EP2245854A1

EP2245854A1 - Method for displaying multimedia content with variable interference based on receiver/decoder local legislation

Info

Publication number: EP2245854A1
Application number: EP09719039A
Authority: EP
Inventors: Stephane Onno
Original assignee: Thomson Licensing SAS
Current assignee: Thomson Licensing SAS
Priority date: 2008-02-29
Filing date: 2009-02-27
Publication date: 2010-11-03
Also published as: US20100332343A1; BRPI0908795A2; FR2928235A1; KR20100116200A; CN101965731A; KR101559948B1; JP2011517381A; WO2009112771A1

Abstract

The invention relates to a multimedia content receiver/decoder (RD) that receives data representing the multimedia content as well as interference data associated with the content. Said receiver/decoder processes the data representing the content based on the associated interference data locally stored in the same, and transmits the multimedia content to a display means (SV) for displaying with an interference defined by the interference data at an interference level based on local interference legislation.

Description

METHOD FOR DISPLAYING MULTIMEDIA CONTENT WITH DISTURBANCES

VARIABLES BASED ON LOCAL RIGHTS OF

RECEIVERS / DECODER

Technical field of the invention

The invention relates to the transmission of multimedia contents to receivers / decoders connected to a communication network, by broadcast (or

"Broadcast" or point-to-multipoint - such as cable or satellite TV) or broadband (or "broadband" - such as IPTV).

Here, the term "receiver / decoder" is understood to mean any type of equipment comprising, on the one hand, means of communication enabling it at least to receive blocks of content data from a communication network (wired or non-wired), and on the other hand, decoding means responsible for processing the received content data blocks so that the content they define can be viewed by display means of any type, such as a screen, a video projector or a backlight. Therefore, it may for example be a set-top box equipment or a digital decoder possibly forming part of a television set, a fixed or portable computer, a fixed telephone or mobile, a communicating personal digital assistant (or PDA), or a mobile terminal implanted in a transport vehicle and possibly type TNT / DVB-H.

Moreover, here "multimedia content" is understood to mean any type of data set defining at least image sequences, possibly accompanied by sounds, such as for example videos, commercials or television programs. "Multimedia content" can also simply be sound or textual data.

In the remainder of the description, reference is made to the "viewing" or display of multimedia content, but it is obvious that it is more generally a rendering of the content (visual, sound, video rendering). text or mixed display).

State of the art As known to those skilled in the art, there has for some time been a mode of viewing multimedia content called "pay to see" (or in English Pay per view). This visualization mode relies on access to multimedia content, usually encrypted (or encrypted), conditioned by access rights defined according to a payment (possibly in the form of a subscription). The customer who benefits from access rights receives on his receiver / decoder multimedia contents that he has requested or that are part of his subscription (for example in the case of pay television programs), encrypted by means of keys. On the other hand, it receives access control data (usually contained in messages marked ECM - for "Entitlement Control Messages" - or in "Licenses" used in DRM systems - for "Digital Rights Management" ) for recovering the encryption keys of the multimedia contents. The customer usually has a smart card that must be inserted in his receiver / decoder and stores the access rights to the client's content. Secure data, also stored in the card, is used by the receiver / decoder to retrieve the encryption keys from the access rights control data and then decrypt at least some of the received multimedia content, thus allowing their visualization by associated visualization means.

Such a multimedia content broadcasting system is described in particular in document US 2004/068541 A1.

It is moreover known from document US 6 937 730 B1 a system in which content may be masked, particularly shocking or sensitive content, before being presented to users. Depending on whether or not the content transmission channel is reliable and whether the user's receiver is reliable or not, the operation of masking the content is performed upstream of the receiver in the transmission chain or by the receiver itself. - even. The presence or absence of a mask on the content presented to the user depends on the identity of the user and the fact that he is authorized or not to access this content.

Summary of the invention

A disadvantage of the "pay per view" display mode mentioned above lies in the fact that it is of the all-or-nothing type. More specifically, either the user has access rights to the contents and can therefore view decrypted multimedia content, or the user does not have access rights and then he can only view encrypted multimedia content or a usually monochrome still image with a possible message suggesting by example of buying a right of access. In other words, people who do not have access rights to received multimedia content can not know if they can interest them.

