CN116095560A

CN116095560A - Audio signal method, equipment and readable storage medium

Info

Publication number: CN116095560A
Application number: CN202310117921.5A
Authority: CN
Inventors: 芮元庆
Original assignee: Tencent Music Entertainment Technology Shenzhen Co Ltd
Current assignee: Tencent Music Entertainment Technology Shenzhen Co Ltd
Priority date: 2023-02-15
Filing date: 2023-02-15
Publication date: 2023-05-09

Abstract

The application discloses an audio signal method, equipment and a readable storage medium, wherein the method comprises the following steps: obtaining a song signal and a signal amplitude curve of the song signal; mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve; carrying out loudness balance treatment on the loudness curve to obtain a filtering curve; generating a filter matched with the filtering curve; and filtering the song signal by using a filter to obtain a target song signal after loudness compensation. In the method, the loudness of the middle and low frequencies can be dynamically balanced according to the magnitude of the signal amplitude, so that the loudness perception difference of the songs of different songs or different time periods of the same song in the middle and low frequencies can be further reduced, and more consistent loudness experience is obtained.

Description

Audio signal method, equipment and readable storage medium

Technical Field

The present application relates to the field of acoustic technologies, and in particular, to an audio signal method, apparatus, and readable storage medium.

Background

When a person listens to a song, the problem that the sound is big and small often occurs. Thus, the volume of the device is frequently adjusted, thereby avoiding excessive epicophosis, i.e. hurting the ears; too little sound is inaudible and inaudible.

In order to achieve better hearing effect, the current volume balancing technology can ensure that different songs have the same song listening experience, and keep consistent volume without frequent volume adjustment due to song switching.

However, in the same song, there is still a problem that the sound is inattentive, and the period of time is unstable, which is difficult to improve by adjusting the volume of the device.

In summary, how to effectively solve the problems of song loudness equalization and the like is a technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide an audio signal method, equipment and a readable storage medium, which balance the loudness of a song in different time periods, so that the medium-low frequency band can acquire consistent loudness experience in a small-amplitude time period or a large-amplitude time period.

In order to solve the technical problems, the application provides the following technical scheme:

an audio signal processing method, comprising:

obtaining a song signal and a signal amplitude curve of the song signal;

mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve;

carrying out loudness balance treatment on the loudness curve to obtain a filtering curve;

generating a filter matched with the filtering curve;

and filtering the song signal by using the filter to obtain a target song signal after loudness compensation.

Preferably, the loudness balancing process is performed on the loudness curve to obtain a filtering curve, including:

acquiring a loudness reference curve;

and making a difference between the loudness curve and the loudness reference curve to obtain the filtering curve.

Preferably, the acquiring the loudness reference curve includes:

acquiring an equal-loudness curve of the human ear;

calculating a human ear sensitivity curve by using the human ear equal-loudness curve;

and determining a loudness reference curve by using the human ear sensitivity curve.

Preferably, calculating the human ear sensitivity curve by using the human ear equal-loudness curve includes:

and calculating the difference of sound pressure and kilohertz of different frequencies of different equal-loudness curves by using the equal-loudness curve of the human ear to obtain the sensitivity curve of the human ear.

Preferably, the generating a filter matched to the filtering curve includes:

determining filter coefficients using the filter curve;

the filter is generated that matches the filter coefficients.

Preferably, said generating said filter matched to said filter coefficients comprises:

and generating a 1-order low-frame tunable filter matched with the filter coefficient.

Preferably, mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve includes:

and performing energy detection on the signal amplitude curve, and mapping the amplitude to loudness according to loudness perception corresponding to different energy sizes of human ears to obtain the loudness curve.

Preferably, the method further comprises:

if the loudness adaptive switch is in an on state, playing the target song signal;

and if the loudness adaptive switch is in a closed state, playing the song signal.

An electronic device, comprising:

a memory for storing a computer program;

and a processor for implementing the steps of the audio signal method described above when executing the computer program.

A readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the above-described audio signal method.

By applying the method provided by the embodiment of the application, the song signal and the signal amplitude curve of the song signal are obtained; mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve; carrying out loudness balance treatment on the loudness curve to obtain a filtering curve; generating a filter matched with the filtering curve; and filtering the song signal by using a filter to obtain a target song signal after loudness compensation.

