Abstract:
A method for controlling the watermarking of a set of multimedia data includes performing a first detection operation for detecting the presence of a first type of watermark in the multimedia data and generating a first partial authorization or prohibition parameter in response to this first detection operation. The method further performs a second detection operation for detecting the presence of a second type of watermark in the multimedia data and generates a second partial authorization or prohibition parameter in response to this second detection operation. A final authorization or prohibition parameter is then generated on the basis of the partial authorization or prohibition parameters generated to authorize or prohibit the transmission of the multimedia data. A device for carrying out the method is also proposed.

Description:
This application claims the benefit, under 35 U.S.C. § 365 of International Application PCT/FR01/01332, filed Apr. 27, 2000, which was published in accordance with PCT Article 21(2) on Nov. 8, 2001 in French and which claims the benefit of French patent application No. 00/05616 filed May 3, 2000. 
   BACKGROUND OF THE INVENTION 
   1) Field of the Invention 
   The present invention relates to the field of combating the reproduction, representation or any other illicit use of multimedia data. More specifically it relates to controlling multimedia data watermarks. 
   2) Description of the Related Art 
   With the advent of sophisticated multimedia data reproduction means, the general consumer electronics field faces the problem of illicit copies. A user should not be able to illegally copy analog or digital multimedia data. The present situation of audio CD, CD-ROM and MP3 files pirating illustrates the magnitude of this problem. 
   Current proposals (such as XCA, 5C, 4C, JAWS and GALAXY for example) use two basic technologies: encryption and watermarking. The invention relates more specifically to data watermarking methods and devices which have advantages associated with robustness without resorting to keys. 
   It is recalled that watermarking multimedia data consists in inserting an imperceptible or almost imperceptible item of information into these data. This information may relate especially to copying rights or prohibitions. Chapter 18 “A review of watermarking principles and practices” in the book “IEEE Digital Signal Processing for Multimedia Systems” written by I. J. Cox, M. Miller, J. P. Linnartz and T. Kalker, edited by K. K. Parhi and T. Nishitani in 1999, provides a description of the principles of watermarking multimedia digital data. 
   For a specific example of the JAWS technology developed by PHILIPS, one may refer to the article “A video watermarking system for broadcast monitoring” written by Ton Kalker, Geert Depovere, Jaap Haitsma and Maurice Maes, published in 1999 in “Proceedings SPIE, 3657 Security and Watermarking of Multimedia content”. 
   It transpires that security is an endless race between the ingenuity of the fraudsters and measures for combating illicit copies. Thus, watermarking techniques evolve over time without any compatibility being guaranteed between generations of watermarking. This poses two problems:
         first generation multimedia data players cannot control copying of data containing only second generation watermarks;   similarly, second generation players cannot control copying of data containing only first generation watermarks.       

   There is a similar problem when two different watermarking technologies are offered on the market. One player cannot analyse both kinds of watermarking. 
   BRIEF SUMMARY OF THE INVENTION 
   The object of the present invention is to solve the aforementioned problems. 
   More specifically, one of the objectives of the present invention is to enable a method and/or device for controlling multimedia data watermarking to carry out certain operations, in particular:
         the detection of several kinds of watermarking,   the extraction of corresponding information,   the generation of partial authorizations or prohibitions on playing, recording and/or performing a given process on all or part of these multimedia data according to the type(s) of watermarks detected, the possible information extracted and/or external parameters   the generation of final authorizations or prohibitions according to the partial authorizations or prohibitions generated and/or   the transmission of authenticated multimedia data intended for a use authorized by a final authorization applying to these data       

