Television status detection

Abstract

A detection method, performed prior to the implementation of a speech recognition function on a voice signal spoken by a user and captured by a set-top box (1), the detection method comprising the steps of: - verifying that the television (2) is switched on and, if not, issuing a first command to switch on the television; - verifying that the set-top box (1) is an active HDMI source of the television and, if not, issuing a second command to make the set-top box the active HDMI source of the television; - when the television is switched on and the set-top box is the active HDMI source of the television, issuing a request to start the speech recognition function. ABRIDGED FIGURE: Fig. 1

Description

Title of the invention: Detection of the state of a television

[0001] The invention relates to the field of decoder boxes and voice recognition.

[0002] BACKGROUND OF THE INVENTION

[0003] Some recent electronic equipment includes microphones and can be used to implement (at least partially) the voice recognition function of a virtual personal assistant.

[0004] Such electronic equipment then conventionally comprises a detection module. The detection module acquires an audio signal, which is produced by the microphones from a captured sound signal. When the detection module of the electronic equipment detects that a keyword, intended to activate the voice recognition function, has been pronounced by a user, the audio signal produced by the microphones is transmitted to a voice recognition module. The voice recognition function is then implemented by the voice recognition module which analyzes the audio signal and detects the voice commands issued by the user. The electronic equipment then performs the actions corresponding to the voice commands.

[0005] The voice recognition module can be integrated locally in the electronic equipment or can be remoted in one or more external devices separate from the electronic equipment, for example in one or more remote servers (on the cloud). In this latter configuration, the audio signal produced by the microphones is transmitted by the electronic equipment to the voice recognition module via the Internet (possibly after having undergone processing in the electronic equipment, such as echo cancellation), and the voice commands are transmitted by the voice recognition module to the electronic equipment.

[0006] Generally, electronic equipment that implements such a voice recognition function has one or more loudspeakers allowing user feedback (voice feedback) to the user in order to guide him in the event of an anomaly in the interpretation of voice commands.

[0007] It is envisaged to implement a voice recognition function in a decoder box (or STB, for Set-Top Box). However, most decoder boxes do not integrate a loudspeaker, which prevents the implementation of this user feedback.

[0008] SUBJECT OF THE INVENTION

[0009] The object of the invention is to provide user feedback for a voice recognition function implemented at least partially in a decoder box. not incorporating a loudspeaker. Summary of the invention

[0010] In order to achieve this aim, a detection method is proposed, implemented in a decoder box comprising an HDMI port connected via an HDMI cable to a television, the detection method being carried out prior to the implementation of a voice recognition function on a voice signal spoken by a user and captured by the decoder box,

[0011] the detection method comprising the steps of:

[0012] - check that the television is switched on and, if not, produce a first command to turn on the TV;

[0013] - check that the set-top box is an active HDMI source of the TV and, if this is not the case, issue a second command to make the set-top box the active HDMI source for the TV;

[0014] - when the TV is on and the set-top box is the active HDMI source from the TV, generate a request to start the voice recognition function.

[0015] To compensate for the absence of a loudspeaker in the decoder box, the television can therefore be used to provide user feedback (visual or audio) when implementing a voice recognition function.

[0016] The set-top box therefore checks whether the TV is on and whether the set-top box is the active HDMI source for the TV - and, if one or both conditions are not met, produces the first command and / or the second command.

[0017] The decoder box therefore automatically and autonomously determines whether user feedback is available and, if so, triggers the voice recognition function.

[0018] A detection method as previously described is further provided, further comprising the steps of verifying that the television is compatible with a CEC protocol and, if so, using the CEC protocol to verify that the television is turned on and that the set-top box is the active HDMI source of the television, and, if necessary, to produce the first command and / or the second command.

[0019] We further propose a detection method as previously described, comprising the step, to verify that the television is on, of using an HPD signal, then an RXSense signal and / or a signal generated by an HDCP protocol.