Moreover, the system described in document US Pat. No. 6,937,730 B1 has a similar disadvantage, that is to say that it is also of the all-or-nothing type. Either the user is authenticated as a user authorized to access the content, or he is not, and he can not view this content. The invention therefore aims to overcome these disadvantages. For this purpose, the invention firstly proposes a method for displaying multimedia content comprising the steps of: receiving in a receiver / decoder (RD) data representing the multimedia content as well as perturbation data associated with the content ; processing the data representing the content according to the associated perturbation data and according to perturbation rights stored locally in the receiver / decoder; and displaying the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local disturbance rights.

The method according to the invention can comprise the preliminary steps of: reception by the receiver / decoder (RD) of perturbation and storage rights management messages and / or updating of the local perturbation rights in the receiver / decoder in depending on the information contained in the disturbance rights management messages.

According to a first embodiment, the method according to the invention may further comprise the steps of receiving a user command to reduce the level of disturbance in the display of the mutlimedia content; updating the local perturbation rights by decrementing a number of pre-stored tokens in the receiver / decoder, the number of tokens being determined by the user's command; and modifying the display of the mutlimedia content according to a new level of perturbation depending on the updated local disturbance rights.

According to a second embodiment, the method according to the invention may further comprise the steps of receiving a user command to reduce the level of disturbance in the display of the mutlimedia content; sending a request to update the local disruption rights by purchasing tokens to a remote server including a management module (MGN); reception by the receiver / decoder (RD) of a disturbance rights management message containing an update of the local disturbance rights when the purchase of token could be done by the remote server; updating the local disturbance rights in the receiver / decoder according to the information contained in the disturbance rights management message received; and modifying the display of the mutlimedia content according to a new level of perturbation depending on the updated local disturbance rights.

According to a preferred characteristic of the invention, disturbance integrity data is received in the receiver / decoder with the data representing the multimedia content and the perturbation data associated with the content, the method comprises in a sequence the steps of: checking the integrity of the disturbance data received using the disturbance integrity data prior to the display of the multimedia content, and in the case where the integrity checking step reveals that the disturbance data is not Integral, display multimedia content with a predefined maximum level of disturbance; in the case where the integrity checking step reveals that the perturbation data is intact, displaying the multimedia content with a perturbation level depending on the local disturbance rights of the receiver / decoder (RD).

According to another particular characteristic of the method of the invention, during the step of receiving the data representing the multimedia content by the receiver / decoder (RD), these are received in encrypted form, this step further comprising receiving by the receiver / decoder control data access rights. Prior to the data processing step representing the multimedia content in the receiver / decoder, the method also includes a step of decrypting the data representing the multimedia content using encryption key obtained from the control data of the access rights if the receiver / decoder has a right of access to the content.

According to an advantageous characteristic of the invention, the disturbance integrity data and the access control data are received by the receiver / decoder in protected messages, preferably by encryption.

The process of the invention may have other particular characteristics which can be taken separately or in combination, and in particular:

the disturbance data may contain disturbance content intended to mask at least part of the multimedia content or alteration data of the multimedia content intended to modify the rendering of the multimedia content when it is displayed.

the disturbance data may contain several different advertising contents associated with different user profiles, and the method may further comprise a step of determining in the receiver / decoder the advertising content to be inserted, in the form of a perturbation, during the display of multimedia content.

prior to the step of displaying the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local perturbation rights, the method may comprise a step of displaying the multimedia content without any disturbance during a predefined duration.

The invention also proposes a multimedia content receiver / decoder comprising: communication means arranged to receive data representing multimedia content from the communication network as well as perturbation data associated with the content and decoding means arranged to process said data representing the content as a function of the associated perturbation data and as a function of perturbation rights stored locally in the receiver / decoder and for providing to viewing means the multimedia content with a disturbance defined by the perturbation data according to a level of disturbance. perturbation dependent on local disturbance rights.

