WO2020008889A1 - オーディオ信号処理装置および方法、インパルス応答生成装置および方法、並びにプログラム - Google Patents
オーディオ信号処理装置および方法、インパルス応答生成装置および方法、並びにプログラム Download PDFInfo
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- WO2020008889A1 WO2020008889A1 PCT/JP2019/024440 JP2019024440W WO2020008889A1 WO 2020008889 A1 WO2020008889 A1 WO 2020008889A1 JP 2019024440 W JP2019024440 W JP 2019024440W WO 2020008889 A1 WO2020008889 A1 WO 2020008889A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R5/00—Stereophonic arrangements
- H04R5/033—Headphones for stereophonic communication
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- 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
- H04S1/005—For headphones
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- 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
- H04S2420/01—Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
Definitions
- the present technology relates to an audio signal processing device and method, an impulse response generation device and method, and a program, and in particular, an audio signal processing device and method, an impulse response generation device and method capable of obtaining a desired phase characteristic, And the program.
- the amplitude characteristic of the audio signal can be adjusted, but the phase characteristic of the audio signal cannot be set to a desired characteristic.
- the present technology has been made in view of such a situation, and is intended to obtain a desired phase characteristic.
- An audio signal processing device includes an acquisition unit that acquires an impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic, and a phase that convolves the impulse response with an input audio signal.
- a characteristic folding section .
- An audio signal processing method or program includes a step of acquiring an impulse response having a flat or substantially flat amplitude characteristic and having a predetermined phase characteristic, and convolving the impulse response with an input audio signal. Including.
- an impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic is obtained, and the impulse response is convolved with an input audio signal.
- the impulse response generation device generates a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic.
- the impulse response generation method or program according to the second aspect of the present technology includes a step of generating a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic.
- a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic is generated.
- desired phase characteristics can be obtained.
- FIG. 3 is a diagram illustrating a relationship between a frequency characteristic and an impulse response.
- FIG. 4 is a diagram for describing reconstruction of an impulse response.
- FIG. 4 is a diagram illustrating frequency characteristics of a reconstructed impulse response.
- FIG. 4 is a diagram for describing reconstruction of an impulse response.
- FIG. 4 is a diagram illustrating frequency characteristics of a reconstructed impulse response.
- FIG. 4 is a diagram for describing reconstruction of an impulse response.
- FIG. 4 is a diagram illustrating frequency characteristics of a reconstructed impulse response. It is a figure showing the example of composition of an impulse response generation device. It is a flowchart explaining an impulse response generation process. It is a figure showing the example of composition of an impulse response generation device. It is a flowchart explaining an impulse response generation process.
- FIG. 3 is a diagram illustrating content mastering. It is a figure showing the example of composition of a reproducing device. It is a flowchart explaining a reproduction process. It is a figure showing the example of composition of a reproducing device. It is a flowchart explaining a reproduction process. It is a figure showing the example of composition of a reproducing device. It is a flowchart explaining a reproduction process. It is a figure showing the example of composition of a reproducing device. It is a flowchart explaining a reproduction process. It is a figure showing the example of composition of a reproducing device.
- FIG. 11 is a diagram illustrating a configuration example of a computer.
- the present technology generates an impulse response having a flat or substantially flat amplitude characteristic and a desired phase characteristic, thereby adjusting only the phase characteristic while maintaining the amplitude characteristic of the audio signal, and achieving the desired phase characteristic. That you can get.
- the amplitude characteristic is flat or almost flat, and Impulse response having the following phase characteristics can be obtained.
- the amplitude characteristic is flat or substantially flat means, for example, that the value of the amplitude (gain) at each frequency of the amplitude characteristic is 1 or substantially 1.
- a target impulse response is generated by the following method A1 or method A2.
- 0 data zero data
- FFT fast Fourier transform
- the amplitude characteristic and the phase characteristic can be obtained by such an FFT.
- the amplitude (gain) value at each frequency of the amplitude characteristic is set to 1 so that the amplitude characteristic becomes flat, and the flat amplitude characteristic and the FFT IFFT (Inverse Fast Fourier Transform) is performed on the basis of the phase characteristics obtained in step (1). Then, the subsequent stage of the impulse response obtained by the IFFT is subjected to fade processing with an appropriate time constant to obtain a target impulse response.
- the impulse response thus obtained functions as an IIR (InfiniteInImpulse Response) filter that changes only the phase characteristic while maintaining the amplitude characteristic. Therefore, only the phase characteristic can be adjusted by convolving such an impulse response with the audio signal.
- IIR InfiniteInImpulse Response
- FFT is performed without inserting zero data into an impulse response whose phase is to be simulated, and FFT is performed with zero data inserted into a simple impulse.
- phase characteristic obtained by the FFT for the impulse response and the phase characteristic obtained by the FFT for the simple impulse in which 0 data is inserted are added, and the obtained phase characteristic and the value of the amplitude at each frequency are added.
- IFFT is performed based on the flat amplitude characteristic in which is 1. Further, the subsequent stage of the impulse response obtained by the IFFT is faded with an appropriate time constant to obtain a desired impulse response.
- an impulse response having characteristics similar to those in method A1 can be obtained.
- an IIR filter that changes only the phase characteristic while maintaining the amplitude characteristic can be obtained.
- the phase characteristic obtained by the FFT for the impulse response and the phase characteristic obtained by the FFT for the simple impulse into which 0 data is inserted are subtracted instead of added, so that the original impulse response is obtained. It is possible to obtain an impulse response having a characteristic opposite to the phase characteristic.
- the audio signal of the content is convolved with the impulse response having the opposite characteristic to the phase characteristic of the headphone, and the impulse response having the same phase characteristic as that of the speaker is convolved to cancel the phase characteristic of the headphone.
- the creator will produce it in the mastering studio. It is assumed that the user can experience the same sound as the sound that is present.
- FIG. 1 shows the relationship between the frequency characteristics of an IIR HPF having a cutoff frequency Fc of 50 Hz, that is, the amplitude characteristics (gain characteristics) and phase characteristics, and the impulse response of the HPF.
- the portion indicated by arrow Q11 indicates the amplitude characteristics of the frequency characteristics of the HPF
- the portion indicated by arrow Q12 indicates the phase characteristics of the frequency characteristics of the HPF.
- the vertical axis in the amplitude characteristics indicates gain (amplitude), and the horizontal axis indicates frequency.
- the vertical axis in the phase characteristic indicates the phase, and the horizontal axis indicates the frequency. From this frequency characteristic, it can be seen that the gain is small and the phase is a positive value on the low frequency side of the HPF.
- the impulse response of the HPF is shown in the portion indicated by arrow Q13.
- the vertical axis of the impulse response indicates amplitude, and the horizontal axis indicates time, that is, a time sample (sample).
- the impulse response of the HPF is enlarged in the vicinity of the 0th sample.
- Such an impulse response can be used as an IIR filter.
- the audio signal By convolving the impulse response indicated by arrow Q13 with the audio signal, the audio signal can be subjected to HPF filtering.
- the frequency characteristics of the HPF that is, the amplitude characteristics and the phase characteristics, and the impulse response of the HPF have a reversible relationship although there is a conversion error.
- an impulse response indicated by arrow Q13 is ideally obtained.
