet is located.
One aspect of the present invention includes key information and content encrypted with the key information, and inputs a packetized MPEG stream for each packet.
For each packet, determine the information type included in the packet,
When the packet is the key information, the packet count value of the packet is stored in the index information together with the information type,
In the MPEG stream processing method, the packet count value of the packet is stored in the index information together with the information type when the packet is the content information.
According to another aspect of the present invention, an MPEG stream including key information and content encrypted with the key information is input, and a decryption block for outputting a decrypted MPEG stream decrypted based on the key information; ,
An MPEG stream processing apparatus comprising: an index generation block that inputs a decoded MPEG stream from the decoding block and generates position information of key information in the decoded MPEG stream as index information.

  According to the MPEG stream processing method and processing apparatus of the present invention, special playback can be realized with a light load without analyzing the accumulated TS packets in a scrambled MPEG stream.

(First embodiment)
FIG. 3 is a first embodiment of an MPEG stream processing apparatus having an index generation function of the present invention. In FIG. 3, reference numeral 30 denotes an MPEG stream processing apparatus, which sequentially performs three processes surrounded by a dotted line, an encrypted stream decryption process 31, an index generation process 32, and a local stream encryption process 33.
First, in the encrypted stream decrypting process 31, the transmitted encrypted TS packet stream 35 is decrypted. The decryption block 34 takes out the packet 36 including the scramble key information from the transmitted TS packet stream 35 and sends it to the key recovery block 37. In the present embodiment, one key packet 36 includes information on two scramble keys, an ODD key and an EVEN key. The ODD key is a key used first, and the EVEN key is a key used next. Since it takes time to restore the key, the processing speed is increased by sending and restoring the key information to be used next in advance. The key recovery block 37 recovers the scramble key 38 and outputs it to the decryption block 34. The decryption block 34 decrypts the encrypted stream using the sent scramble key 38.

  Next, in the index generation process 40, for the decoded stream 39, in addition to the index generation of the TS packet positions of the I picture, P picture, and B picture, the index of the TS packet position for the key information is also generated. The index generation block 40 generates index information 41 for the decoded TS packet stream 39 sent from the decoding block 34. A method for generating this index information will be described later. The index information generated here is output to the MPEG stream processing apparatus 30 because it is used during reproduction.

  Next, in the local encryption process 33, the local encryption inside the receiver is applied to the decrypted stream. The local cipher block 43 receives the decrypted TS packet stream 42 after index generation, and a key generation block 44 that generates a scramble key for local encryption generates a scramble key 46 and a key packet 45 obtained by packetizing the scramble key, Output to the local cipher block 43. The local cipher block 43 uses the received scramble key 46 to scramble the decrypted TS packet stream 42 again. Further, the local cipher block 43 combines the received key packet 45 together with the scrambled content information packet to generate a local encrypted TS packet stream 47.

By using this MPEG stream processing apparatus, it is possible to perform decoding and decoding processing of local ciphers by efficiently performing rearrangement and cueing of TS packets based on the index information during reproduction. Therefore, special reproduction or the like can be easily realized without analyzing the TS packet accumulated during reproduction and checking the packet position of the key packet.
However, since the MPEG stream processing apparatus of this embodiment generates an index before local encryption, in order to use the generated index effectively, the original MPEG stream is used at the time of local encryption. It is necessary to replace the local key packet with the local encryption key packet in a 1: 1 correspondence so that the position does not shift. Therefore, the local encryption scramble format depends on the original MPEG stream scramble format, and the local encryption scramble format cannot be freely changed.

(Second embodiment)
FIG. 4 is a diagram for explaining a second embodiment in which the MPEG stream processing apparatus of FIG. 3 is improved. In the MPEG stream processing apparatus shown in FIG. 4, as in the MPEG stream processing apparatus 30 shown in FIG. 3, three processes surrounded by a dotted line, an encrypted stream decrypting process 31, an index generating process 48, and a stream local encrypting process 49 are performed. Do each one in turn. The second embodiment is different from the first embodiment in that a key generation block 52 that generates a scramble key for a local cipher that is a cipher inside the receiver side generates a key during the local encryption process 51. Instead, the key is generated during the index generation processing 50. In this MPEG stream processing apparatus, key packet insertion processing is separated from local encryption processing. The encryption stream decryption process 31 is the same as the encryption stream decryption process 31 of FIG.
In the index generation process 48, the index generation block 50 generates index information for the decoded TS packet stream 39 sent from the decoding block 34. At this time, a key generation block 52 that generates a scramble key for local encryption that is an internal cipher of the receiver side generates a scramble key 46 and a key packet 45 obtained by packetizing the scramble key, and an index generation block 50 generates a key packet 45. The key packet insertion position is recorded in the index.

  Next, in the local encryption processing 49, the local cipher block 51 receives the decrypted TS packet stream 42 after the index generation, and uses the scramble key 46 received from the key generation block 52 to convert the decrypted TS packet stream 42. It is scrambled again and a local encrypted TS packet stream 47 is generated.

