FR2826815A1 - Domestic audiovisual terminal interconnections having source/destination node and transmission destination terminal only taking place when token available. - Google Patents

Abstract

The domestic audio visual transmission method has a source node and a destination node. The transmission of audiovisual signals only takes place to the destination node when a token is available.

Description

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 Method of transmitting audiovisual signals within a home audiovisual network, implementing a token mechanism.

 The field of the invention is that of home audiovisual networks, of the type making it possible to interconnect a plurality of audio and / or video terminals (also called devices), of analog and / or digital type, so that they exchange audiovisual signals .

 These terminals belong, for example, to the following list of equipment (which is not exhaustive): television receivers (by satellite, over the air, by cable, xDSL, ...), televisions, video recorders, scanners, digital cameras , digital cameras, DVD players, computers, personal digital assistants (PDAs), printers, etc.

 The domestic audiovisual network is, for example, of the high-speed switched type, comprising a small number of nards and allowing in particular the real-time exchange of animated images, for distribution in the context of a dwelling.

 The home audiovisual network according to the invention comprises a plurality of nards, connected by a plurality of physical communication links. These links are for example of the type allowing bidirectional data transfers, according to the IEEE 1355 standard.

 The audio and / or video terminals communicate with each other via the nords to which they are connected. The nards, which form the backbone of the network, include in particular: first interface means, allowing the connection, via one or more links (for example according to the standard IEEE 1355), of one or more other ncads; second interface means, allowing the connection of one or more analog terminals (that is to say capable of receiving audiovisual signals in analog form); third interface means, allowing the connection (for example via a digital bus according to the IEEE 1394 standard) of one or more

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digital terminals (i.e. capable of receiving audiovisual signals in digital form).

The operation of such a home audiovisual network is as follows: a connection is established, via a plurality of nonds, between a first terminal (or "listener" in English), which wishes to receive audiovisual signals, and a second terminal (or "talker" in English), who can provide them.

 We now specify some elements of the terminology used in the following description.

 The first aforementioned terminal is called "recipient terminal" and the nard to which it is connected is called "recipient nod" (or "Display Unit" in English).

 Regarding the second aforementioned terminal, there are two cases.

 In a first case, the second terminal is integrated into a noad, called "nard source". Thus, it is assumed that the source noad comprises means for receiving and / or reading source signals (of origin external to the network) and means for transmitting these source signals, in the form of the aforementioned audiovisual signals, to the nend. recipient. In other words, the nced source receives and / or reads source signals and introduces them into the home audiovisual network in the form of audiovisual signals. The nond (source) and the second terminal are in this first case combined.

The present invention preferably applies to the case where the source ncnd includes a television receiver (for example, in France, a "TPS" (registered trademark) or "Canal Satellite" (registered trademark) receiver). In this case, the source ncad is also called "Tuner Unit". It makes it possible to introduce directly into the network, in a digital form (generally coded in MPEG2 format), source signals supplied by an operator and containing television programs.

In a second case, the second terminal, called "input terminal", is connected to a nard, called "input noad". Unlike the first case, the noed (input) and the second terminal are not confused. The input noad does

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 does not include means for receiving and / or reading source signals (of origin external to the network). The input ncnd receives audiovisual signals from the input terminal and introduces them into the home audiovisual network.

 By input terminal is meant for example a digital camera, a digital camera, a DVD player with digital output, or any analog device seen through an analog / digital converter, ...

 Currently, digital television receivers ("tuner unit") are designed to deliver a single channel (a single television channel) to a single terminal. They therefore receive a source signal, by cable or by satellite, grouping several tens of channels, and carry out the processing necessary to extract the channel that the user wishes to watch.

 This solution is satisfactory, for the user, if he has a single television. It is not, however, if it has a home network as described above. Indeed, several users may wish to receive different programs, on different televisions (or recording means), or even see the same program on several televisions.

 From the operator's point of view, however, this possibility is undesirable if he cannot control it. The programs it broadcasts are chargeable, by subscription for example, and such a solution represents an unacceptable shortfall.

 Likewise, making multiple access to channels possible without control poses intellectual property problems in the works that are disseminated and, where appropriate, recorded.

 For these different reasons, each digital receiver can only deliver one channel. The only solution for the user is therefore to have several digital receivers to be able to operate several channels on his home network.

 This solution is not practical (connections to be made, dimensions, number of remote controls to use, ...), and expensive (necessary

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 of several receivers comprising the same elements). It is also frozen: the user cannot modify his subscriptions, except to return a receiver or to obtain a new receiver.

 There is therefore a significant need, to which there is currently no answer, for a simple and scalable solution, meeting both the expectations of users and the requirements of operators.

 The invention particularly aims to provide a solution to this need.

It should be noted that the formulation of this need is, in itself, not obvious. Indeed, a person skilled in the art is convinced that there is no reliable alternative to the current technique physically associating a channel with a receiver.

 More specifically, an objective of the invention is to provide a technique for optimally operating a digital television receiver ("tuner unit"), while respecting subscriptions or authorizations issued by one (or more operators) ).

 Thus, an objective of the invention is to provide such a technique allowing several users of the same home network to receive on separate terminals separate channels, delivered by the same digital receiver.

 Another object of the invention is to provide such a technique, making it possible to effectively control the broadcasting and reproduction of programs, and therefore to guarantee compliance with the legislation on intellectual property rights (i.e. say, in particular, to prevent piracy).

 The invention also aims to provide such a technique, which allows operators to offer varied and scalable services, in terms of subscription, promotion, selective access to channels or separate programs, ...

 Yet another objective is to provide such a technique, also making it possible to control access to certain channels or to certain programs within the home network.

 Another object of the invention is to provide such a technique, which

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 requires reduced material means, and therefore less expensive, compared to an installation requiring several digital receivers.

 These objectives, as well as others which will appear subsequently, are achieved according to the invention using a method of transmitting audiovisual signals between at least one source ncnd and at least one destination nend of an audiovisual network. domestic, implementing a token-based mechanism for the transmission of an audiovisual signal, such an audiovisual signal can only be transmitted to a recipient nwd if a corresponding token is available.

possible de diffuser plusieurs canaux distincts vers plusieurs terminaux d'un possi réseau domestique, tout en conservant un contrôle précis, vu d'un opérateur, sur le nombre et/ou le type de canaux délivrés, en fonction d'autorisations ou d'abonnements, concrétisés dans le nctids source par les jetons. Thus, using a single source nend (digital receiver), it is

possible to broadcast several distinct channels to several terminals of a home network possi, while retaining precise control, seen from an operator, on the number and / or the type of channels delivered, according to authorizations or subscriptions , materialized in the source nctids by tokens.