   The invention also has the aim of enabling the watermark control methods and devices to update parameters for watermarks or operations as previously described. 
   Another aim of the invention is the insertion of watermark parameters corresponding to a new type of watermark and/or new operations as previously described. 
   To this end, the invention proposes a method of controlling the watermarking of a set of multimedia data including a step of performing a first detection operation capable of detecting a first type of watermark noteworthy in that it includes a step of performing at least a second detection operation capable of detecting at least a second type of watermark. 
   Thus the invention can be used for performing operations for detecting at least two different types of watermark. Hence, different generations of watermarks and/or those offered by different producers can be advantageously detected. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it includes a step of inserting detection information necessary for performing at least one of the second detection operations. 
   Thus, advantageously, the invention enables an upgrading of the methods or means of watermark detection which can thus be adapted to new generations of watermarks without, however, losing the ability to detect older generations. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it further includes an operation of updating at least one of the detection operations. 
   Thus, the invention can update or replace a method or means of existing watermark detection capable of detecting a first or a second type of watermark according to any criterion. 
   Thus, thanks to its possibilities of updating or installing methods or means of detection, the invention advantageously offers great flexibility of use whilst allowing relatively economic implementation. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that when a watermark is detected, at least one of the detection operations performed is followed by an operation of extracting information from the detected watermark. 
   Thus, the invention enables the extraction of relatively rich information which may subsequently be used for authorizing or prohibiting the use of multimedia data for playing, recording and/or any processing whatsoever. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that an operation of generating at least one partial authorization or prohibition parameter is associated with each of the detection operations, taking into account the result of the detection operation. 
   Thus, the invention takes advantage of the detection of each type of watermark and any possible information extracted to generate an authorization or prohibition parameter. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that the generation operation further takes into account at least one parameter external to the detection operation associated with it. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that the external parameter includes a signature validation and/or information on the presence or absence of encryption and/or information identifying a recordable or non-recordable type of medium. 
   This characteristic is especially advantageous since it enables account to be taken not only of characteristics specific to the watermark, but also of external parameters which may be important for assigning authorizations or prohibitions. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it further includes a step of updating at least one of the operations of generating and/or installing a new operation of generating at least a partial authorization or prohibition parameter. 
   Thus, the invention advantageously enables an upgrading of the methods or means of generating parameters. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it further includes at least an operation of generating at least a final authorization or prohibition parameter, each final authorization parameter taking into account at least a part of the partial authorization or prohibition parameters. 
   Thus, the invention is advantageously used to take into account all or part of the partial authorizations or prohibitions to generate final authorizations or prohibitions. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that the operation of generating a final authorization or prohibition parameter includes a Boolean operation of the set of partial authorization or prohibition parameters. 
   Thus, the invention is advantageously especially simple to implement. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that the operation of generating a final authorization or prohibition parameter further takes into account a priority associated with at least one parameter out of the partial authorization or prohibition parameters. 
   Thus, the invention advantageously uses the partial authorization or prohibition parameters in a very complete and subtle way. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it further includes an operation of updating at least one of the operations of generating a final authorization or prohibition parameter and/or installing at least a new operation of generating a final authorization or prohibition parameter. 
   Thus, all the means and methods of the detection chain up to the transmission of authorized data can advantageously follow the upgrading not only of the types of watermarks, but also of the types of authorizations and prohibitions likely to be used. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that at least one of the final authorization or prohibition parameters belongs to the group including:
         a parameter for authorizing or prohibiting the playing of all or part of the set of multimedia data.   a parameter for authorizing or prohibiting the recording of all or part of the set of multimedia data.   a parameter for authorizing or prohibiting a given processing of all or part of the set of multimedia data.       

   Thus, the invention advantageously enables each authorization parameter to be characterized according to a multimedia data use by a receiver. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it includes a step of transmitting authorized and/or non-prohibited data out of the multimedia data set. 
   Thus, the invention advantageously enables the transmission of authorized multimedia data. 
   According to a particular characteristic, the method for controlling watermarking is noteworthy in that it includes a step of downloading, via at least one downloading channel of the set of multimedia data, at least one item of information belonging to the group:
         of at least a datum necessary for the step of inserting detection information and/or the step of updating,   of at least a datum necessary for the step of updating at least one of the operations of generating and/or installing a new operation of generating at least a partial authorization or prohibition parameter and   of at least a datum necessary for the operation of updating at least one of the operations of generating a final authorization or prohibition parameter and/or installing at least a new operation of generating a final authorization or prohibition parameter.       

