EP3729832A1

EP3729832A1 - Processing of a monophonic signal in a 3d audio decoder, delivering a binaural content

Info

Publication number: EP3729832A1
Application number: EP18833274.6A
Authority: EP
Inventors: Grégory PALLONE
Original assignee: Orange SA
Current assignee: Orange SA
Priority date: 2017-12-19
Filing date: 2018-12-07
Publication date: 2020-10-28
Also published as: FR3075443A1; JP2021508195A; JP2023099599A; WO2019122580A1; BR112020012071A2; JP7279049B2; EP4135350A1; US11176951B2; RU2020121890A; CN111492674B; KR20200100664A; KR102555789B1; US20210012782A1; CN111492674A

Abstract

The invention relates to a method for processing a monophonic signal in a 3D audio decoder, comprising a processing step for binauralizing decoded signals intended to be delivered spatially by a headset. The method is such that, on detection (E200), in a datastream representative of the monophonic signal, of an indication of non-binauralization processing, which indication is associated with spatial delivery position information, the decoded monophonic signal is directed (O-E200) to a stereophonic rendering engine, which takes into account the position information to construct two delivery channels (E220) that are directly processed via a direct mixing step (E230) that sums these two channels with a binauralized signal output from the binauralization processing, in order to be delivered (E240) via the headset. The invention also relates to a decoder device that implements the processing method.

Description

Processing a monophonic signal in a 3D audio decoder rendering binaural content

The present invention relates to the processing of an audio signal in a coded 3D audio decoding system standard MPEG-H 3D audio. The invention relates more particularly to the processing of a monophonic signal intended to be reproduced on a headset which also receives binaural audio signals.

The term binaural aims at a reproduction on headphones or pair of headphones, a sound signal with nevertheless spatialization effects. A binaural processing of audio signals, subsequently called binauralization or binauralization processing, uses HRTF filters (for "Head Related Transfer Function" in English) in the frequency domain or HRIR, BRIR ("Head Related Transfer Function", " Binaural Room Impulse Response "in the time domain that reproduce the acoustic transfer functions between the sound sources and the ears of the listener. These filters are used to simulate auditory location indices that allow a listener to locate sound sources as in real listening situations.

The signal of the right ear is obtained by filtering a monophonic signal by the transfer function (HRTF) of the right ear and the signal of the left ear is obtained by filtering this same monophonic signal by the transfer function of the right ear. left ear.

In the NGA (for "Next Generation Audio") type codecs, such as MPEG-H 3D audio described in the document referenced ISO / IEC 23008-3: "High efficiency coding and media deiivery in heterogeneous environments - Part 3: 3D audio »published on 25/07/2014 or AC4 described in the document referenced ETSI TS 103 190:" Digital Audio Compression Standard "published in April 2014, the signals received at the decoder are at first decoded and then undergo a processing of Binauralization as described above before being rendered on a headset. We are interested here in the case of restitution on audio headphones, with its spatialized, that is to say a binauralized signal.

The encoded codes therefore provide the possibility of a restitution on several virtual speakers through listening to a binaural signal on headphones but also provide the possibility of a reproduction on several real speakers, a sound spatialized.

In some cases, is associated with the binauralization processing, a function of treatment of tracking the head of the listener ("Head tracking" in English) that will be called dynamic rendering, as opposed to static rendering. This treatment makes it possible to take into account the movement of the listener's head to modify the sound reproduction on each ear in order to keep the restitution of the sound stage stable. In other words, the listener will perceive the sound sources in the same place in the physical space if he moves or if he does not move his head. This can be important for viewing and listening to video content

360 °.

However, for certain contents, it is not desirable that they be treated by this type of treatment. Indeed, in some cases, when the content was created specifically for binaural rendering, for example if the signals were recorded directly by an artificial head or already processed by binauralization processing, then they must be returned directly on the headphones helmet. These signals do not require additional binaural processing.

