FR2828047A1 - Digital television chain multimedia signal exchange having host apparatus processing multimedia signal and applications modules with predetermined order exchanges host apparatus modifiable - Google Patents

Abstract

The digital multimedia system has a host apparatus (10) processing a multimedia signal (S1) and application modules (12,16,20) connected to the apparatus. The host apparatus exchanges multimedia signals with each application. The exchanges are effected successively in a predetermined order. The host apparatus can modify (32) the predetermined order exchange.

Description

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 The present invention relates to a digital multimedia system comprising a host device for processing multimedia signals and at least two application modules connected to this host device. The digital multimedia systems concerned by the invention are for example those used in private homes to receive digital television channels. A host device provides reception, generic processing and sending of appropriate signals to the television, while one or more application modules connected to this host device provide specific processing of the signals, such as for example their decryption. Thus, the possibility of accessing certain pay programs or certain pay channels is subject to the possession of the corresponding application module (s), made available to subscribers by program broadcasters.

 The host device is arranged to perform an exchange of multimedia signals with each application module, the exchanges being carried out successively and in a predetermined order.

 The present invention also relates to a host apparatus for such a system.

 A digital multimedia system is known, comprising in particular a digital multimedia decoder forming a host device, receiving a coded multimedia signal, for example according to the MPEG 2 standard (from the English Moving Picture Expert Group 2}}), and providing this decoded multimedia signal. output. It is provided with an interface comprising a succession of connectors intended to each receive an application module.

 Thus, when several application modules are connected, the decoder exchanges the multimedia signal with each of the connected modules in accordance with the predetermined succession of connections according to a chain of elements in series.

However, the order of the application modules in the succession of connections can influence, depending on the nature of these modules, the signal obtained at the output of the decoder. Depending on the multimedia signal desired at the output of the digital multimedia decoder, a user of this system can therefore be led to disconnect the application modules in order to reconnect them in a different order. This manipulation is not very simple, especially if the user is not an IT expert.

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 The invention aims to remedy this drawback by creating a digital multimedia system capable of simply and inexpensively providing the desired multimedia signal as output by the user at any time.

 The subject of the invention is therefore a digital multimedia system comprising a host device for processing multimedia signals and at least two application modules connected to this host device, the host device being arranged to carry out an exchange of multimedia signals with each module. application, the exchanges being carried out successively and in a predetermined order, characterized in that the host apparatus includes means for modifying the predetermined order of the exchanges.

 Thus, the digital multimedia system according to the invention makes it possible to adapt the order of the exchanges carried out between the host device and the application modules as a function of the multimedia signal desired at the output of the host device. This is done without requiring modification of the application module connections to the host device.

 In a particular embodiment of the invention, at least one of the application modules connected to the host device is a module for transmitting multimedia signals to the host device. The other application modules are access control modules for decrypting and descrambling multimedia signals.

 Indeed, as mentioned above, the multimedia signals received directly by the host device or transmitted by the transmission module to the host device are for example provided by any service providers, such as pay television program providers.

 To allow the suppliers to remain owners of the conditional access system to the multimedia signals which they emit, these are scrambled by the suppliers using control words, the control words themselves being transmitted in encrypted form. in multimedia signals. The decryption of the control words and the descrambling of the multimedia signals can only be carried out by access control modules, which a user of the host device will have acquired from these suppliers, generally for payment.

 Conventionally, a multimedia signal emitted by a program supplier comprises data packets of type EMM (for Entitlement Management Message). These contain information on the rights of a user of the host device to access content of the multimedia signal.

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 multimedia also includes ECM type data packets (for "Entitlement Control Message"). These packets include control words to descramble the multimedia signal. EMM and ECM packets are transmitted in advance, in the multimedia signal flow, with respect to the data itself.

 Conventionally, the access control modules process the packets of the EMM type received in the multimedia signal to keep the rights of the user up to date.

They also include a decryptor for extracting control words from ECM type messages received. Also conventionally, these access control modules can also include a descrambler for descrambling the multimedia signal, thanks to the control words.

 Thus, if a multimedia signal supplied by the transmission module must be decrypted and descrambled by one of the other access control modules, the digital multimedia system according to the invention makes it possible to adapt the order of the exchanges between the host device and the various application modules, so that the exchange of multimedia signals between the host device and the transmission module is carried out before the exchange of multimedia signals between the host device and the access control module allowing its decryption and descrambling.

 The digital multimedia system according to the invention may also include one or more of the following characteristics: - the multimedia signal transmission module comprises a multimedia signal demodulator; the multimedia signals supplied to the host device include information in encrypted and scrambled form, and at least one of the application modules connected to the host device is an access control module comprising decryption means and corresponding descrambling; the application modules are connected to the host device by means of an interface chosen from a DVB-CI type interface, an NRSS type interface and an Open Cable type interface; and - the host device is a multimedia digital decoder.

