Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S1/00—Two-channel systems
  • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
  • H04S3/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S2420/00—Techniques used stereophonic systems covered by H04S but not provided for in its groups
  • H04S2420/11—Application of ambisonics in stereophonic audio systems

Definitions

• the sound exchanges essentially concern the emission and reception of sound signals, directly perceptible to the human ear. These include sound signals provided by radio, telephone, messaging, television and others.
• the current techniques consist of either making a spatialized sound recording in the studio, or performing a non-real-time and manual studio treatment, in particular for the spatialization of movie soundtracks.
• ambisonic technique Another example of physical reconstruction of the acoustic field is known as ambisonic technique, which uses a decomposition of the sound field on the basis of eigenfunctions called "spherical harmonics".
• the known technique of stereophony exploits the differences in propagation time or loudness to position the sound sources between two or more speakers, from interaural differences in time and of intensity that define the perceptual criteria of auditory localization in a substantially horizontal plane.
• the binaural techniques aim to reconstruct the acoustic field only in the vicinity of the listener's ears, so that the eardrums of the latter perceive an acoustic field substantially identical to that which would have been generated by real sources.
• the object of the present invention is to overcome the drawbacks of the techniques of the prior art, in order to allow the widest application of spatialization techniques to any monophonic and / or stereophonic sound signal, or even to a more complex sound signal.
• the subject of the present invention is a method for spatialising a sound signal that is remarkable in that it consists at least in subdividing this sound signal into successive frames, analyzing the frames of the sound signal in blocks of frames to determine at least a spectral and / or physiological parameter of this sound signal in each frame, assigning each frame an index representative of at least this spectral and / or physiological parameter, to generate a series of classified frames and to submit each frame or group of classified frames , assigned the same index, to a spatialization processing, depending on the value of this index assigned to each frame.
• the subject of the present invention is furthermore a system for spatializing a remarkable sound signal in that it comprises at least, in combination, a module for analyzing this sound signal in successive frames, to determine and assign to each frame successively an index representative of at least one spectral and / or physiological parameter of said sound signal in each frame, to generate a sequence of indexes of classified frames and a processing module of each frame or group of frames of the sound signal, classified and assigned the same index, according to a spatialization processing, depending on the value of the assigned index.
• the invention is applicable to the electronics industry for processing sound signals, in particular stereo or mono-phonic signals, recording phonograms and / or videograms, to the fixed telephony industry. or mobile, to voice communication and / or transmission of speech signals over the IP network.
• FIG. 1a represents, purely by way of illustration, a flowchart of the essential steps for implementing the method that is the subject of the present invention
• FIG. 1b represents, for purely illustrative purposes, a method of classifying acoustic frames according to acoustic classes, according to a remarkable aspect of the method, object of the present invention
• FIGS. 2a and 2b represent, by way of illustration, a nonlimiting variant of implementation of the method which is the subject of the present invention applied in the deferred mode, either to the recording and restitution, or to the partial offline diffusion, or still the real-time online communication of phonograms and / or the sound portion of videograms, according to the method object of the present invention;
• FIG. 3 a represents, by way of illustration, a spatialization system of a sound signal, in accordance with the subject of the present invention, operating in partial offline diffusion mode;
• FIG. 3b represents, by way of illustration, a system for spatializing a sound signal in online communication mode, more particularly intended for devices of the telephone or other type.
• the method which is the subject of the invention is implemented on a sound signal SS, this sound signal corresponding for example to a digital signal, digital audio, speech or telephony, for example.
• the method which is the subject of the invention consists, in the first place, in a step A in subdividing the sound signal SS into successive frames. The subdivision operation is noted
• the aforementioned subdivision step can be executed in a conventional manner by subdividing the signal into successive frames with a duration of between 10 and 20 milliseconds, for example, typically 16 milliseconds. A sampling of the sound signal is thus performed to obtain a succession of contiguous frames for example, i denoting the rank of the frame. Typical values are frames with a duration of 32 milliseconds, calculated every 16 milliseconds, thus with an overlap of 16 milliseconds.
• Step A is followed by a step B of analyzing a block of frames of the sound signal TSS, to determine at least one spectral and / or physiological parameter of the sound signal in each frame.
• step B of analyzing each frame is represented by the relation
• [PspjJo denotes a set of spectral and / or physiological parameters resulting from the analysis.
• spectral and / or physiological parameter of the sound signal it is indicated that this or these parameters may correspond for example to a frequency parameter for a musical signal, a formant for a speech signal or the like, as will be described later in the description. It is understood in particular that several significant parameters can be associated with each frame in particular when the sound signal
• SS is a signal that includes both music and song lyrics, for example, or in other situations.
• the number of spectral and / or physiological parameters assigned to each frame is not limiting, as will be described later in the description.
