JP2000286838A - Encoder for contents data, recording medium, distribution method and user terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a scramble code from being recognized in the absence of audio data in a distribution system of contents data including the audio data. SOLUTION: An EX-OR circuit 2 exclusively ORs audio data with a PN code generated on the basis of a memory device ID for a voiced period in an encoder 43A so as to scramble the audio data, and a mute flag is set for a non-voice period or a period close thereto. An EX-OR circuit of a descramble side exclusively ORs the audio data scrambled for a voice period with the PN code to descramble the audio data, and zero data and a mute signal are outputted for a non-voice period or a period close thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for encoding content data including audio data, a recording medium,
The present invention relates to a distribution method and a user terminal.

[0002]

2. Description of the Related Art Conventionally, a system for distributing music data and the like using a communication line (Japanese Patent Laid-Open No.
146820) and a system for distributing using a communication satellite (Japanese Patent Laid-Open Nos. 7-143081, 10-16399).
1) has been proposed.

[0003] The applicant of the present application has
A more specific proposal was made in Japanese Patent Application No. 10-288487, filed on 009. The main inventions in this proposal are:
"A user mobile terminal that transmits a mobile terminal ID and electronic money to a store-installed terminal and receives paid content data; a mobile terminal that receives the mobile terminal ID and the electronic money from the mobile terminal; And a store installation terminal that also transmits the installation terminal ID to the charging center, the content ID, and the mobile terminal I.
D, a billing center for receiving the installation terminal ID and the electronic money from the shop installation terminal,
D, receiving the mobile terminal ID and the installation terminal ID,
A content center that distributes the pay content data to the mobile terminal via the store-installed terminal, and a distribution system.

[0004] By the way, distribution in such an example system is charged, and content data to be charged is scrambled by a predetermined method due to copyright management problems. As an example of the scrambling method, there is a method used for a DVD (digital video disk, digital versatile disk). In this method, video data is scrambled by a method called CSS (content scrambling system). In the CSS system, the original data is scrambled by exclusive-ORing the original data with a PN code as a scrambling code at the time of scrambling. Is exclusive-ORed and descrambled. As another example of the scrambling method, there is a scramble method in which a value obtained by a chaos function is added to original data at the time of scrambling, and a descrambling is performed by subtracting a chaos function value from the scrambled data at the time of descrambling.

[0005]

However, in the case of distributing content data including audio data, in particular, the audio signal has a silent section, and the audio data bits in the silent section become all zeros. For example, if this audio data is scrambled by taking an exclusive OR with the PN code, and if the exclusive OR of the scrambled data and the PN code is taken, the PN code is left as it is. There is a problem that the PN code is output and therefore the PN code is known.

In view of the above problems, the present invention takes an exclusive OR of audio data and a scramble code when scrambling in a system for distributing at least content data including audio data. It is an object of the present invention to provide a content data encoding device, a recording medium, and a user terminal that can prevent a scramble code and a chaos function used at the time from being known. Another object of the present invention is to make it possible to use even when a memory device of a user terminal is detached and attached to another terminal.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention comprises the following means 1) to 4). That is,

[0008] 1) A content data distribution system having at least a content center for distributing content data including at least audio data, and a user terminal for requesting the distribution of the content data, and connecting these via communication means for data distribution Encoding means used for detecting identification information assigned uniquely to the memory device from a memory device incorporated in the user terminal; means for detecting at least a silent section of audio data; and the silent section In a non-interval, the audio data is scrambled according to a predetermined method in accordance with identification information given uniquely to the memory device, and in the silence interval, a scramble means for setting a mute flag, and at least the scrambled audio data and Encoding apparatus of the content data having means for formatting the data structure having a Yutofuragu, the.

2) A content data distribution system having at least a content center for distributing content data including at least audio data, and a user terminal for requesting the distribution of the content data, and connecting these via communication means for data distribution A non-silent section in accordance with identification information uniquely assigned to a memory device built in the user terminal, wherein at least a silent section of the audio data is detected. A recording medium for content data in which data is scrambled, a mute flag is set in the silent section, and at least a data structure having the scrambled audio data and a mute flag is recorded.