The invention also relates to a device for providing multimedia contents intended to be transmitted to receivers / decoders connected to a communication network, comprising content perturbation data generation means intended to be used by said receivers / decoders. for processing the data representing the content according to perturbation rights stored locally in the receivers / decoders to display the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local perturbation rights.

Brief description of the drawings

Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings, in which:

FIG. 1 schematically and functionally illustrates an example of communication equipment comprising an exemplary embodiment of a device for providing multimedia content according to the invention, and an embodiment of a receiver / decoder according to the invention, both connected to a communication network,

FIG. 2 schematically illustrates a first example of an image displayed with a disturbance materialized in the form of a gray rectangle,

FIG. 3 schematically illustrates a second example of an image displayed with a disruption materialized in the form of an advertising banner, and

FIG. 4 schematically illustrates an exemplary image displayed with two disturbances materialized respectively in the form of a gray rectangle and in the form of an advertising banner.

detailed description

The object of the invention is to enable the visualization by multimedia receivers / decoders connected to a communication network with a variable perturbation according to local rights.

In what follows, it is considered, by way of illustrative and nonlimiting example, that the communication network is a satellite network. However, the invention relates to any type of communication network capable of transmitting to receivers / decoders which are connected to it (or reachable via it), in point-to-multipoint mode (or "broadcast" mode) or point-to-point (or "unicast" - broadband), and on a go way, blocks of data (such as IP packets) defining multimedia content. It therefore also relates to high-speed wired networks, such as cable networks or xDSL-type telephone networks, wired local networks, such as LAN-type ("Local Area Network"), and communication networks. non-wired (or radio), such as mobile or cellular networks (GSM / GPRS, EDGE, UMTS, CDMA2000 and their extensions and equivalents), and wireless local area networks (Wireless Local Area Network (WLAN) standards - IEEE 802.11, Wi-Fi, MIMO Wi-Fi, ETSI HiperLAN / 2), Bluetooth (IEEE 802.15), WiMAX (IEEE 802.16, ETSI HiperMAN) and Zigbee.

As is schematically illustrated in FIG. 1, the implementation of the invention requires an RC communication network, an equipment for supplying multimedia contents ER and receivers / decoders RD coupled to means for viewing SV contents.

The equipment for providing multimedia content ER is for example a content server delivering multimedia contents (image sequences generally accompanied by a soundtrack), such as television programs (commercials or videos), in the form of blocks of content data, preferably encrypted ( or encrypted). For example, this content server ER is an IP server delivering encrypted content data blocks in the form of IP (Internet Protocol) packets. This content server ER comprises at least one communication module MC1 connected to the communication network RC, a device for providing multimedia content D, according to the invention, and a content database BDC in which the multimedia contents are stored. transmit to RD receivers / decoders. It will be noted that in variants, the device D may itself comprise the BDC content database and / or the communication means MC1.

The device D according to the invention comprises at least a first encryption module MG1 and a second module MG2 for generating disturbance data.

The first encryption module MG 1 is coupled to the content database BDC in order to encrypt the data blocks of the multimedia contents stored therein and to deliver these encrypted blocks on an output coupled to the communication module MC1 in order to from their transmission (broadcast) to RD receivers / decoders. The encryption is done by means of keys which are themselves transmitted in content access control data (such as ECM messages or licenses) that the encryption module MG 1 delivers on its output.

The second perturbation data generating module MG2 is responsible for delivering on at least one output perturbation data which is representative of content disturbance (s) and which will be used locally by the RD receivers / decoders for processing the data blocks. transmitted (broadcast) for the purpose of viewing the contents they represent in a disturbed form according to their respective local disturbance rights. Here we mean by "disturbance" all that can be added in

"Stream on stream" (or overlay) for media content to be viewed and any alteration or degradation of multimedia content. A disturbance does not necessarily imply a degradation of the visualized multimedia content. Therefore, the disturbance data here refers to anything that may constitute a disturbance content (such as an advertisement to be inserted on a multimedia content) or a definition of a disturbance to apply to multimedia content (such as adding a solid rectangle or a frame or deleting an area of multimedia content). The disturbance data is either data that is added to the multimedia content to mask certain parts during the display ("overlay" data), or data for modifying the multimedia content that will modify the appearance of this content during its display.

