Real-time optimized audio playback
Patent Information
- Application Number
- FR2022013266
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-12-13
- Publication Date
- 2025-02-14
- Estimated Expiration
- Not applicable · inactive patent
Smart Images
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Abstract
Description
Title of the invention: Real-time optimized audio reproduction
[0001] The invention relates to the field of audio reproduction systems.
[0002] BACKGROUND OF THE INVENTION
[0003] Many devices today are equipped with loudspeakers and offer excellent quality audio reproduction.
[0004] Among this equipment, we find of course speakers (notably connected speakers, or smart speakers), sound bars, televisions, voice assistants, smartphones, etc. We now also find improved decoder boxes (or STB, for Set-Top Box) equipped with speakers.
[0005] When a user has several recent audio reproduction devices, he can generally configure them to form a multi-channel system.
[0006] To further improve the user experience, we seek to optimize the quality of the audio reproduction depending on the position of the user in the room in which the audio reproduction equipment is located.
[0007] A system is thus known which implements a calibration phase consisting of positioning a microphone in a reference position, then controlling the audio reproduction equipment so that it produces a test sound signal, which is captured by the microphone. The result of the capture is used to adjust the audio parameters (delay and equalization) of each audio reproduction equipment.
[0008] This system has the following drawback. The audio parameters allow the audio reproduction to be optimized in the reference position only, and it is therefore necessary to repeat the calibration phase each time the user moves.
[0009] A system is also known which comprises a plurality of speakers, each equipped with a microphone. This system carries out the following calibration phase. The user positions himself in a reference position. He then pronounces a keyword which is captured by the microphone of each speaker, which makes it possible to determine the distances between the different speakers and the user. The audio parameters make it possible to optimize the audio reproduction in the reference position. However, again, in this system, the calibration phase must be repeated each time the user moves.
[0010] SUBJECT OF THE INVENTION
[0011] The object of the invention is, in a room in which one or more sound sources are positioned, to optimize the audio reproduction according to the current position of a user, without repeating a calibration phase. Summary of the invention
[0012] With a view to achieving this goal, an audio restitution method is proposed, implemented by one or more master devices, and comprising a preliminary phase including the steps of:
[0013] - create a map of a room in which one or more sound sources are located, which includes a position of each sound source and a position of the walls of the room;
[0014] - acquire acoustic characteristics of walls;
[0015] - carry out a simulation, using the map and the acoustic characteristics of the walls, to simulate a propagation in the room of sounds emitted by sound sources;
[0016] - from simulation results, produce, for each reference position of a plurality of reference positions defined in the room, and for each sound source, reference audio parameters making it possible to optimize an audio reproduction of said sound source in said reference position;
[0017] the audio restitution method further comprising an operational phase comprising the steps, carried out in real time, of:
[0018] - determining a current position of a user in the room;
[0019] - have an audio signal reproduced by the sound sources by applying parameters current audio settings obtained from the reference audio parameters and which depend on the current position.
[0020] The simulation, carried out during the preliminary phase, therefore makes it possible to obtain reference audio parameters associated with reference positions which can be distributed throughout the room.
[0021] During the operational phase, the master equipment determines the current position of the user and causes the sound sources to apply current audio parameters, which depend on the current position and which are obtained from the reference audio parameters.
[0022] The audio reproduction is therefore optimized in real time, whatever the position of the user in the room, without it being necessary to repeat the preliminary phase (unless the position of the sound sources and / or the materials of the walls are significantly modified).
[0023] We further propose an audio reproduction method as previously described, in which the simulation uses a ray tracing technique.
[0024] We further propose an audio reproduction method as previously described, in which the acoustic characteristics of the walls comprise, for each wall, values for different frequencies of an absorption coefficient of a material of the wall or of a category of materials including said material.
[0025] We further propose an audio reproduction method as previously described, in which the reference audio parameters comprise, for each reference position and for each sound source, gain and phase shift values for dif- different frequencies, associated with the said sound source.
[0026] We further propose an audio reproduction method as previously described, in which the reference positions of the plurality of reference positions are nodes of a mesh having a mesh of predefined length.
