Audio compression method and apparatus

Abstract

To provide an audio compression method and device for suppressing distortion of an audio signal during reproduction and improving reproduction quality. [Solution] The audio compression method includes the steps of obtaining a first audio signal to be processed (an original audio signal to be reproduced), filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum related to the distortion band of the audio reproduction device to obtain a second audio signal, processing the second audio signal with a predetermined dynamic range compressor (DRC) to obtain a compression coefficient, and outputting a compressed signal based on the compression coefficient.

Description

[Technical Field]

[0001] The present application is in the field of audio processing technology, and in particular relates to audio compression methods and apparatus. [Background technology]

[0002] A dynamic range compressor (DRC) is a core audio processor in audio playback devices (e.g., earphones, audio players, mobile phones, etc.) that is configured to compress the dynamic range (i.e., the logarithm of the ratio between the maximum and minimum amplitude values ​​of an audio signal) of a playback audio signal to a specified dynamic range. That is, when the volume (i.e., loudness) is high, the signal amplitude is attenuated to within a threshold (a compression coefficient set in the DRC), and when the volume is low, the signal amplitude is appropriately increased to balance the volume of the audio signal. By reducing the dynamic range of the audio signal, the DRC controls the peak value of the audio signal so that it does not exceed the acoustic output threshold (i.e., the maximum digital signal output supported by the hardware of the audio playback device in the corresponding frequency band). This allows the audio signal output from the audio playback device to better adapt to the playback environment, improving audibility and preventing excessive volume differences in the audio signal, which could damage the audio playback device.

[0003] However, when different audio signals have different amplitudes and audio signals with different amplitudes are compressed to the same dynamic range, the peak values ​​of the audio signals with large amplitudes are compressed within the acoustic output threshold, but the amplitude values ​​of some bands still exceed the acoustic output threshold and cannot be adjusted, resulting in distortion of those bands.On the other hand, if the compression range is simply expanded to reduce the amplitude of the audio signals, the low-frequency gain will decrease at high volumes, which may cause distortion and affect audibility. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application provides an audio compression method and device that can suppress distortion of audio signals during playback and improve playback quality. [Means for solving the problem]

[0005] A first aspect of the present application is an audio compression method applied to an audio playback device, comprising: obtaining a first audio signal to be processed; filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum to obtain a second audio signal, the target frequency spectrum being related to a distortion band of the audio reproduction device; processing the second audio signal with a predetermined dynamic range compressor DRC to obtain compression coefficients; and outputting a compressed signal based on the compression coefficient.

[0006] In one embodiment, the step of obtaining the first audio signal to be processed comprises: obtaining an original audio signal to be played; inputting the original audio signal to be played into a sound effect processing module for processing to obtain a third audio signal, the third audio signal being the first audio signal, and the sound effect processing module including at least one sound effect processor; The step of outputting a compressed signal based on the compression coefficient includes: The step of compressing the third audio signal based on the compression factor and outputting the compressed signal is included.

[0007] In one embodiment, the method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: Turning off the frequency spectrum compensation filter and debugging the sound effect processing module, and then detecting a distortion band of the audio playback device; determining the target frequency spectrum based on the distortion band; and debugging the frequency spectrum compensation filter based on the target frequency spectrum.

[0008] In one embodiment, the method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: Turning off the frequency spectrum compensation filter and debugging the sound effect processing module, and then detecting the acoustic output threshold curve of the audio playback device; determining a compression curve based on a difference between an acoustic output threshold curve and a frequency response curve of an audio signal output from the sound effects processing module; determining the target frequency spectrum based on the compression curve; and performing debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0009] In one embodiment, the first audio signal is an original audio signal to be reproduced, or the first audio signal is an audio signal obtained by attenuating the original audio signal to be reproduced based on a predetermined threshold.

[0010] In one embodiment, the step of outputting a compressed signal based on the compression factor comprises: a step of compressing the original audio signal to be reproduced based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: turning off the frequency spectrum compensation filter and testing an acoustic output threshold curve of the audio reproduction device; determining a compression curve based on the acoustic output threshold curve and an original audio signal for debugging; determining the target frequency spectrum based on the compression curve; and performing debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0011] In one embodiment, the step of outputting a compressed signal based on the compression factor comprises: inputting the original audio signal to be played into a sound effect processing module for processing to obtain a third audio signal, wherein the sound effect processing module includes at least one sound effect processor; compressing the third audio signal based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: detecting an acoustic output threshold curve of the audio playback device after turning off the frequency spectrum compensation filter and the sound effect processing module; determining a compression curve based on the acoustic output threshold curve and an original audio signal for debugging; determining the target frequency spectrum based on the compression curve; and performing debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0012] In one embodiment, the step of determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging comprises: determining the compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of the original audio signal for debugging;

[0013] In one embodiment, the step of determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging comprises: The step of determining the compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of a fourth audio signal, the fourth audio signal being an audio signal obtained by attenuating the original audio signal for debugging according to the predetermined threshold.