 This also makes it possible to introduce great flexibility in the management of these subscriptions or authorizations, simply by allocating or removing tokens, without it being necessary to intervene on the hardware, or to add digital receivers.

 As will be seen below, the tokens can correspond to any channel or to a particular channel, or even be associated with particular conditions.

 The invention can in particular apply, advantageously, to a home audiovisual network is a switched type network.

 According to a preferred implementation mode, said method comprises, prior to said transmission of said audiovisual signal, a step of assigning a token to a connection allowing said transmission between the source noad and the destination nwd.

 Preferably, at least some tokens are conditional access tokens, authorizing the processing of said audiovisual signal only if the recipient nred fulfills a predetermined condition.

 This allows you to reserve certain channels for certain source ncads, for example

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 example for assigning "parental permission".

 In this case, advantageously, said audiovisual signal associated with a conditional access token carries control information specifying said determined condition. This can in particular ensure the control of the reproduction and / or the distribution of said audiovisual signals by said at least one addressee.

 According to a preferred aspect of the invention, said control information comprises a first element of information specifying whether a recipient nocd or not authorizes at least one recipient terminal connected to said nond recipient to reproduce said audiovisual signal on a data medium, so that said conditional access token relates to the reproduction of said audiovisual signal.

 Said first piece of information is, in a simplified implementation mode, coded on one bit.

 Preferably, said control information comprises a second piece of information specifying whether said audiovisual signal is intended for a particular destination terminal connected to a destination noad and / or for a particular user, or if it can be transmitted to any connected destination terminal. to a recipient nwd, so that said conditional access token relates to the broadcasting of said audiovisual signal.

 Advantageously, said second piece of information is also coded on one bit.

 According to another advantageous characteristic of the invention, said predetermined condition comprises the presence of a local key, known to said recipient nwd and / or entered by said user.

 Preferably, said control information comprises said first piece of information and said second piece of information.

 Thus, it is possible to effectively and independently control the distribution (second information) and the reproduction (first information).

 According to a preferred aspect of the invention, information relating to the

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 audiovisual signal intended for a particular destination terminal and / or a particular user is not accessible to the other nords of the network.

 Advantageously, said tokens are managed by said at least one source ncad.

 In addition, we can advantageously distinguish two types of tokens (which may or may not coexist, depending on the needs: generic tokens and dedicated tokens.

 Thus, preferably, at least some of said tokens are generic tokens allowing access to any one of the channels of a set of channels received by said source ncad.

 Likewise, advantageously, at least some of said tokens are dedicated tokens allowing access to predetermined audiovisual signals. These predetermined audiovisual signals can in particular belong to the group comprising: the audiovisual signals relating to a predetermined channel of a set of channels received by said source node; audiovisual signals relating to a predetermined program of a channel from a set of channels received by said source nwd; audiovisual signals relating to a predetermined family of programs.

 Preferably, said predetermined family of programs groups together at least two programs according to a criterion belonging to the group comprising: - the type of said programs; - the content of said programs; the time of broadcast of said programs on a channel.

 Furthermore, according to an advantageous aspect of the invention, at least some of said tokens are dated, time stamped and / or having a predetermined lifetime.

 This allows for even more optimized management.

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 The invention also relates to a device included in a domestic audiovisual network interconnecting at least one source nend and at least one recipient ncad, said device comprising means for managing a set of tokens, an audiovisual signal being unable to be transmitted from an ncad source to a recipient noad only if a corresponding token is available.

 Preferably, said device is included in a noed source. In other words, in this case, the source nodes implementing the method described above.

 The invention also relates to a method of control, by a remote operator, of an authorization to transmit an audiovisual signal, supplied by said remote operator, from a nord'source to a destination noad of a home audiovisual network. According to the invention, said remote operator transmits information relating to a token mechanism to said source noad, according to user requests and / or promotional operations, said audiovisual signal being able to be transmitted to said recipient ncad only if a corresponding token is available.

 The technique of the invention indeed allows the operator to manage in a very flexible and scalable manner the authorizations which it delivers to subscribers to its television broadcasting service. For example, during the duration of a sporting event, a television operator can sell additional tokens, so as to temporarily extend the access of a user to its sports channels.

 The invention also relates to a computer program comprising sequences of instructions suitable for implementing a method as mentioned above, when said program is executed on a computer.

 The invention also relates to a computer program product, suitable for the transmission of audiovisual signals between at least one source nard and at least one ncad intended for a home audiovisual network. According to the invention, said computer program product comprising program code instructions recorded on a medium usable in a computer,

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 comprising computer-readable programming means for carrying out an implementation phase of a token-based mechanism for the transmission of an audiovisual signal, such an audiovisual signal being able to be transmitted to a recipient nwd only if a corresponding token is available .

 Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given by way of simple illustrative and nonlimiting example, and of the appended drawings, among which: - the figure 1 shows a block diagram of a home audiovisual network in which the present invention can be implemented; - Figure 2 illustrates the structure of a source nend of the home audiovisual network of Figure 1-; - Figure 3 illustrates the structure of a recipient noad of the home audiovisual network of Figure 1; - Figure 4 shows a flowchart describing an algorithm for processing a packet, according to the invention, in a recipient noad of the home audiovisual network of Figure 1; - Figure 5 illustrates the structure of a packet according to the invention, conveying an audiovisual signal between a source noad and a destination noad of the home audiovisual network of Figure 1; - Figure 6 illustrates a remote control unit allowing a user to communicate with a recipient need of the home audiovisual network of Figure 1; Figures 7 to 9 show different flowcharts describing algorithms for operating the remote control unit of Figure 6, allowing in particular a user to formulate a connection request between a destination terminal ("listener") and a source noad or a terminal d 'entry ("talker"); FIG. 10 presents a flowchart describing an algorithm for processing a packet, according to the invention, in a source north of the home audiovisual network of FIG. 1;

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FIG. 11 presents a flowchart describing an algorithm for creating a sub-list of active destination listeners that can be viewed by a user; FIG. 12 presents a flowchart describing an algorithm for creating a sub-list of active transmitter equipment ("talkers") that can be viewed by a user; FIG. 13 presents a flowchart describing an implementation algorithm, in a source nwd of the home audiovisual network of FIG.
1, of the token mechanism according to the invention.

 The general principle of the invention is based on the implementation of a token mechanism making it possible to manage the broadcasting of several distinct channels to several terminals of a home network, according to authorizations or subscriptions, embodied in the ncsd source by tokens.

 We now present, in relation to the block diagram of FIG. 1, an example of a home audiovisual network in which the present invention can be implemented.

 It will be recalled that the home audiovisual network is of the type comprising a plurality of nodes, making it possible to interconnect a plurality of audiovisual terminals.

