EP2247122A1 - Method and apparatus for controlling the reproduction of audio contents by two loudspeakers - Google Patents

Abstract

The method involves delivering a first audio content to two loudspeakers (HPG, HPD). An auxiliary audio content (CADX) e.g. monophonic content, is received. A second audio content (CADX2) comprising temporal delaying of the auxiliary audio content with delay dependent on a spacing between the two loudspeakers, is formulated. The second audio content is delivered to the one of the loudspeakers. A third audio content (CADX3) comprising inversion of the auxiliary audio content is formulated. The third audio content is delivered to the second loudspeaker. An independent claim is also included for a device for controlling broadcasting of audio contents by two loudspeakers.

Description

The invention relates to the broadcasting of audio contents by loudspeakers having in particular a large directivity angle.

Television program broadcasters, transmitted directly or via Set Top Boxes, which are well-known to those skilled in the art, sometimes transmit dual audio content (two different audio programs). ) associated with a single video channel, to provide additional services to their customers (for example, a program associated with audio description of this program for visually impaired people).

The transmission of multiple audio contents is becoming more common, and their decoding is supported by most current TV sets and decoders.

A problem occurs when you want to listen to both audio contents at the same time using the speakers of a TV, for example.

Indeed, as the right and left speakers generally have a large directivity, it is not possible to deliver the sound of both audio programs simultaneously (for example, using the left speaker for the left program and the right speaker for the right program). Indeed, the sound will be mixed acoustically and people watching television will hear both audio programs simultaneously.

This problem also occurs with game consoles when two players are playing on the same screen. Indeed, while the two players can share the same musical atmosphere, it is not desirable that the sounds generated by the part of the game intended for a player can be heard by the other player.

A conventional solution is to broadcast audio content on the speakers while the other audio content is broadcast on a headphone jack.

However, with such a solution, a person wishing to listen to an auxiliary audio program must purchase additional equipment (eg headphones) to be able to listen to his audio program without disturbing the other listener. In addition, the number of people watching the program is limited by the number of headphones that can be connected to the TV.

According to an embodiment and embodiment, a method and a device are provided for controlling the directivity of the loudspeakers so as to create two independent zones allowing, for example, a visually impaired person to hear an audio description. a TV program without the broadcast of this audio description may interfere with another viewer, not visually impaired, who simultaneously watching the same TV program.

It is also possible, for example for two viewers, to listen to and watch two TV programs at the same time on the same TV without additional equipment while not interfering with each other at the sound level.

• une délivrance d'un premier contenu audio, par exemple un programme de télévision, aux deux haut-parleurs,
• une réception d'un contenu audio auxiliaire, par exemple une audiodescription de ce programme de télévision,
• une élaboration d'un deuxième contenu audio comportant un retardement temporel du contenu audio auxiliaire avec un retard dépendant de l'espacement entre les deux haut-parleurs et d'une distance entre un premier haut-parleur, par exemple le haut-parleur de gauche, et un endroit situé en face de ce premier haut-parleur,
• une délivrance du deuxième contenu audio à ce premier haut-parleur,
• une élaboration d'un troisième contenu audio comportant une inversion du contenu auxiliaire, et
• une délivrance du troisième contenu audio au deuxième haut-parleur, par exemple le haut-parleur de droite.

According to one aspect, there is thus provided a method for controlling the broadcasting of audio contents by two loudspeakers; this method is particularly applicable to loudspeakers having a broad directivity, that is to say respectively having diffusion zones having a common portion that can extend in front of the two loudspeakers; this process comprising:

• delivering a first audio content, for example a television program, to the two loudspeakers,
• a reception of an auxiliary audio content, for example an audio description of this television program,
• a development of a second audio content comprising a delay time of the auxiliary audio content with a delay depending on the spacing between the two speakers and a distance between a first speaker, for example the speaker on the left , and a place in front of this first speaker,
• a delivery of the second audio content to this first speaker,
• developing a third audio content including an inversion of the auxiliary content, and
• delivering the third audio content to the second speaker, for example the right speaker.

Thus, a visually impaired person in front of the right speaker will hear the normal television program and audio description of this program, while another viewer, who is not visually impaired, located in front of the speaker of left, will only perceive the television program without perceiving the audio description of this program.

Preferably, the development of the third audio content comprises, in addition to the inversion of the auxiliary content, an amplification of the inverted auxiliary content with a gain whose value depends on said distance, and a compensation processing of the non-linearity of the frequency response the second speaker, along an axis connecting the second speaker to said location.

In order to improve the audio content of each channel, it is advantageously provided a pretreatment of the auxiliary audio content before the development of the second and third audio contents.

When the auxiliary audio content is monophonic content, this pretreatment comprises at least a first and a second elementary processing monophonic auxiliary content, each elementary processing containing a band-pass filtering followed by dynamic compression processing and a summation of signals respectively from said elementary treatments. This makes it possible to obtain a clear voice with existing but not very disturbing related signals.

When the auxiliary audio content is stereophonic content, the pretreatment comprises prior to the elementary treatments that have just been mentioned, a transformation of the stereophonic auxiliary audio content into a monophonic auxiliary audio content.

So as to homogenize the entire signal and thus reduce the characteristics of the sound environment, it is advantageously provided that the pretreatment further comprises a third elementary treatment comprising a low-pass filter followed by dynamic compression processing.