[0014] In one embodiment, the sound effects processing module includes an equalizer.

[0015] In one embodiment, the DRC debugging method comprises: The method further includes a step of performing parameter debugging based on the audio signal output from the frequency spectrum compensation filter.

[0016] In one embodiment, the frequency spectrum compensation filter is an IIR filter or an FIR filter.

[0017] A second aspect of the present application provides an audio playback device comprising a processor, a memory, and a computer program stored in said memory and executable by said processor, wherein said device implements a method according to the first aspect or any one of the embodiments of the first aspect when said processor executes said computer program.

[0018] A third aspect of the present application provides a computer readable storage medium having stored thereon a computer program that, when executed by a processor, implements a method according to the first aspect or any one of the embodiments of the first aspect.

[0019] A fourth aspect of the present application provides a computer program product which, when executed by a processor, implements the method of the first aspect or any one of the embodiments of the first aspect. [Effects of the Invention]

[0020] The present application has the following technical advantages over the prior art: The audio compression method of the present application adds a frequency spectrum compensation filter before the DRC, i.e., performs filtering on the amplitude of a corresponding region in the distortion band of the audio signal, sets the frequency spectrum of the processed signal as the target frequency spectrum, inputs the processed signal to the DRC to calculate a compression coefficient, and compresses the audio signal to be output based on the compression coefficient, thereby expanding the compression range, suppressing distortion during playback, and improving playback quality without significantly reducing the gain in the loud volume band. [Brief explanation of the drawings]

[0021] In order to more clearly explain the solutions in the embodiments of the present application, the following briefly introduces drawings required in the description of the embodiments or prior art. Needless to say, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any creative labor. [Figure 1] FIG. 1 is a schematic diagram of an audio processing system in the related art. [Figure 2] FIG. 1 is a schematic diagram of a compression effect of a frequency response curve in the related art. [Figure 3] FIG. 1 is a schematic diagram of a compression effect of a frequency response curve in the related art. [Figure 4] FIG. 1 is a schematic diagram of a compression effect of a frequency response curve in the related art. [Figure 5] FIG. 1 is a schematic diagram of a compression effect of a frequency response curve in the related art. [Figure 6] 1 is a flowchart of an audio compression method according to an embodiment of the present application; [Figure 7]1 is a block diagram of an audio processing system according to an embodiment of the present application; [Figure 8] FIG. 10 is a schematic diagram of the compression effect of a frequency response curve according to an embodiment of the present application. [Figure 9] FIG. 10 is a schematic diagram of the compression effect of a frequency response curve according to an embodiment of the present application. [Figure 10] FIG. 10 is a comparison diagram of frequency response curves and acoustic output threshold curves according to an embodiment of the present application. [Figure 11] FIG. 2 is a schematic diagram of a compression curve according to an example of the present application. [Figure 12] FIG. 2 is a block diagram of an audio processing system according to another embodiment of the present application. [Figure 13] FIG. 10 is a comparison diagram of a frequency response curve and an acoustic output threshold curve according to another embodiment of the present application. [Figure 14] FIG. 10 is a schematic diagram of a compression curve according to another embodiment of the present application. [Figure 15] FIG. 2 is a block diagram of an audio processing system according to another embodiment of the present application. [Figure 16] 1 is a structural diagram of an audio compression device according to an embodiment of the present application; [Figure 17] 1 is a structural diagram of an audio playback device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0022] As described in the background art, audio playback devices generally use DRC to adjust the dynamic range of an audio signal and achieve loudness adjustment of the audio signal. In the related art, the DRC is usually installed after a sound effect processor. The sound effect processor adjusts the sound effect of the audio signal, and different sound effect processors can obtain different playback effects.

[0023] For example, the sound effect processor may include, but is not limited to, an equalizer, a reverberator, a tone controller, a special effect processor, etc. Among them, an equalizer (EQ) is a set of filters in an audio playback device that is used to adjust the frequency response curve of an original audio signal so that the audio output from the audio playback device achieves a desired sound effect (e.g., bass boost, treble boost, noise reduction, etc.). A reverberator is used to impart a spatial effect to the audio output from the audio playback device. A tone controller can change the timbre and / or tone of the original audio signal to achieve an audio modification function.