- the FFT is performed on the impulse response indicated by the arrow Q13, ideally, a frequency characteristic including the amplitude characteristic indicated by the arrow Q11 and the phase characteristic indicated by the arrow Q12 is obtained.
- the impulse response to be obtained by reconstruction is an impulse response in which only the phase characteristic shown in FIG. 1 is added to the audio signal without changing the amplitude characteristic, that is, a desired impulse response without changing the amplitude characteristic.
- This is an impulse response to which only the phase characteristic is added.
- the phase characteristic of the target speaker can be changed without changing the amplitude characteristic. It can be added to the sound of the content. This allows the listener (user) to experience substantially the same sound as the sound produced by the creator in the mastering studio.
- an impulse response that functions as a filter that adds a desired phase characteristic without changing the amplitude characteristic is also referred to as a target phase characteristic impulse response.
- a zero padding process of adding 0 data which is a sample whose sample value is 0, is performed on the rear side (end) of the impulse response in the time direction, and the entire length (number of samples) of the impulse response is 4096. Make it a sample.
- the target target phase characteristic impulse response has a flat or substantially flat amplitude characteristic
- the phase characteristic is the phase characteristic indicated by arrow Q12.
- the amplitude (gain) value of each frequency in the amplitude characteristic obtained by the FFT is adjusted to “1”.
- the amplitude of the amplitude characteristic obtained by the FFT is adjusted so as to have a flat amplitude characteristic.
- phase characteristic obtained by the FFT should be the target phase characteristic shown by the arrow Q12, no particular phase adjustment is performed on the phase characteristic obtained by the FFT.
- IFFT is performed on the frequency characteristic including the flat amplitude characteristic obtained by the amplitude adjustment and the phase characteristic obtained by the FFT.
- the impulse response obtained by the IFFT does not converge to 0
- the impulse response obtained by the IFFT is faded out on the rear side (the tail side) in the time direction of the impulse response to converge to 0. Is performed.
- the target phase characteristic impulse response indicated by the arrow Q25 ideally has a flat or substantially flat amplitude characteristic, and should have the same phase characteristic as the original HPF.
- the portion indicated by arrow Q31 indicates amplitude characteristics
- the portion indicated by arrow Q32 indicates phase characteristics.
- the vertical axis indicates gain (amplitude)
- the horizontal axis indicates frequency
- the vertical axis in the phase characteristic indicates the phase
- the horizontal axis indicates the frequency.
- the curve L11 indicates the amplitude characteristic of the target phase characteristic impulse response indicated by the arrow Q25 in FIG. 2
- the curve L12 indicates the amplitude characteristic of the original HPF indicated by the arrow Q21 in FIG. I have. From the curve L11, in the amplitude characteristic of the target phase characteristic impulse response, although not as high as the original HPF, the gain in the low-frequency part, that is, the part shown by the arrow W11 is reduced, and the amplitude characteristic is not flat. I understand.
- the curve L13 indicates the phase characteristic of the target phase characteristic impulse response indicated by the arrow Q25 in FIG. 2
- the curve L14 indicates the phase characteristic of the original HPF indicated by the arrow Q21 in FIG. That is, a target phase characteristic is shown.
- the curve L13 is substantially the same as the curve L14, and it can be seen that the target characteristic is obtained with respect to the phase characteristic in the target phase characteristic impulse response.
- the impulse response basically has a symmetrical shape. It has been known.
- the present applicant performs a zero padding process so that the impulse response becomes substantially symmetrical with respect to the portion where the pulse rises, and the front and the back of the portion where the pulse rises have the same length section. For example, it was thought that an impulse response having a flat amplitude characteristic could be obtained.
- the initial impulse response of the HPF is padded with zeros at least on the front side (past side) in the time direction so that the impulse response has a substantially symmetrical shape, and then the FFT and IFFT are performed.
- the impulse response is reconstructed, and the target phase characteristic impulse response is generated.
- FIG. 4 the portion indicated by arrow Q41 shows the impulse response of the HPF shown by arrow Q13 in FIG. 1, and this impulse response converges at approximately 1024 samples.
- zero-padding processing is performed on the impulse response of the HPF indicated by arrow Q41 as indicated by arrow Q42.
- 0 data is added not only on the rear side (end side) but also on the front side (head side) of the impulse response in the time direction.
- 0 data is added to the front of the impulse response in the time direction by 8192 samples, and 0 data is also added to the rear of the impulse response in the time direction so that the impulse length itself is 8192 samples. Has been added.
- the impulse response indicated by the arrow Q42 has a substantially symmetrical shape, and the overall length is 16384 samples.
- the amplitude characteristic of the target target phase characteristic impulse response is flat
- the value of the amplitude (gain) of each frequency in the amplitude characteristic obtained by the FFT is adjusted to “1”, and the flat characteristic is obtained. It is assumed to be an amplitude characteristic.
- phase characteristics obtained by the FFT should be the target phase characteristics, no particular phase adjustment is performed on the phase characteristics obtained by the FFT.
- IFFT is performed on the frequency characteristic including the flat amplitude characteristic obtained by the amplitude adjustment and the phase characteristic obtained by the FFT, and the impulse response obtained as a result is obtained.
- Fade processing is performed in the same manner as in the case of arrow Q24 in FIG.
- the impulse response obtained by the fade processing is set as the target phase characteristic impulse response.
- a target phase characteristic impulse response indicated by arrow Q45 is obtained, and the target phase characteristic impulse response has a shape close to left-right symmetry.
- the length of the target phase characteristic impulse response is 16384 samples.
- the portion indicated by arrow Q51 indicates amplitude characteristics
- the portion indicated by arrow Q52 indicates phase characteristics.
- the vertical axis indicates gain (amplitude)
- the horizontal axis indicates frequency
- the vertical axis in the phase characteristic indicates the phase
- the horizontal axis indicates the frequency.
- the curve L31 indicates the amplitude characteristic of the target phase characteristic impulse response indicated by the arrow Q45 in FIG. 4, and the curve L32 indicates the amplitude characteristic of the original HPF indicated by the arrow Q41 in FIG. I have.
- the value of the amplitude (gain) at each frequency falls within a range of ⁇ 0.2 dB, and it can be seen that a substantially flat characteristic is obtained. That is, it can be seen that the target amplitude characteristic is obtained.
- the curve L33 indicates the phase characteristic of the target phase characteristic impulse response indicated by the arrow Q45 in FIG. 4, and the curve L34 indicates the phase characteristic of the original HPF indicated by the arrow Q41 in FIG. That is, a target phase characteristic is shown. Further, a curve L35 shows a phase characteristic of a simple impulse delayed by 8192 samples, that is, a linear phase.
- the curve L33 and the curve L34 almost overlap each other, and it can be seen that the phase characteristic of the target phase characteristic impulse response is substantially the same as the target characteristic.
- the curve L35 is shown for comparison. Since the curve L35 shows the phase characteristic of a simple impulse that is a linear phase, the difference between the curve L33 and the curve L35 at each frequency is the phase value at each frequency of the phase characteristic shown by the arrow Q12 in FIG. Then, the target characteristic is obtained as the phase characteristic of the target phase characteristic impulse response.