In order to correct the brilliance and the clarity of the sound, it is advantageously provided a fourth elementary treatment comprising a high-pass filtering followed by dynamic compression processing.

It is also proposed, according to another embodiment, a method of controlling the broadcasting of audio contents by two loudspeakers, which is for example more particularly intended for the simultaneous broadcasting of two television programs by the loudspeakers. speakers of the same TV.

• une réception d'un premier contenu audio, par exemple le premier programme de télévision,
• une élaboration d'un deuxième contenu audio comportant un retardement temporel du premier contenu audio avec un retard dépendant de l'espacement entre les deux haut-parleurs et d'une première distance entre un premier haut-parleur, par exemple le haut-parleur de gauche, et un premier endroit situé en face de ce premier haut-parleur,
• une délivrance du deuxième contenu audio à ce premier haut-parleur,
• une élaboration d'un troisième contenu audio comportant une inversion du premier contenu audio, et
• une délivrance du troisième contenu audio au deuxième haut-parleur, par exemple au haut-parleur de droite,
• une réception d'un quatrième contenu audio, par exemple le deuxième programme de télévision,
• une élaboration d'un cinquième contenu audio comportant un retardement temporel du quatrième contenu audio avec un retard dépendant de l'espacement entre les haut-parleurs, et d'une deuxième distance entre le deuxième haut-parleur (le haut-parleur de droite, par exemple), et un deuxième endroit situé en face de ce deuxième haut-parleur,
• une délivrance du cinquième contenu audio à ce deuxième haut-parleur,
• une élaboration d'un sixième contenu audio comportant une inversion du quatrième contenu audio, et
• une délivrance du sixième contenu audio au premier haut-parleur, par exemple le haut-parleur de gauche.

According to this other embodiment, this method comprises:

• a reception of a first audio content, for example the first television program,
• developing a second audio content having a time delay of the first audio content with a delay depending on the spacing between the two loudspeakers and a first distance between a first speaker, for example the speaker of left, and a first place located in front of this first speaker,
• a delivery of the second audio content to this first speaker,
• developing a third audio content including an inversion of the first audio content, and
• delivering the third audio content to the second speaker, for example to the right speaker,
• a reception of a fourth audio content, for example the second television program,
• developing a fifth audio content having a time delay of the fourth audio content with a delay depending on the spacing between the speakers, and a second distance between the second speaker (the right speaker, for example), and a second place in front of this second speaker,
• delivering the fifth audio content to this second speaker,
• developing a sixth audio content including an inversion of the fourth audio content, and
• delivering the sixth audio content to the first speaker, for example the left speaker.

Thus, the television viewer placed in front of the left speaker visualizes on the left side of the television the first television program, and perceives the audio content relating to this first television program, without perceiving the audio content relating to the second television program. .

Similarly, the viewer located in front of the right speaker visualizes the second television program on the right side of the television, and perceives the audio content relating to the second television program without being bothered by the audio content relating to the first program of TV.

According to one mode of implementation, the development of the third audio content further comprises an amplification of the first content inverted audio with a gain whose value depends on the first distance, and a compensation processing of the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said first location; and the development of the sixth audio content further comprises an amplification of the fourth inverted audio content with a gain whose value depends on the second distance, and a compensation processing of the non-linearity of the frequency response of the first speaker the along an axis connecting the first speaker to said second location.

• un premier prétraitement du premier contenu audio avant l'élaboration des deuxième et troisième contenus audio, et
• un deuxième prétraitement du quatrième contenu audio avant l'élaboration des cinquième et sixième contenus audio,
• chaque prétraitement comportant une transformation du contenu audio stéréophonique correspondant en un contenu audio monophonique, au moins un premier et un deuxième traitements élémentaires du contenu audio monophonique, chaque traitement élémentaire contenant filtrage passe-bande suivi d'un traitement de compression de dynamique, et une sommation des signaux respectivement issus desdits traitements élémentaires.

According to one embodiment, the first and fourth audio contents are stereophonic contents and the method further comprises

• a first preprocessing of the first audio content before the development of the second and third audio contents, and
• a second preprocessing of the fourth audio content before the development of the fifth and sixth audio contents,
• each pretreatment comprising a transformation of the corresponding stereophonic audio content into monophonic audio content, at least a first and a second elementary processing of the monophonic audio content, each elementary processing containing bandpass filtering followed by dynamic compression processing, and a summation of the signals respectively derived from said elementary treatments.

Each pretreatment may advantageously comprise a third elementary treatment comprising a low-pass filter followed by dynamic compression processing and / or a fourth elementary treatment comprising high-pass filtering followed by dynamic compression processing.

In other applications, for example in video game applications, provision may be made for the delivery of audio content additional to the two speakers, this additional audio content may be audio content of sound environment.

• des premiers moyens de délivrance configurés pour délivrer un premier contenu audio aux deux haut-parleurs,
• des moyens de réception configurés pour recevoir un contenu audio auxiliaire,
• des premiers moyens d'élaboration configurés pour élaborer un deuxième contenu audio comportant des moyens de retard configurés pour un retarder temporellement le contenu audio auxiliaire avec un retard dépendant de l'espacement entre les hauts parleurs et d'une distance entre un premier haut-parleur et un endroit situé en face de ce premier haut-parleur,
• des deuxièmes moyens de délivrance configurés pour délivrer le deuxième contenu audio à ce premier haut-parleur,
• des deuxièmes moyens d'élaboration configurés pour élaborer un troisième contenu audio comportant des moyens d'inversion configurés pour effectuer une inversion du contenu audio auxiliaire, et
• des troisièmes moyens de délivrance configurés pour délivrer le troisième contenu audio au deuxième haut-parleur.