Examples of disturbances are illustrated in FIGS. 2 to 4. The example illustrated in FIG. 2 corresponds to a disturbance of each image of a displayed content (past a certain chosen delay) which consists of an insertion of a gray rectangle (or the replacement of some pixels by gray pixels) in a selected area (whose location may vary from one image to another). The example illustrated in FIG. 3 corresponds to a disturbance of each image of a displayed content (past a certain chosen delay) which consists of an insertion of a banner containing a chosen advertising message (whose location may vary from one image to another).

Disturbance data can also be a combination of at least two different types of disturbance. This is particularly the case in the example illustrated in FIG. 4, in which each image of a displayed content (past a certain chosen period of time) is the subject of both an insertion of a gray rectangle (or the replacement of some pixels by gray pixels) in a chosen area (whose location may vary from one image to another) and insertion of a banner containing a chosen advertising message (whose location may vary from one image to another).

Numerous other examples of disturbance and combination of disturbances can be envisaged, with a progressive or constant character.

It is important to note that content disturbances, which are delivered in the form of disturbance data, are applied to multimedia content based on disturbance rights which should not be confused with the rights of access to content. multimedia. These disturbance rights define the level of perturbation that is applied locally. For example, the level of disturbance may be a level of transparency (from 0% - completely transparent - to 100% - completely opaque) of the disturbance data superimposed on the original multimedia content. The disturbance level can also be a sound volume when the disturbance data is sound data.

Any type of content disruption can be considered, including: the insertion (or overlay) on images of a multimedia content of a banner containing other advertising content, for example from the supplier of the multimedia content to be viewed,

the insertion (or overlay) on images of a multimedia content of a copyright (or "copyright"), visual and / or audible warning message,

the insertion (or overlay) on images of a multimedia content of an information message, such as an invitation to purchase the program defined by the content,

the insertion (or overlay) on images of a multimedia content of at least one identifier representative of the user concerned, such as his name and / or his communication identifier,

- the addition of sounds unrelated to the multimedia content,

the degradation or the suppression of the sound accompanying the sequences of images, the replacement of a multimedia content to be displayed by at least one monochrome still image (or "blank image"), for example a black or white screen background ,

the degradation of the images of a multimedia content to be displayed defined by at least one chosen type (progressive deterioration between an optimal quality level and a degraded level, constant degradation defined by a chosen right of disturbance, degradation of a part of the image only, rotation of image areas, deletion of some parts of the image, etc.).

It is important to note that several types of disturbances can be jointly applied. In addition, the disturbance data may optionally define a plurality of different advertising contents associated with different user profiles. In this case, the advertising content that is inserted (in overlay) on the multimedia content to be viewed is locally chosen by a decoder module MD of the receiver / decoder according to the profile of the user (which he stores in a local memory ).

As the content disturbances can possibly be functions of the contents they complement, the second disturbance data generation module MG2 is preferably coupled to the first encryption module MG1 in order to be able to synchronize their operations, as illustrated in FIG.

Encrypted content data blocks (encrypted), data from additional disturbances (which contain, for example, the content - text, image, etc. - of the disturbance as well as its positioning on the screen), and the control data of the access rights to the content (containing the keys for encrypting the content ), are transmitted by the communication module MC1 to the network RC so that it transmits them (in turn) to the RD receivers / decoders concerned.

Preferably, when the data is transmitted broadcast-type broadcast, the content data blocks are transmitted on the forward channel in a transport stream, with the disturbance data. For example, if the ISO / IEC 13818-1 encoding standard is used, the data blocks containing the video are transmitted in packets having a first unique PID (for "Packet Identifier") identifier, the data blocks containing the packet. audio are transmitted in packets having a second PID and the disturbance data is transmitted in data packets having a third PID. Furthermore, the access rights control data are transmitted on the forward path in additional messages, for example of ECM type ("Entitlement Control Message") which are themselves transmitted in packets with their own PID. These ECM type messages are preferably protected by encryption and only the receivers / decoders that are authorized contain the keys for decrypting these ECMs. When the data is transmitted in broadband broadcast mode, the content data blocks are transmitted in a point-to-multipoint ("broadcast" or "multicast") stream with the disturbance data and the rights control data. access.