The human ear has slightly different perceptibility to different frequency bands, and especially has weaker sensitivity to low frequency. According to the equal loudness curve of the human ear, if the same loudness is to be achieved in different frequency bands, with 1kHz as a reference, a higher sound pressure level is required for the low frequency band to keep consistent with the 1kHz loudness. Because the amplitude of the signals in different time periods is different for different songs, the perception capability of the human ear to low frequency is not as obvious as the signal amplitude when the signal amplitude is small. In this application, a loudness curve of a song may be obtained by obtaining a signal amplitude curve of a song signal and mapping the amplitude to loudness. Then, the loudness curve is subjected to loudness balance processing, a filter curve can be obtained, a filter is generated based on the filter curve, and the target song after loudness compensation can be obtained by filtering the song signal through the filter. That is, the loudness of the middle and low frequencies is dynamically balanced according to the magnitude of the signal amplitude, so that the human ear can further reduce the perception difference of the loudness of different songs or songs of the same song in different time periods in the middle and low frequencies, and more consistent loudness experience is obtained.

Accordingly, the embodiment of the application further provides an electronic device and a readable storage medium corresponding to the audio signal method, which have the above technical effects and are not described herein.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for a person having ordinary skill in the art.

Fig. 1 is a flowchart of an implementation of an audio signal method according to an embodiment of the present application;

FIG. 2 is a graph of human ear equal loudness with IOS226 standard;

FIG. 3 is a graph of a human ear sensitivity curve in an embodiment of the present application;

FIG. 4 is a schematic diagram of a compensation curve for different loudness according to the embodiments of the present application;

FIG. 5 is a schematic diagram of a filter according to an embodiment of the present application;

FIG. 6 is a graph comparing the song "ferry" before and after adaptive loudness balancing and a graph of the gain of the filter at 20Hz in the examples of the present application;

fig. 7 is a schematic structural diagram of an audio signal device according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

fig. 9 is a schematic diagram of a specific structure of an electronic device in an embodiment of the application.

Detailed Description

In order to provide a better understanding of the present application, those skilled in the art will now make further details of the present application with reference to the drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

In order to facilitate understanding of the audio signal method provided by the embodiment of the present application, a deduction and presentation are made below on the core theory on which the audio signal method depends.

Referring to fig. 2, fig. 2 is a graph of the equal loudness of the human ear, as measured by IOS 226. As shown, the sound pressure level and loudness are equal based on the IOS226 standard human ear equal loudness curve, with the human ear perceiving different frequencies being different, based on 1kHz (kilohertz). Taking the loudness of 20 photon (square) as an example, i.e. the bottom curve of fig. 2, the bass 20Hz is equal to 1kHz, and the sound pressure level needs to reach about 90dB, which is different by 70dB. Since the sound pressure corresponds to the signal amplitude, the smaller the signal, the poorer the perception of low frequencies by the human ear, at which time the loudness of low frequencies and medium-high frequencies need to be balanced.

Where phon (square), this unit is the unit of loudness level. It is specified that at 1000Hz, 1 dbspl=1 phon.

For a plurality of equal-loudness curves, a sensitivity curve relative to 1000Hz is calculated according to the following formula, and the sensitivity curve represents the sound pressure level difference of different frequencies relative to 1000Hz under different equal-loudness curves:

S(f，L _n )＝-L _p (f，L _n )+L _p (1000，L _n )

referring to fig. 3, fig. 3 is a graph of human ear sensitivity in the embodiment of the present application, showing the difference between the sound pressure and 1kHz of different frequencies of different sound curves, assuming that the second curve is based on 80Phon, the difference between 20Hz and 1000Hz is about 38dB, and the difference between 20Phon, i.e. the lowest curve, 20Hz and 1000Hz is about 70dB.

Based on the above analysis, again based on 80 photon, if the playback sound pressure level reaches 80 photon, it can ensure the loudness balance of the song, and if it is below 80dB, according to fig. 3, it is shown that the middle and low frequencies below 1kHz require compensation below 1kHz because the loudness perception of the human ear is small relative to 1 kHz. For simplicity, only the compensation in the range of 20-1000Hz is considered (in practical application, the frequency band of 20-1000Hz can be expanded, i.e. a wider frequency band can be considered), and a compensation curve for different loudness can be obtained based on the curve of 80Phon, as shown in fig. 4 below, when the playback sound pressure level is 80dB, the loudness compensation is not needed, and when the playback sound pressure level is 20dB, the loudness balance of each frequency band of 20Phon is ensured, and the low frequency needs to be greatly improved, see the uppermost curve of fig. 4.