[0020] We further propose a detection method as previously described, comprising the steps, to verify that the decoder box is the active HDMI source of the television, of:

[0021] - transmitting via the HDMI port an emitted audio signal comprising a test signal;

[0022] - acquire a received audio signal produced by one or more microphones of the box decoder;

[0023] - determine whether a resulting signal, representative of a difference between the audio signal received and the transmitted audio signal is below a predetermined threshold;

[0024] - if this is the case, deduce that the decoder box is indeed the active HDMI source of the TV.

[0025] A detection method as previously described is further proposed, the decoder box integrating an echo cancellation module, the resulting signal being an output signal of the echo cancellation module.

[0026] A detection method is further proposed as previously described, in which, if the television is not switched on and / or if the set-top box is not the active HDMI source of the television, the first command and / or the second command are transmitted to a remote control of the set-top box so that the latter produces a first secondary command to switch on the television and / or a second secondary command so that the set-top box becomes the active HDMI source of the television.

[0027] A detection method is further proposed as previously described, in which the remote control is arranged to control the television via an infrared link, the detection method further comprising the steps of acquiring a first infrared code and / or a second infrared code and transmitting to the remote control the first infrared code and / or the second infrared code, the first infrared code being used by the remote control to produce the first secondary command and the second infrared code being used by the remote control to produce the second secondary command.

[0028] A detection method is further proposed as previously described, in which the acquisition of the first infrared code and / or the second infrared code consists of accessing an EDID of the television, or of acquiring identification information of the television provided by a user via a configuration menu of the decoder box, or of acquiring identification information of the television provided by the user via a configuration procedure carried out with the remote control.

[0029] We further propose a decoder box comprising an HDMI port, at least one microphone, and a processing unit arranged to implement the detection method as previously described.

[0030] A computer program is further provided comprising instructions which cause the processing unit of the decoder box as previously described to execute the steps of the detection method as previously described.

[0031] A computer-readable recording medium is further provided, on which the computer program as previously described is recorded.

[0032] The invention will be better understood in light of the following description of a particular non-limiting embodiment of the invention. Brief description of the drawings

[0033] Reference will be made to the attached drawings, among which:

[0034] [Fig. 1] [Fig. 1] represents a television, a set-top box and a remote control;

[0035] [Fig.2] [Fig.2] represents the television, the set-top box and a user;

[0036] [Fig.3] [Fig.3] represents steps of the detection method according to the invention, in case the TV is compatible with the CEC protocol;

[0037] [Fig.4] [Fig.4] represents steps of the detection method according to the invention, in case the TV is not compatible with the CEC protocol;

[0038] [Fig.5] [Fig.5] represents steps of an HDCP negotiation process. DETAILED DESCRIPTION OF THE INVENTION

[0039] Referring to [Fig. 1], a set-top box 1 is connected to a television 2 via an HDMI 3 (High Definition Multimedia Interface) cable. The HDMI 3 cable connects an HDMI port 4 of the set-top box 1 to an HDMI port 5 of the television 2.

[0040] The decoder box 1 further comprises an input port 6, microphones 7 and a processing unit 8.

[0041] The processing unit 8 is an electronic and software unit, comprising one or more processing components 10 mounted on one or more electrical cards.

[0042] The processing component(s) 10 comprise, for example, a “general purpose” processor, a processor specialized in signal processing (or DSP, for Digital Signal Processor), a microcontroller, or a programmable logic circuit such as an FPGA (for Field Programmable Gate Arrays) or an ASIC (for Application Specified Integrated Circuit). The processing components 10 are adapted to execute program instructions. The processing unit 8 also comprises one or more memories 11 in which the programs are stored. The invention is not limited to a particular architecture of the processing unit 8.

[0043] The processing unit 8 implements a plurality of functional modules.

[0044] The processing unit 8 firstly implements, conventionally, a module of decoding and a synchronization module.