 Each ncnd is equipped with: a first interface (input / output) of the IEEE 1355 type, allowing this nccd to be connected to other ncodes; a second IEEE 1394 type (input / output) interface, allowing this nood to be connected to a digital bus to which digital terminals can be connected or, via analog / digital converters, analog terminals; a third analog interface (output only), allowing this north to be connected to an analog terminal; a fourth infrared type (input) interface, allowing commands to be sent from a remote control unit 9 to the scud, within the framework of a man / machine interface between a user and the nard.

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In the example of FIG. 1, the home audiovisual network comprises: a source nard 3, including a satellite television receiver, whose antenna is referenced 4. This source nard 3 is connected to the no @ ds referenced 5 and
32, via links of the IEEE 1355 type. For the sake of simplification, no analog terminal is connected to its analog interface and no bus of the IEEE 1394 type is connected to its corresponding interface; a ncad referenced 5, connected to the nards referenced 3,7 and 32, via links of the IEEE 1355 type. A television 6 is connected on its analog interface. An IEEE 1394 type bus is connected on its corresponding interface, and two terminals are connected on this bus, namely a video recorder 30 and a DVD player 34, each via an analog / digital converter 31 and 35; a nard referenced 32, connected to the nards referenced 3 and 5, via links of the IEEE 1355 type. A television 33 is connected to its analog interface; a scud referenced 7, connected to no @ d referenced 5, via a type link
IEEE 1355. A television 37 is connected on its analog interface. A bus of the IEEE 1394 type is connected on its corresponding interface, and a terminal is connected on this bus, namely a camcorder (registered trademark) 8, via an analog / digital converter 36. It is clear that if the camcorder 8 has a digital output, it can be connected directly to the IEEE 1394 type bus.

 By way of illustrative example, the following two cases are considered in the following description: first case: the user wishes to receive on television 6, connected to node 5, a satellite television program received by the source ncad 3 ( "talker"). In this first case, the television 6 constitutes a destination terminal ("listener") and the nwd referenced 5 a destination ncod; second case: the user wishes to receive on television 6, connected to the noad 5, audiovisual signals generated by the camcorder 8 connected to the

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 nood referenced 7. As in the first case, the television 6 constitutes a recipient terminal ("listener") and the nood referenced 5 a recipient nend. Furthermore, the camcorder 8 constitutes an input terminal ("talker") and the node referenced 7 an input nood.

 We now present, in relation to FIGS. 2 and 3, examples of the structure of a source ncod (FIG. 2) and of a destination nood (FIG. 3) belonging to a home audiovisual network according to the invention.

 It will be recalled that such a source noad comprises for example a device for receiving satellite data, such as data representative of satellite television signals. Such a source ncad can of course also be any other device capable of receiving and then introducing audiovisual signals into the home audiovisual network of the invention.

 For the sake of simplification, the rest of the document will be limited to the case where the source node comprises a device for receiving source signals from satellite television. It will of course be easy for a person skilled in the art to extend the description below to any other type of nood source.

 The source nood of figure 2 can be broken down into two distinct parts: a first set of elements (not referenced in figure 2) ensures the processing of the source signals received from a source external to the network, such as the received source signals on a satellite antenna for example; a second set of elements 1 is intended to ensure the functionality of the source north within the switched audiovisual network to which it belongs.

 The first set of elements comprises: a tuner 10, which extracts, from the data received by a satellite antenna not shown in FIG. 2, a channel multiplexing several audiovisual channels;

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a demultiplexer 11, which demultiplexes the signals coming from the tuner 10, so as to select one of the audiovisual channels of the channel; a decryption device 12, which decrypts the signals from the demultiplexer 11, so as to decrypt the audiovisual channels received in encrypted form by the source ncad; a central processing unit (or CPU for English "Central
Processing Unit ") 13a; a permanent ROM-type storage medium (in English" Read
Only Memory ") 14a, which stores the algorithms specific to the invention, described below in connection with FIGS. 10 and 13; a temporary storage means of RAM type (in English" Random
Access Memory ") 15a; a conditional access device 16a, ensuring the management and the verification of keys making it possible to control the access of the northern recipients of the network to certain audiovisual signals; a module 17 for coding audiovisual signals in DTCP format ( in English "Digital Transmission Copy Protection", for "copy protection of digital transmissions" as defined in "Digital Transmission Content Protection Specification Volume 1 (Informational Version) revision 1.1, July 25,2000), allowing to apply a coding specific protector for audiovisual signals intended for a digital terminal. Only the digital terminals authorized to receive these audiovisual signals are equipped with a decoder in the corresponding DTCP format, so as to be able to decode and then process the received signal.

 The second set of elements 1 of the source ncad brings together functional elements characteristic of the technology implemented on the switched audiovisual network of the invention, and has at least two external input / output ports connected respectively to a communication bus

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 series designed to operate according to the IEEE 1394 standard, and to a switched network according to the IEEE 1355 standard.

Note that the IEEE 1394 standard is described in the following reference documents:
IEEE Std 1394-1995, Standard for High Performance Serial Bus;
IEEE Std 1394a-2000, Standard for High Performance Serial Bus;
IEEE P1394.1 Draft 0.17 Standard for High Performance Serial Bus Bridges.

 The IEEE 1355 standard is defined by the reference IEEE Std 1355-1995 Standard for Heterogeneous InterConnect (HIC) (Low Cost Low Latency Scalable Serial Interconnect) (aka ISO / IEC 14575 DIS).

Set 1 includes in particular: a block 18a for transporting packets of CIP type (in English "Common Isochronous Packet" for "common isochronous packet"), according to the standard IEC 61883 as defined in "International
Standard Consumer Audio / Video Equipment-Digital Interface,
First edition 1998-02, IEC 61883-1 / 2/3/4/5 "). Such a block 18a is supplied with data from the demultiplexer 11 and the decryption device 12 and delivers CIP type packets, after the block 18a thus inserts into the packets it delivers absolute time information, indicating when a packet should be consumed by the application for which it is intended; a module 19a which provides the interface with the central unit for the blocks referenced 18a, 20a and 2 la; a transport module 20a, produced for example using technology
FPGA, making it possible in particular to insert information for controlling the distribution and / or reproduction in the packets intended to be transmitted by the non-source to the switched audiovisual network of the invention; a device 21a, called "bridge 1394", ensuring the interface, within the source nosd, between on the one hand the switched audiovisual network of

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PHY/LINK 1394 qui est par exemple constitué d'un composant PHY TSB21LV03A et d'un composant LINK TSB12LV01A commercialisés par la société TEXAS INSTRUMENT (Marque déposée) et de connecteurs 1394, par exemple commercialisés par la société MOLEX (Marque déposée), par exemple sous la référence
53462. Le moyen d'interfaçage 23 comporte au moins un port externe destiné à être connecté à un terminal (appareil de traitement de données ou périphérique), via un bus de communication série 1394. the invention consisting of IEEE 1355 links and on the other hand a serial communication bus intended to operate according to the IEEE 1394 standard to which the nond source is attached; a switching module 22a having an output port connected to the switched audiovisual network of the invention consisting of IEEE 1355 links; an interfacing means 23a comprising a set of components

PHY / LINK 1394 which for example consists of a PHY component TSB21LV03A and a LINK component TSB12LV01A marketed by the company TEXAS INSTRUMENT (Registered trademark) and 1394 connectors, for example marketed by the company MOLEX (Registered trademark), by example under reference
53462. The interfacing means 23 comprises at least one external port intended to be connected to a terminal (data processing device or peripheral), via a 1394 serial communication bus.