[0010] 3) A content data distribution method in a content data distribution system having at least a content center that distributes content data including at least audio data, and a user terminal that requests distribution of the content data, Consists of at least a common header in which the ID of the user terminal is set, and a content set. The content set is provided with at least a silent section of audio data, and is uniquely assigned to a memory device built in the user terminal. In accordance with the identification information, scrambling is performed in a predetermined manner in a section that is not the silent section, a mute flag is set in the silent section, and at least the mute flag is set corresponding to the scrambled audio data and the silent section. The method of distributing content data, wherein the data and a Yutofuragu are distributed are arranged.

[0011] 4) Distribution of content data that has at least a content center that distributes content data including at least audio data, and a user terminal that requests distribution of the content data, and that is connected by communication means to distribute data. Used in the system, at least a silent section of the audio data is detected, and in a section other than the silent section according to identification information uniquely assigned to a memory device built in the user terminal, scrambling is performed by a predetermined method in a section that is not the silent section, A user terminal that sets a mute flag and descrambles and deformats a data structure having at least the scrambled audio data and a mute flag set corresponding to the silence period. The silence The audio data descrambled, the means for outputting the zero data and muted signal based on the mute flag is the silent section, the user terminal of the content data with a predetermined method in a section not.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are general concept block diagrams of a system for distributing content data including at least audio data to which the present invention is applied. The system includes a user portable terminal (transmission side) 40,
Store installation terminal 41, charging center (management center) 4
2. It comprises a content center 43, a communication line 44, a communication satellite 45, and a user portable terminal (reception side) 46.

Each of the portable terminals 40 and 46 has a unique identification code (hereinafter referred to as a player ID or a user terminal I).
D. ). In addition, each user mobile terminal 40,
The memory device and each content in 46 also have a unique identification code (hereinafter, referred to as a memory device ID and a content ID). The mobile terminal 40 requests the store setting terminal 41 to transmit the content data.
At that time, the mobile terminal 40 transmits the content ID, the player ID, and the memory device ID.

Each store-installed terminal 41 also has a unique identification code (hereinafter, referred to as a company ID). The installation terminal 41 requested to transmit the content data notifies the charging center 42 and the content center 43 together with the communication data that the transmission of the content data has been requested from the mobile terminal 40.

The billing center 42 is notified of the content ID, the player ID, and the company ID. The billing center 42 sends a request to send a content data fee corresponding to the content ID to the mobile terminal 40 via the communication line 44 and the installation terminal 41 with reference to a fee table created in advance.

The portable terminal 40 requested to send the content data fee sends the electronic money to the charging center 42 via the installation terminal 41 and the communication line 44 as the content fee. As electronic money, an IC that stores a monetary amount on an IC chip and makes payment through an IC card reader
Card type electronic money (for example, Mondex, VISA
A cash) or an electronic wallet (for example, an NTT flexible electronic ticket) can be used.

When the billing center 42 receives the predetermined electronic money, it notifies the content center 43 of the receipt. Upon receiving the electronic money receipt notification from the charging center 42, the content center 43 sends the content data to the portable terminal 40 via the communication satellite 45 and the installation terminal 41.

After the portable terminal 40 receives the content data via the installation terminal 41, the portable terminal 40 can be detached from the installation terminal 41 and freely carried, and the received content data (for example, music data ) Can be played and enjoyed.

As shown in FIG. 1B, after receiving the content data, the portable terminal (transmitting side) 40 can be detached from the installation terminal 41, can be carried freely, and stored in the portable terminal (transmitting side) 40. The content data can be copied (transferred) to the portable terminal (reception side) 46. The installation terminal 41 does not participate in such copying. In other words, where there is no installation terminal 41, the mobile terminal (transmission side) 40
Content data can be copied between the portable terminal (receiving side) 46 and the portable terminal (receiving side) 46. A fee is also charged for copying the content data between the portable terminals, and electronic money corresponding to the content data fee is sent from the portable terminal (receiving side) 46 to the portable terminal (transmitting side) 40. When the content data is copied between the portable terminals, the portable terminal ID of the portable terminal (receiving side) 46 and the content ID of the copied content data are stored in the portable terminal (transmitting side) 40 as a transfer history. You. This transfer history is stored in the store installation terminal 4 together with the electronic money when the portable terminal (transmission side) 40 is connected to the store installation terminal 41 at a later date.
1 and transferred to the charging center 42. As a result, information as to which portable terminal has acquired which content and electronic money are collected at the charging center 42.