[0027] We further propose an audio restitution method as previously described, in which, during the operational phase, the current audio parameters which are applied are the reference audio parameters of a node closest to the current position.
[0028] We further propose an audio restitution method as previously described, in which, during the operational phase, the current audio parameters which are applied are obtained by averaging reference audio parameters of several nodes closest to the current position.
[0029] We further propose an audio reproduction method as previously described, in which at least one of the master devices comprises a first UWB module, and in which the production of the map and / or the detection of the current position of the user are implemented using the first UWB module.
[0030] We further propose an audio restitution method as previously described, in which the preliminary phase comprises the steps, for determining the position of the walls, of:
[0031] - send a first message to the user to ask him to take a route along the walls as close as possible to them;
[0032] - determine the real-time position of the user when the latter performs said route, and determine the position of the walls from this position in real time.
[0033] We further propose an audio reproduction method as previously described, in which the user is equipped when he makes said journey with mobile equipment comprising a second UWB module, the determination of the real-time position of the user being carried out by a UWB geolocation technique using the first UWB module and the second UWB module.
[0034] We further propose an audio reproduction method as previously described, in which, during the operational phase, the user is provided with mobile equipment comprising a second UWB module, the determination of the current position of the user being carried out by a UWB geolocation technique carried out using the first UWB module and the second UWB module.
[0035] We further propose an audio reproduction method as previously described, in which the first UWB module is arranged to implement a UWB radar technology, the determination of the position of the walls of the room being carried out by the master equipment using said UWB radar technology.
[0036] We further propose an audio restitution method as previously described, in which the user, during the preliminary phase, is provided with mobile equipment comprising a second UWB module, the preliminary phase comprising the step, for at least one sound source, of transmitting a second message to the user to request the latter to position the mobile equipment in the immediate vicinity of the sound source, the position of said sound source then being assimilated to the position of the mobile equipment, which is determined by a UWB geolocation technique using the first UWB module and the second UWB module.
[0037] We further propose an audio reproduction method as previously described, in which at least one sound source comprises a UWB tag, the master equipment being arranged to determine the position of said sound source using a UWB geolocation technique carried out using the first UWB module and the UWB tag.
[0038] We further propose a master device comprising a first UWB module arranged to carry out geolocation, and a processing unit arranged to implement the audio reproduction method as previously described.
[0039] We further propose a master device as previously described, the master device being a decoder box.
[0040] A computer program is further provided comprising instructions which cause the processing unit of the master equipment as previously described to execute the steps of the audio reproduction method as previously described.
[0041] A computer-readable recording medium is further provided, on which the computer program as previously described is recorded.
[0042] The invention will be better understood in light of the following description of particular non-limiting embodiments of the invention. Brief description of the drawings
[0043] Reference will be made to the attached drawings, among which:
[0044] [Fig-1] [Fig.l] represents a room seen from above, in which are positioned a set-top box, a television and two speakers;
[0045] [Fig.2] [Fig.2] represents a decoder box in which the invention is implemented;
[0046] [Fig.3] [Fig.3] illustrates the ray tracing technique and represents the sound rays between a source and a reference position (a single ray in this case), without reflection on the walls;
[0047] [Fig.4] [Fig.4] is a figure similar to [Fig.3], with a reflection on the walls;
[0048] [Fig.5] [Fig.5] is a figure similar to [Fig.3], with two reflections on the walls;
[0049] [Fig.6] [Fig.6] is a figure similar to [Fig.3], with three reflections on the walls;
[0050] [Fig.7] [Fig.7] represents a map produced during the mapping stage, on which is also represented by a virtual listener;
[0051] [Fig.8] [Fig.8] represents results of the ray tracing simulation;
[0052] [Fig.9] [Fig.9] is a figure similar to [Fig.8], obtained by taking into account the directivity of the sound source enclosure;
[0053] [Fig. 10] [Fig. 10] illustrates the transmission of current audio parameters from the decoder box to the sound sources, and the restitution of an audio signal. DETAILED DESCRIPTION OF THE INVENTION
[0054] With reference to [Fig.l], a decoder box 1, a television 2 and two speakers 3a, 3b are located in a room.