[0045] The decoder box 1 can receive via its input port 6 a transport stream F of digital television signals (or TS, for Transport Stream). The transport stream F can be transmitted to the decoder box 1 by cable, by satellite, but also via an IP link (for example DASH or HLS), that is to say via a link which uses an Internet protocol.

[0046] The transport stream F comprises a video stream comprising video samples, and an audio stream comprising audio samples.

[0047] The decoding module decodes the video samples and the audio samples. The synchronization module synchronizes the video samples and the audio samples.

[0048] The processing unit 8 then transmits to the television 2, via the HDMI port 4, the HD MI cable 3 and the HDMI port 5, an emitted audio signal (comprising the audio samples) and an emitted video signal (comprising the video samples).

[0049] The television 2 then reproduces a video signal on its screen 12, and an audio signal via its speakers 14.

[0050] The processing unit 8 also partially implements a voice recognition function.

[0051] When the user pronounces a voice signal including a keyword, this voice signal is captured by the microphones 7 of the decoder box 1, which transmits the audio signal to remote servers via the Internet. The remote servers analyze the audio signal and transmit commands contained in the audio signal to the decoder box 1, which then performs the actions corresponding to the voice commands. The analysis of the audio signals to extract the voice commands is therefore not carried out in the decoder box 1, which explains why it is considered that the voice recognition function is only partially carried out in the decoder box 1.

[0052] To carry out this function, and with reference to [Fig.2], the processing unit 8 here comprises a detection module 15 and an echo cancellation module 16.

[0053] The role of the detection module 15 is to detect the keyword in the voice signal Sv emitted by the user and captured by the microphones 7 of the decoder box 1.

[0054] The role of the echo cancellation module 16 is as follows.

[0055] It is possible that, when the user pronounces the voice signal Sv, the television 2 is in the process of reproducing a sound signal Ss. This sound signal Ss possibly results from an emitted audio signal Sae, produced by the decoder box 1 and transmitted by the decoder box 1 to the television 2 via the HDMI port 4, the HDMI cable 3 and the HDMI port 5. The emitted audio signal Sae is applied to the input of an amplifier 17 then to the speakers 14 of the television 2, which thus produces the sound signal Ss.

[0056] In this case, the microphones 7 of the decoder box 1 capture both the voice signal Sv emitted by the user and the sound signal Ss emitted by the speakers 14 of the television 2, which degrades the quality of the voice recognition.

[0057] The echo cancellation module 16 therefore acquires the transmitted audio signal Sae and the received audio signal Sar produced by the microphones 7 (which contains the sound signal Ss and the voice signal Sv). The echo cancellation module subtracts the transmitted audio signal Sae from the received audio signal Sar to provide a “cleaned” resulting signal Sr, as close as possible to the voice signal Sv (and not containing the sound signal Ss). It is this resulting signal Sr which is transmitted to the detection module 15 for detection of the keyword, and to remote servers to perform voice recognition.

[0058] The processing unit 8 is also arranged to implement the detection method according to the invention. The memory 11 forms a computer-readable recording medium, on which is recorded a computer program comprising instructions which cause the processing unit 8 to execute the steps of the detection method according to the invention.

[0059] The detection method aims to ensure that, when a keyword is pronounced by the user in order to launch the voice recognition function, the television 2 is indeed switched on and the decoder box 1 is indeed the active HDMI source of the television 2.

[0060] By “on” we mean that the television 2 is neither off nor on standby.

[0061] By “active HDMI source” is meant that the television 2 is configured to play and to reproduce the video signal emitted and / or the audio signal emitted possibly present on the HDMI 5 port (and therefore transmitted by the decoder box 1 via the HDMI 4 port and the HDMI 3 cable) - and not to read or reproduce signals produced by another source.

[0062] If these conditions are verified, the user can benefit from user feedback when implementing the voice recognition function. This feedback is provided via the television 2: it can therefore be audio feedback (using the speakers 14 of the television 2) and / or visual feedback (using the screen 12 of the television 2).