In another aspect, there is provided a device for controlling the broadcasting of audio content by two loudspeakers, comprising

• first delivery means configured to deliver a first audio content to the two loudspeakers,
• receiving means configured to receive auxiliary audio content,
• first generating means configured to develop a second audio content having delay means configured to temporally delay the auxiliary audio content with a delay dependent on the spacing between the speakers and a distance between a first speaker and a place in front of that first speaker,
• second delivery means configured to deliver the second audio content to that first speaker,
• second generating means configured to develop a third audio content having inversion means configured to invert the auxiliary audio content, and
• third delivery means configured to deliver the third audio content to the second speaker.

According to one embodiment, the second generation means further comprise amplification means configured to amplify the inverted auxiliary audio content with a gain whose value depends on said distance, and a processing block configured to carry out a processing of compensating for the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said location.

According to one embodiment, the auxiliary audio content is a monophonic content and the device further comprises a preprocessing module coupled between the receiving means and the first and second means of production, this preprocessing module comprising at least a first and a second processing branches of the monophonic auxiliary audio content, each processing branch containing bandpass filtering means followed by a dynamic compression processing block, and summing means coupled to the outputs of the processing branches.

According to one embodiment, in which the auxiliary audio content is stereophonic content, the device furthermore comprises a preprocessing module coupled between the reception means and the first and second means of elaboration, this preprocessing module comprising a stage of transforming the stereophonic auxiliary audio content into monophonic auxiliary audio content, at least first and second processing branches of the monophonic auxiliary audio content, each processing branch containing bandpass filtering means followed by a compression processing block dynamics, and summing means coupled to the outputs of the processing branches.

According to one embodiment, the preprocessing module further comprises a third processing branch comprising low-pass filtering means followed by a dynamic compression processing block.

According to one embodiment, the preprocessing module further comprises a fourth processing branch comprising high-pass filtering means followed by a dynamic compression processing block.

According to another embodiment, there is provided a device for controlling the broadcasting of audio contents by two loudspeakers, comprising
first reception means configured to receive a first audio content,
first generating means configured to develop a second audio content having first delay means configured to temporally delay the first audio content with a delay dependent on the spacing between the speakers and a first distance between a first speaker and a second speaker; speaker and a first place in front of that first speaker,
first delivery means configured to deliver the second audio content to that first speaker,
second generating means configured to develop a third audio content having first inversion means configured to invert the first audio content,
second delivery means configured to deliver the third audio content to the second speaker,
second reception means configured to receive a fourth audio content,
third developing means configured to develop a fifth audio content having second delay means configured to temporally delay the fourth audio content with a delay depending on the spacing between the speakers and a second distance between the second speaker; speaker and a second location opposite this second speaker,
third delivery means configured to deliver the fifth audio content to that second speaker,
fourth generation means configured to develop a sixth audio content having second inversion means configured to invert the fourth audio content, and
fourth delivery means configured to deliver the sixth audio content to the first speaker.

According to one embodiment, the second elaboration means further comprise first amplification means configured to amplify the first inverted audio content with a gain whose value depends on the first distance, and a first processing block configured to perform compensation processing of the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said first location, and
the fourth generation means further comprise second amplification means configured to amplify the fourth inverted audio content with a gain whose value depends on the second distance, and a second processing block configured to perform a compensation processing of the second non-linearity of the frequency response of the first speaker along an axis connecting the first speaker to said second location.

According to one embodiment, the first and fourth audio contents are stereophonic contents and the device further comprises a first pretreatment module coupled between the first reception means and the first and second elaboration means and a second coupled preprocessing module. between the second reception means and the third and fourth generation means,
each pretreatment module comprising a stage for transforming the corresponding stereophonic audio content into monophonic audio content, at least a first and a second processing branch of the monophonic audio content, each branch containing bandpass filtering means followed by a block dynamic compression processing, and summing means coupled to the outputs of said processing branches.

According to one embodiment, each preprocessing module further comprises a third processing branch comprising low-pass filtering means followed by a dynamic compression processing block.

According to one embodiment, each preprocessing module further comprises a fourth processing branch comprising high-pass filtering means followed by a dynamic compression processing block.

The device may further comprise means capable of delivering additional audio content to the two loudspeakers.

The device can be incorporated in a signal processing processor.

• la figure 1 illustre un premier mode de réalisation d'un dispositif selon l'invention ;
• la figure 2 illustre de façon schématique un exemple de mise en oeuvre de l'invention ;
• la figure 3 illustre de façon schématique un exemple de module de prétraitement d'un dispositif de la figure 1 ;
• la figure 4 illustre schématiquement une autre application de l'invention ; et
• les figures 5 à 9 illustrent schématiquement d'autres modes de réalisation et de mise en oeuvre de l'invention.