It should be noted that the curves shown in fig. 2-4 are discrete curves, and that in practice linear interpolation of the equivalent curves according to IOS226 may result in smaller step-size curves.

Based on the conclusion of the above curves, the sound pressure level of playback is large and small due to the different magnitudes of the song signal at different times. The present application therefore applies this conclusion to the loudness balancing based on the signal amplitude level by detecting the amplitude of the input signal, mapping to loudness, and dynamically performing a 20-1000Hz loudness balancing process. Specifically, referring to fig. 1, fig. 1 is a flowchart of a method for audio signals according to an embodiment of the present application, the method includes the following steps:

s101, obtaining a song signal and a signal amplitude curve of the song signal.

The song signal may be obtained by directly reading from the storage medium, may be obtained from another device by receiving or downloading, or may be obtained by a microphone. In the present embodiment, how the song signal is obtained is not limited in particular.

The song signal may be a signal of one song or a signal of a plurality of songs. Signals of different frequencies exist in the song signal.

The signal amplitude profile may specifically be a signal amplitude profile obtained by performing energy detection on the song signal. The signal amplitude curve may be obtained together with the song signal, or may be obtained by first obtaining the song signal and then performing energy detection on the song signal, thereby obtaining the signal amplitude curve.

S102, mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve.

The loudness of sound is related to the energy of the signal, and thus the amplitude can be mapped to loudness. I.e. the one that is the one. After the signal amplitude curve is obtained, the amplitude is mapped to loudness, thereby obtaining a loudness curve.

Specifically, mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve, including: and (3) carrying out energy detection on the signal amplitude curve, and mapping the amplitude to the loudness according to the loudness perception of the human ear corresponding to different energy sizes to obtain a loudness curve.

In general, the human ear has slightly different perceptibility to different frequency bands, especially to a lesser extent to low frequencies. According to the equal loudness curve of the human ear, if the same loudness is to be achieved in different frequency bands, with 1kHz as a reference, a higher sound pressure level is required for the low frequency band to keep consistent with the 1kHz loudness. Because the amplitude of the signals in different time periods is different for different songs, the perception capability of the human ear to low frequency is not as obvious as the signal amplitude when the signal amplitude is small.

S103, performing loudness balance processing on the loudness curve to obtain a filtering curve.

And (3) performing loudness balance processing on the loudness curve, namely performing gain processing on the position with low loudness, and performing suppression processing on the position with high loudness, so as to obtain a filtering curve.

The filtering curve is a curve that characterizes when gain is needed, when suppression is needed, and when it passes directly.

In one specific embodiment of the present application, the loudness balancing process is performed on the loudness curve to obtain a filtering curve, including:

step one, obtaining a loudness reference curve;

and step two, making a difference between the loudness curve and the loudness reference curve to obtain a filtering curve.

For convenience of description, the two steps are described in combination.

In this embodiment, loudness reference curves corresponding to different loudness may be set, and when a filtering curve needs to be determined, the corresponding loudness reference curve may be obtained according to an actual configuration requirement. Thus, the loudness curve is differenced from the loudness reference curve, thereby yielding a filtered curve.

Wherein, obtain loudness reference curve, include:

step 1, obtaining an equal-loudness curve of the human ear;

step 2, calculating a human ear sensitivity curve by using the human ear equal-loudness curve;

and step 3, determining a loudness reference curve by using the human ear sensitivity curve.

Wherein, utilize the equal response curve of human ear, calculate the sensitive curve of human ear, include:

and calculating the difference of sound pressure and kilohertz of different frequencies of different equal-loudness curves by using the equal-loudness curves of human ears to obtain a sensitive curve of human ears.

In particular, the human ear loudness equal loudness curve may be specifically referenced to fig. 2, and the human ear sensitivity curve may be specifically referenced to fig. 3. The implementation of the above steps may specifically refer to the core theory deduction process described above, and will not be described herein in detail.

S104, generating a filter matched with the filtering curve.

After the filter curve is obtained, a filter matched to the filter curve can be directly generated. I.e. the filter is one that can achieve the effect of the filter curve.

It should be noted that the filter herein does not simply refer to filtering a signal, but includes filtering a signal, and adjusting a gain, suppression, and the like of a signal.

In one embodiment of the present application, generating a filter that matches a filtering curve includes:

step one, determining a filter coefficient by utilizing a filtering curve;

and step two, generating a filter matched with the filter coefficient.