 The subject of the invention is also a host apparatus for processing multimedia signals comprising an interface for connection to application modules, the host apparatus being arranged to carry out an exchange of multimedia signals with each application module, the exchanges s '' performing successively and in a

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 predetermined order, characterized in that it includes means for modifying the predetermined order of exchanges.

 The host device according to the invention may also include one or more of the following characteristics: the interface is one of the interfaces chosen from a DVBCI type interface, an NRSS type interface and an Open type interface Cable ; and - the host device is a multimedia digital decoder.

 The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings in which: - Figure 1 schematically represents a digital multimedia system according to the invention; - Figure 2 is a flowchart showing the steps of a method implemented in the system of Figure 1; and - Figures 3,4 and 5 schematically represent means for modifying the order of a succession of exchanges for the system of Figure 1, according to a first, a second and a third configuration.

 The digital multimedia system shown in FIG. 1 comprises a digital decoder 10, designed to receive, demodulate and decode a multimedia signal 81, conventionally transmitted by satellite, cable or terrestrial hertzian way.

 This signal 81 received by the digital decoder 10 is supplied by any service provider, such as a provider of pay television programs.

 A first application module 12 comprises first access control means 14 for decrypting and descrambling signals from a first supplier and a second application module 16 comprises second access control means 18 for decrypting and descrambling signals from a second provider. These first and second application modules 12 and 16 are connected to the digital decoder 10, in order to possibly decrypt and descramble the multimedia signal 81 if it comes from one of the two aforementioned suppliers.

 Similarly, a third application module 20 is connected to the digital decoder 10. This third application module 20 allows the transmission of an additional multimedia signal S2, also called the second signal, in the

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 digital decoder 10. For this, it includes means 22 for demodulating the second multimedia signal S2 it receives.

 In this example, the first and second multimedia signals 81 and S; ? are provided either by the first supplier and then require decryption and descrambling by the first application module 12, or by the second supplier and then require decryption and descrambling by the second application module 16, or by another supplier not having encrypted them and therefore do not require decryption or descrambling.

 Conventionally, each of the first, second and third modules 12, 16, 20 can be in the form of a microprocessor card or a box to be connected to the rear of the digital decoder 10.

 Certain elements constituting these application modules, such as the access control means 14, 18 and the demodulator 22, are proprietary elements which cannot be standardized. On the other hand, the digital decoder 10 is standardized, for example according to the MPEG 2 standard.

 It is therefore necessary to define common rules for exchanging data between, on the one hand, the digital decoder 10 and, on the other hand, the three application modules 12, 16 and 20. For this, the digital decoder 10 comprises a connection interface 24 defining, in a standardized manner, communication rules between the decoder 10 and the application modules 12, 16 and 20.

 The invention applies in particular in the context of a connection interface 24 conforming to the DVB-CI standard (from the English Digital Video Broadcasting-Common Interface) which is notably described in the European standard EN 50221 published by the CENELEC (European Committee for Electrotech Standardization).

 More generally, it can be applied in the context of most known digital video interface standards, notably NRSS and Open Cable.

 The DVB-CI, NRSS and Open Cable standards pursuing similar goals with similar means, for the sake of clarity we will now limit the description to the DVB-CI standard, its aspects being directly transposable to the Open Cable and NRSS standards and more generally to most standards relating to digital multimedia interfaces.

 Thus, the DVB-CI connection interface 24 between the digital decoder 10 and any one of the application modules 12, 16 or 20 consists of two logical interfaces:

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 a control interface which allows the central processing units of the digital decoder 10 and of any of the application modules to communicate, in particular for the transmission of commands; and a transport flow interface which transmits the first signal 81 or second signal 82 on a bidirectional bus between the digital decoder 10 and the application modules 12, 16 and 20.

 Conventionally, the digital decoder 10 comprises a demodulator 26 receiving as input the signal 81 supplied at the input of the decoder 10, and an MPEG decoder 28 supplying as output the signal 81 decoded and possibly decrypted.

 Also conventionally, the digital decoder 10 comprises a conditional access management module 30 in bidirectional communication with each of the application modules 12, 16 and 20, via the control interface of the DVB-CI connection interface. 24.

 In addition, the digital decoder 10 comprises a switch 32 whose input is connected to the output of the demodulator 26 and whose output is connected to the input of the MPEG decoder 2 28. The switch 32 is further connected, of a part to the conditional access management module 30, and, secondly, to each of the three application modules 12, 16 and 20, via the transport flow interface of the DVB-CI connection interface 24 .

 The multimedia signal 81 or 82 received by each of the first two application modules 12 or 16, via the transport flow interface of the DVB-CI connection interface 24 and coming from the switch 32, is either retransmitted as it is to the switch 32, either decrypted and descrambled by the access control means 14 or 18 of this application module 12 or 16 before being retransmitted to the switch 32. For this, each of the first two application modules 12, 16 comprises a switching device 34, controlled by the conditional access management module 30 and making it possible to short-circuit or not the access control means 14 and 18.