[0024] Due to the differences in the acoustic structure design of different audio playback devices, the sound effect processors debugged based on the reference standard of the target sound effect are also different.

[0025] For example, Figure 1 is a schematic diagram of a typical audio processing system architecture in the prior art, in which the data obtained by processing the original audio signal through an equalizer (in this application, the audio signal output through the sound effect processor is referred to as the third audio signal) is input to and processed by a DRC to obtain the corresponding compression coefficient, and then the third audio signal is compressed by the compression coefficient, and finally the compressed signal is sent to a loudspeaker for playback.

[0026] The DRC includes pre-debugged compression parameters, such as, but not limited to, a threshold, a compression ratio, an attack time, and a release time. Based on the compression parameters, the DRC can determine the amount of compression corresponding to each band of the third audio signal. For example, when the gain (unit: dBFs) of the third audio signal exceeds the threshold, the DRC activates compression within the attack time, attenuates the gain of the corresponding band in the third audio signal to below the threshold according to the compression ratio, and determines the amount of compression for that band. The DRC releases the compression within the release time until the gain of the third audio signal falls below the threshold. The compression coefficient includes at least the amount of compression corresponding to each band in the third audio signal whose gain exceeds the threshold.

[0027] For example, as shown in Figure 2, the threshold in the DRC is -5 dBFs, and curve a is the frequency response curve of the third audio signal (where the abscissa is frequency and the ordinate is gain), where the gain corresponding to 45 Hz to 80 Hz exceeds -5 dBFs. After compressing the gain corresponding to 45 Hz to 80 Hz in the third audio signal based on the compression coefficient output from the DRC, the frequency response curve of the resulting compressed signal 1 is shown by curve b, and the gain corresponding to 45 Hz to 80 Hz in the compressed signal 1 is compressed to -5 dBFs or less. As shown in Figure 3, if the dotted line indicates the acoustic output threshold curve of the audio reproduction device, in an ideal state, the gain in each frequency band of compressed signal 1 obtained by the equalizer and DRC processing should not exceed the acoustic output threshold of the audio reproduction device.

[0028] However, because DRC compression parameters are fixed and subject to debug, it is difficult to achieve satisfactory compression results for large amounts of audio signals with different amplitudes. The maximum digital signal that an audio playback device can output is not a constant value across the entire frequency band, but rather fluctuates. Unlike the threshold value in DRC, the acoustic output threshold curve varies with frequency (e.g., the acoustic output threshold curve shown in Figure 3). Therefore, after a large-amplitude audio signal is compressed, the gains corresponding to each band will not exceed the DRC threshold, but the gains corresponding to some bands will still exceed the acoustic output threshold, potentially resulting in distortion during playback.

[0029] For example, as shown in Fig. 4, an audio signal having a larger amplitude than the original audio signal of compressed signal 1 is processed by an equalizer and DRC to obtain compressed signal 2. The gain corresponding to the loud volume band (45 Hz to 80 Hz shown in Fig. 4) of compressed signal 2 is compressed to within the acoustic output threshold via DRC, but adjacent bands of the loud volume band (e.g., 35 Hz, 100 Hz) are not compressed because they do not exceed the DRC threshold, and still exceed the acoustic output threshold corresponding to the adjacent band of the audio playback device, resulting in distortion of the audio signal output from the adjacent band.

[0030] In some embodiments, a larger compression range is adopted to compress the gain of all bands of the audio signal within the acoustic output threshold. For example, as shown in Fig. 5, the intra-DRC threshold is set to -6 dBFS, and an audio signal with a larger amplitude is processed with an equalizer and DRC to obtain compressed signal 3. Compared with compressed signal 2 shown in Fig. 4, compressed signal 3 has gains in all bands that do not exceed the corresponding acoustic output thresholds, but the gains in louder bands are significantly reduced, resulting in insufficient audibility and the risk of distortion in louder bands.

[0031] Therefore, the present application provides an audio compression method that can expand the compression range, suppress distortion during playback, and improve playback quality without significantly reducing the gain in loud volume bands.

[0032] 6 is a flowchart of an audio compression method according to an embodiment of the present application. The audio compression method is applied to an audio playback device, which may be an earphone, an audio player, or an electronic device capable of playing audio and video containing audio (e.g., a mobile phone, a computer, a tablet, a television, etc.). As shown in FIG. 6, the audio compression method according to the present application may include the following steps:

[0033] In S601, a first audio signal to be processed is acquired.

[0034] Here, the first audio signal may be a third audio signal output from a sound effect processor, may be the original audio signal to be reproduced, or may be an attenuated version of the original audio signal to be reproduced.