- the phase characteristic of the original HPF indicated by the arrow Q41 in FIG. 4 is the same as the phase characteristic indicated by the arrow Q12 in FIG.
- the method of generating the target phase characteristic impulse response described with reference to FIG. 4 as described above is the above-described method A1.
- the length of the impulse response subjected to the zero padding processing becomes an infinite sample, the error between the frequency characteristic of the target phase characteristic impulse response and the target characteristic becomes extremely close to zero.
- the processing amount is reduced both at the time of generation and at the time of convolution after generation.
- FIG. 6 the portion indicated by arrow Q61 shows the impulse response of the HPF shown by arrow Q13 in FIG. 1, and this impulse response converges at approximately 1024 samples.
- zero-padding processing is performed on the impulse response of the HPF shown by arrow Q61 as shown by arrow Q62.
- 0 data is added to the front of the impulse response in the time direction by 384 samples, and 0 data is also added to the rear of the impulse response in the time direction so that the entire length of the impulse response is 4096 samples. Have been.
- the amplitude (gain) value of each frequency in the amplitude characteristic obtained by the FFT is adjusted to “1” to obtain a flat amplitude characteristic, and the phase characteristic obtained by the FFT is obtained. No phase adjustment is performed.
- IFFT is performed on a frequency characteristic including a flat amplitude characteristic obtained by the amplitude adjustment and a phase characteristic obtained by the FFT, and the impulse response obtained as a result is obtained.
- Fade processing is performed in the same manner as in the case of arrow Q24 in FIG.
- the impulse response obtained by the fade processing is set as the target phase characteristic impulse response.
- the target phase characteristic impulse response indicated by arrow Q65 is obtained, and the length of the target phase characteristic impulse response is 4096 samples.
- the target phase characteristic impulse response indicated by the arrow Q65 is not symmetrical.
- the portion indicated by arrow Q71 indicates amplitude characteristics
- the portion indicated by arrow Q72 indicates phase characteristics.
- the vertical axis indicates gain (amplitude)
- the horizontal axis indicates frequency
- the vertical axis in the phase characteristic indicates the phase
- the horizontal axis indicates the frequency.
- curve L51 shows the amplitude characteristic of the target phase characteristic impulse response shown by arrow Q65 in FIG. 6, and curve L52 shows the amplitude characteristic of the original HPF shown by arrow Q61 in FIG. I have.
- the value of the amplitude (gain) at each frequency falls within a range of ⁇ 1 dB, and it can be seen that a substantially flat characteristic is obtained. That is, it can be seen that sufficient amplitude characteristics are obtained.
- the amplitude characteristic shown by the curve L51 has a larger error from the target characteristic as compared with the amplitude characteristic shown by the curve L31 in FIG. 5, but the error falls within a sufficiently small range. I understand that there is.
- the curve L53 indicates the phase characteristic of the target phase characteristic impulse response indicated by the arrow Q65 in FIG. 6, and the curve L54 indicates the phase characteristic of the original HPF indicated by the arrow Q61 in FIG. That is, a target phase characteristic is shown. Further, the curve L55 shows the phase characteristic of the delayed simple impulse, similarly to the curve L35 of FIG.
- the curve L53 and the curve L54 have a larger error than in the case of FIG. 5, but almost overlap each other, and a characteristic substantially equivalent to the target characteristic is obtained as the phase characteristic of the target phase characteristic impulse response. I understand.
- the amplitude characteristic is flat or substantially flat and the amplitude characteristic is flat.
- a target phase characteristic impulse response can be obtained.
- the amount of 0 data to be added before the impulse response in the time direction is a trade-off between an allowable error with a target characteristic and a processing amount. And adjust it.
- zero padding processing is performed on a simple impulse as shown by a curve L35 in FIG. 5 to generate a target phase characteristic impulse response. May be.
- Such a method for generating the target phase characteristic impulse response is the method A2 described above.
- phase characteristic of the frequency characteristic obtained by the FFT for the simple impulse after the zero padding process will be particularly referred to as the phase characteristic of the simple impulse.
- the zero filling process is not performed on the impulse response having the target phase characteristic, and the FFT is performed on the impulse response as it is.
- the phase characteristics of the frequency characteristics obtained by the FFT for the impulse response having the target phase characteristics will be particularly referred to as target phase characteristics.
- phase characteristic of the simple impulse and the target phase characteristic are obtained by the FFT in this way, the phase characteristic of the simple impulse and the target phase characteristic are added, and the phase characteristic obtained by the addition and the flat amplitude IFFT is performed on the frequency characteristic including the characteristic.
- Fade processing is performed on the impulse response obtained by the IFFT, and the impulse response obtained as a result is set as a target phase characteristic impulse response.
- the target phase characteristic impulse response obtained in this way is an impulse response having a flat or substantially flat amplitude characteristic and having a target phase characteristic.
- the target phase characteristic is subtracted from the phase characteristic of the simple impulse. It can be obtained as a characteristic impulse response.
- a phase characteristic obtained by performing FFT without performing zero padding processing on a predetermined HPF impulse response is subtracted from a phase characteristic of a simple impulse, and a phase characteristic obtained as a result is obtained.
- IFFT is performed on a frequency characteristic including a flat amplitude characteristic.
- a fade process is performed on the impulse response obtained by the IFFT, and the resulting impulse response is used as a target phase characteristic impulse response.
- the phase characteristic of the obtained target phase characteristic impulse response is the inverse characteristic of the original HPF phase characteristic.
- the zero impulse response is performed on the impulse response having the target phase characteristic, and then the FFT, IFFT, and the fade processing are performed to generate the target phase characteristic impulse response.
- the simple impulse is subjected to zero padding processing, and thereafter, FFT, IFFT, and fade processing are performed to generate a target phase characteristic impulse response.
- Both the impulse response used in the method A1 and the simple impulse used in the method A2 are impulse information, that is, information on the impulse. Therefore, when the method A1 and the method A2 are generalized, zero-padding processing is performed on the impulse information, and FFT, IFFT, and fade processing are performed on the resulting phase characteristic, and the target phase characteristic impulse is obtained. It can be said that a response has been generated.
- a desired phase characteristic can be added to the audio signal without changing the amplitude characteristic.
- the phase characteristic of the reproducing headphone or speaker can be canceled for the audio signal of the content.
- an audio signal in which the phase characteristics of the headphone or speaker on the reproduction side has been canceled is referred to as a corrected audio signal.
- the target phase characteristic impulse response having the opposite characteristic to the phase characteristic of the reproducing headphone or speaker may be generated by the above-described method A2 or by the method A1.
- the FFT, IFFT, and fade processing are performed by performing a zero padding process on an impulse response having a characteristic opposite to that of a reproducing headphone or a speaker. Just do it.
- the phase characteristic of the mastering speaker is corrected with respect to the corrected audio signal, that is, the sound of the content. Can be added.
- the listener plays the sound of the content with headphones on the playback side
- the head-related transfer function that is, the head-related transfer function (HRTF)
- the creator can use the head-related transfer function (HRTF). It is possible to present a sound that is closer to the sound that is being produced.
- the HRTF is a function indicating a sound transfer characteristic from the sound source to the listener's ear, more specifically, to the vicinity of the listener's eardrum or to the ear canal entrance.
