(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2002/0078178A1
`Senoh
`(43) Pub. Date:
`Jun. 20, 2002
`
`US 20020078178A1
`
`(54) CONTENT DISTRIBUTION CONTROL
`(75) Inventor: Takanori Senoh, Osaka (JP)
`
`(52) U.S. Cl. .............................................................. 709/219
`(57)
`ABSTRACT
`
`Correspondence Address:
`SES & BERNSTEIN, P.L.C.
`RESTON SN
`RS PLACE
`9
`(US)
`(73) ASSignee: MESS,ECTIS INDUS-
`es
`., Osaka (JP)
`09/938,664
`9
`Aug. 27, 2001
`(22) Filed:
`Foreign Application Priority Data
`(30)
`Aug. 29, 2000 (JP)...................................... 2000-258651
`Publication Classification
`
`(21) Appl. No.:
`y
`- - -
`
`7
`(51) Int. Cl." ..................................................... G06F 15/16
`
`Content distribution control over a network in an electroni
`distribution System protects the content copyright while
`distributing content in a format enabling viewing and enjoy
`ment at the user terminal. The method for controlling
`content distribution over a network comprises generating
`content in a first format specification by adding content
`identification data for identifying Specific content to data
`produced in a first format specification for viewing, Sending
`the content to a network, receiving the content via the
`network; separating the received content into the content
`identification data and the data in the first format Specifica
`tion; converting the Separated data in the first format speci
`fication to data in a different, Second format Specification;
`generating content in a Second format Specification by
`adding the Separated content identification data to the data
`converted to the Second format Specification; and then
`Sending the content in the Second format Specification to a
`user terminal.
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`CONTENT SERVER 3
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`CONTENT D
`GENERATING UNIT
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`CONTENT D
`321 APSENDING UNIT
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`AUDIO/WIDEO DATA
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`20 COPYRIGHT
`HOLDER TERMINAL
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`RELAY SERVER 2
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`TABLE
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`WERFICATION
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`DATA
`STORAGE UNIT
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`BULLETIN
`UNIT
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`FORMAT
`SEPARAON CONVERTER APPENING
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`CONTENT IN THE
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`PURCHASE
`REQUEST
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`CONTENTIN THE
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`-10
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`1 USER
`TERMINAL
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`PLAYBACK
`UNIT
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`RECORDER
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`D
`EXTRACTION
`UNIT
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`VIDEOLABS, INC.
`EX2004
`NETFLIX, INC. v. VIDEOLABS, INC.
`IPR2023-00628
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`

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`Patent Application Publication Jun. 20, 2002 Sheet 1 of 7
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`US 2002/0078178A1
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`Fig. 1
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`COMMUNICATION
`NETWORK 4
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`CONTENT
`SERVER
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`Patent Application Publication
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`Jun. 20, 2002 Sheet 2 of 7
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`US 2002/0078178A1
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`Patent Application Publication
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`Jun. 20, 2002 Sheet 3 of 7
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`Patent Application Publication
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`Jun. 20, 2002 Sheet 4 of 7
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`US 2002/0078178 A1
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`Patent Application Publication Jun. 20, 2002 Sheet 5 of 7
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`US 2002/0078178 A1
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`Fig.5
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`coPYTIGHT HOLDERIDENTIFIERI
`conTENT DENTIFICATION CODE
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`CONTENT
`too
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`CONTENT 2 conTENT 3
`1054
`75000s
`AAAB
`I
`ZacD
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`ID TABLE 22
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`Patent Application Publication
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`US 2002/0078178 A1
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`Z HEAHES AWTEH ?– ? ?-8 HENHHS INHINO0
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`Patent Application Publication Jun. 20, 2002 Sheet 7 of 7
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`US 2002/0078178 A1
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`Fig. 7 PRIOR ART
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`CONTENT-OWNER
`TERMINAL
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`100
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`101
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`USER
`TERMINAL
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`TERMINAL
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`102
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`US 2002/0078178 A1
`
`Jun. 20, 2002
`
`CONTENT DISTRIBUTION CONTROL
`
`BACKGROUND OF THE INVENTION
`0001) 1. Field of the Invention
`0002 This invention relates to controlling an electronic
`distribution System for distributing digital multimedia con
`tent, including audio and Video, by way of a network.