The portable terminal (transmitting side) 40 and the portable terminal (receiving side) 46 are distinguished as a “transmitting side” and a “receiving side” for the sake of convenience, but both have both transmitting and receiving functions. The same thing. The term “sending side” means that the data is transferred between the portable terminals, and the term “transmitting side” is used. The term “receiving side” is used when the data is transferred between the portable terminals. ”.

FIG. 2 is a block diagram showing the configuration of the transmitting-side encoding device. The encoding device 43A is installed in the content center 43 (FIG. 1) and is used to encode transmission data into a predetermined format.

In FIG. 2, for example, the input stereo two-channel L and R audio signals are converted into M-bit digital data by A / D converter 1 for each channel, and then the M-bit data of each channel is converted into parallel data. Is applied to one input terminal of one of the M EX-OR circuits 2. The PN code generator 3 is provided with one word as an initial value for each sector by the scramble key determined by the scramble key determination unit 9 according to the memory device ID, and generates a PN of the number of words corresponding to M bits by a periodic pulse. Generate codes and execute EX-O in parallel
The audio data is output to the other input terminal of the R circuit 2, so that the audio data is exclusive-ORed with the PN code and scrambled. The scrambled audio data is applied to the DVD audio formatting circuit 8. Further, the data of the player ID and the scramble key data encrypted by the encryption unit 10 using the memory device ID are also applied to the DVD audio formatting circuit 8.

Further, the audio signals of the two channels L and R converted by the A / D converter 1 are applied to silent interval detectors 6L and 6R, respectively, and based on the reference data 10 shown in detail in FIG. Alternatively, a section close to silence is detected. As shown in FIG. 3, the reference data 10 is a code for determining whether N pieces of M-bit data are “+0” or “−0” continuously, and N is, for example, a serial number for scrambling. It is almost equal to the number of words in the code, and is determined by the number of data stored in the audio pack. This detection signal is logically ORed by the AND gate 7 to detect a silent section or a section close to silent on both channels, and is applied to the DVD audio formatting circuit 8 as a mute flag setting flag Fsc.

DVD audio formatting circuit 8
Contains a scrambled or unscrambled audio data in a compressed PCM audio pack (A pack) in the title set of the applied physical information section, and includes a mute flag FM based on a mute set flag Fsc.
Is stored in the physical information section that manages the data of the applied physical information section. In addition, the above data is converted to DV
When recording on a D audio disk or a memory IC, data contained in the physical information section is recorded in the lead-in area, and data contained in the applied physical information section is recorded in the data area. . The area configuration of the DVD audio disk is a well-known configuration, and includes a PCA (post-cutting area) area, a lead-in area, a data area, and a lead-out area from the inner circumference to the outer circumference. .

FIG. 4A shows the data structure of the physical information section. This physical information section includes: ・ Sector number “02F000” from lead-in start
h ”before the“ 00h ”block; ・ Sector number“ 02F000h ”to sector number“ 02 ”
F020h ”and two reference code blocks before“ F020h ”. ・ Sector number“ 02F020h ”to sector number“ 02 ”
All 00h for 30 blocks before "F200h"
And from the sector number "02F200h" to the sector number "02
192 control data blocks before “FE00h”; • Sector number “02FE00h” to sector number “03”
All 00h for 32 blocks before "0000h"
Block.

The application information section recorded in the data area stores ISO 9660 and micro UDF (universal disc format) data from the beginning (sector number "030000h"), and then stores the audio title set ( TS), a video TS, a computer TS, and the like.