[0063] Since the user can benefit from feedback, the voice recognition function can be implemented, and the resulting signal Sr is transmitted by the decoder box 1 to the remote servers.

[0064] The detection method is therefore implemented following the acquisition (and detection) of the keyword by the detection module 15.

[0065] The processing unit 8 therefore checks that the television 2 is switched on and, if this is not the case, produces a first command to switch on the television 2. Then, the processing unit 8 checks that the decoder box 1 is indeed the active HDMI source of the television 2 and, if this is not the case, produces a second command so that the decoder box 1 becomes the active HDMI source of the television 2. When the television 2 is switched on and the decoder box 1 is the active HDMI source of the television 2, the television 2 is available to provide audio and / or visual feedback to the user.

[0066] In this case, the processing unit 8 produces a request to start the voice recognition function. The request here consists of transmitting the resulting signal Sr to the remote servers via the Internet.

[0067] The processing unit 8 first checks whether the television 2 is compatible with the CEC protocol (for Consumer Electronic Control).

[0068] The CEC protocol works as follows.

[0069] The CEC protocol exchanges, on a bus connected to all the HDMI ports of the television 2 (including HDMI 5 port), a CEC signal. The CEC signal is a low-bit-rate bidirectional signal (1Kbps) that is common to all equipment connected to the TV 2.

[0070] The architecture of the CEC signal is relatively simple and is broken down as follows:

[0071] - a start sequence;

[0072] - a header block in which the source and destination addresses are data ;

[0073] - a data block 1 which contains an opcode (Y opcode, which can be translated as “code operation”, specifies the operation to be performed);

[0074] - a data block 2 which contains an operand and which is optional depending on 1' opcode sent (the operand is the element on which the operation is applied).

[0075] The header block, data block 1 and data block 2 are all three coded on 10 bits, including 8 useful bits, 1 EOM bit (for End Of Message) and 1 acknowledgment bit.

[0076] As soon as a new device, compatible with the CEC protocol, is connected in the HDMI chain, a physical address is assigned to it according to its rank in relation to television 2.

[0077] Once the physical address is assigned, the device will launch a logical address allocation sequence. Its logical address is assigned in priority according to the role of the device in the HDMI chain (amplifier, tuner, recorder, etc.). The association between the physical address and the logical address of the device is broadcast throughout the CEC chain via the opcode < Report Physical Address >.

[0078] There are a large number of opcodes defined in the standard, some of which can determine the status of equipment on the CEC chain, such as the “Report Power Status” and “Request Active Source” opcodes.

[0079] If the television 2 is compatible with the CEC protocol, the processing unit 8 therefore uses the CEC protocol to check that the television 2 is switched on and that the decoder box 1 is indeed the active HDMI source of the television 2, and, if necessary, to produce the first command and the second command.

[0080] With reference to [Fig.3], if the television 2 is compatible with the CEC protocol, the method begins with a starting step E0. The processing unit 8 checks, via a first CEC request, whether the following combined condition is met: the television 2 is switched on and the active HDMI source of the television 2 is the set-top box 1 (step E1).

[0081] If this is the case, no further action is necessary. The processing unit 8 considers that the HDMI port 5 of the television set 2, connected to the HDMI port 4 of the set-top box 1, is activated (i.e., the set-top box 1 is the active HDMI source): step E2. The set-top box 1 then issues the request to start the voice recognition function (i.e., transmits the resulting signal Sr to the remote servers): step E3.

[0082] If this is not the case, the processing unit 8 produces a second CEC request (step E4) to obtain the status of the television 2 (step E5).

[0083] If the television 2 is in standby, the processing unit 8 produces a first command, via a third CEC request, to take the television 2 out of the standby state (step E6).

[0084] In step E5, if the television 2 is switched on, the processing unit 8 considers that the active HDMI source of the television 2 is not the decoder box 1.

[0085] Following step E5 or step E6, the processing unit 8 produces a second command, via a fourth CEC request, to activate the HDMI port 5 and therefore for the decoder box 1 to become the active HDMI source of the television 2: step E7.