`0003 2. Description of Related Art
`0004 FIG. 7 shows a prior art electronic distribution
`system 100, which as shown in the figure has plural user
`terminals 101 and 102 and a content-owner terminal 103.
`The plural user terminals 101 and 102 and content-owner
`terminal 103 are connected to a common network 104, Such
`as the Internet, whereby they can communicate with each
`other.
`0005. When content is conventionally distributed using
`this electronic distribution system 100, the content owner
`loads a catalog of the available content onto a web site and
`Solicits users wanting the content. When a user provides
`credit card information to pay for desired content, the
`electronic distribution system 100 verifies the credit card
`information to authenticate the user, and then delivers the
`requested content to the user.
`0006 More specifically, the content owner publishes a
`directory of the content that is available for distribution and
`makes the directory accessible via the network 104. The
`published directory is a catalog containing at least titles,
`content Summaries and price information that is uploaded to
`a web site on the content-owner terminal 103. When a user
`of a user terminal 101 wants to obtain particular content, the
`user connects to the network 104 using the user terminal 101
`and accesses the web site where the desired content is
`located either by using a Search engine Site to find the web
`Site address or inputting the web site address found from a
`magazine, for example. If the Summary and price of the
`desired content found in the catalog on the web site are
`acceptable to the user, the user Sends his credit card number
`and other information to the content-owner terminal 103. If
`the content owner Successfully verifies the credit card infor
`mation, the content-owner terminal 103 sends the content to
`the user terminal 101.
`0007. The technology described above is described in
`U.S. Pat. No. 6,055,513, “Method and Apparatus for Intel
`ligent Selection of Goods and Services in Telephonic and
`Electronic Commerce.”
`0008. A problem arises with this prior art electronic
`distribution system 100 when the specifications of the dis
`tributed content differ from the specifications of content that
`is viewable on the user's terminal or monitor, resulting in the
`user being unable to enjoy the content. This problem occurs,
`for example, when the content-owner terminal 103 distrib
`utes content in the high definition TV (HDTV) format but
`the terminal on the user terminal 101, 102 side can only
`display content in the standard definition TV (SDTV) for
`mat.
`0009. Another problem with this prior art electronic
`distribution system 100 is that it is not possible to prevent
`illegal copying of content. More specifically, it is not poS
`sible to prevent the user of a user terminal 101 from loading
`purchased content to the user's own web site without the
`
`permission of the content owner So that a third party (Such
`as the user of user terminal 102) can copy the content from
`the first user's web site either for a fee or for free. This act
`Subjects the producer and legal owner of the content to
`Significant loSS of income and is piratical.
`SUMMARY OF THE INVENTION
`0010. An object of this invention is therefore to provide
`an electronic distribution System that can protect the copy
`right of the content and also provide content in a format that
`can be viewed on the user terminal.
`0011 To achieve these objects, a method according to the
`present invention for controlling content distribution over a
`network has steps of generating content in a first format
`Specification by adding content identification data identify
`ing Specific content to data produced in a first format
`Specification for viewing, Sending the content to a commu
`nication network, receiving the content via the communica
`tion network; Separating the received content into the con
`tent identification data and the data in the first format
`Specification; converting the Separated data in the first
`format Specification to data in a Second format Specification
`that is different from the first format Specification; generat
`ing content in a Second format Specification by adding the
`Separated content identification data to the data converted to
`the Second format Specification; and Sending the content in
`the Second format Specification to a user terminal.
`0012. The objects of the invention can also be achieved
`by writing the content distribution control method of the
`invention as a computer-executable content distribution con
`trol program.