[0035] In S602, a second audio signal is obtained by filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum, where the target frequency spectrum is related to a distortion band of an audio reproduction device.

[0036] The present application filters a first audio signal to be input to the DRC by adding a frequency spectrum compensation filter before the DRC, and adjusts the amplitude of the first audio signal corresponding to the distortion band in the audio playback device, so that the frequency spectrum of the adjusted second audio signal becomes a target frequency spectrum.

[0037] Here, the frequency spectrum compensation filter may be any filter that can attenuate the amplitude of a digital signal, such as an infinite impulse response (IIR) filter or a finite impulse response (FIR) filter.

[0038] The distortion band of an audio playback device refers to the frequency range distorted when the audio playback device plays a sweep signal (i.e., a pure tone signal with maximum amplitude) at maximum volume (i.e., an amplitude of 0 dBFS). The filtering range of the frequency spectrum compensation filter may be the same as the distortion band or may include the distortion band. Specifically, adaptive debugging can be performed according to the requirements of the actual compression effect.

[0039] According to the embodiments of the present application, after the frequency spectrum compensation filter performs frequency spectrum compensation on the first audio signal, the amplitude values ​​corresponding to the distortion bands in the first audio signal are compressed, that is, the waveforms corresponding to the distortion bands in the frequency spectrum of the second audio signal are gentler than those in the frequency spectrum of the first audio signal.

[0040] In S603, the second audio signal is processed according to a predetermined DRC to obtain a compression coefficient.

[0041] According to an embodiment of the present application, a frequency spectrum compensation filter is added before the DRC, so that the parameters in the DRC (e.g., threshold, compression rate, effective time, release time, etc.) are debugged based on the audio signal output from the frequency spectrum compensation filter. Because the waveform of the audio signal processed by the frequency spectrum compensation filter is gentler, the debugged DRC can obtain a larger compression range when calculating the compression coefficient corresponding to the second audio signal.

[0042] In S604, a compressed signal is output based on the compression coefficient.

[0043] According to an embodiment of the present application, the audio playback device may obtain a compression coefficient corresponding to the second audio signal, and then compress the audio signal to be played back to obtain a compressed signal. For example, if a sound effect processor is installed in the audio processing system of the audio playback device, the audio playback device may compress the audio signal output from the sound effect processor using the compression coefficient to obtain a compressed signal. If the audio processing system does not include a sound effect processor, the audio playback device may compress the original audio signal to be played back using the compression coefficient to obtain a compressed signal. The obtained compressed signal is sent to a loudspeaker of the audio playback device for playback.

[0044] According to an audio compression method according to an embodiment of the present application, a frequency spectrum compensation filter is added before a DRC, frequency spectrum compensation is performed on a first audio signal, the first audio signal is filtered with respect to amplitude values ​​in a region corresponding to a distortion band, the processed signal is input to a DRC to calculate a compression coefficient, and the audio signal to be output is compressed based on the compression coefficient, thereby expanding the compression range, suppressing distortion during playback, and improving playback quality without significantly reducing the gain in loud volume bands.

[0045] The audio compression method according to the present application will be described below in specific embodiments. Some of the following specific embodiments can be combined with each other. The same or similar concepts or processes may be omitted in some embodiments.

[0046] In addition, the DRC, sound effect processor, and filter in this document are all concepts well known to those skilled in the art, and their parameter debugging processes and signal processing processes are also well known to those skilled in the art. Therefore, this application does not provide a detailed description of the specific debugging processes and signal processing processes of the DRC, sound effect processor, and filter.

[0047] For an audio processing system including a sound effects processor, in one example, the frequency spectrum compensation filter may be provided between the sound effects processor and the DRC, and the first audio signal may be a third audio signal output from the sound effects processor.

[0048] For example, the audio processing system may include a sound effect processing module, a frequency spectrum compensation filter, a DRC, and a compression module, as shown in Figure 7. The sound effect processing module includes at least one sound effect processor, such as an equalizer, a reverberator, a tone controller, a special effect unit, etc.

[0049] An original audio signal to be played is input to the audio processing system and processed by the audio processing module to obtain a third audio signal. The third audio signal is input to a compression module and a frequency spectrum compensation filter. The frequency spectrum compensation filter performs frequency spectrum compensation on the third audio signal output from the sound effects processing module, adjusting the amplitude of a band corresponding to the distortion band of the third audio signal to obtain a second audio signal. The second audio signal is input to a DRC, which calculates a compression coefficient corresponding to the second audio signal based on pre-debugged parameters. The obtained compression coefficient is input to the compression module, which compresses the third audio signal to be output based on the compression coefficient to obtain a compressed signal. The compressed signal is then sent to a loudspeaker for playback.