[0055] The decoder box 1 is connected to the television 2, for example by an HD MI (High-Definition Multimedia Interface) type cable.
[0056] With reference to [Fig. 2], the decoder box 1 comprises components 4 conventionally present in a decoder box 1, and in particular components arranged to acquire an audio-video stream coming from any source (satellite television network, Internet connection, Blu-ray player, etc.) and comprising an audio signal and a video signal, and to process and transmit to the equipment to which it is connected (here the television 2 and the speakers 3a, 3b) the audio signal and the video signal for their reproduction.
[0057] The decoder box 1 further comprises two loudspeakers 5, as well as an audio module 6 arranged to acquire, process, amplify audio signals, and transmit them to the loudspeakers 5.
[0058] The decoder box 1 also comprises a processing unit 7. The processing unit 7 comprises at least one processing component 8 (electronic and / or software), which is for example a “generalist” 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 unit 7 also comprises one or more memories 9 (and in particular one or more non-volatile memories), connected to or integrated in the processing component 8. At least one of these memories 9 forms a computer-readable recording medium, on which is recorded at least one computer program comprising instructions which cause the processing component 8 to execute at least some of the steps of the audio reproduction method which will be described below.
[0059] The decoder box 1 further comprises a first UWB module 10 (for Ultra Wide Band), which comprises a UWB communication component 11, a set of at least one UWB antenna 12 and a microcontroller 13. The microcontroller 13 is connected to the processing unit 7 (via a serial link for example). The microcontroller 13 communicates with the UWB communication component 11 and with the processing unit 7.
[0060] The assembly of at least one UWB antenna 12 here comprises two UWB antennas which are connected to the UWB communication component 11.
[0061] The first UWB module 10 can thus measure not only the distance between an external device which itself transmits and receives UWB signals, but also the angle of arrival of the UWB signals transmitted by said external device.
[0062] The microcontroller 13 in particular provides the processing unit 7 with location information produced by the first UWB module 10.
[0063] The audio reproduction method is implemented by one or more master devices. Here, and in a non-limiting manner, the audio reproduction method is implemented entirely by the processing unit 7 of the decoder box 1 (which is therefore the master device).
[0064] The room in which the system just described is located belongs to the home of a user 20.
[0065] The user 20 is equipped with mobile equipment 21, a smartphone in this case, which integrates a second UWB module 22. The second UWB module 22 comprises a UWB communication component 23, a set of at least one UWB antenna 24 and a microcontroller 25.
[0066] The aim of the audio reproduction method is to optimize the audio reproduction carried out by the decoder box 1 and the speakers 3a, 3b depending on the position of the user 20 in the room.
[0067] The audio restitution method comprises a preliminary phase and an operational phase.
[0068] The preliminary phase can be likened to a calibration phase.
[0069] The operational phase, for its part, corresponds to the normal, usual use of its equipment by the user 20. When the user 20 moves around the room and listens to audio content, the audio reproduction method optimizes the acoustic experience of the user 20 in real time, depending on its position (and whatever it may be).
[0070] The preliminary phase firstly comprises a mapping step, which consists of producing a map of the room. This map comprises at least the position of each sound source, i.e. in this case the decoder box 1 and the two speakers 3a, 3b, and a position of the walls 26 of the room.
[0071] Here, by "walls" we mean all the elements of the room which extend vertically and which delimit the surface of the room: walls, windows, bay windows, furniture (such as cupboards), etc.
[0072] A first embodiment of this mapping step is described.
[0073] To determine the position of the walls 26, the processing unit 7 of the decoder box 1 firstly sends a first message to the user 20 to ask the latter to take a route along the walls 26 as close as possible to them.
[0074] The processing unit 7 determines the real-time position of the user 20 when the latter performs said route (more precisely the position of the smartphone 21), and thus determines the position of the walls 26 in the room from this real-time position. The processing unit 7 therefore assimilates the path taken by the user 20 to the base of the walls 26.