`0013 These objects can yet further be achieved with a
`recording medium Storing this content distribution control
`program.
`0014. Yet further, the objects of the invention can be
`achieved with a System according to the present invention
`for controlling content distribution over a network, the
`System having a first identification data adding unit for
`generating content in a first format Specification by adding
`content identification data for identifying Specific content to
`data produced in a first format Specification for viewing, and
`then Sending the content to a communication network, an
`identification data separating unit for receiving the content
`from the first identification data adding unit via the com
`munication network, and Separating the received content
`into the content identification data and the data in the first
`format Specification; a converter for converting data in the
`first format Specification Separated by the identification data
`Separating unit to data in a Second format Specification that
`is different from the first format Specification; and a Second
`identification data adding unit for generating content in a
`Second format specification by adding the content identifi
`cation data separated by the identification data separating
`unit to the data to the data converted to the Second format
`Specification by the converter, and then Sending the content
`in the Second format Specification to a user terminal.
`0015. By converting content from a first format specifi
`cation to a Second format Specification and Sending the
`reformatted content to a viewer (user) terminal, the content
`distribution System of the present invention enables a user to
`enjoy content in the format of a display device that is
`different from the specifications of the user terminal.
`
`

`

`US 2002/0078178 A1
`
`Jun. 20, 2002
`
`0016. In addition, by adding the identification data
`inserted to content in the first format Specification to the
`content converted to the Second format Specification, the
`rights of the content owner can be protected even after the
`format of the content has been changed.
`0.017. Yet further, content ID appropriate to content in the
`Second format specification can be achieved by converting
`the content ID extracted from content in the first format
`Specification according to the conversion to the Second
`format and then adding the converted content ID to the
`content in the Second format.
`0.018. A drop in the quality of content in the second
`format can also be prevented by converting content from the
`first to the second format after removing the content ID from
`the content in the first format.
`0019. Other objects and attainments together with a fuller
`understanding of the invention will become apparent and
`appreciated by referring to the following description and
`claims taken in conjunction with the accompanying draw
`IngS.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0020. These and other object and features of the present
`invention will become clear from the following description
`taken in conjunction with the preferred embodiments thereof
`with reference to the accompanying drawings, in which:
`0021
`FIG. 1 is a diagram showing the configuration of
`a content distribution system according to a preferred
`embodiment of the present invention;
`0022 FIG. 2 is a block diagram showing a specific
`configuration of this content distribution System;
`FIG. 3 is an example of content identification data;
`0023
`0024 FIG. 4 is an example of a catalog containing plural
`catalog data entries,
`0.025
`FIG. 5 is an example of an identification data table;
`0.026
`FIG. 6 is the concept of the format conversion
`process, and
`0.027
`FIG. 7 is a prior art electronic distribution system.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0028. The preferred embodiments of the present inven
`tion are described below with reference to the accompanying
`figures wherein parts having the same reference numeral
`also have the same function.
`0029 FIG. 1 shows the configuration of a content dis
`tribution system 10 according this preferred embodiment of
`the invention. Content distribution system 10 has a user
`terminal 1, relay Server 2, and content Server 3. The user
`terminal 1, relay Server 2, and content Server 3 are each
`connected to a communication network 4, Such as the
`Internet, through which they can communicate with each
`other. With content distribution system 10, the content server
`3 provides the content available for distribution (selling) on
`the relay server 2. Users can view the content published on
`the relay Server 2 and purchase the desired content. User
`purchase requests are Sent to the content Server 3. The
`content Server 3 then Sends the requested content to the relay
`
`Server 2 in a first format Specification. The relay Server 2
`converts the content received from the content server 3 in the
`first format to a Second format Specification, and sends the
`reformatted content to the user terminal 1. It will be obvious
`to one with ordinary skill in the related art that while only
`one user terminal 1 is shown in the figure, plural user
`terminals can be connected.