Similarly, a content producer may wish that a sound signal be reproduced independently of the sound scene, that is to say that it is perceived as a sound apart from the sound scene, for example as in the case of an "OFF" voice.

This type of reproduction may allow for example to give explanations on a sound scene otherwise restored. For example, the content producer may wish the sound to be reproduced on one ear to be able to obtain a voluntary effect of "headset" type, that is to say that the sound is heard only in one ear . We may also wish that this sound remains permanently only on this ear even if the listener moves his head, which is the case in the previous example. The content producer may also wish this sound to be rendered at a precise position in the sound space, relative to an ear of the listener (and not only within a single ear), even if he moves his head.

Such monophonic signal decoded and put in input of a system of reproduction of a codice of type MPEG-H 3D audio or AC4, will be binauralised. The sound will then be spread over both ears (although it will be less loud in the contra-lateral ear) and if the listener moves his head, he will not perceive the sound in the same way on his ear, since the follow-up treatment of the head, if implemented, will ensure that the position of the sound source remains the same as in the initial sound stage: depending on the position of the head, the sound will appear stronger in the one or the other of the ears.

In a proposal to modify the codec MPEG-H 3D audio, a contribution referenced "ISO / IEC JTC1 / SC29 / WG11 MPEG2015 / M37265" of October 2015 proposes to identify the contents that should not be altered by binauralization.

Thus, a "Dichotic" identification is associated with the contents that should not be processed by binauralization.

All the audio elements will then be binauralised except those referenced "Dichotic". "Dichotic" means that you have a different signal on each ear.

In the same way, in the AC4 standard, an information bit indicates that a signal is already virtualized. This bit allows the deactivation of the post-processing. The contents thus identified are contents already formatted for the audio headphones, that is to say in binaural. They have two channels. These methods do not deal with the case of a monophonic signal for which, the producer of the sound stage does not wish to binauralization.

This does not make it possible to restore a monophonic signal independently of the sound stage, at a precise position with respect to an ear of a listener who will be called in the "ear" mode. Using two-channel state of the art techniques, one solution would be to create a 2-channel content consisting of a signal in one of the channels and a silence in the other channel for a desired rendition on a single ear or to create a stereophonic content taking into account the desired spatial position and to identify this content as having already been spatialized before transmitting it.

However, this type of processing creates complexity by the creation of this stereophonic content and requires an additional bit rate of transmission of this stereophonic content.

There is therefore a need to offer a solution that makes it possible to pass a signal that will be restored to a precise position relative to an ear of an audio headphone wearer independently of a sound scene restored by the same headset, while optimizing the rate of the coded used.

The present invention improves the situation.

To this end, it proposes a method of processing an audio monophonic signal in a 3D audio decoder comprising a binauralization processing step of the decoded signals intended to be spatially reproduced by an audio headset. The method is such that, upon detecting, in a data flow representative of the monophonic signal, an indication of binaural non-processing associated with a restitution spatial position information, the decoded monophonic signal is directed to a transmission engine. stereophonic rendering taking into account the position information to construct two rendering channels processed by a direct mixing step summing these two channels with a binauralized signal resulting from binauralization processing, to be rendered on the headphones.

Thus, it is possible to specify that a monophonic content must be rendered at a precise spatial position with respect to an ear of a listener and that it does not undergo binauralization processing so that this restored signal can have an "ear" effect, that is to say, it is heard by the listener at a specific position with respect to an ear, inside the head in the same way as a stereophonic signal and this even if the listener's head moves.

Indeed, stereophonic signals are characterized by the fact that each sound source is present in each of the 2 output channels (left and right) with an intensity difference (or ILD for "Interaural Level Difference") and sometimes time (or ITD for "Interaural Time Difference") between the channels. When listening to the headphones of a stereophonic signal, the sources are perceived inside the head, at a location between the left ear and the right ear, depending on the ILD and / or ITD. Signals Binaurals oppose stereophonic signals in that the sources are applied a filter reproducing the acoustic path from the source to the ear of the listener. When listening to the headphones of a binaural signal, the sources are perceived outside the head, at a location on a sphere, depending on the filter used.