- the HRTF is further convoluted with the corrected audio signal to which the phase characteristics of the mastering speaker have been added, so that the listener can experience a sound closer to the sound received when the creator is producing in the mastering studio. Can be done.
- FIG. 8 is a diagram illustrating a configuration example of an impulse response generation device that generates a target phase characteristic impulse response, that is, an impulse response having a flat or substantially flat amplitude characteristic and a desired phase characteristic by the above-described method A1. .
- the impulse response generation device 11 shown in FIG. 8 has a zero padding processing unit 21, an FFT processing unit 22, an IFFT processing unit 23, and a fade processing unit 24.
- the # 0 padding processing unit 21 is supplied with an impulse response having a target phase characteristic used for generating a target phase characteristic impulse response.
- an impulse response having such a target phase characteristic is referred to as an input impulse response.
- the $ 0 padding processing unit 21 performs a zero padding process on the supplied input impulse response, and supplies the result to the FFT processing unit 22.
- the FFT processing unit 22 performs an FFT on the input impulse response after the zero padding processing supplied from the zero padding processing unit 21 and supplies a phase characteristic of the resulting frequency characteristic to the IFFT processing unit 23. .
- the IFFT processing unit 23 is supplied with a flat amplitude characteristic (gain characteristic) in which the gain (amplitude) of each frequency is “1” from the outside.
- the IFFT processing unit 23 performs an IFFT on a frequency characteristic composed of a flat amplitude characteristic supplied from the outside and a phase characteristic supplied from the FFT processing unit 22, and converts the resulting impulse response into a fade processing unit. 24.
- the IFFT is performed based on the flat amplitude characteristic and the phase characteristic supplied from the FFT processing unit 22, and an impulse response is generated.
- the IFFT processing unit 23 does not use a flat amplitude characteristic supplied from the outside, but performs a gain adjustment on the amplitude characteristic of the frequency characteristic obtained by the FFT in the FFT processing unit 22 to obtain a flat amplitude characteristic.
- a characteristic may be generated, and the amplitude characteristic may be used for IFFT.
- the fade processing unit 24 performs a fade process on the impulse response supplied from the IFFT processing unit 23, and outputs the resulting impulse response as a target phase characteristic impulse response.
- step S11 the zero padding processing unit 21 performs zero padding processing on the supplied input impulse response and supplies the result to the FFT processing unit 22.
- step S11 in step S11, as described with reference to FIG. 4 and FIG. 6, zero padding processing for adding zero data to the rear or front in the time direction of the input impulse response is performed.
- zero padding processing zero data is added at least on the front side in the time direction in the input impulse response.
- step S12 the FFT processing unit 22 performs FFT on the input impulse response after the zero padding process supplied from the zero padding processing unit 21, and converts the phase characteristic of the resulting frequency characteristic to the IFFT processing unit 23. To supply.
- step S13 the IFFT processing unit 23 performs an IFFT on a frequency characteristic including a flat amplitude characteristic supplied from the outside and a phase characteristic supplied from the FFT processing unit 22, and converts the impulse response obtained as a result. It is supplied to the fade processing unit 24.
- step S14 the fade processing unit 24 performs a fade process on the impulse response supplied from the IFFT processing unit 23, and outputs the impulse response obtained as a target phase characteristic impulse response.
- the target phase characteristic impulse response is generated by fading out the rear side (tail side) of the impulse response supplied from the IFFT processing unit 23 in the time direction and converging to 0. If the impulse response obtained by the IFFT converges to 0, no particular fade processing is required.
- an impulse response having the inverse characteristic of the headphone phase characteristic is used as the input impulse response, for example, the headphone phase characteristic is canceled as the target phase characteristic impulse response, that is, an impulse response having the inverse characteristic of the headphone phase characteristic is obtained. be able to.
- the impulse response generation device 11 performs the zero padding process of adding 0 data at least to the front side in the time direction of the input impulse response, and performs FFT, IFFT, and fade on the zero-padded input impulse response. By performing the processing, a target phase characteristic impulse response is generated.
- FIG. 10 ⁇ Second embodiment> ⁇ Configuration example of impulse response generation device>
- the impulse response generation device is configured as shown in FIG. 10, for example.
- parts corresponding to those in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
- the impulse response generation device 51 shown in FIG. 10 includes an FFT processing unit 61, a zero filling processing unit 62, an FFT processing unit 63, an arithmetic processing unit 64, an IFFT processing unit 23, and a fade processing unit 24.
- the configuration of the impulse response generation device 51 has a configuration in which an FFT processing unit 61 to an arithmetic processing unit 64 are provided instead of the zero padding processing unit 21 and the FFT processing unit 22 in the impulse response generation device 11.
- the FFT processing unit 61 is supplied with an impulse response having a target phase characteristic, that is, an input impulse response, which is used for generating a target phase characteristic impulse response.
- the FFT processing unit 61 performs an FFT on the supplied input impulse response, and supplies a phase characteristic among the obtained frequency characteristics to the arithmetic processing unit 64. Note that the FFT processing unit 61 does not need to be provided as long as the target phase characteristic itself can be obtained and the target phase characteristic can be supplied to the arithmetic processing unit 64.
- a simple impulse used to generate a target phase characteristic impulse response is supplied to the # 0 padding processing unit 62.
- the zero padding processing unit 62 performs a zero padding process on the supplied simple impulse and supplies the simple impulse to the FFT processing unit 63.
- the FFT processing unit 63 performs an FFT on the simple impulse after the zero padding process supplied from the zero padding processing unit 62 and supplies the phase characteristic of the frequency characteristics obtained as a result to the arithmetic processing unit 64.
- the arithmetic processing unit 64 performs arithmetic processing based on the phase characteristics supplied from the FFT processing unit 61 and the phase characteristics supplied from the FFT processing unit 63, and supplies the obtained phase characteristics to the IFFT processing unit 23. I do.
- addition processing or subtraction processing is performed as arithmetic processing.
- step S41 the FFT processing unit 61 performs an FFT on the supplied input impulse response, and supplies a phase characteristic of the obtained frequency characteristic to the arithmetic processing unit 64.
- step S42 the zero padding processing unit 62 performs a zero padding process on the supplied simple impulse, and supplies the simple impulse to the FFT processing unit 63.
- the zero padding process 0 data is added to the front side of the simple impulse in the time direction, and the simple impulse is appropriately delayed.
- step S43 the FFT processing unit 63 performs the FFT on the simple impulse after the zero padding process supplied from the zero padding processing unit 62, and outputs the phase characteristic of the resulting frequency characteristic to the arithmetic processing unit 64. Supply.
- step S44 the arithmetic processing unit 64 performs arithmetic processing based on the phase characteristics supplied from the FFT processing unit 61 and the phase characteristics supplied from the FFT processing unit 63, and compares the resulting phase characteristic with the IFFT processing unit. 23.
- the arithmetic processing unit 64 determines the phase characteristic of the input impulse response supplied from the FFT processing unit 61. And the phase characteristic of the simple impulse after the zero padding supplied from the FFT processing unit 63, and the resulting phase characteristic is supplied to the IFFT processing unit 23.