 FIG. 3 illustrates an example of a recipient nend according to the invention. The structure of such a noad is close to that of the nood source described above, in that it comprises: a first set of elements 2 grouping together functional elements characteristic of the technology implemented on the switched audiovisual network of the invention, and having at least two input ports connected respectively to a serial communication bus intended to operate according to the IEEE 1394 standard, and to a switched network according to the IEEE 1355 standard. Thus, a destination north can receive data packets by the one of the three input / output ports of the switching nood 22b, coming from the switched audiovisual network consisting of links of the IEEE 1355 type, or by one of the two input / output ports of the interfacing means 23b coming from '' a terminal (data processing device or peripheral), via a 1394 serial communication bus;

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 a second set of elements not referenced in Figure 3, ensuring the processing of data packets from the switched network of the invention, before their transfer to a terminal connected to the recipient noad. Such a terminal can be analog or digital in nature.

The assembly 2 of FIG. 3 comprises elements similar to those of the assembly of elements 1 described in relation to FIG. 2, namely: a block 18b of packet transport of CIP type (in English "Common Isochronous Packet "for" common isochronous packet "), according to standard IEC 61883. a module 19b which provides the interface with the central unit for the blocks referenced 18b, 20b and 21b; a transport module 20b ensuring the processing of the aforementioned control information. This module 20a comprises storage means, storing and implementing in particular the algorithm, specific to the invention, described below in relation to FIG. 4; a device 21b, known as a "1394 bridge", ensuring the interface, within the recipient ncad, between the switched audiovisual network of the invention consisting of IEEE 1355 links and a serial communication bus, designed to operate according to the IEEE 1394 standard , to which the recipient node is attached; a switching module 22b having three input / output ports connected to the switched audiovisual network of the invention consisting of links
IEEE 1355; an interface means 23b comprising a set of components
PHY / LINK 1394.

The elements of the recipient nood ensuring the processing of data packets, before their transfer to a terminal connected to the recipient noad, include: a central processing unit (or CPU for English "Central
Processing Unit ") 13b;

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 a permanent ROM-type storage means (in English "Read Only Memory") 14b, which stores the algorithms specific to the invention described below in relation to FIGS. 11 and 12; a RAM type temporary storage means (in English "Random Access Memory") 15b; a conditional access device 16b, ensuring the management of local keys required by the source noad to control access by the destination nords of the network to certain audiovisual signals; an infrared reception device 24, ensuring the reception of infrared signals, emitted for example by a device of the remote control type intended for the receiving noad, and their transmission to the central unit 13b; a decoder 26 in DV format (in English "Digital -Video" for "digital video" according to the DV IEC 61834 standard, described in the document "Specifications of consumer-use digital VCRs using 6.3 mm Magnetic Tape" published in December 1994 by " HD digital VCR conference "), enabling the decoding of audiovisual signals received by the recipient nood and encoded in DV format; a decoder 27 in MPEG2 format (in English "Moving Pictures Experts Group" for "Group of experts for the coding of moving pictures" according to ISO / IEC 13818-1,13818-2, 13818-3), allowing '' decoding audiovisual signals received by the recipient nood and encoded in MPEG2 format; a video processing module 28; a module 29 ensuring on the one hand the analog digital conversion of audiovisual signals intended for an analog recipient terminal connected to the recipient node, and on the other hand the activation of anti-reproduction means according to the "macrovision" system (designed and developed by MACROVISION, registered trademark) when the content of the audiovisual signal intended for such an analog destination terminal must be protected. The module

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29 includes one or more analog output port (s) to which one or more analog terminals can be connected, such as a television or a video recorder for example.
It is recalled that the activation of the "macrovision" makes it possible to scramble the analog signal coming from the analog output port of the module 29, in a manner not perceptible for an analog terminal of television type, but preventing the reproduction of such a signal by an analog reproduction terminal such as a video recorder.

 We now present, in relation to the flowchart of FIG. 13, an algorithm for placing copper, in the source noad 3, of the token mechanism according to the invention.

 This algorithm is for example stored in the ROM of the nond source. It is loaded into RAM when the power is turned on and the central unit (CPU) will execute the instructions corresponding to this algorithm.

 It is assumed that the source noad ("Tuner unit") receives an instruction (or request) which relates to the channels which it manages and which is a function of an action performed by the user (step 130).

 There are three types of user requests: - "request to release a channel": for example, the user switches off a recipient terminal (for example a television) to which the source nood transmitted, via a recipient nend, audiovisual signals relating to a given channel;, - "request for a new channel": for example, the user makes a request via a non-recipient (for example using an infrared remote control) to receive, on a given destination terminal, audiovisual signals corresponding to a given channel; - "channel change request": for example, the user formulates via a recipient nood, a request to change, on a given recipient terminal, the channel he receives from the source nood.

 We now detail the actions of the nood source associated with these three pes of user requests.

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 If the request is of the "request to release a channel" type, the nood source releases the token which had previously been assigned to this channel (between the source nocd and a given destination terminal) (step 131). Then, the source nmd releases the output of the demultiplexer which corresponded to the released channel (step 132).

 If the request is of the "request for a new channel" type, the nood source searches for an available token (step 133). If no token is available, the user's request is rejected (step 134). Otherwise, a token is allocated to the new channel requested by the user (step 135). Then, the nood source selects an output from the demultiplexer in order to associate it with the released channel (step 136). Finally, the nond source calculates and assigns a value to the field CP of the header of each packet carrying the audiovisual signals of this new channel (step 137). This step 137 is detailed below in relation to the flow diagram of FIG. 10.

If the request is of the "channel change request" type, the source nccd directly performs the steps referenced 136 and 137 and discussed above; In other words, in this particular embodiment, the user can change the channel while keeping the same token.