As shown in FIG. 4B, the control data block in the physical information section is composed of sectors of physical format information, sectors of disk manufacturing information, and sectors of copyright information. . As shown in FIG. 4C, the sectors of the physical format information include an area for book type and part version, an area for disk size and minimum readout rate, an area for disk structure,
It is composed of a recording density area, a data area allocation area, a main data area, and the like.

The book type and part version areas are assigned as disc identifiers. According to the upper bits, "DVD-ROM disc", "DVD-RAM disc", or "DVD-write once" Once) disc, and in the case of “DVD-ROM disc”, the lower bits indicate “computer program disc”, “pure video disc”, or “video + audio navigation”. disk:
Van disc "or" audio disc "is described. In addition, the above-mentioned mute flag MF is based on the fute flag setting flag Fsc,
It is stored in the main data area.

Further, the scrambled audio data is stored in the compressed physical format in the title set (TS) of the applied physical information section stored in the data area shown in FIG.
It is formatted into a CM audio pack (A pack).

The audio pack (A pack) of the compressed PCM has a structure as shown in FIG. The A-pack of the compressed PCM is composed of 2048 bytes or less, and the breakdown is composed of a 14-byte pack header and an A packet. The A packet is composed of a packet header of 17, 9, or 14 bytes, a private header, and 1 to 2011 bytes of audio data (scrambled or unscrambled compressed PCM data).

The private header includes: an 8-bit substream ID; a 4-bit reserved area in the ISRC; a 4-bit ISRC number in the ISRC; an 8-bit ISRC data in the ISRC; It is composed of an 8-bit private header length, 16-bit first access unit pointer, 6-byte audio data information (ADI), and 0 to 7 stuffing bytes.

The ADI includes: a 1-bit audio emphasis flag; a 3-bit mute flag; a 4-bit downmix code; and a 4-bit group "1" quantization word length "1".
And the quantization word length “2” of the 4-bit group “2”
A 4-bit audio sampling frequency fs1 of group "1"; a 4-bit audio sampling frequency fs2 of group "2"; a 4-bit reserved area; and a 4-bit multi-channel type. , 3 bits of reserved area, 5 bits of channel allocation information, and 8 bits of dynamic range control information.

Next, the processing of the DVD audio formatting circuit 8 will be described with reference to FIG. First, each time data is input, it is determined whether or not it is the audio pack start time (step S1). If it is the start time, the data counter DC is set to start counting (step S1).
2) Then, the management data for mute flag setting is reset (step S3), and then the process proceeds to step S4. On the other hand, if it is not the start time in step S1, the process proceeds to step S4, and the mute flag setting flag Fsc is determined.

If "set flag exists" in step S4, it is determined whether or not the count value of the data counter DC is equal to or more than N (step S5). Sets the mute flag MF (step S6), and then proceeds to step S7. Here, as an example, two channels, M = 24
When the audio data in one bit is 1800 bytes, the count value of the data counter DC is 15 at the maximum.
0, but N = 150. On the other hand, if it is determined in step S4 that "there is no flag for setting",
If the count value of the data counter DC is not equal to or larger than N in step 5, the process directly proceeds to step S7. Step S
At 7, it is determined whether or not the audio pack has ended. If not, the process returns to step S1. On the other hand, if the audio pack has ended, this process ends. Then, the mute flag MF is set in the physical information section and the ADI based on the mute flag setting management data.

When accommodating text accompanying audio data, the text data is formatted into a text pack (not shown) by the DVD audio formatting circuit 8 without being scrambled. Note that the compression PCM may be a lossless compression method adopted in the DVD audio standard,
The compression method with loss employed in the above may be used, and other compression methods may be used, and the present invention is not limited thereto.

The data thus formatted by the DVD audio formatting circuit 8 is supplied to an output terminal, and is output to, for example, a D
It is recorded on a VD audio disk or a memory device, or transmitted via a satellite broadcast transmitter (not shown) or the Internet. In data distribution, output data is further subjected to a specific encryption (distribution encryption).

FIG. 7 shows a data structure at the time of transmission generated by the DVD audio format circuit 8. As shown in FIG. 3A, the data is composed of a common header area and each content area. The common header area includes a player ID area, a scramble key area,
It is composed of a title information area, a content set number area, a use area information area, a transfer prepaid area, and a transfer history area.