- the arithmetic processing unit 64 attempts to obtain the inverse characteristic of the phase characteristic of the input impulse response as the phase characteristic of the target phase characteristic impulse response, the input impulse response supplied from the FFT processing unit 61 Is subtracted from the phase characteristic of the simple impulse after the zero padding process supplied from the FFT processing unit 63, and the resulting phase characteristic is supplied to the IFFT processing unit 23.
- the impulse response generation device 51 performs the zero padding process of adding 0 data to the front side in the time direction of the simple impulse, and performs the target phase based on the simple impulse response subjected to the zero padding and the input impulse response. Generate a characteristic impulse response.
- the audio signal of the content obtained by the mastering is reproduced by a reproduction system including a reproduction device or the like owned by the listener.
- a reproduction system including a reproduction device or the like owned by the listener.
- any sound such as a headphone, a speaker, and an earphone may be used to reproduce the sound of the content, but the description will be continued below assuming that a headphone is used as a specific example.
- the playback device used to play back the content is configured, for example, as shown in FIG.
- the playback device 121 is configured by a portable player, a smartphone, a personal computer, or the like capable of controlling playback of at least audio content, and the playback device 121 is connected to headphones 122.
- the playback device 121 includes an acquisition unit 131, a speaker phase characteristic convolution unit 132, and a playback control unit 133.
- the audio signal of the content obtained by the mastering by the creator M11 is supplied to the speaker phase characteristic convolution unit 132.
- the acquisition unit 131 acquires and holds a target phase characteristic impulse response from an external device such as the impulse response generation device 11 or the impulse response generation device 51 at an arbitrary timing. Further, the acquisition unit 131 supplies the held target phase characteristic impulse response to the speaker phase characteristic convolution unit 132.
- the target phase characteristic impulse response obtained by the obtaining unit 131 is generated by the impulse response generator 11 or the impulse response generator 51 using the input impulse response having the phase characteristic of the speaker 91 used for mastering. It is. That is, the target phase characteristic impulse response is an impulse response having the same phase characteristic as that of the speaker 91.
- the target phase characteristic impulse response may not be acquired by the acquisition unit 131 at an arbitrary timing, but may be held in the acquisition unit 131 in advance.
- a target phase characteristic impulse response having the same phase characteristic as that of the speaker 91 will be particularly referred to as a speaker characteristic impulse response.
- the speaker phase characteristic convolution unit 132 convolves the speaker characteristic impulse response supplied from the acquisition unit 131 with the supplied audio signal, and supplies the resulting audio signal to the reproduction control unit 133.
- the reproduction control unit 133 supplies the audio signal supplied from the speaker phase characteristic convolution unit 132 to the headphones 122 to reproduce the sound of the content.
- the playback control unit 133 controls playback of the sound of the content on the headphones 122.
- the headphone 122 reproduces the sound of the content based on the audio signal supplied from the reproduction control unit 133.
- the playback device 121 is not provided with the headphone 122 here, the headphone 122 may be provided in the playback device 121, or the acquisition unit 131 and the playback control The unit 133 may be provided.
- step S71 the speaker phase characteristic convolution unit 132 convolves the supplied audio signal with the speaker characteristic impulse response supplied from the acquisition unit 131, and supplies the resulting audio signal to the reproduction control unit 133.
- phase characteristic of the speaker characteristic impulse response that is, the phase characteristic of the speaker 91 can be added to the sound of the content based on the audio signal.
- step S72 the reproduction control unit 133 supplies the audio signal supplied from the speaker phase characteristic convolution unit 132 to the headphones 122 to reproduce the sound of the content, and the reproduction process ends.
- the listener who is listening to the sound of the content receives the content that the creator M11 has heard in the studio. A sound of almost the same sound quality as the sound of is heard.
- the desired phase characteristic can be added to the sound of the content without changing the amplitude characteristic, so that the gain of the sound of the content does not change.
- the reproducing device 121 reproduces the sound of the content after convolving the speaker characteristic impulse response with the audio signal of the content. By doing so, even when the sound of the content is reproduced by the headphones 122, the phase characteristic of the speaker 91 used for mastering can be added to the sound of the content. That is, desired phase characteristics can be obtained.
- ⁇ Fourth embodiment> ⁇ Configuration example of playback device> It has been described that the playback device 121 adds the same characteristic as the phase characteristic of the speaker 91 to the sound of the content. However, when the sound of the content is reproduced by the headphones 122, the phase characteristics of the headphones 122 are also added to the sound.
- the sound of the content closer to the sound of the content that the creator M11 has heard in the studio.
- the sound may be made available to the listener.
- the playback device is configured as shown in FIG. 15, for example.
- FIG. 15 portions corresponding to those in FIG. 13 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
- the headphones 122 are connected to the playback device 161 shown in FIG.
- the playback device 161 includes an acquisition unit 131, a headphone inverse characteristic convolution unit 171, a speaker phase characteristic convolution unit 132, and a reproduction control unit 133.
- the configuration of the playback device 161 is such that a headphone inverse characteristic convolution unit 171 is provided in a stage preceding the speaker phase characteristic convolution unit 132 in the reproduction device 121.
- the reproducing device 161 not only the above-described speaker characteristic impulse response but also a target phase characteristic impulse response having a characteristic opposite to the phase characteristic of the headphones 122 is obtained by the acquisition unit 131 such as the impulse response generating device 11 or the impulse response generating device 51. Obtained from an external device and held.
- a target phase characteristic impulse response having a characteristic opposite to the phase characteristic of the headphone 122 will be particularly referred to as a headphone reverse characteristic impulse response.
- the headphone inverse characteristic impulse response is obtained by, for example, using an input impulse response having the phase characteristic of the headphone 122 and performing subtraction as an arithmetic processing in the arithmetic processing unit 64 to generate the target phase characteristic impulse response generated by the impulse response generating device 51. It is.
- the headphone inverse characteristic impulse response may not be acquired by the acquiring unit 131 but may be held in the acquiring unit 131 in advance.
- the acquisition unit 131 supplies the held headphone inverse characteristic impulse response to the headphone inverse characteristic convolution unit 171.
- the headphone inverse characteristic convolution unit 171 convolves the headphone inverse characteristic impulse response supplied from the acquisition unit 131 with the supplied audio signal of the content, and supplies the resulting audio signal to the speaker phase characteristic convolution unit 132. I do.
- step S101 the headphone inverse characteristic convolution unit 171 convolves the headphone inverse characteristic impulse response supplied from the acquisition unit 131 with the supplied content audio signal, and converts the resulting audio signal into the speaker phase characteristic convolution unit. 132.
- phase characteristic of the headphones 122 can be added to the sound of the content.
- the phase characteristic of the headphone 122 added when the headphone 122 reproduces the sound of the content is canceled.
- the phase characteristic can be adjusted without changing the amplitude (gain) of the sound of the content.
- the phase characteristic of the headphones 122 is canceled for the content sound, and then the phase characteristic of the speaker 91, which is the characteristic to be added, is added.
- a target phase characteristic impulse response to which the phase characteristic of the headphone 122 can be added and the phase characteristic of the speaker 91 can be added at the same time is generated, and the target phase characteristic impulse response is convolved with the audio signal of the content. May be.