[0075] The determination of the real-time position of the user 20 is carried out by a UWB geolocation technique using the first UWB module 10 (of the decoder box 1) and the second UWB module 22 (of the smartphone 21). As seen earlier, the first UWB module 10 precisely locates the smartphone 21 from UWB signals emitted by it.
[0076] To determine the position of each sound source, the processing unit 7 sends a second message to the user 20 to ask the user to position the smartphone 21 in the immediate vicinity of the sound source. For example, the user places the smartphone 21 on or against the sound source, or positions himself right next to the sound source. The position of said sound source is then assimilated to the position of the smartphone 21, which is determined by a UWB geolocation technique using the first UWB module 10 and the second UWB module 22.
[0077] Of course, here, this only concerns the speakers 3a, 3b because the position of the decoder box 1 (as a sound source) is known.
[0078] The processing unit 7 then acquires acoustic characteristics of the walls 26.
[0079] The acoustic characteristics of the walls 26 comprise, for each wall 26, values for different frequencies of an absorption coefficient of a material of the wall 26. By "a material of the wall" is meant either a material with which the wall is made, or a material of a covering covering the internal wall (room side) of the wall, or a material of any element positioned on or against the wall (a hanging for example).
[0080] The user uses for example an application loaded in his smartphone 21 to provide the type of material of the walls 26 of the room (concrete, glass, curtain, parquet, carpet, etc.). This information is transmitted to the processing unit 7 via any communication channel between the smartphone 21 and the decoder box 1 (e.g. Wi-Fi, Bluetooth, etc.).
[0081] The processing unit 7 uses a table 27 stored in one of the memories 9 (non-volatile). The table 27 associates with each material an absorption coefficient for each frequency.
[0082] Alternatively, it is possible to provide several general categories, each of which groups together a plurality of materials. Then, for a given wall 26, either the user 20 enters the material and the processing unit 7 deduces a general category to which said material belongs, or the user 20 directly enters the general category to which said material belongs.
[0083] An example of table 27 is given below. This table 27 associates, for each general category of materials and for several frequencies, an absorption coefficient associated with said general category and said frequency. Sound absorption coefficient of the material General category of materials 125Hz 250Hz 500Hz 1kHz 2kHz 4kHz Untreated glass - floor / wall 0.10 0.10 0.10 0.10 0.10 0.10 Curtains - curtains - carpet 0.10 0.20 0.40 0.50 0.65 0.60 Absorbent treatment 0.20 0.55 0.60 0.70 0.80 0.90
[0084] We therefore have three general categories of materials here: windows - untreated floor / wall; curtains - drapes - carpet; absorbent treatment.
[0085] The processing unit 7 then carries out a simulation, using the map and the acoustic characteristics of the walls 26, to simulate a propagation in the room of sounds emitted by the sound sources
[0086] The simulation uses a ray tracing technique. This technique makes it possible to define the acoustic impact of the room on the acoustic propagation of sound waves generated by the sound sources: decoder box 1 and speakers 3a, 3b.
[0087] First, the principle of the ray tracing technique is described. This technique consists of shooting rays from a sound source towards the measurement point, taking into account the paths with the reflections on the walls, and summing the contributions of each ray.
[0088] This simulation therefore reproduces, for each reference position of a plurality of reference positions, the path of the sound rays between each sound source and said reference position, taking into account the reflections on the walls and the ceiling.
[0089] The simulation takes into account each reflection on the walls 26 by evaluating the level Nr of the reflected sound wave, as a function of the level Ni of the incident sound wave and of the absorption coefficient of the wall 26 against which the wave is reflected, as follows:
[0090] Nr = Ni xa
[0091] where a is the absorption coefficient of the wall material (between 0 and 1).
[0092] For example, in the case of carpet, at 1 kHz, aa = 0.5. The reflected sound wave level is then equal to the level of the incident sound wave divided by 2 (i.e. an attenuation of 6 dB).
[0093] [Fig.3] shows a direct sound beam (without reflection on the walls 26) between a sound source 29 and a reference position 30.
[0094] In [Fig.4] we see the sound rays with a reflection on the walls 26.
[0095] In [Fig.5] we see the sound rays with two reflections on the walls 26.
[0096] In [Fig.6] we see the sound rays with three reflections on the walls 26.