Other advantages and characteristics of the invention will appear on examining the detailed description of embodiments and embodiments, in no way limiting, and the appended drawings, in which:

• the figure 1 illustrates a first embodiment of a device according to the invention;
• the figure 2 schematically illustrates an example of implementation of the invention;
• the figure 3 schematically illustrates an example of a preprocessing module of a device of the figure 1 ;
• the figure 4 schematically illustrates another application of the invention; and
• the Figures 5 to 9 schematically illustrate other embodiments and implementation of the invention.

On the figure 1 , the reference DISP designates a device for controlling the broadcasting of audio contents on the HPD and HPG loudspeakers of a television set, for example.

This device comprises at its head a digital receiver REC receiving a television signal for example, and delivering a digital signal DSTR to a first audio decoder AD1 of conventional structure and known per se, and a second decoder AD2 also of conventional structure and known in itself.

The digital flow DSTR comprises in fact a first audio content relating for example to a television program, as well as auxiliary audio content, for example an audio description of this television program.

The first audio content is decoded in the audio decoder AD1, while the auxiliary content is decoded in the audio decoder AD2 which delivers here a monophonic output.

The first audio decoder AD1 thus delivers on its two left and right outputs the first audio content CAD1G and CAD1D to a stereophonic mixer MIX of conventional structure and known per se.

The monophonic output of the decoder AD2 delivers the auxiliary audio content CADX to a preprocessing block MPTR which will be discussed in more detail below on the structure.

The signal coming from the MPTR block undergoes a first processing process in first RTD generation means so as to provide a second audio content CADX2.

More precisely, this processing is a time delay of the auxiliary audio content with a delay T which depends on the geometry of the television and more particularly on the spacing W between the speakers of the television set ( figure 2 ) and a distance D between a first speaker, for example the left speaker HPG, and a place located in front of the first speaker and where stands for example a first viewer AUDIT1.

The second audio content CADX2 is delivered on the left channel G of the mixer MIX.

The signal from the preprocessing block MPTR is also subjected to another processing in second processing means, so as to provide a third audio content CADX3.

This second processing process comprises inverting the signal in an inverter INV so as to provide an inverted signal SINV. Then, optionally but preferentially, the inverted signal is amplified with a gain G whose value depends on the distance D. This gain adjustment is performed in an AMPX amplifier.

Then, the amplified signal undergoes equalization Eq in an EQ equalizer of conventional structure and known per se, so as to compensate for the non-linearity of the frequency response of the second speaker, here the right speaker HPD, along an axis Ax ( figure 2 ) connecting this second loudspeaker HPD to the location C where the viewer AUDT1 is located ( figure2 ).

The third audio content CADX3 delivered by the equalizer EU is delivered on the right channel D of the mixer MIX.

Although advantageous, the means AMPX and EQ are not mandatory.

In this respect, it is assumed by referring to figure 2 , that the audio signal delivered to the location B by the speaker HPD is the inverted signal SINV. The signal delivered to location A by the left speaker is the delayed signal CADX2. For the purpose of simplification, it is assumed that in this figure, the speakers HPD and HPG do not deliver the first audio signal CAD1.

The delay T is defined by the formula (1) below: $$\mathrm{T}\mathrm{=}\left(\mathrm{delta\_d}\right)\mathrm{/}\mathrm{vs}$$

In this formula, the variable DELTA_D is defined by the formula (2) below: $$\mathrm{delta\_d}=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="imgf0003.png"\; state="\{\{state\}\}">D</figure-callout>}}^{\mathrm{2}}\mathrm{+}{\mathrm{W}}^{\mathrm{2}}}\mathrm{-}\mathrm{D}$$

In other words, the delay therefore depends on the distance D and the spacing w between the loudspeakers.

As a result, as shown on the curves at the bottom of the figure 2 at the location C, the viewer AUDT1 does not perceive the auxiliary audio content relating to the audio description of the television program. On the other hand, the viewer AUDT2, located at the location D, in front of the right speaker HPD, actually perceives the auxiliary content with an amplitude substantially equal to twice the amplitude of this auxiliary content.

If now we take into account the first audio content CAD1, which is broadcast by the two speakers HPG and HPD, the auditor AUDT1, who is not visually impaired, normally perceives this content CAD1 without being disturbed by the audiodescription of the television program, whereas the auditor AUDT2, who is visually impaired, hears the audio content CAD1 as well as the audiodescription of the program that is being broadcast by the TV.

Thus, it is noted that this implementation and embodiment of the invention makes it possible to control the directivity of the speakers, which basically have a very wide directivity angle.

In order for the CADX3 signal delivered by the HPD loudspeaker to have substantially the same amplitude as the CADX2 signal delivered by the HPG loudspeaker, it is preferable that the inverted signal SINV undergo a gain adjustment in the AMPX amplifier. . The gain G is then a function of the distance D. We can for example use the following function with the gain G expressed in decibels (dB): $$\mathrm{BOY\; WUT}\left(\mathrm{dB}\right)\mathrm{=}\mathrm{-}\mathrm{20}\log \left(\mathrm{D}\mathrm{/}\left(\mathrm{D}\mathrm{+}\mathrm{delta\_d}\right)\right)$$

This gain is there to compensate the additional attenuation due to the distance difference between the viewer AUDT1 and each of the speakers.