   Thus, advantageously, all the information necessary for updating a module and/or installing a new module can be downloaded via the same channel, which simplifies the implementation of such updating and/or installation and may make it locally or remotely automatic. 
   The invention also proposes a multimedia terminal noteworthy in that it includes means of controlling watermarking using a watermark control method such as that previously described. 
   The invention further proposes a device for controlling the watermarking of a set of multimedia data including a first means of detection capable of detecting a first type of watermark and intended to cooperate with a multimedia terminal noteworthy in that it includes at least a second means of detection capable of detecting at least a second type of watermark. 
   Since the particular characteristics and advantages of the multimedia terminal, the watermark control device and the network including this device are the same as those for the watermark control method according to the invention, they are not repeated here. 
   The invention further proposes a computer program suitable for implementing a watermark control method as previously described. 
   The invention also proposes a means of storing information readable by a computer or a microprocessor noteworthy in that it stores the instructions of a computer program. 
   The invention also proposes a removable means of storing information, partially or totally readable by a computer or a microprocessor noteworthy in that it includes instruction sequences suitable for implementing a watermark control method as previously described. 
   Thus, the invention can be advantageously implemented in a hardware or software form. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
     Other characteristics and advantages of the invention will appear on reading the following description of a particular embodiment, given as a simple, illustrative and non-restrictive example of the invention referring to  FIGS. 1 to 9 , in which: 
       FIG. 1  is a schematic representation of a home network or apparatus comprising a source and several receivers conforming to a particular embodiment of the present invention; 
       FIG. 2  is a schematic representation of a home network or apparatus comprising several sources and several receivers conforming to a particular embodiment of the present invention; 
       FIG. 3  is a block diagram of a watermark controller conforming to a particular embodiment of the present invention; 
       FIG. 4  is a block diagram of a watermark controller further including an external parameter analyser according to a first variant conforming to a particular embodiment of the present invention; 
       FIG. 5  is a schematic representation of a watermark control device conforming to a particular embodiment of the present invention; 
       FIG. 6  is flowchart of a watermark control method conforming to a particular embodiment of the present invention; 
       FIG. 7  is a flowchart showing details of a watermark control method further including an external parameter analysis operation according to a first variant conforming to a particular embodiment of the present invention; 
       FIG. 8  is a flowchart showing details of an operation for detecting watermarking and extracting watermark information; 
       FIG. 9  is flowchart of updating parameters corresponding to a given type of watermark or adding one or more modules conforming to a particular embodiment of the present invention; 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   One of the general principles of the invention is based on operations carried out from a set of multimedia data, in particular the detection of several types of watermark, the extraction of watermark information, the handling of external parameters, the generation of partial or final authorizations or prohibitions and/or the transmission of all or part of multimedia data for an authorized use. 
   Another general principle of the invention is based on an updating of the previously described operations or on an installation of new operations as previously described. 
   A particular embodiment and several variants of the present invention are now described with the aid of  FIGS. 1 to 9 . 
     FIG. 1  schematically illustrates a home multimedia network or apparatus  100 . 
   The network or apparatus  100  comprises in particular:
         a multimedia data source  110     N multimedia data receivers  106 ,  107  . . .  108  (N being an integer greater than or equal to one).       

   The source is a network or apparatus element whose role is to control the watermarking of multimedia data in order to deliver only authorized data to receivers suitable for playing (that is to say for example for representing or displaying), recording and/or generally processing multimedia data. 
   The source  110  accepts as input data Dext  101  having in particular:
         multimedia data including or capable of including one or more watermarks and/or   parameters appropriate to the updating or addition of watermarks.       

   The source  110  supplies data with authorization Dp, Dr at outputs  102 ,  103 , . . .  104  respectively inputs of receivers  106 ,  107 , . . .  108 . 
   In the case of a home network  100 , the source  110  is for example a multimedia digital decoder (set top box) connected to several peripheral receivers  106  to  108  such as television sets, video tape recorders, DVD recorder. 
   In the case of a home apparatus  100  such as, for example, a video tape recorder or audio CD, CD-ROM, DVD or audio-video cassette player-recorder, the source  110  and the receivers  106  to  108  are built into the same apparatus. 
     FIG. 2  schematically illustrates a home multimedia network or apparatus  200  including several sources. 
   The network or apparatus  200  comprises in particular:
         P multimedia data sources  210  . . .  211  (P here being an integer greater than or equal to two)   N multimedia data receivers  206 ,  207  . . .  208  (N being an integer greater than or equal to one)       