  By using this MPEG stream processing apparatus, the packet position does not change when local encryption is performed, and TS packets are rearranged and cued efficiently based on the index information 41. Decoding processing can be performed.

Next, a method for generating index information will be described in more detail with reference to FIG. First, when recording starts, the number of packet counters is reset to 0 as an initialization process. Next, the index generation block sequentially receives TS packets, but increments the number of packet counters by one each time the TS packets are received.
Next, the TS header part of the received TS packet is read to determine the type of information contained in the packet. For example, when the PID information included in the TS header portion is “0100”, it is determined that the image information is video image information, when “0101” is audio audio information, and when “0102” is scramble key information. The correspondence between the value of the PID information and the information type is defined by a PMT (Program Map Table) included in the stream. If the information type of the packet is image information or scramble key information, index information is generated. Here, the index information includes information on the packet count number of each picture and the packet count number of each scramble key.
Next, a method of using index information created using FIG. 6 will be described. In this case, fast forward special reproduction is taken as an example. First, I-picture or P-picture information necessary for fast-forward playback is found from the index information, and its packet count number In is obtained. Next, in the index information, the packet count number An of the next information of the I or P picture is obtained. By subtracting In from An, the number of consecutive packets of the picture can be obtained.
Next, the packet count number Pn of the packet including information on the scramble key used by the picture is found. The index of the key information used for scrambling the picture is searched in the index information before the index of the picture, and the closest scramble key information corresponds to this. Therefore, by using the packet count numbers In, An, and Pn obtained from the index information, a key information packet and a continuous packet of I or P picture are extracted and used for fast-forward playback.

(Third embodiment)
FIG. 7 is a diagram for explaining a third embodiment of an MPEG stream processing apparatus having an index generation function according to the present invention. This example shows a specific example in which the MPEG stream processing apparatus is applied to a right protection LSI used for digital broadcast reception. In FIG. 7, reference numeral 70 denotes a right protection LSI for restricting copying and movement of digital contents, and 80 denotes a processing unit of the MPEG decoder.
First, the decryption block 71 in the right protection LSI 70 extracts the packet 36 including the scramble key information from the transmitted TS packet stream 35 and sends it to the IC card 72 connected externally. The IC card 72 restores the scramble key 38 such as the ODD key and the EVEN key from the key packet 36 and outputs it to the decryption block 71. The decryption block 71 decrypts the encrypted stream using the sent scramble key 38.
Next, the index generation block 73 generates index information 41 for the decoded TS packet stream 39 sent from the decoding block 71. At this time, a key generation block 75 for generating a scramble key for local encryption that is an encryption in the receiver-side PC generates a scramble key 46 and a key packet 45 obtained by packetizing the scramble key, and an index generation block 73 is a key packet. 45 is received and the insertion position of the key packet is recorded in the index.
The local cipher block 74 receives the decrypted TS packet stream 42 after the index generation, re-scrambles the decrypted TS packet stream 42 using the scramble key 46 received from the key generation block 75, and generates a local encrypted TS packet stream. 76 is generated.
The local encrypted TS packet stream 76 and the index information 41 from the index generation block 75 are stored in an external storage device 77 such as an external HDD via the storage control unit 76.
At the time of reproduction, the input controller 78 receives the index information 41 from the external storage device 77 via the storage device 76, and issues a packet output order instruction 79 based on this information. In the case of special playback such as fast-forwarding, the input controller 78 instructs stream rearrangement. The local cipher TS 81 is output to the local cipher decryption block 82 in the PC processing unit 80 in accordance with the packet output order instruction 79. In the local encryption / decryption block 82, the raw TS stream 83 is decrypted and passed to the MPEG decoder 84. Finally, a decoded image 85 decoded by the MPEG decoder 84 is output.
Thus, in this embodiment, since the input controller 78 can perform stream rearrangement using the index information 41, special reproduction is efficiently performed without analyzing the accumulated content. It is possible.

(Fourth embodiment)
FIG. 8 is a diagram for explaining a fourth embodiment of an MPEG stream processing apparatus having an index generation function according to the present invention. The fourth embodiment is different from the third embodiment in that local encryption is not performed. Such an embodiment is possible when content can be sufficiently protected only by scrambling on the transmission side. In FIG. 8, reference numeral 90 denotes a right protection LSI for restricting copying and movement of digital contents.
First, the decryption block 91 in the right protection LSI 90 extracts the packet 36 including scramble key information from the transmitted TS packet stream 35 and sends it to the IC card 72 connected externally. The IC card 72 restores the scramble key 38 and outputs it to the decryption block 71. The decryption block 71 decrypts the encrypted stream using the sent scramble key 38.
Next, the index generation block 93 generates index information for the decoded TS packet stream 92 sent from the decoding block 91. The index information is stored in the external storage device 100 via the storage control unit 95. On the other hand, the transmitted TS packet stream 35 is also stored in the external storage device 100.
At the time of reproduction, the input controller 97 receives the index information 98 from the external storage device 100, and issues a packet output order instruction 99 based on this information. In accordance with the packet output order instruction 99, the decoding block 91 outputs the raw TS stream 83 and passes it to the MPEG decoder 84. A decoded image 85 decoded by the MPEG decoder 84 is output outside the right protection LSI 90.