• Step B is then followed by a step C of assigning to each frame TSSj an index representative of at least one spectral or physiological parameter to generate a sequence of classified frames.
• step C of assigning an index is represented by the symbolic relation
• index assigned to each frame corresponds for example to an index j assigned a sub-index k, the subindex k allowing, for example, to specify classification variants for the main classification j assigned to each frame.
• Step C thus makes it possible to obtain a fine classification of each frame as a function of the spectral and / or physiological parameter or parameters of the sound signal SS in the frame considered TSSi.
• Step C is then followed by a spatialization step D itself, this step consisting in submitting each classified frame or group of frames of the same index and noted to the same spatialization processing function of the value of the aforementioned index assigned to the frame in question.
• S j , k (.) Indicates the specific spatialization treatment applied to any rank i-frame to which the index j, k has been assigned or to any corresponding frame group. It is understood in particular that for a frame duration typically equal to 16 milliseconds, for example, a succession of frames can of course be assigned the same index j, k.
• step D of FIG. 1a is followed by a step E consisting of comparing the value of rank i of the frame considered TSSj with a maximum value I of the decomposition or subdivision into frames.
• the rank of the frame considered i is incremented to the value i + 1 in step F to return to step A and continue the process as long as there is a frame not subject to the subdivision process of step A to ensure the complete processing of the SS sound signal. More specifically, it is indicated that the method that is the subject of the invention with reference to FIG. 1b consists in classifying each frame or group of frames according to a plurality of acoustic classes denoted by C j .
• each acoustic class C j such as Music, Speech / Talker Type, Brouhaha, or Silence, for example, can be associated with an index value j taking the corresponding value 0, 1, 2, 3. for the aforementioned acoustic classes in a non-limiting manner.
• the value of the index j, 0, 1, 2 or 3 is a value obtained by analysis from the spectral and / or physiological parameters of the sound signal SS in each frame and that the value subindex k associated with each index value may be an arbitrary value or corresponding to a particular quality of the sound signal.
• the technique used to process documents that are a priori unknown is the following: - a change of speaker is detected (break in the signal of a particular index);
• the speaker after change is compared to all the speakers already identified in the document and he is either recognized as one of them, or considered as a new speaker and therefore increases the size of the "reference dictionary" of speakers for this document or sound signal.
• the spatialization process applied to each classified frame may be chosen from among a plurality of spatialization processes such as reverberation, attenuation, the fundamental frequency change, the harmonic filtering coloration, the delay for example, or the holophonie, stereophonic, binaural or other techniques. It will be understood that for any index value j and subindex k assigned to each frame TSSj or group of frames can thus be chosen, as a function of the aforementioned index and subindex value, a specific spatialization treatment. and in particular the most appropriate treatment according to the desired effect.
• the processing may consist in applying a so-called "fun" effect by changing the speech signal.
• voice tone for example, for one or more speakers of the SS sound signal.
• the method which is the subject of the invention thus makes it possible to automatically apply sound renderings or differentiated sound positions to any sound documents which result in SS sound signals for which no additional information is available or for which there is no control. not the sound.
• the latter also makes it possible to reduce the load or the bit rate of the networks or the spectrum of the radio waves, since while the transmission of the sound signal SS can be carried out on a signal monophonic for example, he. then it is quite possible to execute the spatialization process upon reception of this signal and therefore after transmission at least from the point of view of the load or the speed of the transmission network.
• the method which is the subject of the invention can advantageously be executed in off-line mode in deferred time.
• steps A, B represent the same steps as those bearing the same reference in FIG.
• the index assignment step can then be subdivided into a step Co corresponding to choosing the corresponding index j and subindex k, assigned to each frame TSSj, the step Co being followed by a step C 1 consisting of compare the rank of the frame i to the final value I representative of the number of frames.
• step C 1 consisting of compare the rank of the frame i to the final value I representative of the number of frames.
• step Ci On the contrary, on a positive response to the test of step Ci, a record C 3 of all the frames noted [TSSiJ, and a series of indexes noted
• step C 3 refers to a recording on any storage medium such as, for example, a non-volatile memory, a permanent memory, a CD or DVD type optical recording disk. example.
• the offline mode implementation in deferred time of the method which is the subject of the invention then consists, as represented in FIG. 2b, from the record available, obtained in step C 3 , of reading the support of corresponding record, comprising at least the index sequence assigned to the. sound signal subdivided into frames and the sound signal or at least the sequence of frames representative of the latter in a step C shown in Figure 2b.
• step D 0 is then followed by a step D 1 of applying to the sound signal and to each current frame of this sound signal, a spatialization processing function of the index assigned to the current frame of the sound signal according to the symbolic relationship of step D of figure la.
• the spatialized sound signal is thus restored in accordance with the method that is the subject of the present invention.
• the method that is the subject of the present invention can also be implemented in offline broadcast mode with a limited time offset, not exceeding the duration of a few frames, by analysis and classification of each successive frame and successive spatialization processing. each frame according to the assigned index.