For simplicity, the filter may be implemented with a modified 1-order low-shell filter, i.e., a filter that is matched to the filter coefficients is generated, including: a 1 st order low-shelf tunable filter (1 st order low-shell filter) is generated that matches the filter coefficients.

Specifically, the filter can be implemented by adopting a modified 1-order low-shell filter, only the gain at 20Hz in fig. 3 needs to be determined, the filter can be approximately implemented by using the 1-order low-shell filter with the cut-off frequency of 122Hz, and the filter coefficient can be calculated by the following formula:

wherein omega _c To normalize the cut-off frequency, ω _c ＝2*pi*f _c /f _s ，f _c Is 122Hz, f _s G is a linear gain value at 20Hz for the sampling rate. The filtering process may be implemented by the following formula:

the curve simulation of the filter is shown in fig. 5.

Note that in the present embodiment, filtering may be implemented using different IIR or FIR filters, and is not limited to the 1 st order low-shell filter.

S105, filtering the song signal by using a filter to obtain a target song signal after loudness compensation.

After the filter is generated, the song signal may be filtered using the filter, thereby obtaining a loudness-compensated target song signal. That is, the target song signal may effectively shrink in loudness differences over different periods.

In one embodiment of the present application, the target song signal may be played after the target song signal is obtained. When the target song signal is played, there is no longer an audible perception of inattention. Of course, in practical application, a loudness adaptive switch may also be provided, and different signals are selected for playing based on the state of the switch. I.e., play the target song signal, comprising:

step one, if the loudness adaptive switch is in an on state, playing a target song signal;

and step two, playing the song signal if the loudness adaptive switch is in a closed state.

That is, the steps S101 to S105 described above may be performed based on the state of the loudness adaptive switch, and further play the processed target song signal.

In order to facilitate a person skilled in the art to better implement the audio signal method provided in the embodiments of the present application, the following describes the audio signal method in detail with reference to a specific implementation scenario as an example.

As can be seen from the description of the above embodiments, the implementation flow of the audio signal method may be as follows:

step 1, performing energy detection on an input signal (song signal), and supposing that 0dB is mapped into 80 photon, wherein low frequency is basically not compensated at the moment, and when the detection signal is-10 dB, performing loudness balance adjustment by adopting a curve corresponding to 70 photon, so that the same is true;

step 2, selecting a filtering curve to calculate filter coefficients according to the detection result in the step 1, and updating/generating a filter in real time;

and 3, filtering the input signal by using the filter obtained in the step 2, thereby finishing the loudness equalization processing and obtaining an output signal (target song signal) after the loudness equalization processing.

Illustrating: as shown in fig. 6, fig. 6 is a comparison graph of the song "ferry" before and after self-adaptive loudness balancing and a gain graph of a filter at 20Hz, it can be seen that when the signal amplitude is small, the compensation of the middle-low frequency energy is performed, and when the signal amplitude is large, the gain value is large, and when the signal amplitude is large, the gain is small, so that a self-adaptive middle-low frequency loudness compensation can be achieved.

Therefore, according to the method and the device, the balance of loudness is realized at different times for different songs, the loudness experience that the size signal is acquired to be better close is ensured, and the listening experience is further improved.

Corresponding to the above method embodiments, the embodiments of the present application further provide an audio signal device, where the audio signal device described below and the audio signal method described above may be referred to correspondingly.

Referring to fig. 7, the apparatus includes the following modules:

a signal acquisition module 101, configured to acquire a song signal and a signal amplitude curve of the song signal;

the loudness mapping module 102 is configured to map the amplitude in the signal amplitude curve to loudness, so as to obtain a loudness curve;

the loudness balancing module 103 is configured to perform loudness balancing processing on the loudness curve to obtain a filtering curve;

a filter generation module 104 for generating a filter matched to the filtering curve;

the filtering module 105 is configured to perform filtering processing on the song signal by using a filter, so as to obtain a target song signal after loudness compensation.

By applying the device provided by the embodiment of the application, the song signal and the signal amplitude curve of the song signal are obtained; mapping the amplitude in the signal amplitude curve to loudness to obtain a loudness curve; carrying out loudness balance treatment on the loudness curve to obtain a filtering curve; generating a filter matched with the filtering curve; and filtering the song signal by using a filter to obtain a target song signal after loudness compensation.

In one embodiment of the present application, the loudness balancing module 103 is specifically configured to obtain a loudness reference curve;

and (5) making a difference between the loudness curve and the loudness reference curve to obtain a filtering curve.