[0097] These simulations are carried out for each sound source in the room, for each reference position, and for a plurality of frequencies.
[0098] Calculating ray tracing is equivalent to positioning an ambient microphone via its physical measurement. All necessary data is calculated, as for a microphone calibration. All attenuation data of the listening point in relation to the different speakers is thus calculated. Data for immersive sound processing is calculated to compensate for distances and reflections.
[0099] From the results of the simulation, the processing unit 7 produces, for each reference position of the plurality of reference positions, and for each sound source, reference audio parameters making it possible to optimize an audio reproduction of said sound source in said reference position.
[0100] The reference audio parameters comprise, for each reference position and for each sound source, gain and phase shift values for different frequencies, associated with said sound source.
[0101] The reference positions of the plurality of reference positions are here nodes of a mesh having a mesh of predefined length.
[0102] With reference to [Fig.7], a map 31 was produced by the decoder box 1. The decoder box 1 and the speakers 3a, 3b (omnidirectional speakers) are located in a parallelepiped living room of 6 mx 10 m.
[0103] We can therefore see on this map 31 the position of the sound sources 1, 3a, 3b and the walls 26.
[0104] The mesh 32 is defined on this map 31. The mesh is for example equal to 1m.
[0105] We also see in [Fig.7] a virtual listener 33 which, of course, does not actually appear on the map 31. The virtual listener is positioned on one of the nodes 34 of the mesh 32.
[0106] We are interested in the simulation of the sounds emitted by the speaker 3a.
[0107] The enclosure 3a is positioned on one of the nodes of the mesh.
[0108] The reference positions correspond to the nodes of the mesh.
[0109] The delay r of the sound signal emitted by the speaker 3a is directly linked to the distance between speaker 3a and virtual listener 33:
[0110] r = [(Xlistener - Xspeaker) + (Ylistener Yspeaker)] / G,
[0111] where (Xlistener; Ylistener) and (Xspeaker; Yspeaker) are the coordinates of the virtual listener 33 and the speaker 3a in a frame of reference defined by the OX and OY axes and associated with the map, and where c is the speed of the sound.
[0112] For example, we consider that the two longest side walls (N and S) are not acoustically treated, so that they have an average absorption coefficient a equal to 0.1 at 1 kHz (see table above).
[0113] For example, we consider that the other two walls (O and E) are covered with curtains, so that they have an average absorption coefficient a equal to 0.5 at 1 kHz (see table above).
[0114] The results of the ray tracing simulation, visible in [Fig.8], give, for a given frequency, an amplification of the sound level at the level of the virtual listener 33 of +10.1 dB compared to the free-field signal.
[0115] This amplification must be compensated, at the given frequency (here 1 kHz), by a gain value of -10.1 dB. This gain value is one of the reference audio parameters associated with the given frequency and the reference position in the room corresponding to the position of the virtual listener 33.
[0116] This calculation is therefore carried out for each of the nodes 34 of the mesh, frequency by frequency.
[0117] In order to improve the accuracy, this calculation can be refined by integrating the directivity of the sound source enclosure according to the frequencies. The results of this new simulation are visible in [Fig.9].
[0118] In the previous example, if we remove the rays beyond + / - 60° from the axis of the speaker 3a, the effect of the room at the level of the virtual listener would be reduced to +6.9 dB (instead of +10.1 dB without taking into account the directivity).
[0119] The simulation makes it possible to obtain, for each reference position, that is to say for each node 34 of the grid 32, and for each sound source, a transfer function defining a gain (function of the frequency) and a phase shift (function of the frequency).
[0120] We therefore have, for each reference position (x, y): - a transfer function Fl (x, y) for the first sound source; - a transfer function F2 (x, y) for sound source number 2; - Etc.
[0121] It is noted that a loudspeaker is considered to form a sound source. Consequently, multi-way speakers comprising a plurality of loudspeakers are considered to be as many sound sources positioned in the same place (and possibly with the same orientation).
[0122] The reference audio parameters are recorded in one of the memories 9 (non-volatile) of the processing unit 7.
[0123] Once the preliminary phase has been completed, the operational phase can begin.