The stereophonic and binaural signals are similar in that they consist of 2 left and right channels, and are distinguished by the content of these 2 channels.

This monaural signal (for monophonic) restored then superimposes the other restored signals that form a 3D sound scene.

The rate required to indicate this type of content is optimized since it is sufficient to code only a position indication in the sound scene in addition to the indication of non-binauralization to inform the decoder of the treatment to be performed, unlike a method that would require encoding, transmit and decode a stereo signal taking into account this spatial position.

The various particular embodiments mentioned below may be added independently or in combination with each other, to the steps of the treatment method defined above.

In a particular embodiment, the restitution spatial position information is a binary data indicating a single channel of the reproduction audio headset.

This information requires only one coding bit, which further allows the necessary bit rate to be restricted.

In this embodiment, only the playback channel corresponding to the channel indicated by the binary data is summed to the corresponding channel of the binauralized signal in the direct mixing step, the other playback channel being of zero value.

The summation thus performed is simple to implement and provides the desired "headset" effect of superposition of the mono signal to the sound scene restored.

In a particular embodiment, the monophonic signal is a channel-type signal directed to the stereophonic rendering engine with the spatial position feedback information.

Thus, the monophonic signal does not undergo a binauralization processing step and is not treated as channel-type signals usually processed by state-of-the-art methods. This signal is processed by a stereophonic rendering engine different from that existing for the channel type signals. This rendering engine consists of duplicating the monophonic signal on the 2 channels, by applying function factors of the spatial position information of restitution, on both channels.

This stereophonic rendering engine can also be integrated into the channel rendering engine with a differentiated processing according to the detection made for the signal at the input of this rendering engine or the direct mixing module summing the channels resulting from this rendering engine. stereophonic signal binauralized binaural processing module. In an embodiment related to the channel-type signal, the restitution spatial position information is an interaural sound level difference data type ILD or more generally a level report information between the left and right channels.

In another embodiment, the monophonic signal is an object type signal associated with a set of reproduction parameters including the non-binauralization indication and the restitution position information, the signal being directed to the rendering engine. stereophonic with spatial position feedback information.

In this other embodiment, the restitution spatial position information is for example an azimuth angle datum.

This information makes it possible to give a restitution position with respect to an ear of the headset carrier so that this sound is superimposed on a sound stage.

Thus, the monophonic signal does not undergo a binauralization processing step and is not treated as the object type signals usually processed by the methods of the state of the art. This signal is processed by a stereophonic rendering engine different from that existing for the object type signals. Binaural non-processing indication and rest position information are included in the rendering parameters (Metadata) associated with the object type signal. This rendering engine can also be integrated with the object rendering engine or with the direct mixing module summing the channels resulting from this stereophonic rendering engine with the binauralized signal coming from the binauralization processing module.

The present invention also relates to a device for processing an audio monophonic signal comprising a processing module for binauralization of decoded signals intended to be spatially reproduced by an audio headset. This device is such that it comprises:

a detection module adapted to detect, in a data flow representative of the monophonic signal, an indication of binaural non-processing associated with a restitution spatial position information;

a redirection module, in the case of a positive detection by the detection module, able to direct the monophonic signal to a stereophonic rendering engine;

a stereophonic rendering engine adapted to take into account the position information to construct two rendering channels;

a direct mixing module able to directly process the two rendering channels by summing them with a binauralized signal from the binauralization processing module, to be rendered on the headphones.

This device has the same advantages as the method described above, which it implements. In a particular embodiment, the stereophonic rendering engine is integrated in the direct mixing module.

Thus, only the direct mixing module that the playback channels are built, only the position information is then transmitted with the mono signal to the direct mixing module. This signal may be of the channel type or of the object type.