• step C3 the recording operation as described in connection with Figure 2a in step C3 can be started.
• the system adapts to the recording.
• the method that is the subject of the present invention can be executed in line communication mode with minimum time shift, not exceeding the duration of a frame, by analyzing and classifying and spatially processing each frame of the delayed sound signal to a maximum of one frame duration.
• FIGS. 2a and 2b can be performed with storage in a memory such as a random access memory for example, the time offset being able to be reduced to the calculation time of the analysis operation of frame and index assignment for a current frame, that is to say the B and Co steps of Figure 2a, this calculation time can of course be made much smaller than the duration of a frame.
• the abovementioned procedure for execution in online communication mode of the method that is the subject of the present invention can advantageously be used for a spatialization processing of a telephone communication, for example, on a speech signal transmitted over a fixed or mobile telephone network. for example. It can also be implemented in online communication mode for the transmission of an IP network speech signal - for example.
• FIGS. 3a and 3b A more detailed description of a spatialization system of a sound signal according to the subject of the present invention will now be given in connection with FIGS. 3a and 3b.
• the system which is the subject of the invention comprises at least in combination a module 1 for analyzing the sound signal in successive frames in order to determine and assign to each successive frame an index representative of minus one spectral and / or physiological parameter of the sound signal in each frame to thus generate a sequence of indexes of classified frames.
• the index sequence of classified frames is represented by the relation
• the system according to the invention furthermore comprises a module 2 for processing each frame or group of frames of the sound signal SS and in particular frames classified and assigned the same index according to a same spatialization processing, a function of the value of the assigned index and, as previously described in the description, of the sub-index k associated with any index value j representative of an acoustic class.
• the spatialization processing module 2 is able, from the sequence of indexes of the aforementioned classified frames and, of course, from the sequence of frames which it has at its disposal. apply the spatialization processing and reproduce the spatialized sound signal on a set of loudspeakers denoted HP in FIGS.
• the analysis module 1 delivers to the spatialization processing module 2 a signal representative of the index sequence as indicated above, as well as either the sound signal SS or the sequence of frames [TSSi] J shifted (e) temporeinlement of a duration substantially equal to a plurality of frame duration to the spatialization processing module 2.
• the analysis module 1 and the processing module 2 are connected substantially in parallel as shown in the above-mentioned figure, to execute each subdivided into frames in parallel with the sound signal.
• the analysis module 1 and the spatialization processing model 2 may advantageously each comprise a frame subdivision module, bearing the reference Io respectively 20 , which are synchronized by a signal synchronization S y exchanged for example between the module 1 and module 2 analysis processing by spatialization.
• the analysis module 1 furthermore comprises a module 1 1 executing the operations B and C of FIG. 1a, that is to say allowing the analysis of frames and the assignment of indexes to generate the sequence of classified frames and, in particular, the index sequence previously described.
• the spatialization processing module 2 comprises a processing module ensuring the actual spatialization operation on the series of classified frames.
• FIG. 3b it is indicated that the processing of analysis module 1 and, in particular, the module I 1 of the latter can be much lower than that of a frame duration, which makes it possible to ensure a mode of operation of the system shown in Figure 3b with a processing time much lower than a frame time.
• the corresponding system then appears particularly well suited to processing the sound signal SS in online communication mode under the conditions indicated above in the description.
• the method which is the subject of the present invention and the corresponding system as described in FIGS. 3a and 3b can be implemented from corresponding software modules and in particular from a program recorded on a storage medium and executed by a computer.
• this module makes it possible to execute the subdivision into frames, as well as software modules allowing the analysis of each successive frame of the signal. sound to determine at least one spectral and / or physiological parameter of the sound signal in each frame, and then assign to each frame the representative index of the spectral and / or physiological parameter to generate a sequence of classified frames, that is to say say the signal corresponding to the index sequence previously described in the description.
• These operations are executed by a software module I 1 implanted on the analysis module 1 represented in FIG. 3a or 3b.
• the spatialization module 2 ⁇ which makes it possible to execute and submit each frame to the group of classified frames affected. from the same index to a spatialization process according to the value of the index assigned to each frame.
• the operating mode is that shown in FIG. 1a.
• the sound signal SS is then successively subjected to the steps A, B, C, D and E of the above-mentioned figure on a terminal from a transmitted SS sound signal. via IP packets without any prior processing performed at the server transmitting the corresponding html pages.
• the operating mode corresponds to an on-line processing with a processing delay corresponding to at most one frame duration.

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• Stereophonic System (AREA)

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• 2006
  • 2006-03-15 EP EP06743580A patent/EP1869949A1/de not_active Withdrawn
  • 2006-03-15 WO PCT/FR2006/000580 patent/WO2006097633A1/fr not_active Application Discontinuation

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