   The source  210  (respectively  211 ) accepts as input data Dext  201  similar to the data  101  mentioned with regard to  FIG. 1  and supplies data with authorization Dp, Dr at outputs  202  to  204  (respectively  212  to  214 ). 
   The receiver  206  accepts the data with authorizations Dp, Dr  202  and  212  as input. 
   Similarly, the receiver  207  accepts the data with authorizations Dp, Dr  213  as input. (It should be noted that all the receivers and sources are not necessarily connected) 
   Similarly, the receiver  208  accepts the data with authorizations Dp, Dr  204  and  214  as input. 
   In the case of a home network  200 , the sources  210  to  211  (respectively the receivers  206  to  208 ) may be of the same type as the source  110  (respectively the receivers  106  to  108 ) illustrated in  FIG. 1 . 
     FIG. 3  shows a general flow diagram of a watermark controller or control device  315  as installed in a source  110 ,  210  or  211 . 
   The watermark controller  315  comprises in particular:
         an input/output port I/O  316     n detection modules WD 1   317  to WDn  318  (n being an integer greater than or equal to one)   n partial authorization generation modules Fi  319  to  320     two final decision modules Dplay  321  and Drec  322     two switches Splay  323  and Srec  324     an adding and updating control module  330 .       

   The input/output port  316  accepts as input multimedia data Dext  301  of the same type as the data  101  and  201  described in relation to  FIGS. 1 and 2 . 
   It formats these data Dext  301  at outputs Din  302 ,  303  and  304 . 
   The detection module WD 1   317  (resp. WDn  318 ) accepts as input the data Din  304 , detects the possible presence of a first (resp. n th ) type of watermark in a sequence of multimedia data and where appropriate extracts information from the watermark. 
   The detection module WD 1   317  (resp. WDn  318 ) supplies as output I 1   305  (resp. In  306 ) a signal of non-detection of watermark if no watermark has been detected and the information extracted from the watermark if this is not the case. 
   The partial authorization generation module F 1   319  (resp. Fn  320 ) accepts as input the information I 1   305  (resp. In  306 ) and, based on this information, generates a partial authorization or prohibition on playing Fp 1 (I 1 ) (resp. Fpn(In)) which it presents at an output  307  (resp.  309 ) or recording Fr 1 (I 1 ) (resp. Frn(In)) presented at an output  308  (resp.  310 ). Playing is considered, for example, as an operation of representing or displaying multimedia data. 
   The play final decision module Dplay  321  accepts as input the partial authorizations or prohibitions on playing Fp 1 (I 1 )  307  to Fpn(In)  309 . It generates a final authorization or prohibition signal on playing Fp at an output  311 . 
   The record final decision module Drec  322  accepts as input the partial authorizations or prohibitions on recording Fr 1 (I 1 )  308  to Frn(In)  310 . It generates a final authorization or prohibition signal on recording Fr at an output  312 . 
   The play switch Splay  323  accepts as input the multimedia data Din  302  and the final authorization or prohibition on playing signal Fp  311 . If the play authorization signal  311  is valid or in an equivalent manner if the play prohibition signal is invalid and only in these instances, the play switch  323  presents at its output  313  a sequence of multimedia data Dp, derived from the input sequence Din  302 . 
   The record switch Srec  324  accepts as input the multimedia data Din  303  and the final authorization or prohibition on recording signal Fr  312 . If the record final authorization signal  312  is valid or in an equivalent manner if the record prohibition signal is invalid and only in these instances, the record switch  324  presents at its output  314  a sequence of multimedia data Dr, derived from the input sequence Din  303 . 
   The adding and updating control module  330  includes a data input  334 . When the input data include a datum for updating one of the modules Wd 1   317  to Wdn  318 , the control module  330  updates this module via the intermediary of its output Cwd  331 . When the input data include a datum for updating one of the modules F 1   319  to Fn  320 , the control module  330  updates this module via the intermediary of its output Cf  332 . When the input data include a datum for updating one of the modules Dplay  321  or Drec  322 , the control module  330  updates this module via the intermediary of its output Cd  333 . 
   The control module  330  is responsible for adding additional modules to the watermark controller  315  when the input data  330  include data for additions of the corresponding modules. Thus, the control module  330  will be able, in particular, to add:
         a watermark detection module WD(n+1) and/or   a partial authorization generation module F(n+1) and/or   a final decision module Dx and/or   a switch Sx.       