Furthermore, it is well known that the frequency response of a loudspeaker is altered when measured outside its main axis AxP ( figure 2 ). Also, in order to obtain better acoustic performances, the non-linearity of the frequency response of the loudspeaker HPD along the axis Ax is compensated by an equalization processing Eq which is a function of the angle alpha ( figure 2 ), so as to be as close as possible to the frequency response of the loudspeaker along its main axis AxP.

ou bien $$H\left(s\right)=\frac{\frac{s}{{\omega }_{\mathit{0}}\left(1+\alpha \right)}+1}{\frac{s}{{\omega }_{\mathit{0}}\left(1-\alpha \right)}+1}$$

avec $$\alpha =\frac{G-1}{G+1}$$

The frequency response following the alpha (off-axis) angle of a loudspeaker is characterized by high frequency attenuation. This attenuation may vary depending on the nature of the speakers used. This attenuation can be compensated by a High Pass Shelving type filter, whose transfer function H (s) can be the following: $$H\left(s\right)=\mathrm{BOY\; WUT}\frac{s+{\omega }_{\mathit{0}}\left(1-\alpha \right)}{s+{\omega }_{\mathit{0}}\left(1+\alpha \right)}$$

or $$H\left(s\right)=\frac{\frac{s}{{\omega }_{\mathit{0}}\left(1+\alpha \right)}+1}{\frac{s}{{\omega }_{\mathit{0}}\left(1-\mathrm{<figure-callout\; id="1"\; label="\alpha \; +"\; filenames="imgf0001.png,imgf0006.png"\; state="\{\{state\}\}">\alpha \; </figure-callout>}\right)}+1}$$

with $$\alpha =\frac{\mathrm{BOY\; WUT}-1}{\mathrm{<figure-callout\; id="1"\; label="BOY\; WUT\; +"\; filenames="imgf0001.png,imgf0006.png"\; state="\{\{state\}\}">BOY\; WUT\; </figure-callout>}+1}$$

In these formulas ω _o is the cutoff frequency and G the gain. G is a function of the speaker used and the alpha angle.

To return now to the figure 1 , the various signals CAD1G, CAD1D, CADX2 and CADX3 are mixed in the stereo mixer MIX. Then, the two left and right channels are converted into a CNA digital conversion stage before being amplified in an AMP amplifier and then delivered to the speakers HPG and HPD.

We now refer more particularly to the figure 3 to illustrate an exemplary embodiment of the preprocessing block MPTR, which allows in particular to improve the quality of the voice.

When the CADX signal delivered by the decoder AD2 is a stereophonic signal, a transformation of the stereophonic auxiliary audio content into a monophonic auxiliary content in a conventional stereophonic / monophonic transformation stage ETTF is first provided.

When the CADX auxiliary audio content is directly monophonic content, this ETTF stage is of course not present in the MPTR block.

The MPTR block also comprises several processing branches, here four processing branches BR1, BR2, BR3 and BR4.

The treatment branches BR1 and BR2 make it possible to improve the auditory quality of the dialogs.

In general, we can identify four characteristic frequency zones in the signal of the human voice (see table below). Low cut Fundamental Sensitive Freq harmonics Male voice 100 Hz 200 Hz 2 kHz (+) 4 to 5 kHz Female voice 120 Hz 300 to 400 Hz 2.5 kHz 5 to 6 kHz Spoken voice 120 Hz 200 Hz 2 to 3 kHz 4 kHz

The characteristics of the four treatment branches are adapted according to these frequencies. Examples of adaptation are given below.

The first processing branch BR1 first comprises a bandpass filtering performed in filtering means FLTBB1. The band concerned here is the band 150Hz - 500Hz.

The second processing branch BR2 also comprises a bandpass filtering performed in FLTBB2 filtering means. But this time, the band concerned is the band immediately higher, namely the band 500Hz ~ 3.5kHz

Each processing branch furthermore comprises, following the filtering means, a dynamic compression block BEXDi.

A dynamic compression block has a conventional structure and is known per se.

As its name implies, a dynamic compression block reduces the dynamics of the audio signal.

Compression is usually defined by a ratio a: b which means that the input level of the signal must increase by "a" decibels to create an increase of "b" decibels at the output, and this when the signal level of entry exceeds a certain threshold.

Moreover, the response time of the compressor when the input level exceeds this threshold, is generally called "attack time" A. When the input level of the signal drops back to below the threshold, the compressor will then take some time to increase the gain again. This duration is called "re-amplification time" D. This duration is generally greater than the duration of attack.

By way of indication, the dynamic compression blocks BEXD1 and BEXD2 have ratios that can be between 1: 2 and 1: 5 with A values of the order of 10 milliseconds and D values between 100 and 400 milliseconds.

These dynamic compression blocks will thus allow equalization of the voice content of the audio signals.

In addition to these two processing branches BR1 and BR2, the pretreatment module MPTR advantageously comprises a third processing branch BR3 also comprising filtering means and a dynamic compression block.

The filtering means FLTBB3 of the processing branch BR3 are this time low-pass filtering means having a cutoff frequency of the order of 150 Hz and allow homogenization of the entire signal so as to reduce in particular the acoustic characteristics of the sound environment.

The ratio of the dynamic compression block BEXD3 can vary this time between 1: 2 and 1: 10 while the value A can be taken equal to 50 milliseconds and the value D between 200 and 500 milliseconds.