 As regards the third application module 20, this receives, from the digital decoder 10, the signal 81 transmitted by the switch via the transport flow interface of the DVB-CI connection interface 24 and supplies the digital decoder 10, either this same signal Si, or the signal 82 which it receives from an external source and which it demodulates thanks to the demodulator 22. For this, the application module 20 also includes a switching device 36

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 controlled by the optional access management module 30, as a function of the signal 81 or 82 desired at the output of the digital decoder 10.

 The operation of this digital multimedia system will now be described with reference to FIGS. 2, 3, 4 and 5.

 First of all, it will be noted that in the embodiment described above, the user can receive at the output of the digital decoder 10, either the multimedia signal 81 received at the input of the digital decoder 10, or the multimedia signal S2 received from a external source by the third application module 20. In addition, this signal is either encrypted and scrambled by one of the two aforementioned suppliers, or unencrypted and unscrambled. There are therefore six possible cases, for each of which an order of exchanges between the digital decoder 10 and the three application modules is preferable, even necessary.

 Thus, if the desired signal at the output of the digital decoder 10 is the signal 81 and whatever the supplier, that is to say in the first 3 cases, it is preferable that this signal is processed by the first two modules d application 12 and 16 before being processed by the third application module 20, because if a change of positioning of the switching device 36 is necessary in the third application module 20, this will not affect the decryption and possible descrambling of signal 81.

 In these cases, the conditional access management module 30 chooses a first configuration of the exchanges associated with a first configuration of the switch 32, in which the digital decoder 10 first exchanges the multimedia signal with the first application module 12, then with the second application module 16, then with the third application module 20, as illustrated in FIG. 3.

 If the desired signal at the output of the digital decoder 10 is the signal S2 received by the third application module 20, and if this signal S2 is neither encrypted nor scrambled, the first configuration of the switch 32 is satisfactory and can therefore be chosen by the conditional access management module 30.

 On the other hand, if the desired signal at the output of the digital decoder 10 is the signal S2, and if this signal is encrypted and scrambled by the first supplier, it is necessary that this signal 82 is processed by the third application module 20, before to be processed by the first application module 12.

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 In this case, the conditional access management module 30 chooses a second configuration of the exchanges associated with a second configuration of the switch 32, in which the exchanges between the digital decoder 10 and the application modules are done first with the second application module 16, then with the third application module 20, then with the first application module 12, as illustrated in FIG. 4.

 Likewise, if the desired signal at the output of the digital decoder 10 is the signal S2, and if this signal is encrypted and scrambled by the second supplier, it is necessary that this signal S2 is processed by the third application module 20, before to be processed by the second application module 16.

 In this case, the conditional access management module 30 chooses a third configuration of the exchanges associated with a third configuration of the switch 32 in which the exchanges between the digital decoder 10 and the application modules are done first with the first application module 12, then with the third application module 20, then with the second application module 16, as illustrated in FIG. 5.

 There are therefore three possible configurations in the succession of exchanges between the digital decoder 10 and the application modules 12, 16 and 20, associated with three possible configurations of the switch 32, depending on the desired signal at the output.

 For this, the method represented in FIG. 2, implemented by the conditional access management module 30, comprises a first step 40, during which the conditional access management module 30 verifies the connection of the modules. application 12, 16 and 20 to the digital decoder 10. During this step 40, the conditional access management module 30 receives, from each of the connected application modules, information allowing it to know that the first application module 12 connected is an access control module for decrypting and descrambling a signal from the first supplier, that the second application module 16 connected is an access control module for decrypting and descrambling a a signal from the second supplier and that the third application module 20 connected is a multimedia signal supply module 82.

 During the following test step 42, the conditional access management module 30 determines which multimedia signal is desired at the output of the digital decoder 10.

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 If the desired signal is signal 81, we go to a step 44, during which the conditional access management module 30 controls the positioning of the switching device 36 of the third application module 20 so that the signal output of this third module, namely signal 81.

 Next, we pass to a test step 48, during which the conditional access management module 30 determines what decryption and descrambling of the signal 81 is necessary.

 If the signal SI is neither encrypted nor scrambled, we go to a step 50, during which the conditional access management module 30 controls the positioning of the switching devices 34 of the first and second application modules 12 and 16, so that the access control means 14 and 18 are short-circuited.

 If the signal 81 comes from the first supplier, we go to a step 52, during which the conditional access management module 30 controls the positioning of the switching devices 34 so that the signal 81 is processed by the control means. access 14 of the first application module 12 and so that the second access control means 18 are short-circuited.