The player ID area is an area for storing an ID for confirming whether the user terminal is a legitimate user terminal. The player ID is first sent from the data transfer destination to the data transfer source. That is, when the mobile terminal 40 receives data from the installation terminal 41, the player ID of the mobile terminal 40 is transmitted from the mobile terminal 40 to the installation terminal 41. When the portable terminal 46 receives data from the portable terminal 40, the player ID of the portable terminal 46 is transmitted from the portable terminal 46 to the portable terminal 40.

The scramble key area is an area for storing the above-mentioned encrypted scramble key used as a secret key in the encryption processing. The title information area is an area for storing title information composed of a character string whose contents can be identified. The total number of content sets stored in the content area is stored in the content set number area. The use area information area in this area stores an area name obtained by dividing the whole country into a plurality. In the case of Japan, Kanto, Kansai, Kyushu,
For example, Hokkaido, etc., in the case of the world, use the country name.
The transfer prepaid area stores content sales information (value).

The transfer history area contains a content ID.
(Hereinafter, referred to as CID) area, a transfer count area, and a transfer date and time area. The number of transfers refers to the number of times data has been transferred from the portable terminal 40 on the transmitting side to the portable terminal 46 on the receiving side, and the transfer date and time refers to the date and time at which the transfer was performed.

FIG. 7B shows a detailed data structure of each content area. As shown in the figure, the content area includes a content header area and a content data area following the content header area. The content header area includes a content ID area, a provider ID area, a player ID area, a transfer level flag area, and an additional information area.

The company ID area stores a company ID, which is an identification code assigned to each installation terminal that receives distribution data. The transfer level flag area stores a transfer level flag which is a type of transfer rate.
The additional information area includes TOC (Total Of Co).
tents) is stored. TOC is
This is a table of contents in which address information for so-called song start and performance time are recorded. The TOC may be stored in the common header or in both the common header and the content header.

In the content data area, a physical information section according to the DVD audio standard, audio management information (AMG), a scrambled A pack of the compressed PCM shown in FIG. A content set including an audio title in which the text data having the data structure of is combined is stored.

Next, the reproducing means 40A and 46A in the user terminal device will be described with reference to FIG. The input data stream reproduced from the storage unit 23 in the device is:
The distribution encryption is decrypted by the data changing unit 24, the data is deformatted by the DVD audio deformat processor 11b, and separated into the scrambled audio data and the mute flag MF. Also, scramble key data (encryption key data) is read from the scramble key area, and decrypted by the encryption key data decryption unit 11d using the ID read from the memory device ID 23a in the storage unit (memory device) 23. You.
Therefore, if the terminal is not a legitimate user terminal configured with a storage unit having a memory device ID, the encryption key data cannot be decrypted and the scramble cannot be decrypted.

The mute flag MF is applied to the control terminal of the switch 11c, the PN code generator, and the D / A converter. The switch 11c has a mute flag M
F, when the mute flag MF is not output, that is, when it is not a silent section, the control terminal b
The control terminal a is selected during the silent period.

The PN code generator 12 generates a P code corresponding to the scramble key data supplied from the data format processor 11b and the initial value supplied from the initial value generation circuit 18.
An N code is generated at each clock, and when the control terminal b is selected, the DVD audio deformat processor 11b
The exclusive scoring of the scrambled audio data supplied through the PN code by the EX-OR circuit 13 is performed on the scrambled audio data, descrambled and output as it is as a data signal, or the D / A converter 16 Is converted into an analog signal, converted into an analog audio signal, and output. The PN code is not a fixed length, but is generated functionally, continues infinitely, and is initialized with an initial value. Further, the initial value generation circuit 18
Is designed to generate an initial value based on sector information from the system control unit 20.