1 H is clear that the invention also relates to the variant according to which when the user changes the channel, the token allocated to the previous channel is released and a new search for available token must be carried out (steps 133 and following). This variant is for example of interest if the tokens are of the dedicated type (and not generic), that is to say each allow access to a particular channel (with which specific audiovisual signals are associated).

 It is recalled that the packets make it possible to convey audiovisual signals, from a nood (source or input) to another nced (recipient). Thus, in the first aforementioned illustrative case, the packets convey for example audiovisual signals in MPEG2 format, from the source rmd 3 to the destination noad 5. In the aforementioned second illustrative case, the packets convey for example audiovisual signals in format DV, from entry nond 7 to recipient nood 5.

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 It is assumed, in the following description, that each packet has the particular structure illustrated in FIG. 5, comprising a header 51 and a data field (also called "content") 52.

 The header 51 includes: fields, referenced 53 to 56, relating to the routing of the packet. They are not affected by the present invention and will therefore not be described in more detail; a "sourcenoadid" field 57, containing an identifier of the source noad; a "CP" field 58, containing, specifically to the present invention, information for controlling the reproduction and / or broadcasting of the audiovisual signal conveyed by the data field 52 of the packet; a "CV" field 59, containing a virtual channel identifier, making it possible to distinguish different flows originating from the same source nend (and therefore to identify the destination terminal, in the case where several terminals connected to the same destination nend receive audiovisual signals from the same nood source).

 As explained in detail below, the nond source fills the field CP, that is to say gives a value to the control information, depending on the nature (analog or digital) of the destination terminal, the level of protection to be applied to the audiovisual signal and any broadcasting criteria to be applied.

 The control information is for example coded, in the CP field, on two bits: a first bit, called protection, and a second bit, said broadcast. The criteria for assignment by the source nood of the value 0 or 1 to each of these two bits, as well as the use by the recipient nood of these two bits, are described in detail in the following description.

<Desc / Clms Page number 21>

 We now present, in relation to the flowchart of FIG. 4, an example of a packet processing algorithm, according to the invention, in a destination nccd of the home audiovisual network of FIG. 1.

 This algorithm is stored in the ROM associated with the transport module. On power up, the transport module loads and executes the instructions corresponding to this algorithm.

 After receiving a packet (step 40), the destination noad detects whether the sending equipment ("talker") is a source neud or an input nood (step 41).

 If the transmitting equipment ("talker") is an input nood 7 (second illustrative case mentioned above), the receiving ncad selects its DV decoder (step 42). The CP field is not taken into account (step 43). The data in the data field 52 of the packet is sent to the DV decoder (step 44).

 If the transmitting equipment ("talker") is a source 3 (first illustrative case mentioned above), the nond recipient selects its MPEG decoder (step 45). The CP field is taken into account (step 46). The recipient node analyzes the value of the protection bit of the CP field (step 47).

 If the protection bit of the CP field takes the value "O", the recipient nood verifies the nature of the recipient terminal (television 6 ("listener") in the first and second illustrative cases mentioned above) (step 48). If it is an analog terminal, the addressee nend deactivates "Macrovision" (step 49) and sends the data of the data field 52 of the packet to the MPEG decoder (step 410). If it is a digital terminal, the packet is sent on the IEEE 1394 bus, on which the digital terminal is connected (step 411).

 If the protection bit of the CP field takes the value "1", the destination ncnd checks the nature of the destination terminal 6 (step 412). If it is a digital terminal, the recipient nood rejects the packet (step 413).

If it is an analog terminal, the recipient nend analyzes the value of the broadcast bit of the CP field (step 414).

<Desc / Clms Page number 22>

 If the broadcast bit of the CP field takes the value "l", the destination node detects whether it is the one which previously supplied the private key (step 415). If not, the destination node rejects the packet (step 416). If so, the destination node activates "Macrovision" (step 417) and sends the data from the data field 52 of the packet to the MPEG decoder (step 418).

 If the diffusion bit of the CP field takes the value "0", the steps referenced 417 and 418 discussed above are carried out directly.

 We now present, in relation to the flowchart of FIG. 10, an example of a packet processing algorithm, according to the invention, in a source node of the home audiovisual network of FIG. 1.

 This algorithm is stored in the ROM of the source node. It is loaded into RAM when the power is turned on and the central unit (CPU) will execute the instructions corresponding to this algorithm.

 Before transmitting a packet (step 100), the destination node detects the nature of the destination terminal (television 6 in the first and second illustrative cases mentioned above) (step 101).

 If the destination terminal ("listener") is a digital terminal, the source node assigns the value "0" to the protection bit of the CP field and applies a DTCP type coding (step 1012).

 If the destination terminal ("listener") is not a digital terminal (that is to say is an analog terminal), the source node does not apply DTCP type coding (step 102). It detects whether the audiovisual signals must be protected (that is to say, for example, if the source signals are encrypted and must only be decrypted under certain conditions) (step 103).

 If the audiovisual signals are not to be protected, the source node assigns the value "0" to the protection bit of the CP field (step 104).

 If the audiovisual signals are to be protected, the source node assigns the value "1" to the protection bit of the CP field (step 105). Then, the recipient node detects whether it has a global key (step 106). In

<Desc / Clms Page number 23>

 if so, it assigns the value "0" to the diffusion bit of the CP field and performs a decryption (step 107). If not, the source nood asks the recipient nood for a private key (also called local key) (step 108). If the nond recipient provides the private key (response "yes" to the step referenced 109), the source ncad assigns the value "1" to the broadcast bit of the CP field and performs a decryption (step 1011). If the recipient nosd does not provide the private key (response "no" to the step referenced 109), the source noad does not perform decryption (step 1010).

 It will be recalled that the term “receiving terminal” (active listener) and active transmitting equipment (“talker”) means two entities involved in a connection within the audiovisual home network.

 It is assumed that the system (and therefore each of the north of the network) has: the full list of active destination terminals ("listeners"); the full list of active talkers.

 When he wishes to establish a connection between a sending equipment ("talker") and a destination terminal ("listener"), the user has several possibilities: either he directly identifies this sending equipment and / or this destination terminal (for example by entering a specific identifier for each); either he chooses this transmitting equipment within a sub-list of active transmitting equipment ("talkers") that the system allows him to view, and / or he chooses this destination terminal within a sub-list of terminals active recipients ("listeners") that the system also allows him to view.

 In a first embodiment, each sublist is merged with the corresponding complete list. In this case, the user can view all the active transmitting devices ("talkers") and / or all the active receiving terminals ("listeners").

<Desc / Clms Page number 24>

 In a second embodiment, each sublist that the user can view is limited to a part of the corresponding complete list, as a function of at least one predetermined filtering criterion.