`0030 The configuration of this content distribution sys
`tem 10 is described in greater detail with reference to FIG.
`2. FIG. 2 is a block diagram showing a specific configura
`tion of the content distribution system 10. Note that for
`convenience the communication network 4 is not shown.
`This configuration is described next in conjunction with data
`flow.
`0031. The content producer first produces audio and/or
`Video (AV) data (multimedia data) according to a particular
`digital Specification. This multimedia data is what the user
`ViewS and listens to, and is commonly and herein referred to
`as “content.” It will also be noted that multimedia data to
`which content identification data (hereinafter referred to as
`“content ID' and further described below) has been added
`for copyright protection is also referred to herein as content.
`It will be further noted that “data” when used alone means
`multimedia data to which content ID has not been added.
`0032. The content producer is typically the copyright
`holder. The content could be only video or only audio. In
`order to distribute content, the copyright holder Sends the
`content from the copyright holder terminal 20 to the content
`server 3. The copyright holder terminal 20 is a computer
`terminal whereby the copyright holder transmits data. The
`copyright holder terminal 20 and content server 3 could be
`the same computer.
`0033. The content server 3 has a content identification
`data generating unit 31 and a content identification data
`appending unit 32 (hereinafter referred to as “content ID
`generating unit 31' and “content ID appending unit 32',
`respectively). The content ID generating unit 31 generates
`the content ID according to a specified process. The content
`ID is uniquely and uniformly assigned in order to identify
`the content.
`0034 FIG. 3 shows an example of the content ID. As
`shown in FIG. 3, the content ID preferably contains the
`following information in a Specified format: a copyright
`holder identifier, content identification code, content record
`ing date, who recorded the content, title, genre, content type,
`duplication fee, and a contact address for the buyer.
`0035. The copyright holder identifier is uniformly and
`uniquely assigned to each copyright holder, and enables the
`owner of the copyright to the content to be identified. The
`copyright holder identifier is transmitted with the content
`from the copyright holder terminal 20 Sending the content,
`or the sender is identified by the content server 3.
`0036) The content identification code is a unique value,
`and is added when the content is commercial content pro
`duced by a production company or other content creation
`company for resale purposes. The content identification
`code of content 2 in FIG. 3 is AAAB. The content ID
`generating unit 31 (FIG. 2) generates the content identifi
`cation code using not only the content creation date, but also
`the hour, minute, Second, and even millisecond data as
`parameters. If it is desirable to uniquely identify content 2
`
`

`

`US 2002/0078178 A1
`
`Jun. 20, 2002
`
`Worldwide, the producer can apply to an organization for
`assigning identification codes that are common Worldwide
`and ask for the unique content identification code AAAB for
`use with the particular content. As will be further described
`below, this content identification code and copyright holder
`identifier can be used to determine if content is an illegal
`copy.
`0037. The name of the recorder, title, and other informa
`tion is input by the producer.
`0.038
`Returning again to FIG. 2, the content ID append
`ing unit 32 embeds the content ID generated by the content
`ID generating unit 31 as a digital watermark in the content
`received from the copyright holder terminal 20.
`0039. A digital watermark is characterized primarily in
`that the digital watermark is not lost when the copyrighted
`material (audio or video) is edited or compressed or
`expanded; is embedded at a level that is not detectable to the
`human eye or ear; and the original quality of the copyrighted
`material is maintained even when a digital watermark is
`embedded. The content ID is thus integral to and inseparable
`from the content, overwriting the content ID can be pre
`vented, and the content ID can be used to control playback
`and recording of the content.
`0040 Various methods can be used to embed a digital
`watermark. One method is to randomly add the digital
`watermark data to a specific frequency component of the
`content. More Specifically, the Signal containing embedded
`digital watermark data is
`(1)
`ai-xici
`0041 where ai is the specific frequency component of the
`content where the digital watermark is inserted, ci is a
`random value of +1 or -1, and Xi is the value of the content
`ID that is embedded as the digital watermark.