In a silent section, the mute flag M
F, the switch 11c is switched to the control terminal a side, and zero data is output from the zero data generator 11a to EX-O.
It is supplied to one input terminal of the R circuit 13. At the same time, the mute flag MF is supplied to the PN code generator 12 to clear the generating operation, and zero data is sent to the EX-O.
It is supplied to the other input terminal of the R circuit 13. This gives E
The X-OR circuit 13 outputs zero data. At the same time, the mute signal is output from the D / A converter 16.
In this silent section, the circuit function is stopped, and the generation of unnecessary noise is prevented. Although not shown, the text data pack is separated by the DVD audio deformatting circuit 11 and output as character information via the text data generator 17.

Electronic money corresponding to the content fee of the received content data is paid from the electronic wallet 19. If the TOC is recorded in the TOC memory 18, a high-speed content search stored in the storage unit 23 can be performed. When the user designates the first content set, the second content set,..., The Nth content set from the operation hand unit 21, the TOC refers to the corresponding location of the TOC via the system control unit 20. , The address, the reproduction time, and the like, to start the access and to display the reproduction time. Since there is no need to scan the header of the content, there is no so-called waiting time, and access is easy, so that it can be effectively used for high-speed scanning (intro scan). When the terminal shown in FIG. 8 is used for transfer (transmission), the content stored in the storage unit 23 is decrypted by the data change unit 24 and transmitted from the data transfer interface 25. When the terminal in FIG. 8 receives a content from another terminal, the content is encrypted by the data changing unit 24 before being stored in the storage unit 23.

Next, FIG. 9 shows a second embodiment of the encoding apparatus. In this embodiment, the memory device ID is directly used as the scramble key. Therefore, the scramble determining unit 9 and the encrypting unit 10 in the encoding device shown in FIG. 2 are not required, and the memory device ID itself is formatted instead of the encrypted scramble key. At the time of data transmission, the above-described memory device ID is stored in the common header in place of the encrypted scramble key in the common header. As the reproducing means in the user terminal, for example, a memory device ID confirming section is provided instead of the decryption section 11d of the encryption key data in the reproducing means of FIG. 7 shown as the first embodiment, and transmitted from the encoding device side. Memory device ID and storage unit 23 in the reproducing means.
The IDs read from the memory device ID 23a are compared with each other, and when they match, the matched memory device ID itself is output to the PN code generator 12 as key data. In the case of the second embodiment, the configuration on the encoding side is particularly simplified.

Therefore, according to each of the above embodiments, the mute flag is set in the silence section on the encoder side, and zero data is output using the mute flag on the descrambling apparatus side. It is possible to avoid a situation in which only the scramble signal is output and the scramble code is known to others.

Further, according to the present embodiment, the mute flag for controlling the device is also used as a signal for detecting a silent section, so that it is not necessary to prepare a signal for each of them, and it is not necessary to prepare a signal for the silent section. Since the D / A converter is muted, generation of noise can be prevented.

The above-mentioned mute flag is added to mute the audio data output, and is also supplied to the above-mentioned audio data D / A converter for mute control. As another embodiment of the mute flag, the mute flag is added to a text data pack and supplied to a D / A converter for audio data for mute control when the pack is transmitted. Also, the mute flag may be added to mute the video data output instead of being set for the audio data. In this case, the mute flag is used as a signal for detecting a silent section and the video signal is output. What is necessary is just to supply it for the control for making the output of data a white screen.

In this embodiment, the descramble device outputs zero data based on the mute flag. However, the scramble device may generate and encode zero data. Although zero data is generated in a silent section, the scrambling method may be changed only in that section. Also,
In the present embodiment, the mute flag MF is set in the physical information section and the ADI based on the mute flag setting management data, but may be set in either the physical information section or the ADI. . In the present embodiment, the scramble method based on the CSS method has been described, but another scramble method such as a chaos function method may be used. In the present embodiment, the description has been given of the case where the PN code is generated as a function given the initial value. However, the present invention can be realized by a simple generation method of repeatedly outputting the data of the scramble key, and can be realized by a method not using the initial value. It is not limited to this. Further, in the above embodiment, the data structure has been described using DVD audio. However, this is an example of the data structure, and is, for example, a data broadcasting transmission protocol (MPEG standard is representative) used for a multimedia service. However, the present invention is not limited to this.