It should also be noted that a mechanism for verifying the integrity of the perturbation data transmitted with the content can be provided. To do this, the device D can add disturbance integrity data to disturbance data that is transmitted preferentially in the protected messages (ECM type) already containing the access control data. This integrity data is generated based on the perturbation data that can be applied to the transmitted multimedia content, for example by applying a hash function to the disturbance data.

This integrity data is then used at each receiver / decoder to verify that the disturbance data has not been modified (eg to make the minimum disturbance) fraudulent.

We will come back later on additional modules that can possibly comprise the device D according to the invention.

Each receiver / decoder RD comprises at least one communication module MC2 and a module (or a unit) for decoding MD.

The receiver / decoder RD is for example a communication equipment type Set-Top Box or digital decoder. It can for example be connected to, or be part of, an SV television set (as in the example illustrated in Figure 1), desktop or mobile computer, landline or mobile phone, PDA (or PDA) communicating, or mobile terminal implanted in a transport vehicle and possibly type TNT / DVB-H.

The communication module MC2 is coupled to the communication network RC. It is at least responsible for receiving from the latter, on a forward path, on the one hand, blocks of content data (preferentially encrypted) and complementary perturbation data and on the other hand disturbance integrity data as well as that control data access rights transmitted in protected messages, all from the content server ER.

The decoding module MD is coupled to the communication module MC2 in order to receive the content data blocks, the perturbation data, the disturbance integrity data and the access rights control data that it receives from the network. RC.

This decoding module MD is responsible for processing the blocks of content data according to the associated perturbation data received in addition to the content and according to the perturbation rights stored locally in the receiver / decoder so that the content to be displayed integrates each disturbance. according to the right of local disturbance.

As illustrated in FIG. 1, the decoding module MD comprises, for example, an SMD decryption sub-module, responsible for decrypting the blocks of content data when they are received in encrypted form to deliver a content to be viewed. The module MD also comprises a SMP perturbation integration sub-module, coupled to the output of the SMD decoding sub-module and responsible for disturbing the continuous to be displayed according to the local perturbation right (ie ie specific to the RD receiver / decoder considered). This right of local disturbance is received beforehand in the receiver / decoder RD, for example in disturbance rights management messages (similar to the messages noted EMM - for "Entitlement"). Management Message "- in conditional access systems or" Licenses "used in DRM systems. These disturbance rights management messages are addressed specifically to the receiver / decoder and are therefore intended for a single receiver / decoder (or a specific group of receivers / decoders). These disturbance rights management messages are sent in a decorrelated manner with respect to the content itself. Typically, when the content is transmitted by broadcasting broadcast type, disturbance rights management messages are transmitted in a carousel, that is to say, repeatedly, in the stream. When the content is transmitted in broadband broadcast mode, the disturbance rights management messages are transmitted in a "point-to-point" (or "unicast") stream between the server ER and the receiver / decoder RD. New disturbance rights management messages are sent to the receiver / decoder when the user modifies his subscription or when he buys additional rights to reduce the disturbances for example.

The submodules SMD and SMP are, in the exemplary embodiment, connected to an access control module MCA. This access control module MCA retrieves the encryption keys of the content from the access rights control data and secure data stored in a secure local memory.

This local memory is for example contained in a smart card CP. In this case, and as illustrated in FIG. 1, the access control module MCA comprises an LC card reader capable of receiving the smart card CP and reading the information that is stored in its memories. Once the content encryption keys determined, the access control module MCA transmits them to the sub-module SMD. The latter is then able to decrypt the blocks of encrypted content data received.

This results in content fractions that are transmitted to the SMP perturbation integration sub-module. The latter is, for example, deactivated for a chosen duration following the beginning of the local reception of a multimedia content in order to allow its visualization without any disturbance during a chosen duration. In this case, it transmits directly to the display means SV content fractions decrypted by the decryption sub-module SMD so that they begin to be displayed without any disturbance.