In one embodiment, the monophonic signal is a channel-type signal and the stereophonic rendering engine is integrated with a channel rendering engine that also builds rendering channels for multi-channel signals.

In another embodiment, the monophonic signal is an object type signal and the stereophonic rendering engine is integrated with an object rendering engine that also builds rendering channels for monophonic signals associated with sets of rendering parameters.

The present invention relates to an audio decoder comprising a processing device as described and a computer program comprising code instructions for implementing the steps of the processing method as described, when these instructions are executed by a processor.

Finally, the invention relates to a storage medium, readable by a processor, integrated or not to the processing device, possibly removable, storing a computer program comprising instructions for executing the processing method as described above.

Other features and advantages of the invention will appear more clearly on reading the following description, given solely by way of nonlimiting example, and with reference to the appended drawings, in which:

FIG. 1 illustrates a decoder of the MPEG-H 3D audio type as it exists in the state of the art;

FIG. 2 illustrates the steps of a processing method according to one embodiment of the invention;

FIG. 3 illustrates a decoder comprising a processing device according to a first embodiment of the invention;

FIG. 4 illustrates a decoder comprising a processing device according to a second embodiment of the invention; and

FIG. 5 illustrates a hardware representation of a processing device according to one embodiment of the invention.

FIG. 1 schematically illustrates a decoder as standardized in the MPEG-H 3D audio standard according to the document referenced above. Block 101 is a heart decoding module which decodes both channel-type multichannel audio signals (Ch.) And object-type monophonic audio signals (Obj.) Associated with spatialization ("Metadata") (Obj.MeDa.) and audio signals in Higher Order Ambisonic Audio (HOA) format (HOA).

A channel-type signal is decoded and processed by a channel rendering engine 102 ("Channel renderer" in English, also called "Format Converter" in MPEG-H 3D Audio) in order to adapt this channel signal to the audio rendering system. The channel rendering engine knows the characteristics of the rendering system and thus provides a signal by way of reproduction (Rdr.Ch.) to supply either real speakers or virtual speakers (which will then be binauralised for a rendering at helmet).

These rendering channels are mixed by the mixing module 110 to other rendering channels from the object rendering engines 103 and HOA 105 described later.

Object-type signals (Obj.) Are monophonic signals associated with data ("Metadata") such as spatialization parameters (azimuth angles, elevation) which make it possible to position the monophonic signal in the spatialized sound scene, priority parameters or sound volume settings. These object signals are decoded, together with the associated parameters, by the decoding module 101 and are processed by an object rendering engine 103 ("Object Renderer" in English) which, knowing the characteristics of the rendering system, adapts these monophonic signals to these characteristics. The various reproduction channels (Rdr.Obj.) Thus created are mixed with the other rendering channels from the channel and HOA rendering engines, by the mixing module 110.

In the same way, the "Higher Order Ambisonic" (HOA) type signals are decoded and the decoded surround components are inputted from an ambient rendering engine 105 ("HOA renderer") to adapt these components to the sound reproduction system.

The reproduction channels (Rdr .HOA) created by this rendering engine HOA are mixed at 110 with the reproduction channels created by the other rendering engines 102 and 103.

The signals at the output of the mixing module 110 can be restored by HP real speakers located in a playback room. In this case, the signals at the output of the mixing module can directly supply these real speakers, a channel corresponding to a loudspeaker.

In the case where the signals at the output of the mixing module are to be reproduced on an AC headset, then these signals are processed by a binauralization processing module 120 according to binauralization techniques described for example in the document cited for the MPEG standard. -H 3D audio.

Thus, all the signals intended to be rendered on a headphone, are processed by binauralization processing module 120.