- the phase characteristic added to the sound of the content can be freely changed. That is, for example, in the reproducing apparatus 161, it is possible to select an arbitrary speaker 91 from among a plurality of speakers 91 of different manufacturers and convolve a speaker characteristic impulse response having a phase characteristic of the selected speaker 91. .
- the reproducing device 161 convolves the headphone reverse characteristic impulse response with the audio signal of the content, and further convolves the speaker characteristic impulse response with the audio signal, and then reproduces the sound of the content.
- phase characteristic added by the headphones 122 is canceled, and the phase characteristic of the speaker 91 used for mastering is added to the sound of the content. can do. That is, desired phase characteristics can be obtained.
- a sound closer to the sound of the content that the creator M11 has heard in the studio can be heard than in the reproduction processing described with reference to FIG. .
- ⁇ Fifth Embodiment> ⁇ Configuration example of playback device>
- the sound source for example, HRTF indicating the transmission characteristic of the sound from the speaker 91 to the creator M11 is folded, it is closer to the sound of the content that the creator M11 was listening to in the studio. You can hear the sound. That is, the listening environment of the studio at the time of mastering can be reproduced.
- the playback device When the HRTF is convolved with the audio signal of the content, the playback device is configured, for example, as shown in FIG. In FIG. 17, portions corresponding to those in FIG. 15 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
- a headphone 122 is connected to the playback device 201 shown in FIG. Further, the playback device 201 includes an acquisition unit 131, a headphone inverse characteristic convolution unit 171, a speaker phase characteristic convolution unit 132, an HRTF convolution unit 211, and a reproduction control unit 133.
- the configuration of the playback apparatus 201 is such that the HRTF convolution section 211 is provided at the subsequent stage of the speaker phase characteristic convolution section 132 in the playback apparatus 161.
- the reproducing device 201 not only the above-described speaker characteristic impulse response and the headphone reverse characteristic impulse response but also the HRTF are acquired from the external device by the acquisition unit 131 and held.
- the HRTF may not be acquired by the acquiring unit 131 but may be held in the acquiring unit 131 in advance.
- the acquisition unit 131 supplies the held HRTF to the HRTF convolution unit 211.
- the HRTF convolution unit 211 convolves the HRTF supplied from the acquisition unit 131 with the audio signal supplied from the speaker phase characteristic convolution unit 132, and supplies the obtained audio signal to the reproduction control unit 133.
- the HRTF convolution unit 211 may be provided in the playback device 121 shown in FIG.
- steps S131 and S132 are performed. However, since these processes are the same as the processes of steps S101 and S102 in FIG. 16, description thereof will be omitted.
- step S133 the HRTF convolution unit 211 convolves the HRTF supplied from the acquisition unit 131 with the audio signal supplied from the speaker phase characteristic convolution unit 132, and supplies the resulting audio signal to the reproduction control unit 133. .
- step S134 the reproduction control unit 133 supplies the audio signal supplied from the HRTF convolution unit 211 to the headphones 122 to reproduce the sound of the content, and the reproduction process ends.
- the phase characteristic of the headphones 122 is canceled, and the phase characteristic of the speaker 91 and the transmission characteristic of the sound in the studio are added.
- the reproducing apparatus 201 reproduces the sound of the content after convolving the headphone reverse characteristic impulse response, the speaker characteristic impulse response, and the HRTF into the audio signal.
- the headphones 122 By doing so, even when the sound of the content is reproduced by the headphones 122, the desired phase characteristic and the transfer characteristic in a desired listening environment such as a studio are added, and the creator M11 listens in the studio. The listener can hear substantially the same sound as the sound of the content.
- a generator that generates a target phase characteristic impulse response may be provided inside the playback device 121, the playback device 161, or the playback device 201.
- the playback device 161 is configured as shown in FIG. In FIG. 19, parts corresponding to those in FIG. 15 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
- 19 includes a generation unit 241, an acquisition unit 131, a headphone inverse characteristic convolution unit 171, a speaker phase characteristic convolution unit 132, and a reproduction control unit 133.
- the configuration of the playback device 161 shown in FIG. 19 is such that the generation unit 241 is further provided in the playback device 161 shown in FIG.
- the generation unit 241 corresponds to the impulse response generation device 11 or the impulse response generation device 51. That is, the generation unit 241 performs the same processing as the impulse response generation processing described with reference to FIGS. 9 and 11 to generate the headphone reverse characteristic impulse response and the speaker characteristic impulse response, and supplies the headphone inverse characteristic impulse response and the speaker characteristic impulse response to the acquisition unit 131.
- phase characteristics of any speaker used for mastering in music production can be added to the sound source while the amplitude characteristics remain flat (flat).
- the amplitude characteristics remain flat (flat).
- the target speaker is unknown, if the impulse response of an arbitrary general IIR filter imitating the phase characteristic of the speaker is used as the above-described input impulse response, the obtained speaker characteristic impulse response is used.
- a low-frequency phase characteristic equivalent to that of a speaker can be added without changing the amplitude characteristic.
- the headphone phase characteristic particularly the reverse characteristic of the low-frequency phase characteristic
- the headphone phase characteristic can be canceled.
- the phase characteristic of the speaker especially the low frequency characteristic is added by the speaker characteristic impulse response, an effect closer to the low frequency sound quality effect in the mastering studio can be obtained.
- an impulse response having the phase characteristic of the speaker may be used as an input impulse response. If the speaker used in the mastering studio cannot be specified, an impulse response such as an IIR type HPF that simulates the phase characteristic of the speaker may be used as the input impulse response.
- the HRTF is convolved with the audio signal of the content, thereby improving the listening environment in the mastering studio.
- Low-frequency phase characteristics can be simulated with headphones.
- the above-described series of processing can be executed by hardware or can be executed by software.
- a program constituting the software is installed in a computer.
- the computer includes a computer incorporated in dedicated hardware, a general-purpose personal computer capable of executing various functions by installing various programs, and the like, for example.
- FIG. 20 is a block diagram illustrating a configuration example of hardware of a computer that executes the series of processes described above by a program.
- a CPU Central Processing Unit
- ROM Read Only Memory
- RAM Random Access Memory
- the input / output interface 505 is further connected to the bus 504.
- the input / output interface 505 is connected to an input unit 506, an output unit 507, a recording unit 508, a communication unit 509, and a drive 510.
- the input unit 506 includes a keyboard, a mouse, a microphone, an image sensor, and the like.
- the output unit 507 includes a display, a speaker, and the like.
- the recording unit 508 includes a hard disk, a nonvolatile memory, and the like.
- the communication unit 509 includes a network interface and the like.
- the drive 510 drives a removable recording medium 511 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.
- the CPU 501 loads, for example, a program recorded in the recording unit 508 to the RAM 503 via the input / output interface 505 and the bus 504 and executes the program. Is performed.
- the program executed by the computer (CPU 501) can be provided by being recorded on a removable recording medium 511 as a package medium or the like, for example. Further, the program can be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.
- the program can be installed in the recording unit 508 via the input / output interface 505 by attaching the removable recording medium 511 to the drive 510. Further, the program can be received by the communication unit 509 via a wired or wireless transmission medium and installed in the recording unit 508. In addition, the program can be installed in the ROM 502 or the recording unit 508 in advance.
- the program executed by the computer may be a program in which processing is performed in chronological order according to the order described in this specification, or may be performed in parallel or at a necessary timing such as when a call is made. It may be a program that performs processing.