  Here, when the present invention is arranged, the present invention includes at least the following features.

(Appendix 1)
An MPEG stream including key information and content encrypted with the key information is input,
An MPEG stream processing method characterized in that position information in the MPEG stream of the key information used for encryption is generated as index information.

(Appendix 2)
The MPEG stream processing method according to appendix 1, wherein the MPEG stream is an MPEG-TS packet stream encrypted for each packet.

(Appendix 3)
The MPEG stream processing method according to appendix 1, wherein the position information of the key information is a packet count number of packets including the key information in the MPEG stream.

(Appendix 4)
In the MPEG stream processing method of further performing local encryption after decrypting the MPEG stream,
2. The MPEG stream processing method according to appendix 1, wherein the index information is generated by combining the packet including the key information used in the local encryption with the decrypted MPEG stream and then generating the index information.
(Appendix 5)
An MPEG stream including key information and content encrypted with the key information is input,
Generating position information in the MPEG stream of the key information used for encryption as index information;
An MPEG stream processing method characterized in that, during reproduction of an MPEG stream, a position of a packet including key information is obtained based on the index information.
(Appendix 6)
Including key information and content encrypted with the key information, and inputting a packetized MPEG stream for each packet;
For each packet, determine the information type included in the packet,
When the information type is the key information, the packet count number of the packet is stored in the index information together with the information type indicating the key information,
An MPEG stream processing method, wherein, when the information type is the content information, the packet count number of the packet is stored in the index information together with the information type indicating the content information.
(Appendix 7)
A decryption block that inputs an MPEG stream including key information and content encrypted with the key information, and outputs a decrypted MPEG stream decrypted based on the key information;
An MPEG stream processing apparatus comprising: an index generation block that inputs a decoded MPEG stream from the decoding block and generates position information of key information in the decoded MPEG stream as index information.
(Appendix 8)
A local cipher block for encrypting the decrypted MPEG stream;
The MPEG stream processing apparatus according to appendix 7, further comprising a key generation block for generating key information used for encryption by the local encryption block.
(Appendix 9)
9. The MPEG stream processing apparatus according to appendix 8, wherein the key generation block outputs a packet including key information used in the local encryption block and key information used in the index generation block.
(Appendix 10)
The key generation block outputs a packet including key information to the index generation block,
9. The MPEG stream processing apparatus according to appendix 8, wherein the index generation block generates index information after combining the packet including the key information with the decoded MPEG stream.

It is a figure for demonstrating the special reproduction | regeneration processing performed with an MPEG stream reproduction | regeneration apparatus. It is a figure for demonstrating the scrambled TS packet stream. It is a figure for demonstrating 1st embodiment. It is a figure for demonstrating 2nd embodiment. It is a figure for demonstrating the index information generation method. It is a figure for demonstrating the index information utilization method. It is a figure for demonstrating 3rd embodiment. It is a figure for demonstrating 4th embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 ... MPEG stream processing apparatus 31 ... Encryption stream decryption process 32, 48 ... Index generation process 33, 49 ... Stream local encryption process 34, 71, 91 ... Decryption block 37 ... Key recovery block 40, 50, 73, 93 ... Index generation block 43, 51, 74 ... Local encryption block 44, 52, 75 ... Key generation block 82 ... Local encryption / decryption block 84 ... MPEG decoder

Claims (4)

Including key information and content encrypted with the key information, and inputting a packetized MPEG stream for each packet;
For each packet, determine the information type included in the packet,
When the information type is the key information, the packet count number of the packet is stored in the index information together with the information type indicating the key information,
When the information type is the content information, the packet count number of the packet is stored in the index information together with the information type indicating the content information.
An MPEG stream processing method. A decryption block that includes key information and content encrypted with the key information, inputs a packetized MPEG stream for each packet, and outputs a decrypted MPEG stream decrypted based on the key information;
The decoded MPEG stream is input from the decryption block, the information type included in the packet is determined for each packet, and when the information type is the key information, the packet count number of the packet is the key information. An index that stores in the index information together with the information type indicating that the packet information is stored in the index information together with the information type indicating that the information type is content information. Generation block and
An MPEG stream processing apparatus comprising: A local cipher block for encrypting the decrypted MPEG stream;
3. The MPEG stream processing apparatus according to claim 2, further comprising a key generation block for generating key information used for encryption by the local encryption block. 4. The MPEG stream processing apparatus according to claim 3, wherein the key generation block outputs a packet including key information used in the local encryption block and key information used in the index generation block.

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