[0050] For example, if the distortion band of the audio playback device is 30 Hz to 100 Hz and the filtering range of the frequency spectrum compensation filter is 20 Hz to 200 Hz, as shown in FIG. 8 , compared with the frequency response curve of the third audio signal output from the sound effect processor, the frequency response curve of the second audio signal obtained after the frequency spectrum compensation filter performs frequency spectrum compensation on the third audio signal has a waveform corresponding to the distortion band that is relatively gentle.

[0051] According to an embodiment of the present application, the parameters in the DRC are debugged based on the audio signal output by the frequency spectrum compensation filter, which has a waveform corresponding to the distortion band that is gentler than the audio signal output by the sound effect processor, so the debugged DRC can obtain a larger compression range when calculating the compression coefficient.

[0052] For example, as shown in Figure 8, threshold B obtained by debugging based on the audio signal output from the sound effect processor is greater than threshold A obtained by debugging based on the audio signal output from the frequency spectrum compensation filter. When the compression coefficient corresponding to the third audio signal is calculated based on threshold B, the compression range is 35Hz to 100Hz. When the compression coefficient corresponding to the second audio signal is calculated based on threshold A, the compression range is 20Hz to 200Hz. That is, the compression range of the DRC increases due to changes in the frequency spectrum of the audio signal input to the DRC.

[0053] Taking the amplitude value corresponding to 100 Hz as an example, the amplitude value corresponding to 100 Hz is attenuated from y1 to y2 due to the compensation of the frequency spectrum compensation filter. When the third audio signal is input to the DRC to calculate the corresponding compression coefficient, the amplitude value corresponding to 100 Hz of the third audio signal does not exceed the threshold B, so the compression amount gain is 0. Then, when the compression module compresses the third audio signal based on the compression coefficient, the amplitude value corresponding to 100 Hz is not compressed.

[0054] When the second audio signal is input to the DRC to calculate the compression coefficient, the amplitude value corresponding to 100 Hz of the second audio signal exceeds the threshold A, so the compression amount gain is y2-A. After the compression module compresses the third audio signal based on the compression coefficient, the amplitude value corresponding to 100 Hz of the resulting compressed signal is y1-gain=y1-(y2-A).

[0055] By expanding the compression range, the third audio signal obtains a greater amount of compression in the region corresponding to the distortion band, thereby further ensuring that the amplitude of the compressed signal in the distortion band is within the range limited by the acoustic output threshold, and suppressing distortion when the compressed signal is played back.

[0056] FIG. 9 is a comparison diagram of frequency response curves (curves c1, d1, e1, and f1 shown in FIG. 9(a)) obtained when original audio signals to be reproduced with different amplitudes are compressed using the audio processing system shown in FIG. 1 , frequency response curves (curves c2, d2, e2, and f2 shown in FIG. 9(b)) obtained when the original audio signals are compressed using the audio processing system according to the present application, and acoustic output threshold curves. All compressed signals obtained using the audio processing system according to the present application are compressed to within the acoustic output threshold. Furthermore, because the frequency spectrum of the second audio signal has a more gradual waveform corresponding to the distortion band, the amount of compression calculated by the DRC results in a smaller change in amplitude with frequency. This means that the gain in the louder bands is not significantly reduced, ensuring the loudness of the louder audio bands.

[0057] When debugging the frequency spectrum compensation filter for the audio processing system shown in Figure 7, the frequency spectrum compensation filter can be turned off and the sound effects processing module can be debugged. When the sound effects processing module is debugged, the distortion band of the audio playback device is detected, i.e., the frequency range where distortion occurs is detected using a sweep signal played at maximum volume. Based on the obtained distortion band, a target frequency spectrum (i.e., a frequency spectrum that prevents the amplitude value corresponding to the distortion band of the output signal from exceeding the acoustic output threshold) can be determined. The initial filtering range of the frequency spectrum compensation filter is then set based on the target frequency spectrum. The frequency spectrum compensation filter is then activated, the original audio signal to be debugged is input into the audio processing system, the compressed signal output from the audio processing system is detected, and the filtering range of the frequency spectrum compensation filter is adjusted based on the detection result. The final filtering range of the frequency spectrum compensation filter is obtained, resulting in a debugged frequency spectrum compensation filter.