As explained below in relation to FIGS. 11 and 1.2, this filtering criterion is for example linked to the level of protection (value of the CP field) associated with each connection in which an active sending equipment and a receiving terminal are involved. active.

destinataires ("listeners") actifs pouvant être visualisée par un utilisateur. We now present, in relation to the flowchart of Figure 11, an example of algorithm for creating a sublist of terminals

active recipients ("listeners") that can be viewed by a user.

This algorithm is for example stored in the ROM of the recipient noad (in the case where this assumes the role of "control unit"). It is loaded into RAM when the power is turned on and the central unit (CPU) will execute the instructions corresponding to this algorithm.

 After retrieving the complete list of active destination terminals (step 110), the level of protection associated with the connection in which this destination terminal is involved is analyzed for the first active destination terminal in the list (step 111).

 In other words, the value of the CP field associated with this connection is analyzed. It will be recalled that the field CP includes: a protection bit, which takes the value "1" if it is desired to prohibit the reproduction of the audiovisual signals contained in the data field of the corresponding packet. The protection bit takes the value "0" if no protection of audiovisual signals is necessary; a broadcast bit, which takes the value "1 It if no destination terminal must be authorized to derive (" spy function ") the audiovisual signals received by the destination terminal which has provided the private key. The broadcast bit takes the value "0" otherwise.

<Desc / Clms Page number 25>

If the CP field does not take the high value (answer "no" to the question of the step referenced 112), the active destination terminal is added to the sublist of active destination terminals that the user will view (step 113 ) then we go to the next active destination terminal of the complete list (step 114). By high value of the CP field is meant the case where the protection bit and the broadcast bit each take the value "1".

If the field CP takes the high value (answer "yes" to the question of the step referenced 112), we go directly to the next active destination terminal of the complete list (step 114).

This mechanism is repeated until all the active destination terminals of the complete list have been analyzed (step 115).

We now present, in relation to the flowchart of FIG. 12, an example of an algorithm for creating a sub-list of active transmitting equipment ('talkers') that can be viewed by a user.

This algorithm is for example stored in the ROM of the recipient noad (in the case where this assumes the role of "control unit"). It is loaded into RAM when the power is turned on and the central unit (CPU) will execute the instructions corresponding to this algorithm.

After retrieving the complete list of active transmitting equipment (step 120), the protection level associated with the connection in which this transmitting equipment is involved is analyzed for the first active transmitting equipment on the list (step 121).

If the CP field does not take the high value (answer "no" to the question in step referenced 122), the active sending equipment is added to the sub-list of active sending equipment which the user will view (step 123) then we go to the next active transmitter equipment from the complete list (step 124).

If the field CP takes the high value (answer "yes" to the question of the step referenced 122), we go directly to the next active transmitter equipment from the complete list (step 124).

<Desc / Clms Page number 26>

 This mechanism is repeated until all the active destination terminals of the complete list have been analyzed (step 125).

 FIG. 6 illustrates an example of a remote control unit 9 which can be used in an embodiment of the invention, within the framework of a man / machine interface between a user and a nood of the home audiovisual network. It is recalled in fact that a ncad of the home audiovisual network has, in a preferred embodiment of the invention, an infrared type input interface, allowing data to be sent from a remote control unit 9 to the north.

 Such a housing 9 comprises for example three sets of keys: a first set of keys referenced 60, comprising specific control keys; a second set of alphanumeric keys referenced 61; a key referenced 62, allowing a user to access a menu, for example a menu of additional functionalities which could be implemented within the audiovisual network of the invention, but which will not be described in more detail in as part of this application.

 The set of control keys referenced 60 comprises for example: a button referenced 64 for controlling the standby or activity state of the ncad of the audiovisual network (secondary) associated with the remote control unit 9; two keys "Proven." referenced 66 and "Destinat." referenced 67, used to select a particular terminal of the audiovisual network.

 The "Proven." Key referenced 66 allows the user to select a transmitting device (namely a source ncad or an input terminal, also called talker) from the audiovisual network of the invention. The "Destinate" key. "referenced 67 allows a user to select a destination terminal of the audiovisual network of the invention, for example the television referenced 6 in FIG. 1;

<Desc / Clms Page number 27>

a connection key "CNX" referenced 65, used to establish a connection between the sending equipment and the destination terminal selected using the keys referenced 66 and 67 described above; an "END" button referenced 63, which can serve as an end button for the active key, or to end any specific processing carried out by the nond recipient controlled by the remote control unit 9. For example, the "END" key referenced 63 allows switching off a sending device to which the recipient nood in question is connected; up and down navigation buttons respectively referenced 68a and
68b, allowing the user to move up or down within a menu or a list; an "OK" button referenced 69 for validating the choice of an item from a list or a menu.

 The alphanumeric keys of the set referenced 61 allow a user to choose an item referenced using an alphanumeric character from a list or menu, or even to enter a string of alphanumeric characters to using the remote control 9.

 We will now describe in more detail with reference to FIGS. 7 to 9 examples of algorithms for operating the destination node, as a function of the commands it receives from the infrared remote control unit 9.

 It will be noted that the instructions appearing in the flowcharts of FIGS. 7 to 9 are expressed in the computer terminology used for programming the remote control unit 9 and the recipient nood 5 which is associated with it.

 The algorithm described in relation to FIG. 7 is stored in the ROM of the recipient nend. When the power is turned on, it is loaded into RAM and the central unit will execute the instructions corresponding to this algorithm.

 We start from an initial state "init" referenced 70. A user actuates the button referenced 64 of the remote control 9, thus triggering the sending of an "IRon" command referenced 71 to the recipient noad 5. During a step referenced 72, by default, all the nords of the audiovisual network connected to or comprising a transmitting device (a "talker") are listed, according to the "List talkerbox" instruction. For example, such a list could look like this:

<Desc / Clms Page number 28>

 parent's room ; TV room; cooked.

By default, the television referenced 6 connected to the nond recipient 5 constitutes the "listener", or recipient terminal, according to the instruction "TV-on, L = default".

 The recipient node 5 then goes into a state referenced 73 "OselectT '.

 The user therefore has two possibilities: if he presses the "Proven" key referenced 66, the recipient node receives an instruction referenced 741 "IR ~ talk", and lists (742) all of the transmitting equipment ( "talkers") active within the audiovisual network of the invention. Such a list can for example be displayed on a screen of the destination node 5, or on the television 6 which is connected to it, so that the user can read it, and present himself in the following manner: AVI equipment of the TV room; AV3 equipment in the TV room; AV2 kitchen equipment.