`0042. This results in content having the content ID Super
`imposed as a digital watermark on the content. It will also
`be obvious that when the content ID is Superimposed as
`digital watermark data to the content from the copyright
`holder terminal 20, the content ID can be encrypted before
`being Superimposed. In this case the value of Xi in equation
`1 is the value of the encrypted content ID. Either the content
`ID generating unit 31 or the content ID appending unit 32
`can process the encryption. Using encrypted content ID as
`the digital watermark data also makes unauthorized decryp
`tion of the information by a user more difficult and thus more
`reliably protects the copyright.
`0043. The content server 3 then generates and sends
`catalog data for the content to the relay Server 2 in order to
`market the content to a wider audience. The catalog data
`could contain previews of content highlights, a copyright
`notice, the title, content type, price, and where to contact to
`purchase the content.
`0044) Referring again to FIG. 2, the relay server 2 is a
`Server computer accessible from the network and Storing a
`compiled catalog of plural catalog data entries. If the content
`contains video, the relay Server 2 preferably enables the
`content highlights to be previewed. If the content is audio
`(music), a selection of a particular length could be provided
`as a preview. The copyright notice and warning about illegal
`act of copying is likewise displayed.
`
`0045. A sample catalog compiling plural catalog data
`entries is shown in FIG. 4. The catalog can be posted to a
`common bulletin board (electronic bulletin board) acces
`sible from the network. Users can then select desired content
`by accessing the bulletin board on the relay Server 2 and
`viewing the catalog. It should be further noted that the
`content ID is also contained in the preview data extracted
`from the content.
`0046) The configuration of the relay server 2 is described
`next. As shown in FIG. 2, the relay server 2 has an
`identification data extraction unit 21 (hereinafter referred to
`as “ID extraction unit 21'), identification data table 22
`(hereinafter referred to as “ID table 22”), verification unit
`23, catalog data Storage unit 24, bulletin board 25, identi
`fication data separation unit 26 (hereinafter referred to as
`“ID separation unit 26’), format converter 27, and identifi
`cation data appending unit 28 (hereinafter referred to as “ID
`appending unit 28).
`0047 The ID extraction unit 21 extracts the identification
`data added to the content from the preview part used in the
`catalog data. The identification data referred to here is the
`copyright holder identifier (10001), 10054) in FIG. 4) and
`the content identification code (AAAB in FIG. 4), that is,
`the digital watermark data added randomly to the Specific
`frequency component.
`0048. The specific method of extracting the identification
`data is described below. That is, the content is first passed
`through the same bandpass filter used to insert the digital
`watermark to extract the frequency component where the
`identification data is embedded. The same random number
`used for digital watermark insertion is multiplied with the
`frequency component, and the result is passed through a
`filter for extracting only the DC component. As described
`above with reference to equation 1, the Signal containing
`embedded digital watermark data can be written as ai+
`Xici where ai is the specific frequency component of the
`content where the digital watermark is inserted, ci is a
`random value of +1 or -1, and Xi is the value of the content
`ID that is embedded as the digital watermark. The value after
`the ID extraction unit 21 is multiplied by random number ci
`is therefore
`
`0049. When public key encryption is used random num
`ber ci is encrypted using the public key and Sent only to the
`relay Server 2 and the user terminal of the authorized user.
`The relay Server 2, for example, then decrypts random ci
`using a unique Secret (private) key. More specifically, ran
`dom number ci is +1 or -1, so the DC component of ai ci
`is 0 and ci^2=1. Filtering this signal with the dc component
`extraction filter results in (ai-Xici)*ci=xi, and the identifi
`cation data embedded as the digital watermark can be
`extracted.
`0050. If the content ID used as the digital watermark was
`first encrypted, a key is needed for decryption. This key can
`be obtained from the content server 3. The ID extraction unit
`21 uses this key to decode the content ID. If public key
`encryption is used, the public key used for encryption and
`the private key used for decryption are both required.