[0086] The decoder box 1 then sends the request to start the voice recognition function: step E3.

[0087] However, not all televisions are compatible with the CEC protocol. If the television 2 does not support the CEC function, the processing unit 8 of the set-top box 1 will have to use a two-part detection method, first determining whether the television 2 is switched on, and then checking what its active source is.

[0088] With reference to [Fig.4], the processing unit 8 therefore implements an alternative method using an HPD signal (for Hot Plug Detection), then an RXSense signal belonging to the TMDS signals (for Transition Minimized Differential Signaling) and / or a signal generated by an HDCP protocol (for High-bandwidth Digital Content Protection). The method begins with a starting step E100.

[0089] The processing unit 8 first reads the state of the HPD signal (step E101). If it is in a low state (typically 0V), the processing unit 8 deduces that the television 12 is off or on standby (step E102).

[0090] If the latter is in a high state (typically 5V), the processing unit 8 reads the state of the RXSense signal and the state of the signal generated by the HDCP protocol (step E103).

[0091] The state of the RXSense signal makes it possible to detect whether the decoder box 1 sends a video signal and / or an audio signal to the television 2 and therefore whether the decoder box 1 is the active HDMI source of the television 2.

[0092] HDCP is an encryption method for protecting audio / video content transmitted via HDMI between a source (here the decoder box 1) and a receiver (here the television set 2). Once authentication has been established via an encryption key exchange, a Link Integrity Check request is sent every second at the initiative of the television set 2 and must be acknowledged by the decoder box 1. This request makes it possible to verify that encryption synchronization is maintained between the decoder box 1 and the television set 2. Thus, the content sent by the decoder box 1 can be viewed on the television set 2.

[0093] When TV 2 is put into standby mode, it will no longer send a Link Integrity Check request. The absence of this request therefore makes it possible to determine that TV 2 is in standby mode.

[0094] The signal generated by the HDCP protocol, and used here, is therefore the Link Integrity Check request.

[0095] The HDCP negotiation protocol is illustrated in [Fig.5].

[0096] At step E200, the television 2 is not powered (off) and the HDCP is inactive. Then, TV 2 is powered on, and the protocol proceeds to step E201. HDCP is not authenticated. The protocol proceeds to step E202, and waits for authentication from set-top box 1. At step E203, set-top box 1 is ready. At step E204, the link has failed, and the protocol returns to step E201. At step E205, the link does not fail, and the link is authenticated. The protocol proceeds to step E206, during which encryption is added to the stream, so HDCP is active—until TV 2 is turned off.

[0097] Thus, returning to [Fig.4], in step E103, if the state of the RxSense signal and if the state of the signal generated by the HDCP protocol are inactive, the processing unit 8 deduces that the television 2 is off or on standby (step E102). On the contrary, if the state of the RxSense signal and if the state of the signal generated by the HDCP protocol are active, the processing unit 8 deduces that the television is on (step E104).

[0098] Note that here we use both the RXSense signal and the signal generated by the HDCP protocol to detect whether the television 2 is on, which makes it possible to confirm the result of the detection (and therefore to robustify it). This is not mandatory, however, and only one of these two signals could be used.

[0099] The steps just described make it possible to determine whether the television 2 is on or off, but do not make it possible to know which source is being played back by the television 2. Indeed, the televisions leave the TMDS signals as well as the HDCP activated even if another input is displayed. This is intended to switch instantly from one input to another without going through the long authentication phases.

[0100] Thus, following step E104, it is necessary to determine whether or not the decoder box 1 is the active HDMI source of the television 2.

[0101] For this, the processing unit 8 uses the echo cancellation module 16 which was described previously.