   In addition, the control module  330  will make the necessary input/output connections according to the modules added. 
     FIG. 4  shows a general flow diagram of a first variant  415  of watermark controller as installed in a source  110 ,  210  or  211 . 
   The watermark controller  415  includes similar elements to those previously described in  FIG. 3 , which bear the same reference numbers and will not therefore be further described. 
   In addition to these elements, the watermark controller  415  includes an analyser  426  of external parameters. These external parameters may primarily include those for validation of signature and/or the presence of encrypted data and/or the presence of data identifying a recordable or non-recordable medium. 
   This analyser  426  takes into account:
         the multimedia data present at an input Din  304     external parameters Ext Param at an input  425         

   The analyser  426  supplies an analysis result A 1  at an output  427 . 
   This output  427  is connected to an input of each of the partial authorization generation modules Fi  319  to  320  (i being an integer between 1 and n). Thus, to generate partial authorizations or prohibitions, each of the modules Fi takes into account not only the information li, resulting from the operation performed by the module Wdi but also a parameter external to the watermark. 
     FIG. 5  schematically illustrates a watermark detector  500 . This detector is integrated into the source  110  described in relation to  FIG. 1  or into each of the sources  210  to  211  described in relation to  FIG. 2 . 
   The detector  500  comprises, interconnected via an address and data bus  503 :
         a Digital Signal Processor (DSP)  502  suitable for implementing the flowcharts described in  FIGS. 6 to 9 ;   an input/output port  501 ;   a random access memory  505 ;   a non-volatile memory  504 .       

   Each of the elements illustrated in  FIG. 5  is well-known to persons skilled in the art. These common elements are not described here. 
   It should be noted, however, that the input/output port  501  is suitable for accepting incoming signals representative of multimedia data originating from an external transmitter, not shown, such as a television programme broadcaster or a DVD, audio CD or CD-ROM drive. The port  501  is especially suitable for formatting these signals in the form of binary sequences that can be used by the processor  502 . In addition, the port  501  is suitable for accepting outgoing authorized binary sequences and putting them in the form of outgoing signals representative of multimedia data intended for a receiver as described in relation to  FIG. 1  or  2 . 
   It should be further noted that the word “register” used in the description designates, in each of the memories  504  and  505 , both a low capacity memory area (a few binary data) and a large capacity memory area (enabling an entire program or the whole of a multimedia data sequence to be stored). 
   The random access memory  505  stores data, variables and intermediate processing results in memory registers, which in the description bear the same names as the data whose values they store. The random access memory  505  notably includes:
         a “data” register  520  in which the data Din are stored in the order in which they arrive on the bus  503 ,   a “res” register  521  in which are stored the results of the various operations, including I 1  to In, Fp 1 (I 1 ) to Fpn(In), Fr 1 (I 1 ) to Frn(In), Fp, Fr, Cwd, Cf, Cd, Dp, Dr.       

   When the first variant described in relation to  FIG. 4  is set up, the “data” register  520  further includes external parameters and the “res” register  521  stores A 1 . 
   The non-volatile memory  504  stores in registers, which for convenience have the same names as the data they store:
         the operating program of the processor  502  in a “prog” register  511 ,   the parameters  510  of the different watermarks used by the various modules described in relation to  FIGS. 3 and 4  such as in particular the n detection modules WD 1   317  to WDn  318 , the n partial authorization generation modules F 1   319  to Fn  320 , the two final decision modules Dplay  321  and Drec  322 , the two switches SPlay  323  and Srec  324  and the adding and updating control module  330  and, if it is present, the analyser module  426 .       