The pretreatment module MPTR also preferably comprises a fourth processing branch BR4, comprising high-pass filtering means FLTBB4 having a cut-off frequency of the order of 3.5 kHz, also followed by a dynamic compression block BEXD4 whose The ratio can vary between 1: 2 and 1: 4 with a constant A equal to 3 milliseconds and a constant D also between 50 and 300 milliseconds. The fourth branch of treatment will allow in particular to correct the brightness and clarity of sound.

The outputs of the four processing branches are summed and the resulting signal is output to the BSS output of the preprocessing module.

The different filtering means can preferably be made with finite impulse response filters having linear phases, or with infinite impulse response filters, such as biquadratic filters.

The entire device DISP can be incorporated into a DSP processing processor that can itself be incorporated into a set top box or directly into the TV.

We are now referring particularly to figures 4 and following to illustrate other possible applications of the invention.

On the figure 4 , it is assumed that a TV set simultaneously broadcasts two programs on the screen, ie on the left side of the screen, a PRP main program and on the right side of the screen a PRX auxiliary program.

As illustrated on the figure 7 , each speaker has a broad directivity DVG, DVD. In other words, these angles are such that an auditor AUDT1 located in front of a loudspeaker can also perceive the sound emitted by the other speaker.

If we now refer more specifically to the figure 5 , we see that the device DISP comprises in a similar way to what has been described with reference to the figure 1 a digital receiver REC delivering the digital stream DSTR comprising a first audio content relating to the main program PRP and other audio content relating to the auxiliary program PRX. Each of the audio contents is decoded in a respective audio decoder AD1, AD2.

The corresponding decoded stereo audio contents are pretreated in respective MPTR1 and MPTR2 pretreatment modules of structures analogous to that of the MPTR pretreatment module described with reference to FIG. figure 3 .

The preprocessing module MPTR1 thus delivers the first audio content CAD1, while the preprocessing module MPTR2 delivers a CAD4 audio content that is called here fourth audio content.

These two audio contents will undergo a cross-deletion processing in a CCN stage illustrated more specifically on the figure 6 .

In fact, there are duplicated in this NCC floor, the means of development that have been described in detail with reference to the figure 1 .

More precisely, the stage CCN comprises first means of production, comprising first delay means RTD1, configured to temporally delay the first audio content CAD1 with a delay T1 depending on the spacing W between the loudspeakers, and a first distance D1 between a first speaker (for example the right loudspeaker HPD), and a first place located opposite this first speaker and where the viewer AUDT2 stands.

The delay means RTD1 deliver the second audio content CAD2.

The stage CCN also comprises second processing means comprising first inversion means INV1 for reversing the first audio content CAD1. These first inversion means are followed by first amplification means AMPX1 and first equalization means EQ1.

The first equalization means deliver the third audio signal CAD3.

In a manner similar to that described with reference to the figure 1 , the gain adjustment G1 depends on the first distance D1 while the equalization Eq depends on the angle alpha1.

The stage CCN also comprises third generation means comprising second delay means RTD2 configured to temporally delay the fourth audio content CAD4 with a delay T2 depending on the spacing W between the speakers and a second distance D2 between the second speaker (here the HPG left speaker) and a second place located in face of this second speaker and where stands the viewer AUDT1.

The second delay means RTD2 deliver a fifth audio content CAD5.

Furthermore, the CCN stage also comprises fourth generation means comprising second inversion means INV2 configured to perform a reversal of the fourth audio content CAD4. These second inversion means INV2 are followed by second amplification means AMPX2 and second equalization means EQ2 which deliver a sixth audio content CAD6. The gain adjustment made in the second amplification means AMPX2 depends on the second distance D2 while the equalization processing Eq depends on the angle alpha2.

The third audio content CAD3 and the fifth audio content CAD5 are summed in a first adder ADD1 in order to be delivered on the left channel G of the mixer MIX (not shown for simplification purposes). figure 5 ).

Likewise, the second audio content CAD2 and the sixth audio content CAD6 are summed in a second adder ADD2 before being delivered on the right channel D of the mixer MIX.

So, as we see on the figure 7 , the sound distribution space of the loudspeakers comprises three zones, namely a zone ZPRP coming from the left speaker HPG and in which are present the audio contents relating to the main program and the auxiliary program, a zone ZPRX resulting from speaker right HPD and in which are also present the audio content of the main program and the auxiliary program, and a ZSP zone in which are located viewers AUDT1 and AUDT2.

In the left part of this zone ZSP, that is to say where the viewer AUDT1 is, the audio content relating to the auxiliary program PRX is not audible by the viewer AUDT1, and consequently this one does not perceive as audio content related to the main program.

On the other hand, in the right part of the zone ZSP, the viewer AUDT2 does not perceive the audio content relating to the main program and only perceives the audio content relating to the auxiliary program PRX.

The Figures 8 and 9 schematically illustrate an application of the invention to a video game.

In this case, the device DISP is preferentially incorporated in a game console. The device DISP comprises generation means GS1 capable of delivering an audio content intended for the player PL1 ( figure 9 ).

GS2 generation means deliver audio content for the PL2 player.