Figure 2 now describes the steps of a method of processing according to one embodiment of the invention. This method relates to the processing of a monophonic signal in a 3D audio decoder. A step E200 detects whether the data flow (SMo) representative of the monophonic signal (for example the bitstream at the input of the audio decoder) includes a binaural non-processing indication associated with a restitution spatial position information. In the opposite case (N in step E200), the signal must be binauralized. It is processed by binauralization processing, in step E210, before being restored in E240 on a playback headset. This binauralized signal can be mixed with other stereophonic signals from step E220 described below.

In the case where the representative data stream of the monophonic signal comprises both an indication of non-binauralization (Di.) and a positional spatial position information (Pos.) (O at step E200), the signal monophonic decoded is directed to a stereophonic rendering engine to be processed by a step E220.

This non-binauralization indication may be, for example, as in the state of the art, a "Dichotic" identification given to the monophonic signal or another identification understood as an instruction not to process the signal by a binauralization process. The spatial position information of restitution can be for example an azimuth angle indicating the restitution position of the sound with respect to an ear, right or left, or an indication of difference in level between the left and right channels as a piece of information. ILD for distributing the energy of the monophonic signal between the left and right channels, or simply the indication of a single channel of restitution, corresponding to the right or left ear. In the latter case, this information is binary information that requires very little bit rate (1 bit of information).

In step E220, the position information is taken into account to build two rendering channels for the two earphones of the headphones. These two playback channels thus constructed are processed directly by a direct mixing step E230 summing these two stereo channels with the two channels of the binauralized signal from binauralization processing E210.

Each of the stereophonic reproduction channels is then summed with the corresponding channel of the binauralized signal.

Following this step of direct mixing, the two playback channels from the E230 mixing step are restored in E240 on the AC headphones.

In an embodiment where the restitution spatial position information is a binary data indicating a single channel of the playback headset, this means that the monophonic signal must be rendered only on a headphone of this headset. The two reproduction channels constructed in step E220 by the stereophonic rendering engine consist of a channel comprising the monophonic signal, the other channel being zero, and therefore possibly absent. At the step of direct mixing E230, a single channel is summed with the corresponding channel of the binauralized signal, the other channel being zero. This mixing step is simplified.

Thus, the listener equipped with the audio headset hears on the one hand, a spatialized sound scene from the binauralized signal, this sound scene is heard by him at the same physical place even if he moves his head in the case of a dynamic rendering and on the other hand, a sound positioned inside the head, between an ear and the center of the head, which is superimposed on the sound stage independently, that is, if the listener move your head, this sound will be heard in the same position relative to an ear.

This sound is perceived as a superposition of other binauralized sounds of the sound stage, and will act as an "OFF" voice to this sound scene.

The "headset" effect is then realized.

FIG. 3 illustrates a first embodiment of a decoder comprising a processing device implementing the processing method described with reference to FIG. 2. In this exemplary embodiment, the monophonic signal processed by the method used is a channel type signal (Ch.).

The object (object) and HOA (HOA) type signals are processed in the same way by the respective blocks 303, 304 and 305 as the blocks 103, 104 and 105 described with reference to FIG. way, the mixing block 310 performs a mixing as described for the block 110 of Figure 1.

The block 330 receiving the channel-type signals treats differently a monophonic signal having a non-binauralization indication (Di.) associated with a restitution spatial position information (Pos.) That another signal does not include this information, in particularly a multichannel signal. For these signals not having this information, they are processed by the block 302 in the same way as the block 102 described with reference to FIG.

For a monophonic signal comprising the non-binauralization indication associated with a restitution spatial position information, the block 330 acts as a router or switch and directs the decoded monophonic signal (Mo.) to a stereophonic rendering engine 331. stereophonic rendering engine also receives, from the decoding module, the spatial position information of restitution (Pos.). With this information, it builds two playback channels (2 Vo.), Corresponding to the left and right channels of the playback headphones, for these channels to be output to the AC headphones.