[0102] The processing unit 8 transmits on the HDMI port 4 an emitted audio signal Sae integrating a test signal St, and transmits the emitted audio signal Sae to the television 2 via the HDMI port 4, the HDMI cable 3 and the HDMI port 5 (step E105). This means that, if the decoder box 1 is already transmitting an emitted audio signal Sae (i.e. for example an audio signal associated with a video signal and coming from a TS stream), the processing unit 8 introduces the test signal St into said audio signal emitted Sae. Otherwise, the processing unit 8 sends an emitted audio signal Sae comprising only the test signal St. Advantageously, the test signal St is not audible to a human being.

[0103] The processing unit 8 then acquires the received audio signal Sar produced by the microphones 7 of the decoder box 1.

[0104] The processing unit 8 then determines whether the resulting signal Sr, which is representative of a difference between the received audio signal Sar and the transmitted audio signal Sae, is lower than a predetermined threshold (static threshold): step E106. If this is the case, the processing unit 8 deduces that the HDMI port 5 of the television set 2 is activated and that the decoder box 1 is indeed the active HDMI source of the television set 2 (step E107). The processing unit 8 produces a request to start the voice recognition function (step E108).

[0105] On the contrary, if this is not the case, the processing unit 8 deduces that the HDMI port 5 is not activated and that the decoder box 1 is not the active HDMI source of the television 2 (step E109).

[0106] Following step E102, that is to say if the television 2 is not switched on, the processing unit 8 produces the first command and transmits it to a remote control 18 of the decoder box 1 (step E110) so that the latter produces a first secondary command to switch on the television 2 (step E104). The remote control 18 is visible in [Fig.l].

[0107] Similarly, following step E109, if the decoder box 1 is not the active HDMI source of the television set 2, the processing unit 8 produces the second command and transmits it to the remote control 18 so that the latter produces a second secondary command so that the decoder box 1 becomes the active HDMI source of the television set 2 (step E111).

[0108] The remote control 18 comprises a radio frequency communication module 20 and an infrared communication module 21. The decoder box 1 comprises a radio frequency communication module 22. The television 2 comprises an infrared communication module 23.

[0109] The decoder box 1 and the remote control 18 can therefore communicate via the radio frequency communication modules 20, 22. The radio frequency link is a bidirectional Bluetooth BLE (for Bluetooth Low Energy) link. The communication between the decoder box 1 and the remote control 18 will be carried out according to the GATT method (for Generic Attribute Profile).

[0110] It is noted that other bidirectional protocols are possible for communicating the decoder box 1 and the remote control 18, such as for example ZigBee (RF4CE profile).

[0111] The processing unit 8 first acquires, depending on whether the method is at step E102 or E109, a first infrared code or a second infrared code, the first infrared code being used by the remote control 18 to produce the first secondary command and the second infrared code being used by the remote control 18 to produce the second secondary command.

[0112] To acquire the first infrared code and the second infrared code, the decoder box 1 accesses an EDID (for Extended Display Identification Data) of the television 2.

[0113] The EDID is a table stored in each HDMI television, containing its identification as well as the list of all supported video and audio formats. This table must be read and then stored in the decoder box 1 each time the television 2 and / or the decoder box 1 comes out of standby. The EDID makes it possible in particular to know the manufacturer and model of the television 2, and therefore to deduce (via a correspondence table) the infrared codes to use. Most often, knowledge of the television manufacturer is sufficient to determine the appropriate infrared code.

[0114] Alternatively, to know the infrared codes, the processing unit 8 could acquire identification information of the television 2 provided by a user via a configuration menu of the decoder box 1, or could acquire identification information of the television 2 provided by the user via a configuration procedure carried out with the remote control 18.

[0115] The processing unit 8 of the decoder box therefore uses the remote control 18, normally dedicated to controlling the decoder box 1, to act on the television 2 so as to turn it on or activate the HDMI port 5.

[0116] Thus, in step E110, the processing unit 8 sends the first command, which is a proprietary command, to the remote control 18 using the Bluetooth BLE link. The remote control 18 uses the first infrared code to produce the first secondary command which turns on the television 2. The method then proceeds to step E104.