   The non-volatile memory  504  is preferably of the EEPROM type so that the watermarking parameters  510  can be updated or added. 
   When the first variant is implemented, the external parameters originate from an external entity, not shown. This entity may be, for example, a means of signature validation and/or of detecting the presence of encrypted data and/or of detecting the presence of data identifying a recordable or non-recordable medium. 
   In  FIG. 6 , which shows the operation of a watermark control device such as that included in the electronic device illustrated in  FIG. 5 , it should be noted that after an initialization operation  600  during which the random access memory  505  registers are initialized, in the course of a standby operation  601  the processor  501  waits to receive then receives a sequence of multimedia data. 
   Then, during a detection operation  602 , the processor  502  detects the possible presence of a watermark of the i th  type and updates the information Ii of the register  521  in the memory  505  for each value of the integer i from 1 to n (n being the number of watermark detectors installed when the operation takes place). 
   Then, during a partial authorization or prohibition operation  603 , the processor  502  updates the partial authorization or prohibition information Fpi(Ii) and Fri(Ii) of the register  521  in the memory  505  for each value of an integer i from 1 to n. 
   The partial authorization or prohibition on playing Fpi(Ii) is a Boolean variable indicating whether the multimedia data sequence in question can be played, i.e. in particular whether it can be displayed (if it is an image) or broadcast. Fpi(Ii) will be true if playing is legal or if no watermark has been detected by WDi. In the second variant, Fpi(Ii) will be true if playing is legal and if a watermark has been detected by WDi. 
   Commonly, first generation watermarks may contain information of the “Copy Generation Management System” type: “copy-freely”, “copy-once”, “copy-no-more” and “copy-never”. Thus, the processor  502  updates the partial authorization or prohibition on copying Fri(Ii) for each type of watermark capable of being detected according to the type of information extracted Ii: Fri(Ii) is a Boolean variable that indicates whether the multimedia data sequence in question can be copied. Fri(Ii) will be true if recording is legal or if no watermark has been detected by WDi. In the third variant, Fri(Ii) will be true if recording is legal and if a watermark has been detected by WDi. 
   Next, during a final authorization operation  604 , the processor  502  generates the final authorizations or prohibitions Fp and Fr. 
   The final authorization or prohibition on playing Fp will be specifically obtained thanks to a Boolean operation performed on all the partial authorizations or prohibitions on playing. In preference, this function will be of the logical “and” type denoted by “&amp;&amp;” in the following text. Thus: 
   Fp=Fp 1 (I 1 )&amp;&amp;Fp 2 (I 2 )&amp;&amp; . . . &amp;&amp;Fpn(In). 
   However, any other type of Boolean function may be used. An inclusive or exclusive logical “or” operation may be performed for example. In this case, Fp=Fp 1 (I 1 )ORFp 2 (I 2 )OR . . . ORFpn(In). Priorities may also be assigned to partial authorizations or prohibitions; for example, the most recent watermark version detected may be identified and only this be considered for authorization to play. 
   In the same way, the final authorization or prohibition on recording Fr will be specifically obtained thanks to a Boolean operation performed on all the partial authorizations or prohibitions on recording. In preference, this function will be of the logical “and” type denoted by “&amp;&amp;” in the following text. Thus, Fr=Fr 1 (I 1 )&amp;&amp;Fr 2 (I 2 )&amp;&amp; . . . &amp;&amp;Frn(In). 
   However, any other type of Boolean function may be used. An inclusive or exclusive logical “or” operation may be performed for example. In this case, Fr=Fr 1 (I 1 )ORFr 2 (I 2 )OR . . . ORFrn(In). Priorities may also be assigned to partial authorizations or prohibitions; for example, the most recent watermark version detected may be identified and only this be considered for authorization to record. 
   Next, during a test  605 , the processor  502  checks whether the final authorization to play Fp is valid. If so, during a data transmission operation for playing  606 , it authorizes the transmission and transmits the data Dp intended to be played. 
   In parallel with the test  605  or possibly following the test  605 , during a test  607 , the processor  502  checks whether the final authorization to record Fr is valid. If so, during a data transmission operation for recording  608 , it authorizes the transmission and transmits the data Dr intended to be recorded. 
   Then when the tests  605  and  607  have been carried out, together with the possible data transmission operations  606  and  608 , the standby operation  601  is repeated and the random access memory  505  registers are reinitialized. 
     FIG. 7  shows the operation of a watermark control device such as that included in the electronic device illustrated in  FIG. 5 , according to the first variant of the invention. 
   The flowchart in  FIG. 7  includes similar operations to those previously described in  FIG. 6 , which bear the same reference numbers and will not be further described. 
   It should be noted, however, that in parallel with the detection operation  602 , an analysis of external parameters is carried out during an analysis operation  703 . It is recalled that these external parameters may primarily be of the type for validation of signature and/or the presence of encrypted data and/or the presence of data identifying a recordable or non-recordable medium. The processor  502  takes the result of this analysis into account for generating an analysis result signal A 1 . 