- Embodiments of the present technology are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present technology.
- the present technology can adopt a configuration of cloud computing in which one function is shared by a plurality of devices via a network and processed jointly.
- each step described in the above-described flowchart can be executed by a single device, or can be shared and executed by a plurality of devices.
- one step includes a plurality of processes
- the plurality of processes included in the one step may be executed by one device or may be shared and executed by a plurality of devices.
- the present technology may have the following configurations.
- An acquisition unit whose amplitude characteristic is flat or substantially flat, and acquires an impulse response having a predetermined phase characteristic
- a phase characteristic convolution unit for convolving the impulse response with an input audio signal.
- the audio signal processing device (2) The audio signal processing device according to (1), wherein the predetermined phase characteristic is a phase characteristic of a predetermined speaker.
- the audio signal processing device further including a reproduction control unit configured to control reproduction of a sound based on an audio signal obtained by convolution of the impulse response with a headphone.
- the audio signal processing device according to (3) further including an inverse characteristic convolution unit that convolves an impulse response having an inverse characteristic of a phase characteristic of the headphones with the input audio signal.
- the audio signal processing device according to any one of (1) to (4), further including an HRTF convolution unit that convolves an HRTF with the audio signal obtained by convolution by the phase characteristic convolution unit.
- the audio signal processing device according to any one of (1) to (5), further including an impulse response generation unit that generates the impulse response.
- Audio signal processing device The amplitude characteristic is flat or almost flat, and acquires an impulse response having a predetermined phase characteristic, An audio signal processing method for convolving the impulse response with an input audio signal.
- the amplitude characteristic is flat or almost flat, and acquires an impulse response having a predetermined phase characteristic, A program for causing a computer to execute a process including a step of convolving the impulse response with an input audio signal.
- An impulse response generation device that generates a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic.
- a zero padding processing unit that performs a zero padding process of adding 0 data to predetermined impulse information;
- An impulse information FFT processing unit that performs an FFT on the impulse information to which the 0 data is added;
- the zero padding processing unit adds the zero data to at least a front side of the impulse information in a time direction.
- the impulse response generation device according to (10) or (11), further comprising a fade processing unit that performs a fade process on the impulse response obtained by the IFFT and sets the target characteristic impulse response.
- the impulse response generation device according to any one of (10) to (12), wherein the impulse information is an impulse response having the predetermined phase characteristic.
- the impulse information is a simple impulse, An impulse response FFT processing unit that performs FFT on the impulse response having the predetermined phase characteristic, A phase characteristic obtained by the FFT by the impulse information FFT processing unit, and an arithmetic processing unit that performs an operation based on the phase characteristic obtained by the FFT by the impulse response FFT processing unit.
- the impulse response generation device according to any one of (10) to (12), wherein the IFFT processing unit performs the IFFT based on the phase characteristics obtained by the calculation and the flat amplitude characteristics.
- the arithmetic processing unit performs, as the arithmetic operation, addition of a phase characteristic obtained by the FFT by the impulse information FFT processing unit and a phase characteristic obtained by the FFT by the impulse response FFT processing unit (14)
- the arithmetic processing unit subtracts the phase characteristic obtained by the FFT by the impulse response FFT processing unit from the phase characteristic obtained by the FFT by the impulse information FFT processing unit as the calculation (14)
- the impulse response generation device 1.
- the impulse response generator is An impulse response generation method for generating a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic.
- a program for causing a computer to execute a process including a step of generating a target characteristic impulse response having a flat or substantially flat amplitude characteristic and a predetermined phase characteristic.
- 11 impulse response generator ⁇ 21 ⁇ zero padding processing unit, ⁇ 22 ⁇ FFT processing unit, ⁇ 23 ⁇ IFFT processing unit, ⁇ 24 ⁇ fade processing unit, ⁇ 61 ⁇ FFT processing unit, ⁇ 62 ⁇ zero padding processing unit, ⁇ 63 ⁇ FFT processing unit, ⁇ 64 ⁇ arithmetic processing unit, ⁇ 121 ⁇ reproduction Device, ⁇ 131 ⁇ acquisition unit, ⁇ 132 ⁇ speaker phase characteristic convolution unit, ⁇ 133 ⁇ reproduction control unit, ⁇ 171 ⁇ headphone inverse characteristic convolution unit, ⁇ 211 ⁇ HRTF convolution unit, ⁇ 241 ⁇ generation unit