[0117] Similarly, in step E111, the processing unit 8 sends the second command, which is a proprietary command, to the remote control 18 using the Bluetooth BLE link. The remote control 18 uses the second infrared code to produce the second secondary command, by which the set-top box 1 becomes the active HDMI source of the television 2. The method then proceeds to step E108.

[0118] It is noted that, following the waking up of the television 2, the decoder box 1 could either activate the voice recognition function and send the voice intention to the remote servers, or re-detect the state of the television 2 before possibly activating the voice recognition function.

[0119] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the re- sales.

[0120] It has been described here that the speech recognition function is only partially implemented in the set-top box. However, the set-top box could fully implement the speech recognition function; in this case, the resulting signal is not transmitted to remote servers.

[0121] The request to start the voice recognition function therefore does not necessarily consist of transmitting the resulting signal, but could be of a different nature, for example a simple activation command.

Claims

Claims

1. A detection method, implemented in a set-top box (1) comprising an HDMI port (4) connected via an HDMI cable (3) to a television (2), the detection method being carried out prior to the implementation of a voice recognition function on a voice signal (Sv) spoken by a user and captured by the set-top box, the detection method comprising the steps of: - checking that the television (2) is switched on and, if not, producing a first command to switch on the television; - checking that the set-top box (1) is an active HDMI source of the television and, if not, producing a second command for the set-top box to become the active HDMI source of the television; - when the television is switched on and the set-top box is the active HDMI source of the television, producing a request to start the voice recognition function.

2. A detection method according to claim 1, further comprising the steps of verifying that the television (2) is compatible with a CEC protocol and, if so, using the CEC protocol to verify that the television is switched on and that the set-top box is the active HDMI source of the television, and, if necessary, to produce the first command and / or the second command.

3. Detection method according to one of the preceding claims, comprising the step, to verify that the television (2) is switched on, of using an HPD signal, then an RXSense signal and / or a signal generated by an HDCP protocol.

4. Detection method according to one of the preceding claims, comprising the steps, to verify that the decoder box (1) is the active HDMI source of the television (1), of: - transmitting via the HDMI port (4) an emitted audio signal (Sae) comprising a test signal (St); - acquiring a received audio signal (Sar) produced by one or more microphones (7) of the decoder box; - determining whether a resulting signal (Sr), representative of a difference between the received audio signal (Sar) and the emitted audio signal (Sae), is less than a predetermined threshold; - if this is the case, deducing therefrom that the decoder box is indeed the source Active HDMI on the TV.

5. Detection method according to claim 4, the decoder box integrating an echo cancellation module (16), the resulting signal (Sr) being an output signal of the echo cancellation module (16).

6. A detection method according to one of the preceding claims, wherein, if the television is not switched on and / or if the set-top box is not the active HDMI source of the television, the first command and / or the second command are transmitted to a remote control (18) of the set-top box so that the latter produces a first secondary command to switch on the television and / or a second secondary command to make the set-top box the active HDMI source of the television.

7. A detection method according to claim 6, wherein the remote control (18) is arranged to control the television (2) via an infrared link, the detection method further comprising the steps of acquiring a first infrared code and / or a second infrared code and transmitting to the remote control the first infrared code and / or the second infrared code, the first infrared code being used by the remote control to produce the first secondary command and the second infrared code being used by the remote control to produce the second secondary command.

8. The detection method of claim 7, wherein acquiring the first infrared code and / or the second infrared code involves accessing an EDID of the television, or acquiring identification information of the television provided by a user via a setup menu of the set-top box, or acquiring identification information of the television provided by the user via a setup procedure performed with the remote control.

9. Set-top box comprising an HDMI port (4), at least one microphone (7), and a processing unit (8) arranged to implement the detection method according to one of the preceding claims.

10. Computer program comprising instructions which cause the processing unit of the set-top box according to claim 9 to execute the steps of the detection method according to one of claims 1 to 8.

11. A computer-readable recording medium on which the computer program according to claim 10 is recorded.

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