[0124] It lasts until a possible following preliminary phase, which is implemented only in the event of a significant displacement of one or more sound sources, or in the event of a significant change in the material of a wall in the room.
[0125] During the operational phase, the processing unit 7 of the decoder box 1 determines in real time the current position of the user 20 in the room when the latter listens to an audio signal reproduced by the decoder box 1 and the speakers 3a, 3b.
[0126] The determination of the current position of the user 20 is carried out by a UWB geolocation technique carried out using the first UWB module 10 and the second UWB module 22.
[0127] The processing unit 7 then causes the audio signal to be restored by the sound sources by applying current audio parameters obtained from the reference audio parameters and which depend on the current position.
[0128] In a first embodiment, the current audio parameters that are applied are the reference audio parameters of a node 34 closest to the current position of the user 20.
[0129] In a second embodiment, the current audio parameters that are applied are obtained by averaging reference audio parameters of several nodes 34 closest to the current position of the user 20. The averaging makes it possible to avoid transitions that are too abrupt when the user 20 moves.
[0130] With reference to [Fig. 10], the processing unit 7 of the decoder box 1 transmits in real time the current audio parameters (Fl (x, y), F2 (x, y), etc.), associated with the current position of the user 20, to the audio module 6 of the decoder box 1 and to the audio module 35 of each speaker 3 a, 3b.
[0131] The audio module 6, 35 of each sound source acquires the current audio parameters which are assigned to said sound source, performs processing to apply said current audio parameters, and restores the audio signal. The processing unit 7 therefore controls the sound sources so that they restore the audio signal by applying the current audio parameters.
[0132] Thus the acoustic delays and phases are taken into account by taking into account the acoustic nature of the room.
[0133] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.
[0134] Architectures for the set-top box and for the smartphone have been described, which are of course not limiting. The UWB modules could comprise components different from those described here. In the set-top box, the microcontroller and / or the UWB communication component of the first UWB module could for example be integrated into the processing unit.
[0135] Determining the position of the walls, used to produce the room map, could be done in a different way. For example, if the user's smartphone (or any other mobile device) includes a LiDAR (Light Detection And Ranging) sensor, it is possible to use it to produce a more accurate and faster 3D map of the room.
[0136] UWB radar technology can also be used to create a room map. The set-top box can therefore integrate a UWB radar. The UWB radar positions echoes in the room in polar coordinates. The echoes are then analyzed to create a model of the room and to define the position of the walls, the angles between them, etc.
[0137] Also, the radar method also makes it possible to analyze the movement of a person, who can, as previously, move around the room, in synchronization with his smartphone (or other mobile equipment) and the specific application in order to carry out the calibration part of the room (travel of the perimeter of the room, position of the sound sources). Via the smartphone application, the reflection data of the surfaces can also be entered, to return to the calibration of the room described above.
[0138] In the operational phase, the current position of the user could also be determined by the set-top box using UWB radar technology.
[0139] Similarly, the determination of the position of the sound sources could be carried out in a different way. A speaker could for example be provided with a UWB tag (or UWB label). The decoder box can then determine the position of said sound source using a UWB geolocation technique carried out using the first UWB module and the UWB tag.
[0140] It has been described that the invention is implemented in a master equipment which is the decoder box.
[0141] The invention could be implemented in other master equipment, for example in a connected speaker, or in the user's smartphone.
[0142] The invention can be perfectly implemented in a single master equipment, as is also described here, in particular when the processing unit integrates a processing component powerful enough to carry out the simulation (DSP type).
[0143] It is however possible to implement the invention in several master devices. Thus, for example, the decoder box could carry out the mapping step (alone or by cooperating with other devices, such as a smartphone, as described here), and transmit the map or its constituent elements to a cloud server on which the simulation is carried out. The decoder box then recovers the reference audio parameters and controls the operational phase.