[0058] Preferably, after debugging the audio sound effect processing module, the acoustic output threshold curve of the audio playback device may be detected, and a compression curve may be determined based on the difference between the acoustic output threshold curve and the frequency response curve of the audio signal output from the sound effect processing module. For example, the frequency response curve of the audio signal (shown as F1 in the figure) output after processing the original audio signal to be debugged by the debugged sound effect processing module and the acoustic output threshold curve of the audio playback device are shown in FIG. 10. After subtracting the frequency response curve and the acoustic output threshold curve, a compression curve as shown in FIG. 11 is obtained. Note that the compression curve indicates the band that needs to be compressed in the audio signal output from the sound effect processing module, i.e., the distortion band of the audio playback device.

[0059] Then, a target frequency spectrum is set based on the compression curve, and an initial filter range of the frequency spectrum compensation filter is set based on the target frequency spectrum, and the compression effect of the compressed signal is repeatedly tested to adjust the filter range and determine the final filter range of the frequency spectrum compensation filter, thereby obtaining a debugged frequency spectrum compensation filter.

[0060] In another example, the frequency spectrum compensation filter may be provided independently of the sound effect processor. The first audio signal may be an original audio signal to be reproduced. Preferably, considering that the maximum amplitude value of an audio signal that most audio reproduction devices can process must not exceed 0 dBFS and that the amplitude values ​​within some band ranges of some audio signals may be greater than 0 dBFS, the first audio signal may be a signal obtained by performing attenuation processing on the original audio signal to be reproduced in all bands, in which case the waveform of the frequency response curve of the first audio signal is the same as the waveform of the frequency response curve of the original audio signal to be reproduced.

[0061] For example, as shown in FIG. 12, an audio processing system may include a sound effects processing module, a frequency spectrum compensation filter, an attenuation module, a dynamic range control (DRC), and a compression module. An original audio signal to be reproduced is input to the audio processing system and then input to the attenuation module and the sound effects processing module, respectively. The attenuation module first attenuates the original audio signal to be reproduced according to a predetermined threshold to obtain a first audio signal. The frequency spectrum compensation filter performs frequency spectrum compensation on the first audio signal and adjusts the amplitude of a region corresponding to the distortion band of the first audio signal to obtain a second audio signal. The second audio signal is input to the dynamic range control (DRC), which calculates a compression coefficient corresponding to the second audio signal based on pre-debugged parameters. The original audio signal to be reproduced is processed by the sound effects processing module to obtain a third audio signal. The obtained compression coefficient and the third audio signal are input to the compression module, which compresses the third audio signal to be output based on the compression coefficient to obtain a compressed signal. The compressed signal is then sent to a loudspeaker for playback.

[0062] When debugging the frequency spectrum compensation filter, if the frequency spectrum compensation filter and the sound effects processing module are turned off, an acoustic output threshold curve of the audio playback device can be detected. An original audio signal to be debugged is input to the audio processing system, and the original audio signal to be debugged is attenuated by an attenuation module according to a preset threshold to obtain a fourth audio signal. A compression curve is determined based on the difference between the acoustic output threshold curve and the frequency response curve of the fourth audio signal.

[0063] For example, after subtracting the frequency response curve of the fourth audio signal from the acoustic output threshold curve of the audio reproduction device as shown in Fig. 13, a compression curve is obtained as shown in Fig. 14. Note that the compression curve indicates the band in the original audio signal that needs to be compressed, i.e., the distortion band of the audio reproduction device.

[0064] Preferably, the frequency response curve of the audio processing system of the original audio signal for debugging may be directly acquired, and the compression curve may be determined based on the difference between the acoustic output threshold curve and the frequency response curve of the original audio signal.

[0065] After obtaining the compression curve, a target frequency spectrum is set according to the compression curve, an initial filtering range of the frequency spectrum compensation filter is set according to the target frequency spectrum, and the compression effect of the compressed signal is repeatedly tested to adjust the filtering range and determine the final filtering range of the frequency spectrum compensation filter, thereby obtaining a debugged frequency spectrum compensation filter.

[0066] Note that in the audio processing system shown in Figure 7, the parameters of the frequency spectrum compensation filter change based on changes in the parameters in the sound effect processor. In the audio processing system shown in Figure 12, the sound effect processor and the frequency spectrum compensation filter can be debugged independently, and changes in the parameters in the sound effect processor do not affect the frequency spectrum compensation filter, avoiding the need to synchronously modify the frequency spectrum compensation filter when adjusting the parameters of the sound effect processor.

[0067] In another scenario, the audio processing system may not include a sound effect processor. The first audio signal may be an original audio signal to be reproduced, or the first audio signal may be a signal obtained after performing attenuation processing on the original audio signal to be reproduced in all frequency bands.