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Abstract
Description
〈本技術について〉
本技術は、オーディオ信号の振幅特性(ゲイン特性)を変えずに位相特性だけを調整することができるようにするものである。
続いて、以上において説明した目標位相特性インパルス応答を生成するインパルス応答生成装置の具体的な構成と動作について説明する。
次に、インパルス応答生成装置11の動作について説明する。
〈インパルス応答生成装置の構成例〉
また、上述した手法A2により目標位相特性インパルス応答を生成する場合、インパルス応答生成装置は例えば図10に示すように構成される。なお、図10において図8における場合と対応する部分には同一の符号を付してあり、その説明は適宜省略する。
次に、インパルス応答生成装置51の動作について説明する。
〈再生装置の構成例〉
ここで、以上において説明したインパルス応答生成装置11やインパルス応答生成装置51で生成された目標位相特性インパルス応答を用いて、コンテンツの再生を行う再生装置について説明する。
続いて、再生装置121の動作について説明する。すなわち、以下、図14のフローチャートを参照して再生装置121による再生処理について説明する。なお、この再生処理が開始されるタイミングでは、スピーカ特性インパルス応答が既に取得部131により取得されている。
〈再生装置の構成例〉
なお、再生装置121では、コンテンツの音にスピーカ91の位相特性と同じ特性を付加すると説明した。しかし、コンテンツの音をヘッドフォン122で再生すると、その音にはヘッドフォン122が有する位相特性も付加されることになる。
次に、再生装置161の動作について説明する。すなわち、以下、図16のフローチャートを参照して再生装置161による再生処理について説明する。なお、この再生処理が開始されるタイミングでは、スピーカ特性インパルス応答およびヘッドフォン逆特性インパルス応答が既に取得部131により取得されている。
〈再生装置の構成例〉
なお、コンテンツの音をヘッドフォン122で再生する場合、音源、例えばスピーカ91から制作者M11までの音の伝達特性を示すHRTFを畳み込めば、制作者M11がスタジオで聞いていたコンテンツの音により近い音を聞かせることができる。すなわち、マスタリング時のスタジオの受聴環境を再現することができる。
次に、再生装置201の動作について説明する。すなわち、以下、図18のフローチャートを参照して再生装置201による再生処理について説明する。なお、この再生処理が開始されるタイミングでは、スピーカ特性インパルス応答、ヘッドフォン逆特性インパルス応答、およびHRTFが既に取得部131により取得されている。
〈再生装置の構成例〉
なお、再生装置121や再生装置161、再生装置201内部に目標位相特性インパルス応答を生成する生成部が設けられるようにしてもよい。
ところで、上述した一連の処理は、ハードウェアにより実行することもできるし、ソフトウェアにより実行することもできる。一連の処理をソフトウェアにより実行する場合には、そのソフトウェアを構成するプログラムが、コンピュータにインストールされる。ここで、コンピュータには、専用のハードウェアに組み込まれているコンピュータや、各種のプログラムをインストールすることで、各種の機能を実行することが可能な、例えば汎用のパーソナルコンピュータなどが含まれる。
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得する取得部と、
入力オーディオ信号に前記インパルス応答を畳み込む位相特性畳み込み部と
を備えるオーディオ信号処理装置。
(2)
前記所定の位相特性は、所定のスピーカが有する位相特性である
(1)に記載のオーディオ信号処理装置。
(3)
前記インパルス応答の畳み込みにより得られたオーディオ信号に基づく音のヘッドフォンでの再生を制御する再生制御部をさらに備える
(1)または(2)に記載のオーディオ信号処理装置。
(4)
前記ヘッドフォンの位相特性の逆特性を有するインパルス応答を前記入力オーディオ信号に畳み込む逆特性畳み込み部をさらに備える
(3)に記載のオーディオ信号処理装置。
(5)
前記位相特性畳み込み部による畳み込みにより得られたオーディオ信号にHRTFを畳み込むHRTF畳み込み部をさらに備える
(1)乃至(4)の何れか一項に記載のオーディオ信号処理装置。
(6)
前記インパルス応答を生成するインパルス応答生成部をさらに備える
(1)乃至(5)の何れか一項に記載のオーディオ信号処理装置。
(7)
オーディオ信号処理装置が、
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得し、
入力オーディオ信号に前記インパルス応答を畳み込む
オーディオ信号処理方法。
(8)
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得し、
入力オーディオ信号に前記インパルス応答を畳み込む
ステップを含む処理をコンピュータに実行させるプログラム。
(9)
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
インパルス応答生成装置。
(10)
所定のインパルス情報に対して0データを付加する0詰め処理を行う0詰め処理部と、
前記0データが付加された前記インパルス情報に対してFFTを行うインパルス情報FFT処理部と、
前記FFTにより得られた位相特性と、フラットな振幅特性とに基づいてIFFTを行うことで前記目標特性インパルス応答を生成するIFFT処理部と
をさらに備える(9)に記載のインパルス応答生成装置。
(11)
前記0詰め処理部は、少なくとも前記インパルス情報の時間方向における前側に前記0データを付加する
(10)に記載のインパルス応答生成装置。
(12)
前記IFFTにより得られたインパルス応答に対してフェード処理を行い、前記目標特性インパルス応答とするフェード処理部をさらに備える
(10)または(11)に記載のインパルス応答生成装置。
(13)
前記インパルス情報は前記所定の位相特性を有するインパルス応答である
(10)乃至(12)の何れか一項に記載のインパルス応答生成装置。
(14)
前記インパルス情報は単純インパルスであり、
前記所定の位相特性を有するインパルス応答に対してFFTを行うインパルス応答FFT処理部と、
前記インパルス情報FFT処理部による前記FFTにより得られた位相特性と、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性とに基づく演算を行う演算処理部と
をさらに備え、
前記IFFT処理部は、前記演算により得られた位相特性と、前記フラットな振幅特性とに基づいて前記IFFTを行う
(10)乃至(12)の何れか一項に記載のインパルス応答生成装置。
(15)
前記演算処理部は、前記演算として、前記インパルス情報FFT処理部による前記FFTにより得られた位相特性と、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性との加算を行う
(14)に記載のインパルス応答生成装置。
(16)
前記演算処理部は、前記演算として、前記インパルス情報FFT処理部による前記FFTにより得られた位相特性からの、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性の減算を行う
(14)に記載のインパルス応答生成装置。
(17)
インパルス応答生成装置が、
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
インパルス応答生成方法。
(18)
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
ステップを含む処理をコンピュータに実行させるプログラム。
Claims (18)
- 振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得する取得部と、
入力オーディオ信号に前記インパルス応答を畳み込む位相特性畳み込み部と
を備えるオーディオ信号処理装置。 - 前記所定の位相特性は、所定のスピーカが有する位相特性である
請求項1に記載のオーディオ信号処理装置。 - 前記インパルス応答の畳み込みにより得られたオーディオ信号に基づく音のヘッドフォンでの再生を制御する再生制御部をさらに備える
請求項1に記載のオーディオ信号処理装置。 - 前記ヘッドフォンの位相特性の逆特性を有するインパルス応答を前記入力オーディオ信号に畳み込む逆特性畳み込み部をさらに備える
請求項3に記載のオーディオ信号処理装置。 - 前記位相特性畳み込み部による畳み込みにより得られたオーディオ信号にHRTFを畳み込むHRTF畳み込み部をさらに備える
請求項1に記載のオーディオ信号処理装置。 - 前記インパルス応答を生成するインパルス応答生成部をさらに備える
請求項1に記載のオーディオ信号処理装置。 - オーディオ信号処理装置が、
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得し、
入力オーディオ信号に前記インパルス応答を畳み込む
オーディオ信号処理方法。 - 振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有するインパルス応答を取得し、
入力オーディオ信号に前記インパルス応答を畳み込む
ステップを含む処理をコンピュータに実行させるプログラム。 - 振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
インパルス応答生成装置。 - 所定のインパルス情報に対して0データを付加する0詰め処理を行う0詰め処理部と、
前記0データが付加された前記インパルス情報に対してFFTを行うインパルス情報FFT処理部と、
前記FFTにより得られた位相特性と、フラットな振幅特性とに基づいてIFFTを行うことで前記目標特性インパルス応答を生成するIFFT処理部と
をさらに備える請求項9に記載のインパルス応答生成装置。 - 前記0詰め処理部は、少なくとも前記インパルス情報の時間方向における前側に前記0データを付加する
請求項10に記載のインパルス応答生成装置。 - 前記IFFTにより得られたインパルス応答に対してフェード処理を行い、前記目標特性インパルス応答とするフェード処理部をさらに備える
請求項10に記載のインパルス応答生成装置。 - 前記インパルス情報は前記所定の位相特性を有するインパルス応答である
請求項10に記載のインパルス応答生成装置。 - 前記インパルス情報は単純インパルスであり、
前記所定の位相特性を有するインパルス応答に対してFFTを行うインパルス応答FFT処理部と、
前記インパルス情報FFT処理部による前記FFTにより得られた位相特性と、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性とに基づく演算を行う演算処理部と
をさらに備え、
前記IFFT処理部は、前記演算により得られた位相特性と、前記フラットな振幅特性とに基づいて前記IFFTを行う
請求項10に記載のインパルス応答生成装置。 - 前記演算処理部は、前記演算として、前記インパルス情報FFT処理部による前記FFTにより得られた位相特性と、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性との加算を行う
請求項14に記載のインパルス応答生成装置。 - 前記演算処理部は、前記演算として、前記インパルス情報FFT処理部による前記FFTにより得られた位相特性からの、前記インパルス応答FFT処理部による前記FFTにより得られた位相特性の減算を行う
請求項14に記載のインパルス応答生成装置。 - インパルス応答生成装置が、
振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
インパルス応答生成方法。 - 振幅特性がフラットまたは略フラットであり、かつ所定の位相特性を有する目標特性インパルス応答を生成する
ステップを含む処理をコンピュータに実行させるプログラム。
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