In an exemplary embodiment, the restitution spatial position information is interaural sound level difference information between the left and right channels. This information makes it possible to define a factor to be applied to each of the rendering channels in order to respect this restitution spatial position. The definition of these factors can be done as in the document referenced MPEG-2 AAC: ISO / IEC 13818-4: 2004 / DCOR 2, AAC in section 7.2 describing the stereo intensity.

Before being rendered on the headphones, these rendering channels are added to the channels of a binauralized signal from binauralization module 320 which performs a binauralization processing in the same way as block 120 of FIG.

This channel summing step is performed by the direct mixing module 340 which is the left channel from the stereophonic rendering engine 331 to the left channel of the binauralized signal from binauralization processing module 320 and the right channel from the engine stereophonic rendering 331 to the right channel of the binauralized signal from binauralization processing module 320, before playback on the CA headset.

Thus, the monophonic signal does not pass through the binauralization processing module 320, it is transmitted directly to the stereophonic rendering engine 331 before being directly mixed with a binauralized signal.

This signal will not undergo either head tracking treatment. The restored sound will be in a position of restitution with respect to an ear of the listener and will remain in this position even if the listener moves his head.

In this embodiment, the stereophonic rendering engine 331 can be integrated with the channel rendering engine 302. In this case, this channel rendering engine implements both the adaptation of the conventional channel type signals, as described in FIG. FIG. 1 and the construction of the two renderer rendering channels of the rendering engine 331 as explained above by receiving the restitution spatial position information (Pos). Only the two playback channels are then redirected to the direct mixing module 340 before playback on the AC headphones.

In an alternative embodiment, the stereophonic rendering engine 331 is integrated with the direct mixing module 340. In this case, the routing module 330 directs the decoded monophonic signal (for which the non-binauralization indication has been detected. and the restitution spatial position information) to the direct mixing module 340. On the other hand, the decoded spatial position information (Pos) is also transmitted to the direct mixing module 340. This mixing module direct then comprising the stereophonic rendering engine, implements the construction of the two rendering channels taking into account the spatial position information of restitution as well as the mixing of these two rendering channels with the return channels of a binauralized signal from binauralization processing module 320.

FIG. 4 illustrates a second embodiment of a decoder comprising a processing device implementing the processing method described with reference to FIG. 2. In this exemplary embodiment, the monophonic signal processed by the method implemented is an object type signal (Obj.). The channel type (Ch) and HOA type (HOA) signals are treated in the same way by the respective blocks 402 and 405 as the blocks 102 and 105 described with reference to FIG. 1. In the same way, the block mixer 410 performs a mixing as described for block 110 of FIG.

The block 430 receiving the object type signals (Obj.) Treats differently a monophonic signal for which it has detected a non-binauralization indication (Di.) associated with a spatial position information of restitution (Pos.) That a other monophonic signal for which this information has not been detected.

For these monophonic signals for which this information has not been detected, they are processed by the block 403 in the same way as the block 103 described with reference to FIG. 1 using the decoded parameters of the block 404 decoding the Metadata of the same as the block 104 of Figure 1.

For a monophonic signal of the object type for which the non-binauralization indication associated with a restitution spatial position information has been detected, the block 430 acts as a router or switch and directs the decoded monophonic signal (Mo.) to a stereophonic rendering engine 431.

The non-binauralization indication (Di.) as well as the restitution spatial position information (Pos) are decoded by the decoding block 404 of the metadata or parameters associated with the object type signals. The non-binauralization indication (Di.) is transmitted to the routing block 430 and the restitution spatial position information is transmitted to the stereophonic rendering engine 431.

This stereophonic rendering engine thus receiving the positional restitution position information (Pos.), Builds two rendering channels corresponding to the left and right channels of the reproduction headphones, so that these channels are reproduced on the AC headphones.

In an exemplary embodiment, the restitution spatial position information is an azimuth angle information defining an angle between the desired restitution position and the center of the listener's head.

This information makes it possible to define a factor to be applied to each of the rendering channels in order to respect this restitution spatial position.