[0068] As shown in FIG. 15, another audio processing system according to the present application includes a frequency spectrum compensation filter, an attenuation module, a dynamic range compensation (DRC), and a compression module. An original audio signal to be reproduced is input to the audio processing system, and then input to the attenuation module and the compression module, respectively. The attenuation module first attenuates the original audio signal to be reproduced according to a predetermined threshold to obtain a first audio signal. The frequency spectrum compensation filter performs frequency spectrum compensation on the first audio signal to obtain a second audio signal. The second audio signal is input to the dynamic range compensation (DRC), which calculates a compression coefficient corresponding to the second audio signal based on pre-debugged parameters. The obtained compression coefficient is input to the compression module, which compresses the original audio signal to be reproduced based on the compression coefficient to obtain a compressed signal. The compressed signal is then sent to a loudspeaker for playback.

[0069] Correspondingly, when debugging the frequency spectrum compensation filter, if the frequency spectrum compensation filter is turned off, the acoustic output threshold curve of the audio playback device can be detected. The original audio signal to be debugged is input to the audio processing system, and the original audio signal to be debugged is attenuated according to a predetermined threshold by the attenuation module to obtain a fourth audio signal. A compression curve is determined based on the difference between the acoustic output threshold curve and the frequency response curve of the fourth audio signal. Alternatively, the compression curve is determined directly based on the difference between the frequency response curve of the original audio signal and the acoustic output threshold curve in the audio processing system. A target frequency spectrum is then set based on the compression curve, and an initial filtering range of the frequency spectrum compensation filter is further set based on the target frequency spectrum. The compression effect of the compressed signal is repeatedly tested to adjust the filtering range, thereby determining the final filtering range of the frequency spectrum compensation filter and obtaining a debugged frequency spectrum compensation filter.

[0070] Therefore, by adding a frequency spectrum compensation filter before the DRC, it is possible to expand the compression range and suppress distortion when playing back compressed signals without significantly reducing the gain in louder bands.

[0071] Based on the same inventive concept, as an implementation of the above method, an embodiment of the present application provides an audio compression device, and the embodiment of the device corresponds to the embodiment of the above method. For convenience, the embodiment of the device does not describe the details of the embodiment of the above method one by one, but the device in this embodiment can correspondingly realize all the contents of the embodiment of the above method.

[0072] 16 is a structural schematic diagram of an audio compression device according to an embodiment of the present application. As shown in FIG. 16, the device according to this embodiment includes: an acquisition unit for acquiring a first audio signal to be processed; a frequency spectrum compensation unit for filtering the first audio signal based on a predetermined target frequency spectrum to obtain a second audio signal, the target frequency spectrum being related to a distortion band of the audio playback device; a dynamic range compression unit for processing the second audio signal to obtain a compression factor; a compression unit that outputs a compressed signal based on the compression coefficient.

[0073] Optionally, obtaining a first audio signal to be processed comprises: obtaining an original audio signal to be played; inputting the original audio signal to be played into a sound effect processing module for processing to obtain a third audio signal, the third audio signal being the first audio signal, and the sound effect processing module including at least one sound effect processor; outputting a compressed signal based on the compression coefficient, compressing the third audio signal based on the compression factor and outputting the compressed signal.

[0074] Optionally, the manner of obtaining the target frequency spectrum and the frequency spectrum compensation filter includes: Turning off the frequency spectrum compensation filter and debugging the sound effect processing module, and then detecting a distortion band of the audio playback device; determining the target frequency spectrum based on the distortion band; and obtaining the frequency spectrum compensation filter by debugging based on the target frequency spectrum.

[0075] Optionally, the manner of obtaining the target frequency spectrum and the frequency spectrum compensation filter includes: After turning off the frequency spectrum compensation filter and debugging the sound effect processing module, detecting the acoustic output threshold curve of the audio playback device; determining a compression curve based on a difference between an acoustic output threshold curve and a frequency response curve of an audio signal output from the sound effects processing module; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0076] Optionally, the first audio signal is an original audio signal to be reproduced, or the first audio signal is an audio signal obtained by attenuating the original audio signal to be reproduced based on a predetermined threshold.

[0077] Preferably, the step of outputting a compressed signal based on the compression coefficient comprises: compressing the original audio signal to be reproduced based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: turning off the frequency spectrum compensation filter and testing an acoustic output threshold curve of the audio reproduction device; determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0078] Preferably, the step of outputting a compressed signal based on the compression coefficient comprises: The original audio signal to be played is input to a sound effect processing module for processing to obtain a third audio signal, and the sound effect processing module includes at least one sound effect processor; compressing the third audio signal based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: Detecting an acoustic output threshold curve of the audio playback device after turning off the frequency spectrum compensation filter and the sound effect processing module; determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter.