`
`

`

`US 2002/0078178 A1
`
`Jun. 20, 2002
`
`0051. The identification data can alternatively be
`encrypted as (xi+ci) where ci is randomly +1 or -1 and Xi is
`the value of the content ID used as the digital watermark and
`(+) indicates an exclusive OR. By adding ci to Xi+ci, the
`result is
`
`0.052 and the ID extraction unit 21 can extract the
`identification data. AS noted above, the random number ci is
`Sent only to the relay Server 2 and user terminal of an
`authorized user using public key encryption.
`0053. It will also be noted that encryption and decryption
`using the copyright holder identifier can also be accom
`plished by multiplying the copyright holder identifier and a
`random number or other method.
`0.054 The ID table 22 stores the copyright holder iden
`tifier and content identification code as a set. FIG. 5 shows
`an example of the ID table 22. The information stored to the
`ID table 22 is the content identification code and copyright
`holder identifier information used in the catalog data that is
`Sent from the content Server 3 before the catalog data is sent
`to the relay server 2.
`0055. The verification unit 23 shown in FIG. 2 verifies if
`the combination of copyright holder identifier and content
`identification code extracted by the ID extraction unit 21 is
`correct. More specifically, the verification unit 23 compares
`the copyright holder identifier and content identification
`code combination extracted by the ID extraction unit 21 with
`the copyright holder identifier and content identification
`code combinations Stored in the ID table 22, and if a match
`is found knows that the content is not an illegal copy. This
`means that the verification unit 23 determines whether the
`catalog data and further the content Sent from the content
`server 3 is information that was sent by the copyright holder.
`If the combination is confirmed to be legal, the verification
`unit 23 allows the catalog data Storage unit 24 to Store the
`catalog data. The catalog data Storage unit 24 then Stores the
`catalog data sent from the content server 3. Distribution of
`the content is thus allowed, and the content catalog is posted
`to the bulletin board 25. The catalog shown in FIG. 4
`contains content I and content 2.
`0056. The verification unit 23 detects an illegal copy if
`the combination of copyright holder identifier and content
`identification code extracted by the ID extraction unit 21
`does not match a combination stored in the ID table 22, or
`if the content ID is not detected, and the catalog data is
`therefore not posted to the bulletin board 25. This is because
`there is a high probability that it is an illegal copy of existing
`commercial content. In this case the user requesting that the
`content be posted (the user terminal of the general user that
`made the illegal copy, for example) is notified that the
`content will not be posted. This results in illegally copied
`content not being posted to the bulletin board 25. To
`forcefully protect against illegal copying, the legal holder of
`the content copyright could also be notified that there was an
`attempt to load an illegal copy of the copyrighted content. It
`will be noted that by polling the organization assigning
`common identification codes worldwide to confirm whether
`a copyright holder identifier and content identification code
`combination is correct, the verification unit 23 can deter
`mine the authenticity (legality) of the identification data.
`0057 The user terminal 1 is described next. The user
`terminal 1 is the terminal or computer whereby a user views
`
`the bulletin board 25 containing the catalog data, Views
`previews of content from the catalog data on the bulletin
`board 25, and views or listens to the content. If there is
`content that the user wishes to purchase, the user Sends a
`purchase request to the content provider (marketer or copy
`right holder of the content on the content server 3). This
`request contains the e-mail address or other information
`Specifying the content provider or other party marketing the
`content. When the content Server 3 receives Such a purchase
`request, it sends a request for credit card information,
`electronic money, or other payment method to the user
`terminal 1. The content server 3 also requests the format
`Supported by the user terminal 1 for viewing the content.