The recipient ncsd 5 then goes into a "1select ~ T" state referenced 743; if he presses the "Destinat." key referenced 67, the recipient nood receives an instruction referenced 751 "IRlisten", and lists (752) all of the nords of the audiovisual network of the invention to which one or more destination terminals are connected . Such a list can be presented as follows: parents'room;children'sroom; TV room; cooked.

The recipient nood 5 then goes into a "Oselect-L" state referenced 753. If it receives from the remote control 9 an "IRJisten" instruction referenced 751, the recipient nend 5 lists (755) all of the terminals

<Desc / Clms Page number 29>

 recipients ("listeners") active within the audiovisual network of the invention. Again, such a list can be displayed on a screen of the recipient ncnd 5, or on the television 6 which is connected to it, so that the user can read it. Such a. The list can be presented as follows: children's room / TV room, indicating that a destination terminal for the children's room is active and connected to a transmitter equipment in the TV room; TV room / TV room; - kitchen 1 kitchen.

 The recipient noad 5 then goes into an "Oselect-L" state referenced 756.

 It will be noted that in a particular embodiment of the invention, the recipient noad 5 may display, during the steps referenced 742 and 755, only a subset of the active transmitting equipment or the active destination terminals within the network. Such a subset is for example determined as a function of a predetermined criterion, linked to the information for controlling the broadcasting and / or the reproduction associated with the signal transmitted (respectively received) by the transmitting equipment (respectively by the recipient terminal).

The display of such partial lists is described in more detail in connection with FIGS. 11 and 12.

 FIG. 7b illustrates the operation of the recipient nood 5, when it receives, from any initial state referenced 76, an “IRjoff 'instruction referenced 77. This algorithm is stored in the ROM of the recipient no @ d. loaded into RAM during power-up and the central unit (CPU) will execute the instructions corresponding to this algorithm. The recipient nood then implements the instruction referenced 78 "Close iPCR (x) (TV-off) ", consisting, in a preferred embodiment of the invention, in terminating the connection between the recipient ncod 5 and the analog television referenced 6 which is connected to it, if such a connection exists.

<Desc / Clms Page number 30>

 FIGS. 8a and 8b are described in parallel, allowing a user respectively to switch the recipient nood 5 from a "OselectT" state to a "0selecCL" state, or vice versa.

 These algorithms are stored in the ROM of the recipient nood. They are loaded into RAM when the power is turned on and the central processing unit (CPU) will execute the instructions corresponding to the algorithms.

référencée 81a (respectivement 81b) de l'utilisateur via la télécommande 9. On rappelle, en relation avec la figure 7a, que dans l'état"Oselect-T"référencé 73 (respectivement dans l'état "Oselect~L" référencé 753), l'utilisateur dispose de la liste des noads reliés à, ou comprenant des équipements émetteurs (respectivement connectés à un ou plusieurs terminaux destinataires). The new addressee 5 is in an initial state "Oselect ~ T" referenced 73 (respectively "Oselect-L" referenced 753), and receives a command "IRscan"

referenced 81a (respectively 81b) of the user via the remote control 9. It is recalled, in relation to FIG. 7a, that in the "Oselect-T" state referenced 73 (respectively in the "Oselect ~ L" state referenced 753 ), the user has the list of noads connected to, or comprising transmitting equipment (respectively connected to one or more destination terminals).

 The "IRscan" instruction is received following the actuation by the user of one of the navigation keys or one of the alphanumeric keys of the remote control 9 allowing him to browse one of the lists of nords described above. .

 The addressee noad 5 sets up the @ action "Scan node ~ x Wait screen" referenced 82a (respectively 82b) corresponding, and goes into the state "0scan ~ T" referenced 83a (respectively "Oscan ~ L" referenced 83b ). In a particular embodiment of the invention, the nond recipient 5 then displays a message of the "Scan TV room" type, indicating the search for the transmitting equipment connected to the noad located in the television room.

 On receipt of an instruction "NE ~ scan ~ cnf" referenced 84a (respectively 84b), corresponding to the reception of the information sought at the level of the nood x of the selected network, the recipient no @ d 5 displays the list referenced 85a (respectively 85b ) transmitting equipment belonging to or connected (respectively connected destination terminals) to the selected nood x. For example, the destination nosd 5 displays the names of the VCR-I and STB-2 equipment connected to the ncad located in the TV room. Ncad

<Desc / Clms Page number 31>

destinataire 5 passe alors dans l'état"lselectT"référencé 743 (respectivement dans l'état"lselectJL"référencé 756).

recipient 5 then goes into the "lselectT" state referenced 743 (respectively in the "lselectJL" state referenced 756).

A new instruction "IRscan" referenced 81a (respectively 81b) validates the choice of a particular transmitter equipment ("talker") Xj (respectively of a destination terminal ("listener") particular yj). By default, the recipient ncsd redisplays the list referenced 88a (respectively 88b) of the no @ ds connected to a destination terminal (respectively to a sending device), for example of the type: parents'room;children'sroom; TV room; cooked.

The recipient nood therefore returns to the "Oselect-L" state referenced 753 (respectively "Oselect-T" referenced 73).

From any of the states "lselectT" referenced 743 and "lselect L" referenced 756 of FIG. 8c, the reception by the recipient nood 5 of an instruction "IRtaIk" referenced 741 causes the display of the list 803 network nods connected to or one comprising a transmitting equipment, and the passage of the nood 5 in the "OselectT" state referenced 73. Similarly, the reception of an "IR ~ listen" instruction referenced 751 causes the display of the list 752 of the nords of the network connected to a destination terminal, and the transition from nond 5 to the "Oselect L" state referenced 753. It is recalled that the instructions "IR ~ talk" and "IRJisten" can be respectively triggered by l 'actuation of the keys "Proven." referenced 66 and "Destinat." referenced 67.

 FIGS. 9a and 9b show the operating algorithms of the recipient noad 5 when a user wishes to establish or terminate a connection between a recipient terminal ("listener") and a transmitter equipment ("talker").

 These algorithms are stored in the ROM of the recipient no @ d. They are loaded into RAM when the power is turned on and the central processing unit (CPU) will execute the instructions corresponding to the algorithms.

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touche"CNX"référencée 65 de la télécommande 9, et le nccd destinataire 5 reçoit donc une instruction "IR~CNX" référencée 91. The recipient noctd 5 is in any state referenced 90, which can be for example the state "Oselect L" or "lselectT". the user presses the

"CNX" key referenced 65 on the remote control 9, and the recipient nccd 5 therefore receives an "IR ~ CNX" instruction referenced 91.