[0054]

As described above, according to the present invention, even when pay content data including at least audio data is transmitted, at least a silent section is detected, and a mute flag is set in a silent section. Or output zero data and a mute signal based on the mute flag, so that a scramble code is known or a chaos function is used when taking an exclusive OR of audio data and a scramble code. In this case, it is possible to prevent the chaos function from being known. Further, for example, since the D / A converter can be muted during a silent period, generation of noise during that period can be prevented. Further, in particular, the memory device of the user terminal can be removed and mounted on another user terminal.

[Brief description of the drawings]

FIG. 1 is a block diagram conceptually showing an entire system for performing transmission and reception to which the present invention is applied.

FIG. 2 is a block diagram illustrating an embodiment of a transmitting-side encoding device according to the present invention.

FIG. 3 is an explanatory diagram showing reference data of FIG. 1 in detail;

FIG. 4 is a diagram showing a data structure of DVD audio.

FIG. 5 is an explanatory diagram showing a format of an audio pack of DVD audio.

FIG. 6 is a flowchart showing processing of a DVD audio formatting circuit in the encoding device.

FIG. 7 is a diagram showing a data structure at the time of transmission.

FIG. 8 is a block diagram showing an embodiment of a reproducing unit in the user terminal according to the present invention.

FIG. 9 is a block diagram showing a second embodiment of the encoding device.

[Explanation of symbols]

2 EX-OR circuit (constitutes scramble means by exclusive OR with PN code generator 3) 3,12 PN code generator 6L, 6R Silence section detector (with silence section detection means together with OR gate 7) 7 OR gate 8 DVD audio formatting circuit (formatting means) 11 DVD audio deformatting circuit 13 EX-OR circuit (along with PN code generator 12, constitutes a descrambling means by exclusive OR). 19) Electronic wallet 40, 46 User portable terminal 40A, 46A Reproducing means 41 Retailer installation terminal 43 Content center 43A Encoding device 45 Communication satellite

Claims (4)

[Claims] 1. A content data distribution system having at least a content center for distributing content data including at least audio data, and a user terminal for requesting the distribution of the content data, and connecting these via communication means for data distribution. An encoding device used for: a means for detecting identification information uniquely assigned to the memory device from a memory device built in the user terminal; a means for detecting at least a silent section of audio data; In a non-interval, the audio data is scrambled in a predetermined manner according to the identification information assigned to the memory device, and in the silent interval, a mute flag is set, and at least the scrambled audio data and Mi Means for formatting into a data structure having a hute flag. 2. A content data distribution system having at least a content center for distributing content data including at least audio data, and a user terminal for requesting the distribution of the content data, and connecting these via communication means for data distribution. A non-silent section in accordance with identification information uniquely assigned to a memory device built in the user terminal, wherein at least a silent section of the audio data is detected. A recording medium for content data in which data is scrambled, a mute flag is set in the silent section, and at least a data structure having the scrambled audio data and a mute flag is recorded. 3. A content data distribution method in a content data distribution system having at least a content center that distributes content data including at least audio data, and a user terminal that requests distribution of the content data, Comprises at least a common header in which the ID of the user terminal is set, and a content set. The content set is provided with at least a silent section of audio data, and is uniquely assigned to a memory device built in the user terminal. In accordance with the identification information, scrambling is performed in a predetermined manner in a section that is not the silent section, and a mute flag is set in the silent section. The method of distributing content data, wherein the data and a Tofuragu are distributed are arranged. 4. A content data delivery system comprising at least a content center for delivering content data including at least audio data, and a user terminal for requesting the delivery of the content data, and connecting these via communication means to deliver content data. The system is used for detecting at least a silence section of audio data, and scrambles in a predetermined manner in a section other than the silence section according to identification information uniquely assigned to a memory device built in the user terminal. A user terminal that sets a mute flag and descrambles and deformats a data structure having at least the scrambled audio data and a mute flag set corresponding to the silence period. And the silent section In no section descrambling the audio data in a predetermined manner, means for outputting the zero data and muted signal based on the mute flag is the silent section, the user terminal of the content data with.