`0058 When the credit card information and format Sup
`ported by the user terminal 1 is received, the content Server
`3 verifies the credit card information, electronic money, or
`other payment information, and then Sends the content
`desired by the user to the relay server 2. If the format of the
`content received from the content Server 3 is the Same as
`format Specified by the user, the relay Server 2 simply sends
`the content directly to the user terminal 1.
`0059) If the format of the content sent to the relay server
`2 differs from the format required by the user terminal 1, the
`relay server 2 converts the received format to the format
`viewable by the user terminal 1, and then transmits the
`content to the user terminal 1. The term “viewable” means
`that the user terminal 1 Supports the format in which the
`content will be reproduced, or can display the content at the
`performance of the output display (the display performance
`of the monitor) of the user terminal 1. This process is run
`primarily by the ID separation unit 26, format converter 27,
`and ID appending unit 28.
`0060. The primary steps of the process of this invention
`for format conversion are described next with reference to
`FIG. 6. While the format specification includes the encoding
`method, resolution, and other parameters, a process for
`converting content in MPEG-2 main profile, high level
`format (such as HDTV format) to content in MPEG-4 simple
`profile, level 0 format (such as Quarter Common Interme
`diate Format (QCIF)) is used by way of example. This
`conversion proceSS enables the user to view content using a
`cellular phone or other user terminal 1 on which content
`cannot be viewed in the normal TV format.
`0061
`FIG. 6 shows the concept of this format conversion
`process, which is described in Sequence below. The copy
`right holder produces MPEG-2 main profile, high level AV
`data conforming to the HDTV format, and sends this data to
`the content server 3. The content ID appending unit 32 of the
`content Server 3 generates content in first format by adding
`content ID as a digital watermark encrypted using a public
`key encryption scheme to the AV data. The content server 3
`Sends content in this first format to the relay Server 2.
`0062. Using the private decryption key, the ID separation
`unit 26 of the relay server 2 separates the content ID from
`the content, and thus extracts the content and the content ID.
`More specifically, it separates the content ID from the
`content formatted to this first format specification. The AV
`data is then obtained by subtracting the content ID from the
`first format data.
`0063. It should be noted that the process described below
`can continue by Simply extracting the content ID from the
`content without completely separating the content ID and
`
`

`

`US 2002/0078178 A1
`
`Jun. 20, 2002
`
`AV data. In this case, however, plural different digital
`watermarks will be added to the content, and content quality
`will likely deteriorate.
`0064. The format converter 27 then downsamples the
`MPEG-2 main profile, high level format AV data obtained
`by the ID separation unit 26 to MPEG-4 simple profile, level
`0 format AV data. Using the procedure described above for
`adding a digital watermark, the ID appending unit 28 of the
`relay server 2 then adds the extracted content ID to the
`converted AV data to output data formatted to the Second
`format specification. The ID appending unit 28 sends the
`reformatted content to the user terminal 1 (FIG. 1).
`0065. It will be noted that the extracted content ID is
`re-inserted to the reformatted content as the digital water
`mark without modification in the above example. It will be
`obvious, however, that the format converter 27 could delete
`or modify part of the content ID before inserting it as the
`digital watermark to the AV data. For example, the original
`content ID could contain information indicating that the
`content is formatted to the first format specification, and the
`format converter 27 could modify the content ID inserted to
`the AV data to indicate that content has been reformatted to
`the second format specification. In this case it will still be
`possible to determine that content was illegally obtained
`even if a third party reformats the content because the digital
`watermark cannot be changed by a third party and the
`content ID (digital watermark) will still contain information
`indicating the first format Specification even though the
`content has been reformatted to the second specification.
`0.066. It will also be obvious that different methods and
`encryption keys can be used to add or insert the digital
`watermark data.
`0067. It will also be obvious that while conversion from
`an MPEG-2 main profile, high level format to the MPEG-4
`simple profile, level 0 format is described above, the inven
`tion shall not be so limited as other conversions will also be
`possible. Irrespective of whether the content is moving
`picture data or Still image data, conversion from one format
`to another format such