Claims
Claims
1. Audio reproduction method, implemented by one or more master devices (1), and comprising a preliminary phase comprising the steps of: - producing a map (31) of a room in which one or more sound sources (1, 3a, 3b) are located, which comprises a position of each sound source and a position of walls (26) of the room; - acquiring acoustic characteristics of the walls; - carrying out a simulation, using the map and the acoustic characteristics of the walls, to simulate a propagation in the room of sounds emitted by the sound sources; - from results of the simulation, producing, for each reference position (34) of a plurality of reference positions defined in the room, and for each sound source, reference audio parameters making it possible to optimize an audio reproduction of said sound source in said reference position;the audio reproduction method further comprising an operational phase comprising the steps, carried out in real time, of: - determining a current position of a user (20) in the room; - having an audio signal reproduced by the sound sources by applying current audio parameters obtained from the reference audio parameters and which depend on the current position.;
2. The audio rendering method of claim 1, wherein the simulation uses a ray tracing technique.
3. Audio reproduction method according to one of the preceding claims, in which the acoustic characteristics of the walls (26) comprise, for each wall, values for different frequencies of an absorption coefficient of a material of the wall or of a category of materials including said material.
4. Audio reproduction method according to one of the preceding claims, in which the reference audio parameters comprise, for each reference position and for each sound source (1, 3a, 3b), gain and phase shift values for different frequencies, associated with said sound source.
5. An audio reproduction method according to one of the preceding claims, wherein the reference positions of the plurality of reference positions are nodes (34) of a mesh (32) having a mesh of predefined length.
6. Audio rendering method according to claim 5, wherein, during the operational phase, the current audio parameters which are applied are the reference audio parameters of a node (34) closest to the current position.
7. Audio rendering method according to claim 5, wherein, during the operational phase, the current audio parameters which are applied are obtained by averaging reference audio parameters of several nodes (34) closest to the current position.
8. Audio reproduction method according to one of the preceding claims, in which at least one of the master devices comprises a first UWB module (10), and in which the production of the map (31) and / or the detection of the current position of the user are implemented using the first UWB module (10).
9. Audio reproduction method according to one of the preceding claims, in which the preliminary phase comprises the steps, for determining the position of the walls (26), of: - transmitting a first message to the user to ask the latter to take a route along the walls (26) as close as possible to them; - determining the real-time position of the user when the latter takes said route, and determining the position of the walls (26) from this real-time position.
10. Audio reproduction method according to claims 8 and 9, in which the user (20) is equipped when he performs said journey with mobile equipment (21) comprising a second UWB module (22), the determination of the real-time position of the user being carried out by a UWB geolocation technique using the first UWB module (10) and the second UWB module (22).
11. Audio reproduction method according to claim 8, wherein, during the operational phase, the user (20) is provided with mobile equipment (21) comprising a second UWB module (22), the determination of the current position of the user being carried out by a UWB geolocation technique carried out using the first UWB module (10) and the second UWB module (22).
12. Audio reproduction method according to claim 8, in which the first UWB module is arranged to implement a UWB radar technology, determining the position of the walls (26) of the room being carried out by the master equipment using said UWB radar technology.
13. Audio reproduction method according to claim 8, in which the user (20), during the preliminary phase, is provided with mobile equipment (21) comprising a second UWB module (22), the preliminary phase comprising the step, for at least one sound source (3a, 3b), of transmitting a second message to the user to request the latter to position the mobile equipment (21) in the immediate vicinity of the sound source, the position of said sound source then being assimilated to the position of the mobile equipment (21), which is determined by a UWB geolocation technique using the first UWB module (10) and the second UWB module (22).
14. Audio reproduction method according to claim 8, in which at least one sound source comprises a UWB tag, the master equipment being arranged to determine the position of said sound source using a UWB geolocation technique carried out using the first UWB module (10) and the UWB tag.
15. Master equipment (1) comprising a first UWB module (10) arranged to carry out geolocation, and a processing unit (7) arranged to implement the audio reproduction method according to one of the preceding claims.
16. Master equipment according to claim 15, the master equipment being a set-top box (1).
17. Computer program comprising instructions which cause the processing unit (7) of the master equipment (1) according to one of claims 15 or 16 to execute the steps of the audio reproduction method according to one of claims 1 to 14.
18. A computer-readable recording medium on which the computer program according to claim 17 is recorded.