In one embodiment of the present application, the loudness balancing module 103 is specifically configured to obtain a human ear equal loudness curve;

In a specific embodiment of the present application, the loudness balancing module 103 is specifically configured to calculate differences between the sound pressures of different frequencies and one khz of different equal loudness curves by using the equal loudness curves of the human ear, so as to obtain the sensitivity curve of the human ear.

In one embodiment of the present application, the filter generating module 104 is specifically configured to determine the filter coefficient by using the filtering curve;

a filter is generated that matches the filter coefficients.

In one embodiment of the present application, the filter generation module 104 is specifically configured to generate a 1 st order low-shelf tunable filter that matches the filter coefficients.

In a specific embodiment of the present application, the loudness mapping module 102 is specifically configured to perform energy detection on a signal amplitude curve, and map the amplitude to the loudness according to loudness perception corresponding to different energy sizes by the human ear, so as to obtain a loudness curve.

In a specific embodiment of the present application, further comprising:

the playing module is used for playing the target song signal if the loudness adaptive switch is in an on state;

Corresponding to the above method embodiments, the embodiments of the present application further provide an electronic device, where an electronic device described below and an audio signal method described above may be referred to correspondingly.

Referring to fig. 8, the electronic device includes:

a memory 332 for storing a computer program;

a processor 322 for implementing the steps of the audio signal method of the above-described method embodiment when executing a computer program.

Specifically, referring to fig. 9, fig. 9 is a schematic diagram of a specific structure of an electronic device according to the present embodiment, where the electronic device may have a relatively large difference due to different configurations or performances, and may include one or more processors (central processing units, CPU) 322 (e.g., one or more processors) and a memory 332, where the memory 332 stores one or more computer applications 342 or data 344. Wherein the memory 332 may be transient storage or persistent storage. The program stored in memory 332 may include one or more modules (not shown), each of which may include a series of instruction operations in the data processing apparatus. Still further, the central processor 322 may be configured to communicate with the memory 332 and execute a series of instruction operations in the memory 332 on the electronic device 301.

The electronic device 301 may also include one or more power supplies 326, one or more wired or wireless network interfaces 350, one or more input/output interfaces 358, and/or one or more operating systems 341.

The steps in the audio signal method described above may be implemented by the structure of the electronic device.

Corresponding to the above method embodiments, the embodiments of the present application further provide a readable storage medium, where a readable storage medium described below and an audio signal method described above may be referred to correspondingly.

A readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the audio signal method of the above-described method embodiment.

The readable storage medium may be a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, and the like.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Those skilled in the art may implement the described functionality using different approaches for each particular application, but such implementation should not be considered to be beyond the scope of this application.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Finally, it is further noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms include, comprise, or any other variation is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The principles and embodiments of the present application are described herein with specific examples, the above examples being provided only to assist in understanding the methods of the present application and their core ideas; meanwhile, as those skilled in the art will vary in the specific embodiments and application scope according to the ideas of the present application, the contents of the present specification should not be construed as limiting the present application in summary.

Claims

1. An audio signal processing method, comprising:

obtaining a song signal and a signal amplitude curve of the song signal;

generating a filter matched with the filtering curve;

2. The method of audio signals according to claim 1, wherein performing a loudness balancing process on the loudness curve results in a filtered curve, comprising:

acquiring a loudness reference curve;

3. The method of audio signals as claimed in claim 2, wherein said obtaining a loudness reference curve comprises:

acquiring an equal-loudness curve of the human ear;

4. The method of audio signals according to claim 3, wherein calculating a human ear sensitivity curve using said human ear equal loudness curve comprises:

5. The audio signal method of claim 1, wherein the generating a filter matched to the filtering curve comprises:

determining filter coefficients using the filter curve;

the filter is generated that matches the filter coefficients.

6. The audio signal method of claim 5, wherein the generating the filter that matches the filter coefficients comprises:

7. The method of audio signals according to claim 1, wherein mapping the amplitudes in the signal amplitude profile to loudness results in a loudness profile, comprising:

8. The audio signal method according to any one of claims 1 to 6, further comprising:

9. An electronic device, comprising:

a memory for storing a computer program;

processor for implementing the steps of the audio signal method according to any of claims 1 to 8 when said computer program is executed.

10. A readable storage medium, characterized in that the readable storage medium has stored thereon a computer program which, when executed by a processor, implements the steps of the audio signal method according to any of claims 1 to 8.