In one variant, the received perturbation data may require that the SMP perturbation integration sub-module inserts into each image (or group of images) of the multimedia content to display an information message proposing to access the latter according to disturbance levels that depend on a number of tokens purchased. Indeed, the user can buy additional rights to reduce disruption in the form of chips for example. The purchase of a fixed number of tokens will allow local disturbance rights to be modified to reduce the level of disruption of the displayed content. In this case, the user starts by viewing the multimedia content with the information message, and either he decides to buy tokens and in this case he will view the rest of the multimedia content with a level (or right) of disturbance function the number of chips bought, or he refuses to buy chips. In the latter case, it will view the rest of the multimedia content in a partially or totally disturbed form according to the perturbation data received with the multimedia content and according to the local perturbation right stored in the receiver / decoder. If the disturbance data do not immediately impose the insertion of an information message, it is the access control module MCA which can order the display by the visualization means SV of a message proposing to the user of his receiver / decoder RD to buy a number of tokens to reduce the local disturbance rights. Here, the term "high disturbance right" means a right corresponding to a high (or significant) disturbance and "low disturbance right" a right corresponding to a minor disturbance.

By way of non-limiting example, the purchase of a token may allow a visualization according to a high (but not maximum) perturbation right, such as, for example, an average degradation of the image quality and / or the sound combined with the insertion of an advertising banner), the purchase of three tokens can allow a visualization according to a right of average disturbance (as for example a weak deterioration of the quality of image and / or sound combined with the insertion of advertising banner), the purchase of five tokens may allow visualization according to a low disturbance right (for example a low degradation of image quality and / or sound), and the purchase of ten tokens may allow a visualization according to a right of disturbance null (corresponding to a quality of image and sound optimal - undisturbed).

The number of chips purchased by the user (here between zero (0) and ten (10)) is a sum of money that must be debited either from a bank account or from a local account.

For example, the access control module MCA is arranged to subtract the number of chips that the user wants to buy from a number of pre-purchased tokens that is stored in a local memory MY. The latter is for example contained in the smart card CP. In this case, the LC card reader is also able to read the number of pre-purchased chips that is stored in the MY memory and replace it with a new number that is equal to the result of the retrenchment of the number of chips that the user wants to buy from that number of pre-purchased tokens.

It should be noted that this method of updating the local right of disturbance locally at the receiver / decoder (by removing chips stored in a secure local memory) is an alternative to the method of updating the local rights perturbation previously exposed , by sending disturbance rights management messages (type "EMM").

If the number of tokens stored is not large enough, or if the access control module MCA is not designed to perform the debit (or retrench) operation, then it can establish a connection with the device D , implemented in the content server ER, on a return path of a communication network (which is not necessarily the same as the RC used for the forward path). He can then order the communication module MC2 of his receiver / decoder RD to transmit to the content server ER the request to purchase tokens made by the user.

In this case, the device D comprises a management module MGN coupled to the communication module MC1 and responsible for organizing the debit of an account (bank or pre-purchased tokens) belonging to the user who made the request for payment. 'purchase. If it is possible, the management module MGN debits the account of an amount corresponding to the purchase of the number of chips chosen by the user or this number of tokens chosen. Then, the management module MGN delivers to the communication module MC1 a message confirming the purchase of the number of chips requested (or the rejection of the purchase request) so that it transmits it to the receiver / decoder RD concerned (in mode point-to-point (or "unicast")), preferably on the forward path of the RC communication network (but this can also be done on the return channel which is generally bidirectional type). When the communication module MC2 of the receiving receiver / decoder RD receives such a message, it communicates it to the decoding module MD which transfers it to the access control module MCA.

Note that the MGN management module is not necessarily included in the content distribution server D. It can also be part of a server of a financial intermediary, such as a bank.