 Finally, if the signal 81 comes from the second supplier, we go to a step 54, during which the conditional access management module 30 controls the positioning of the switching devices 34 so that the first access control means 14 are short-circuited and so that the signal 81 is processed by the access control means 18 of the second application module 16.

 If, during step 42, the desired signal at the output of the digital decoder 10 is the signal 82 received by the third application module 20, we go to step 46, during which the conditional access management module 30 controls the positioning of the switching device 36 of the third application module 20, so that the signal 82 demodulated by the demodulator 22 is supplied to the switch 32 of the digital decoder 10, via the transport flow interface of the communication interface. DVB-CI connection 24.

 Then, we pass to a test step 56 identical to the test step 48, during which the conditional access management module 30 determines what decryption and descrambling of the signal 82 is necessary.

 If the signal 82 is neither encrypted nor scrambled, we go to a step 58 identical to step 50, during which the conditional access management module 30

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 controls the positioning of the switching devices 34 of the first and second application modules 12 and 16, so that the access control means 14 and 18 are short-circuited.

 If the signal S2 comes from the first supplier, we go to a step 60 identical to step 52, during which the conditional access management module 30 controls the positioning of the switching devices 34 so that the signal S2 is processed by the access control means 14 of the first application module 12 and so that the second access control means 18 are short-circuited.

 Finally, if the signal S2 comes from the second supplier, we go to a step 62 identical to step 54, during which the conditional access management module 30 controls the positioning of the switching devices 34 so that the first means of access control 14 are short-circuited and so that the signal S2 is processed by the access control means 18 of the second application module 16.

 Following steps 50, 52, 54 and 58, we pass to a step 64, during which the conditional access management module 30 chooses the first configuration of the switch 32. In this first configuration, represented in FIG. 3, the multimedia signal is first exchanged between the switch 32 and the first application module 12, before being exchanged between the switch 32 and the second application module 16, then between the switch 32 and the third application module 20.

 Following step 60, we pass to a step 66, during which the conditional access management module 30 chooses the second configuration of the switch 32. In this second configuration, represented in FIG. 4, the multimedia signal is d first exchanged between the switch 32 and the second application module 16, before being exchanged between the switch 32 and the third application module 20, then between the switch 32 and the first application module 12.

 Following step 62, we pass to a step 68, during which the conditional access management module 30 chooses the third configuration of the switch 32. In this third configuration, represented in FIG. 5, the multimedia signal is d first exchanged between the switch 32 and the first application module 12, before being exchanged between the switch 32 and the third application module 20, then between the switch 32 and the second application module 16.

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 It clearly appears that the digital multimedia system according to the invention facilitates the supply to a user of a desired multimedia signal at the output of a host device for processing this multimedia signal, when several application modules are connected to this host device. and in particular when at least one of these application modules is a module for supplying an additional multimedia signal.

Claims (9)

1. Digital multimedia system comprising a host device (10) for processing multimedia signals (S1 S2) and at least two application modules (12, 16, 20) connected to this host device, the host device (10) being arranged to carry out an exchange of multimedia signals with each application module (12, 16, 20), the exchanges taking place successively and in a predetermined order, characterized in that the host device (10) comprises means (32 ) modification of the predetermined order of exchanges.  2. digital multimedia system according to claim 1, characterized in that at least one of the application modules (20) connected to the host device (10) is a module for transmitting multimedia signals to the host device ( S2).  3. Digital multimedia system according to claim 2, characterized in that the module (20) for transmitting multimedia signals (S2) comprises a demodulator (22) for multimedia signals (S2).  4. Digital multimedia system according to claim 2 or 3, characterized in

 that the multimedia signals (S1 S2) supplied to the host device (10) include information in encrypted and scrambled form, and in that at least one of the application modules (12, 16, 20) connected to the the host device (10) is an access control module comprising corresponding decryption and descrambling means.  5. Digital multimedia system according to any one of claims 1 to 4, characterized in that the application modules (12, 16, 20) are connected to the host device (10) by means of an interface (24 ) chosen from a DVB-CI type interface, an NRSS type interface and an Open Cable type interface 6. digital multimedia system according to any one of claims 1 to 5, characterized in that the host device (10) is a digital multimedia decoder.  7. Host apparatus (10) for processing multimedia signals (S1, S2) comprising an interface (24) for connection to application modules (12, 16, 20), the host apparatus (10) being arranged to perform an exchange of multimedia signals with each application module (12, 16, 20), the exchanges taking place successively and in a predetermined order, characterized in that it includes means (32) for modifying the predetermined order Exchanges.  8. Host device (10) according to claim 7, characterized in that the interface (24) is one of the interfaces chosen from a DVB-CI type interface, an NRSS type interface and an Open Cable type interface . <Desc / Clms Page number 13> 9. Host device (10) according to claim 7 or 8, characterized in that it is a multimedia digital decoder.