In a manner similar to that described with reference to the figure 5 , the device DISP comprises a preprocessing block MPTR1 and a preprocessing block MPTR2 respectively delivering the first and fourth audio contents CAD1 and CAD4 to a stage CCN similar to that illustrated on FIG. figure 6 .

In addition to these means, the DISP device of the figure 8 comprises means GAM capable of generating additional audio content, for example, a background ambient sound. All audio contents are stereo-mixed in a MIX mixer and converted to a DAC digital-to-analog converter before being amplified in an AMP amplifier and broadcast on the HPG and HPD speakers.

Again, as illustrated on the figure 9 the HPG and HPD loudspeakers have three zones, ZPL1, ZPL2 and ZSP.

In zones ZPL1 and ZPL2, the set of audio contents is audible.

On the other hand, as in figure 7 , the ZSP zone is a zone of acoustic suppression of certain audio contents.

More precisely, in the left part of the ZSP zone, that is to say where the player PL1 is, the player will only perceive the background and the sound that is intended for him. Similarly, in the right part ZSP zone, that is to say where the PL2 player is, it will also perceive the sound of the atmosphere and the sound that is intended for him.

Each player will not be disturbed by the audio content intended for the other player.

Other applications of the invention are possible in which two different images broadcast simultaneously do not occupy each of the screen halves. This is the case, for example, for 3D televisions where a first person equipped with 3D glasses views a first image and a second person, also equipped with 3D glasses, displays a second image. However, the two people are not mutually disturbed at the sound level.

Claims (27)