The gain factors for the left and right channels can be calculated as presented in City Pulkki's Virtual Sound Source Positioning Using Vector Base Amplitude Panning in J. Audio Eng. Soc., Vol.45, No.6, of June 1997.

For example, the gain factors of the stereophonic rendering engine can be given by:

gl = (cosO.sinH + sin0.cosH) / (2.cosH.sinH)

g2 = (cosO.sinH - sin0.cosH) / (2.cosH.sinH) Where gl and g2 correspond to the factors for left and right channel signals, where O is the angle between the frontal direction and the object (called azimuth), and H is the angle between the frontal direction and the position of the virtual speaker (corresponding to the half-angle between the speakers), fixed for example at 45 °.

Before being rendered on the headphones, these rendering channels are added to the channels of a binauralized signal from the binauralization module 420 which performs a binauralization processing in the same way as the block 120 of FIG.

This channel summing step is performed by the direct mixing module 440 which is the left channel from the stereophonic rendering engine 431 to the left channel of the binauralized signal from the binauralization processing module 420 and the right channel from the engine stereophonic rendering 431 to the right channel of the binauralized signal from binauralization processing module 420, before playback on the CA headset.

Thus, the monophonic signal does not go through the binaural processing module 420, it is transmitted directly to the stereophonic rendering engine 431 before being mixed directly to a binauralized signal.

In this embodiment, the stereophonic rendering engine 431 can be integrated with the object rendering engine 403. In this case, this object rendering engine implements both the adaptation of the conventional object type signals, as described in FIG. FIG. 1 and the construction of the two renderer rendering channels 431 as explained above by receiving the restitution spatial position information (Pos) of the decoding module 404 of the parameters. Only the two playback channels (2Vo.) Are then redirected to the direct mixing module 440 before playback on the AC headphones.

In an alternative embodiment, the stereophonic rendering engine 431 is integrated with the direct mixing module 440. In this case, the routing module 430 directs the decoded monophonic signal (Mo.) (for which the indication has been detected. non-binauralization and restitution spatial position information) to the direct mixing module 440. On the other hand, the decoded spatial position information (Pos) is also transmitted to the direct mixing module 440 by the parameter decoding module 404. This direct mixing module then including the stereophonic rendering engine, implements the construction of the two reproduction channels taking into account the spatial position information of restitution as well as the mixing of these two paths. rendering with the return channels of a binauralized signal from binauralization processing module 420.

Figure 5 now illustrates an example of a hardware embodiment of a processing device adapted to implement the treatment method according to the invention. The device DIS comprises a storage space 530, for example a memory MEM, a processing unit 520 comprising a processor PROC, driven by a computer program Pg, stored in the memory 530 and implementing the processing method according to the invention .

The computer program Pg comprises code instructions for the implementation of the steps of the processing method in the sense of the invention, when these instructions are executed by the processor PROC, and in particular, on detection, in a representative data stream. of the monophonic signal, binaural non-processing indication associated with a restitution spatial position information, a step of directing the decoded monophonic signal to a stereophonic rendering engine taking into account the position information to construct two paths restitution treated directly by a direct mixing step summing these two channels with a binauralized signal from binauralization processing, to be rendered on the headphones.

Typically, the description of FIG. 2 repeats the steps of an algorithm of such a computer program.

At initialization, the code instructions of the program Pg are for example loaded into a RAM (not shown) before being executed by the processor PROC of the processing unit 520. The program instructions can be stored on a memory card. storage medium such as flash memory, hard disk, or other non-transient storage media.

The device DIS comprises a reception module 510 adapted to receive a representative SMo data stream including a monophonic signal. It comprises a detection module 540 able to detect, in this data stream, an indication of binaural non-processing associated with spatial position information rendition. It comprises a direction module 550, in the case of a positive detection by the detection module 540, of the decoded monophonic signal to a stereophonic rendering engine 560, the stereophonic rendering engine 560 being able to take into account the information position to build two tracks of restitution.