 The recipient ncnd 5 checks (92) whether a "talker" has been selected by the user. It will be recalled that in a preferred embodiment of the invention, the analog television 6 connected to the destination ncnd 5 is chosen as "listener" by default.

référencée 803 des nords connectés à ou comprenant un équipement émetteur, et passe dans l'état"Oselect-T"référencé 73. If no "talker" has been selected, the recipient ncad displays the list

referenced 803 from the nords connected to or comprising transmitting equipment, and goes into the "Oselect-T" state referenced 73.

 Otherwise, the non-recipient requests the establishment of a connection between the "talker" and the "listener" chosen by the user (or chosen by default), during an operation referenced 93 "Open stream oPCR (T), iPCR (L) ", and displays a" Wait screen "message for the user.

 During operation referenced 93, the iPCR registers (in English, "input Plug Control Register") (respectively oPCR for "output Plug Control Register") are updated at the "talker" level (respectively at the " listener "). These registers are described in standard IEC 61883.

 The recipient ncud goes to "Osetup" state referenced 94, then receives an instruction "NE ~ setup ~ cnf" referenced 95, coming from the network (for example coming from a specific processing unit of the network, responsible in particular for management connections between a sending equipment and a destination terminal), indicating the result of the connection request referenced 93. The recipient no @ d 5 checks (96) the connection confirmation 95 received from the network.

 If the connection has been established between the destination terminal and the sending equipment, the listening function of the destination terminal is activated (99) by the command "Ldisplayon" and the function for transmitting the sending equipment by the command "Display T3trl".

<Desc / Clms Page number 33>

 The recipient ncad then goes into the "Octrl ~ AV" state referenced 901.

 If the connection fails, the recipient no @ d 5 displays an error message with the command "Error report" referenced 97 and goes into the "Oerror" state referenced 98.

 If the destination node 5 is in the state "Octrl ~ AV" referenced 901, the reception of an instruction "IR ~ END" referenced 902 (corresponding to the actuation by the user of the key referenced 63 of the remote control unit 9) causes the closure of the current connection between a "talker" and a "listener" by the command referenced 903 "Close current oPCR + attached iPCR".

 The nond recipient 5 then displays the list 803 of the nords connected to or comprising a transmitting equipment ("talker") and goes into the "0selecCTu state referenced 73.

Claims (24)

 CLAIMS 1. Method for transmitting audiovisual signals between at least one source nard and at least one ncad intended for a home audiovisual network, characterized in that it implements a mechanism based on tokens for the transmission of a signal audiovisual, such an audiovisual signal can only be transmitted to a recipient nood if a corresponding token is available. 2. Method according to claim 1, characterized in that said home audiovisual network is a switched type network. 3. Method according to any one of claims 1 and 2, characterized in that, prior to said transmission of said audiovisual signal, said method comprises a step of assigning a token to a connection allowing said transmission between the source nood and the recipient ncetd. 4. Method according to any one of claims 1 to 3, characterized in that at least some tokens are conditional access tokens, authorizing the processing of said audiovisual signal only if the recipient nend fulfills a predetermined condition. 5. Method according to claim 4, characterized in that said audiovisual signal associated with a conditional access token carries control information specifying said determined condition. 6. Method according to claim 5, characterized in that said control information ensures the control of the reproduction and / or the distribution of said audiovisual signals by said at least one recipient nend. 7. Method according to any one of claims 5 and 6, characterized in that said control information comprises a first piece of information specifying whether a recipient ncad authorizes or not at least one destination terminal connected to said nond recipient to reproduce said signal audiovisual on a data carrier, <Desc / Clms Page number 35>  so that said conditional access token relates to the reproduction of said audiovisual signal. 8. Method according to claim 7, characterized in that said first information element is coded on one bit. 9. Method according to any one of claims 5 to 8, characterized in that said control information comprises a second piece of information specifying whether said audiovisual signal is intended for a particular destination terminal connected to a destination noad and / or a particular user, or if it can be transmitted to any destination terminal connected to a destination north, so that said conditional access token relates to the broadcasting of said audiovisual signal. 10. Method according to claim 9, characterized in that said second information element is coded on one bit. 11. Method according to any one of claims 4 to 10, characterized in that said predetermined condition comprises the presence of a local key, known to said recipient noad and / or entered by said user. 12. Method according to claims 7 and 9, characterized in that said control information comprises said first information element and said second information element. 13. Method according to claim 12, characterized in that information relating to the audiovisual signal intended for a particular destination terminal and / or a particular user is not accessible to the other nords of the network. 14. Method according to any one of claims 1 to 13, characterized in that said tokens are managed by said at least one source nood. 15. Method according to any one of claims 1 to 14, characterized in that at least some of said tokens are generic tokens allowing access to any run of the channels of a set of channels received by said source nod. 16. Method according to any one of claims 1 to 15, characterized in that at least some of said tokens are dedicated tokens allowing access to predetermined audiovisual signals. <Desc / Clms Page number 36>  17. Method according to claim 16, characterized in that said predetermined audiovisual signals belong to the group comprising: audiovisual signals relating to a predetermined channel of a set of channels received by said source nod; audiovisual signals relating to a predetermined program of a channel from a set of channels received by said source nocd; audiovisual signals relating to a predetermined family of programs. 18. The method of claim 17, characterized in that said predetermined family of programs includes at least two programs according to a criterion belonging to the group comprising: the type of said programs; the content of said programs; the time of broadcast of said programs on a channel. 19. Method according to any one of claims 1 to 18, characterized in that at least some of said tokens are dated, time stamped and / or having a predetermined lifetime. 20. Device included in a domestic audiovisual network interconnecting at least one source noad and at least one destination ncad, characterized in that it comprises means for managing a set of tokens, an audiovisual signal which cannot be transmitted from a noad source to a recipient nood only if a corresponding token is available. 21. Source node of a domestic audiovisual network interconnecting at least one source nend and at least one recipient nood, characterized in that it comprises a device according to claim 20. 22. Method for controlling, by a remote operator, an authorization to transmit an audiovisual signal, supplied by said remote operator, from a source noad to a destination noad of a home audiovisual network, <Desc / Clms Page number 37>  characterized in that said remote operator transmits information relating to a token mechanism to said source noad, according to user requests and / or promotional operations, said audiovisual signal being able to be transmitted to said recipient nccd only if a matching token is available. 23. Computer program, characterized in that said program comprises sequences of instructions suitable for implementing a method according to any one of claims 1 to 19 when said program is executed on a computer. 24. Computer program product, suitable for the transmission of audiovisual signals between at least one source no. And at least one destination nood of a home audiovisual network, said computer program product comprising instructions of recorded program code on a medium usable in a computer, comprising: computer-readable programming means for carrying out an implementation phase of a token-based mechanism for the transmission of an audiovisual signal, such an audiovisual signal being unable to be transmitted to a no @ d recipient only if a corresponding token is available.