A method of controlling the broadcast of audio contents by two loudspeakers, comprising delivering a first audio content (CAD1) to the two loudspeakers (HPG, HPD), receiving audio auxiliary content (CADX), developing a second audio content (CADX2) having a time delay of the auxiliary audio content with a delay (T) dependent on the spacing (W) between the speakers and a distance between a first speaker and a speaker; located in front of this first speaker, a delivery of the second audio content to this first speaker (HPG), a development of a third audio content (CADX3) including a reversal of the auxiliary audio content and a delivery of the third audio content to the second speaker (HPD). The method of claim 1, wherein developing the third audio content further comprises amplifying (AMPX) the inverted auxiliary audio content with a gain the value of which depends on said distance, and non-compensating (EQ) processing. linearity of the frequency response of the second speaker along an axis connecting the second speaker to said location. Method according to one of the preceding claims, wherein the auxiliary audio content is a monophonic content and the method further comprises a preprocessing (MPTR) of the auxiliary audio content before the development of the second and third audio contents, said preprocessing comprising at least a first and a second elementary processing of the monophonic auxiliary audio content, each elementary processing containing band-pass filtering followed by dynamic compression processing, and a summation of the signals respectively derived from said elementary treatments. Method according to one of claims 1 or 2, wherein the auxiliary audio content is stereophonic content and the method further comprises pretreatment (MPTR) of the auxiliary audio content prior to the development of the second and third audio contents, which pretreatment includes a transformation of the stereophonic auxiliary audio content into a monophonic auxiliary audio content, at least a first and a second elementary processing of the monophonic auxiliary audio content, each elementary processing containing bandpass filtering followed by dynamic compression processing, and a summation of the signals respectively derived from said elementary treatments. The method of claim 3 or 4, wherein the pretreatment further comprises a third elementary processing (BR3) comprising a low pass filtering followed by a dynamic compression process. The method of claim 5, wherein the pretreatment further comprises a fourth elementary processing (BR4) comprising high-pass filtering followed by dynamic compression processing. Method according to one of the preceding claims, wherein the auxiliary audio content (CADX) is an audio description of a video content. A method of controlling the broadcast of audio contents by two loudspeakers, comprising a reception of a first audio content (CAD1), a development of a second audio content (CAD2) comprising a temporal delay of the first audio content with a delay depending on the spacing between the loudspeakers and a first distance between a first speaker and a first place located in front of the first speaker, a delivery of the second audio content to the first speaker, an elaboration a third audio content (CAD3) comprising an inversion of the first audio content and delivery of the third audio content to the second speaker, reception of a fourth audio content (CAD4), development of a fifth audio content ( CAD5) having a time delay of the fourth audio content with a delay depending on the spacing between the speakers and a second distance between the second speaker and a second location opposite the second speaker, delivering the fifth audio content to the second speaker, developing a sixth audio content (CAD6) including a reverse fourth audio content and delivery of the sixth audio content to the first speaker. The method of claim 8, wherein developing the third audio content further comprises amplifying (AMPX1) the first inverted audio content with a gain whose value depends on the first distance, and a compensation processing (EQ1) of the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said first location, and developing the sixth audio content further comprises amplifying (AMPX2) the fourth inverted audio content with a second speaker; gain whose value depends on the second distance, and a compensation processing (EQ2) for the non-linearity of the frequency response of the first speaker along an axis connecting the first speaker to said second location. Method according to one of claims 8 or 9, wherein the first and fourth audio contents are stereophonic contents and the method further comprises a first preprocessing (MPTR1) of the first audio content prior to the development of the second and third audio contents and a second preprocessing (MPTR2) of the fourth audio content before the development of the fifth and sixth audio contents, each pretreatment comprising a transformation of the corresponding stereophonic audio content into monophonic audio content, at least a first and a second elementary processing of the monophonic audio content , each elementary treatment containing band-pass filtering followed by dynamic compression processing, and a summation of the signals respectively derived from said elementary treatments. The method of claim 10 wherein the pretreatment further comprises a third elemental treatment
(BR3) having low pass filtering followed by dynamic compression processing. The method of claim 11, wherein the pretreatment further comprises a fourth elementary processing (BR4) comprising high-pass filtering followed by dynamic compression processing. The method of one of claims 8 to 12, further comprising providing (GAM) additional audio content to both speakers. Device for controlling the broadcasting of audio contents by two loudspeakers, comprising first delivery means configured to deliver a first audio content (CAD1) to the two loudspeakers, receiving means (REC) configured to receive audio content auxiliary, first generation means configured to develop a second audio content having delay means (RTD) configured to temporally delay the auxiliary audio content with a delay depending on the spacing between the speakers and a distance between a first speaker and a location opposite the first speaker, second delivery means configured to deliver the second audio content to the first speaker, second generation means configured to develop a third audio content. having inversion means (INV) configured to invert the auxiliary audio content and the three second delivery means configured to deliver the third audio content to the second speaker. An apparatus according to claim 14, wherein the second generating means further comprises amplification means (AMPX) configured to amplify the inverted auxiliary audio content with a gain whose value depends on said distance, and a processing block ( EQ) configured to perform compensation processing of the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said location. Device according to one of claims 14 or 15, wherein the auxiliary audio content is a monophonic content and the device further comprises a pretreatment module (MPTR) coupled between the receiving means and the first and second means of production, this preprocessing module comprising at least a first and a second processor branches of the monophonic auxiliary audio content, each processing branch containing bandpass filtering means followed by a dynamic compression processing block, and summing means coupled to the outputs of the processing branches. Device according to one of claims 14 or 15, wherein the auxiliary audio content is stereophonic content and the device further comprises a pretreatment module (MPTR) coupled between the receiving means and the first and second means of production, this preprocessing module comprising a stage (ETTF) for transforming the stereophonic auxiliary audio content into a monophonic auxiliary audio content, at least a first and a second processor branches of the monophonic auxiliary audio content, each processing branch containing filtering means passes band followed by a dynamic compression processing block, and summing means coupled to the outputs of the processing branches. Apparatus according to claim 16 or 17, wherein the preprocessing module further comprises a third processing branch (BR3) having low pass filtering means followed by a dynamic compression processing block. Apparatus according to claim 18, wherein the preprocessing module further comprises a fourth processing branch (BR4) having high-pass filtering means followed by a dynamic compression processing block. Apparatus according to one of claims 14 to 19, wherein the receiving means (REC) is configured to receive an audio description of a video content as auxiliary audio content. Device for controlling the broadcasting of audio contents by two loudspeakers, comprising
first reception means (REC) configured to receive a first audio content,
first generating means configured to develop a second audio content having first delay means (RTD1) configured to temporally delay the first audio content with a delay depending on the spacing between the speakers and a first distance between a first speaker and a first place in front of that first speaker,
first delivery means configured to deliver the second audio content to that first speaker,
second generating means configured to develop a third audio content having first inverting means (INV1) configured to invert the first audio content,
second delivery means configured to deliver the third audio content to the second speaker,
second receiving means (REC) configured to receive a fourth audio content,
third generation means configured to develop a fifth audio content having second delay means (RTD) configured to temporally delay the fourth audio content with a delay dependent on the spacing between the speakers and a second distance between the second speaker and a second place in front of that second speaker,
third delivery means configured to deliver the fifth audio content to that second speaker,
fourth generation means configured to develop a sixth audio content having second inverting means (INV2) configured to invert the fourth audio content, and
fourth delivery means configured to deliver the sixth audio content to the first speaker. Device according to claim 21, wherein
the second generating means further comprises first amplification means (AMPX1) configured to amplify the first inverted audio content with a gain whose value depends on the first distance, and a first processing block (EQ1) configured to perform a compensation processing of the non-linearity of the frequency response of the second speaker along an axis connecting the second speaker to said first location, and
the fourth generation means further comprise second amplification means (AMPX2) configured to amplify the fourth inverted audio content with a gain whose value depends on the second distance, and a second processing block (EQ2) configured to perform compensation for the non-linearity of the frequency response of the first speaker along an axis connecting the first speaker to said second location. Device according to one of claims 21 or 22, wherein the first and fourth audio contents are stereophonic contents and the device further comprises a first preprocessing module (MPTR1) coupled between the first reception means and the first and second means a second pretreatment module (MPTR2) coupled between the second receiving means and the third and fourth producing means,
each preprocessing module (MPTR) comprising a stage for transforming the corresponding stereophonic audio content into monophonic audio content, at least a first and a second processing branch of the monophonic audio content, each branch containing bandpass filtering means followed by a dynamic compression processing block, and summing means coupled to the outputs of said processing branches. Apparatus according to claim 23, wherein each preprocessing module further comprises a third processing branch (BR3) having low pass filtering means followed by a dynamic compression processing block. Apparatus according to claim 24, wherein each preprocessing module further comprises a fourth processing branch (BR4) comprising high-pass filtering means followed by a dynamic compression processing block. Device according to one of claims 21 to 25, further comprising means (GAM) adapted to deliver additional audio content to the two speakers. Device according to one of claims 14 to 26, incorporated in a signal processing processor (DSP).

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