   It should be noted that after the operations of detection  602  and analysis  703 , for each integer i between 1 and n, the operation of partial authorization or prohibition  604  described previously may further take account of the analysis result A 1  for example by performing a Boolean operation between a part of the information Ii and the analysis result A 1 . Thus, if A 1  prohibits copying (if, in particular, a signature is not valid), Fri(Ii) will prohibit copying whatever the information Ii may be. 
     FIG. 8  shows details of the detection operation  602  mentioned in relation to  FIGS. 6 and 7  and symbolized by dotted lines in  FIG. 8 . 
   During an initialization operation  800 , a counter i is initialized to 0. 
   Then, during an incrementation operation  801 , the counter i is incremented by one unit. 
   Next, during a test  802 , the processor  502  tries to detect the presence of an i th  known type of watermark in the data sequence  520  in the random access memory  505 , according to the parameters  510  present in the ROM  504 . 
   If the result of the test  802  is negative, i.e. if no i th  type of watermark is detected, the processor  502  updates the information Ii during an updating operation  803  to indicate that no i th  type of watermark has been detected. 
   When the result of the test  802  is positive, the processor  502  extracts the watermark information of the i th  type during an extraction and updating operation  804 , according to the parameters  510  present in the ROM  504  and updates this information in Ii. 
   After one of the operations  803  or  804 , during a test  805 , the processor  502  checks whether the counter i has reached the value n stored in memory. If i and n are equal, the operation  602  is terminated. Otherwise, the incrementation operation  801  is repeated. 
     FIG. 9  describes a function for updating parameters or adding (also called installing) one or more modules such as, for example, a watermark detection module, an analyser, a module for generating partial authorizations or prohibitions, a module for generating final authorizations or prohibitions, or a switch. 
   After an operation  900  of initializing parameters  510  appropriate to the modules present in the EEPROM memory  504 , during a standby operation  901 , the processor  502  goes on standby waiting for updating or addition data. These data pass through the interface  501 . In preference, they will follow the same channel as the multimedia data, but may derive from diverse and varied origins according to data downloading procedures well-known to persons skilled in the art. 
   When updating or addition data have been received, the processor  502  checks during a test  902  whether the data correspond to a simple update of one or more modules already installed such as a watermark detection module WDi and/or a partial authorization Fi generation module and/or a final decision Dp or Dr module and/or a switch Sp or Sr. 
   When the result of the test  902  is positive, in the course of an updating operation  903 , the processor  502  updates the module or modules to which the updating data correspond. 
   Then, when the result of the test  902  is negative or after the updating operation  903 , the processor  502  in the course of a test  904  checks whether the data received correspond to an addition function. 
   When the result of the test  904  is positive, in the course of an installation operation  905 , the processor  502  adds the module or modules to which the updating data correspond, together with the necessary new connections between modules. 
   It should be noted that if a new watermark detection module WD(n+1) is added, this involves installing a new partial authorization or prohibition generation module F(n+1), an update of the final authorization modules and the establishment of connections between the input/output port  316  and WD(n+1), between WD(n+1) and F(n+1), between F(n+1), DPlay and DRec and between the analyser  426  if it is present and F(n+1). 
   It should also be noted that if a final authorization or prohibition module is added, a new switch and the associated output must also be added, all the partial authorization or prohibition modules updated and the connections established between the added final authorization or prohibition module and between all the partial prohibition modules and the new switch. 
   Of course, the invention is not limited to the abovementioned examples of embodiment. 
   In particular, a person skilled in the art could introduce any variant into the definition of the types of operations capable of being authorized by a data watermark or external parameters, into the definition itself of these external parameters and into the operations for obtaining the final authorizations or prohibitions from partial authorizations or prohibitions. 
   It will also be noted that the invention is not limited to simple playing or recording authorizations or prohibitions, but may be applied in particularizing certain types of playing or recording. It should further be noted that the invention can be applied to authorizations or prohibitions of any type of processing on multimedia data such as filters, modifications of original data sequences, and extractions of a part of the data sequences. It will also be noted that the invention relates to digital and/or analog multimedia data. 
   It will be noted that the invention is not limited to a purely hardware installation, but that it may also be implemented in the form of an instruction sequence in a computer program or any mixed, part hardware, part software form. In the case where the invention is installed partially or totally in software form, the corresponding instruction sequence may be stored on a removable means of storage (such as, for example, a floppy disk, a CD-ROM or a DVD-ROM) or a non-removable means, this means of storage being partially or totally readable by a computer or a microprocessor.