The device D may also comprise an MCT control module responsible for determining the rights of access rights to the broadcasted content for a receiver / decoder RD. In this case, it determines in a client database which types of content the user of the receiver / decoder RD is allowed to view according to his subscription or specific purchases of content made "on demand". This mode of operation is particularly known in pay TV applications (or CA TV (for "Conditional Access TV")). These access rights data specific to each receiver / decoder are generally transmitted at the beginning of the month with the perturbation rights data associated with the receiver / decoder. These data are transmitted on the forward path and in a stream by means of complementary messages addressed specifically to a receiver / decoder, for example of the EMM ("Entitled Management Message") type. When the communication module MC2 of the receiver / decoder RD receives a complementary message of this type, it communicates the access right data and the disturbance rights data to the decoding module MD to then store them securely in the memory of the CP card. It should be noted that the content access rights and local disturbance rights are stored in a secure memory such as the memory of a smart card or a secure USB key. They can also be contained in a DRM license file for example which is itself protected by encryption using keys protected by certificates. The MCA, SMD, and SMP modules shown in Figure 1 that apply or handle the content access rights or the disturbance rights must also be secured: they are either applications that are executed by a secure processor (from card to card). puce for example), or applications coded in a secure manner ("secure coding").

When the receiver / decoder RD receives in its decoding module MD the blocks of content data as well as the perturbation data, the disturbance integrity data and the access control data, it performs two checks (in the MCA module typically or in the SMD module). A first check consists in comparing the access rights data stored in the secure memory (for example that of the CP card) of the receiver / decoder with the access rights control data transmitted with the content to ensure that the user of the decoder is authorized to receive this content and also to recover the keys of content encryption as seen previously. A second check is performed to verify the integrity of the disturbance data received using the disturbance integrity data. For example, if the integrity data is generated (by the server ER) by applying a hash function to the disturbance data, the verification in the receiver / decoder consists of applying the same hash function to the received disturbance data and compare the result of this calculation with the disturbance integrity data received.

If this second verification reveals that the disturbance data is not intact (that is, it has been modified from its original content), then a maximum disturbance level will be applied by the receiver / decoder the display of the content, whatever the local disturbance rights.

If, on the other hand, the second verification reveals that the perturbation data are intact, then the SMP submodule will apply the disturbance defined by the perturbation data according to a perturbation level dependent on the local disturbance right. In addition, the user of the receiver / decoder is invited to reduce the disturbance level by acquiring new disturbance rights (in fact, rights to "decrease" the disturbances) either locally, by cutting off chips from his card for example, by an exchange with the ER server.

It should be noted that to prevent a user from frequently switching from one program of interest to another, and thus disabling each time the disturbance integration mechanism (s) so as to benefit substantially continuously from this program which In this case, it is conceivable that the SMP perturbation integration sub-module is configured to automatically apply the highest perturbation right (high disturbance) to the content, for example a fixed monochrome image. possibly without accompanying sound) after a chosen number of changes (for example two or three counted by a dedicated counter). Note also that in the absence of a determination of the right of local disturbance, the SMP perturbation integration sub-module is preferably configured so as to automatically apply by default to the decoded content to view the right of highest perturbation (high disturbance (s) - for example a fixed monochrome image possibly without accompanying sound).

It will also be noted that the decoding module MD, and for example its SMP perturbation integration sub-module, may be arranged from in order to force a local content recording device, which is coupled to one of the outputs of the receiver / decoder RD or of the display means SV, to record the decoded contents with the disturbance (s) corresponding to either the right of disturbance local receiver / decoder, or the highest disturbance right (disruption (s) high - for example a monochrome fixed image possibly without accompanying sound). This last hypothesis is intended to prohibit the reproduction of content without authorization. In one variant, it can be envisaged that the right of disruption, which corresponds to the tokens purchased by the user, also defines a right of reproduction of content. For example, it is conceivable that at least one identifier of the user is recorded at the same time as the decoded content, in order to be able to determine who is at the origin of a reproduction of content.

The decoding module MD (SMD and SMP) is preferably implemented in the form of software modules ("software"). But, we can consider that it is realized in the form of electronic circuits ("hardware") or a combination of software modules and electronic circuits.

Similarly, the device D is preferably made in the form of software modules ("software"). But, we can consider that it is realized in the form of electronic circuits ("hardware") or a combination of software modules and electronic circuits.

The invention is not limited to the embodiments of multimedia content viewing method, receiver / decoder and media content delivery device described above, only by way of example, but it encompasses all variants that may consider those skilled in the art within the scope of the claims below.