The device DIS also comprises a direct mixing module 570 able to directly process the two reproduction channels by summing them with the two channels of a binauralized signal coming from a binauralization processing module. The playback channels thus obtained are transmitted to an AC headset via an output module 560, to be restored.

These different modules are as described with reference to FIGS. 3 and 4 according to the embodiments.

The term module may correspond to a software component as well as a hardware component or a set of hardware and software components, a software component corresponding to one or more programs or subprograms computer or more generally to any element of a program capable of implementing a function or a set of functions as described for the modules concerned. In the same way, a hardware component corresponds to any element of a hardware set (or hardware) able to implement a function or a set of functions for the module concerned (integrated circuit, smart card, memory card, etc. .)

The device can be integrated into an audio decoder as described in FIG. 3 or 4 and can be integrated, for example, in multimedia equipment of the set-top box type, or audio or video content player. They can also be integrated into communication equipment of the mobile phone or communication gateway type.

Claims

A method for processing an audio monophonic signal in a 3D audio decoder comprising a binauralization processing step of the decoded signals intended to be spatially reproduced by an audio headset, characterized in that, at the detection (E200), in a data stream representative of the monophonic signal, a binaural non-processing indication associated with a restitution spatial position information, the decoded monophonic signal is directed (O-E200) to a stereophonic rendering engine taking into account the position information for constructing two playback channels (E220) processed directly by a direct mixing step (E230) summing these two channels with a binauralized signal from the binauralization processing, to be rendered (E240) on the headphones.

The method of claim 1, wherein the restitution spatial position information is a binary data indicating a single channel of the playback audio headset.

3. The method as claimed in claim 2, in which only the playback channel corresponding to the channel indicated by the binary data is summed to the corresponding channel of the signal binauralised in the direct mixing step, the other rendering channel being of value. nothing.

The method of claim 1, wherein the monophonic signal is a channel-type signal directed to the stereophonic rendering engine, with the spatial position feedback information.

The method of claim 4, wherein the restitution spatial position information is interaural sound level difference (ILD) data.

The method of claim 1, wherein the monophonic signal is an object type signal associated with a set of playback parameters including the non-binauralization indication and the playback position information, the signal being directed to the stereophonic rendering engine with playback position information.

The method of claim 6, wherein the restitution spatial position information is azimuth angle data.

8. Device for processing an audio monophonic signal comprising a processing module for binauralization of decoded signals intended to be spatially reproduced by an audio headset, characterized in that it comprises:

a detection module (330; 430) adapted to detect, in a data stream representative of the monophonic signal, an binaural non-processing indication associated with a restitution spatial position information; a redirection module (330, 430), in the case of a positive detection by the detection module, able to direct the decoded monophonic signal to a stereophonic rendering engine;

a stereophonic rendering engine (331; 431) adapted to take position information into account to construct two rendering channels;

a direct mixing module (340; 440) adapted to directly process the two reproduction channels by summing them with a binauralized signal from the binaural processing module (320; 420), to be rendered on the headphones.

9. Processing device according to claim 8, wherein the stereophonic rendering engine is integrated in the direct mixing module.

The apparatus of claim 8, wherein the monophonic signal is a channel-type signal and wherein the stereophonic rendering engine is integrated with a channel rendering engine which further provides playback channels for multi-channel signals.

Apparatus according to claim 8, wherein the monophonic signal is an object type signal and wherein the stereophonic rendering engine is integrated with an object rendering engine, further constructing rendering channels for monophonic signals associated with sets. restitution parameters.

12. Audio decoder comprising a processing device according to one of claims 8 to 11.

Computer program comprising code instructions for implementing the steps of the processing method according to one of claims 1 to 7, when these instructions are executed by a processor.

14. Storage medium, readable by a processor, storing a computer program comprising instructions for executing the treatment method according to one of claims 1 to 7.