Claims

A method of displaying multimedia content comprising the steps of: receiving in a receiver / decoder (RD) data representing the multimedia content as well as disturbance data associated with the content processing the data representing the content according to the data of associated perturbation and according to perturbation rights stored locally in the receiver / decoder; and displaying the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local disturbance rights.

2. Method according to claim 1, characterized in that it comprises the preliminary steps of: reception by the receiver / decoder (RD) disturbance and storage rights management messages and / or update rights perturbation in the receiver / decoder according to the information contained in the disturbance rights management messages.

3. Method according to one of claims 1 or 2, characterized in that it further comprises the steps of receiving a user command to reduce the level of disturbance in the display of the mutlimedia content; updating the local perturbation rights by decrementing a number of pre-stored tokens in the receiver / decoder, the number of tokens being determined by the user's command; and modifying the display of the mutlimedia content according to a new level of perturbation depending on the updated local disturbance rights.

4. Method according to one of claims 1 or 2, characterized in that it further comprises the steps of receiving a user command to reduce the level of disturbance in the display of the mutlimedia content; sending a request to update the local disruption rights by purchasing tokens to a remote server including a management module (MGN); reception by the receiver / decoder (RD) of a disturbance rights management message containing an update of the local perturbation rights when the purchase of token could be carried out by the remote server; updating the local disturbance rights in the receiver / decoder according to the information contained in the disturbance rights management message received; and modifying the display of the mutlimedia content according to a new level of perturbation depending on the updated local disturbance rights.

5. Method according to one of claims 1 to 4, characterized in that disturbance integrity data are received in the receiver / decoder with the data representing the multimedia content and perturbation data associated with the content, and in that that the method comprises the steps of: checking the integrity of the disturbance data received using the disturbance integrity data before the display of the multimedia content, and in the case where the verification step of the integrity reveals that the perturbation data is not integrity, display the multimedia content with a predefined maximum disturbance level; in the case where the integrity checking step reveals that the perturbation data is intact, displaying the multimedia content with a perturbation level depending on the local disturbance rights of the receiver / decoder (RD).

6. Method according to one of claims 1 to 5, characterized in that during the step of receiving data representing the multimedia content by the receiver / decoder (RD), they are received in encrypted form, said step comprising in addition reception by the receiver / decoder access control data and in that prior to the data processing step representing the multimedia content in the receiver / decoder, the method comprises a step of decrypting the data representing the multimedia content using an encryption key obtained from the access control data if the receiver / decoder has a right of access to the content.

7. Method according to claim 6, characterized in that the disturbance integrity data and the access control data are received by the receiver / decoder in protected messages, preferably by encryption.

8. Method according to one of claims 1 to 7, characterized in that the disturbance data contain a disturbance content for hiding at least partially the multimedia content or alteration data of the multimedia content for modifying the rendering multimedia content when it is displayed.

The method according to claim 8, characterized in that the disturbance data contains several different advertising contents associated with different user profiles, and in that the method further comprises a step of determining in the receiver / decoder the advertising content. to be inserted as a disturbance when displaying the multimedia content.

10. Method according to one of claims 1 to 9, characterized in that, prior to the step of displaying the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local perturbation rights, the method comprises a step of displaying the multimedia content without any disturbance for a predefined duration.

11. Multimedia content receiver / decoder (RD) comprising: communication means (MC2) arranged to receive data representing the multimedia content as well as perturbation data associated with the content and means from a communication network (RC); decoding apparatus (MD) arranged to process said data representing the content according to the associated perturbation data and as a function of perturbation rights stored locally in the receiver / decoder and to provide to display means (SV) the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local disturbance rights.

A device (D) for providing multimedia content intended to be transmitted to receivers / decoders (RD) connected to a communication network (RC), comprising means for generating (MG2) perturbation data associated with the content intended for to be used by said receivers / decoders (RD) to process the data representing the content in perturbation rights function stored locally in the receivers / decoders for displaying the multimedia content with a disturbance defined by the perturbation data according to a perturbation level dependent on the local perturbation rights.