[0079] Preferably, the step of determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging comprises: determining the compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of the original audio signal for debugging;

[0080] Preferably, determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging comprises: The compression curve is determined based on a difference between the acoustic output threshold curve and a frequency response curve of a fourth audio signal, and the fourth audio signal is an audio signal obtained by attenuating the original audio signal for debugging according to the predetermined threshold.

[0081] Preferably, the sound effects processing module includes an equalizer.

[0082] Preferably, the debugging method of the dynamic range compression unit comprises: The method further includes a step of performing parameter debugging based on the audio signal output from the frequency spectrum compensation filter.

[0083] Preferably, the frequency spectrum compensation filter is an IIR filter or an FIR filter.

[0084] The audio compression device according to this embodiment can implement the above method embodiment, and the realization principle and technical effect are similar, so the description will be omitted here.

[0085] For the sake of convenience and simplicity, those skilled in the art will understand that only the division of the above functional units and modules is used as an example. In actual applications, the above functional allocations can be realized by different functional units or modules as needed, i.e., the internal structure of the above device can be divided into different functional units or modules to achieve all or part of the above-described functions. The functional units and modules in the embodiments may be integrated into a single processing unit, each unit may exist physically independently, or two or more units may be integrated into a single unit. The integrated unit may be implemented in the form of hardware or software functional units. Furthermore, the specific names of the functional units and modules are used only to distinguish them from one another and do not limit the scope of protection of the present application. For the specific operating processes of the units and modules in the above system, reference may be made to the corresponding processes in the above method embodiments, and further description will be omitted here.

[0086] Based on the same inventive idea, an embodiment of the present application further provides an audio playback device. Figure 17 is a structural schematic diagram of an audio playback device according to an embodiment of the present application. As shown in Figure 17, the audio playback device according to this embodiment includes a memory 210 and a processor 220, the memory 210 stores a computer program, and the processor 220 executes the method described in the above method embodiment when calling the computer program.

[0087] The audio playback device according to this embodiment can implement the above method embodiment, and the realization principle is similar to the technical effect, so the description is omitted here.

[0088] An embodiment of the present application further provides a computer-readable storage medium having stored thereon a computer program that, when executed by a processor, implements the method according to the above method embodiment.

[0089] An embodiment of the present application further provides a computer program product which, when executed on an audio playback device, causes the audio playback device to implement the method according to the above method embodiment.

[0090] In the above embodiments, all or part of the above may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the above may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded into a computer and executed, the processes or functions described in the embodiments of the present application are implemented in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in or transmitted via a computer-readable storage medium. The computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, radio, microwave, etc.) method. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center that includes one or more available media. The usable medium may be a magnetic medium (for example, a flexible disk, a hard disk, or a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).

[0091] Those skilled in the art can understand that all or part of the processes in the methods of the above embodiments can be realized by instructing relevant hardware through a computer program, which may be stored in a computer-readable storage medium, and which may include the processes of the above method embodiments when executed. The storage medium may include various media capable of storing program code, such as a ROM or a random access memory (RAM), a magnetic disk, or an optical disk.

[0092] In the above embodiments, the description of each embodiment is focused on the main points, and for the parts that are not detailed or described in an embodiment, reference can be made to the relevant descriptions of other embodiments.

[0093] It should be noted that the disclosed devices / apparatuses and methods in the embodiments of the present application may be realized in other ways. For example, the device / apparatus embodiments described above are merely schematic, and the division of the modules or units is merely a division of logical functions. In actual implementation, other division methods may be used. For example, multiple units or assemblies may be combined or integrated into another system, or some features may be ignored or not implemented. In other respects, the couplings shown or discussed may be direct couplings or communication connections, or indirect couplings or communication connections via some interfaces, devices, or units, and may be in electrical, mechanical, or other forms.

[0094] It should be noted that the term "comprises," when used in this specification and the appended claims, indicates the presence of stated features, wholes, steps, operations, elements and / or assemblies, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, assemblies and / or groups thereof.

[0095] In the description of this application, unless otherwise specified, " / " indicates that the related objects before and after it are in an "or" relationship, for example, A / B can indicate A or B. "And / or" in this application describes the related relationship between related objects and indicates that three relationships may exist, for example, A and / or B means that A exists alone, A and B exist simultaneously, or B exists alone, and A and B may be one or more.

[0096] Also, in the description of this application, unless otherwise specified, "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of one or more items. For example, at least one of a, b, or c can represent a, b, c, ab, ac, bc, or abc, where a, b, and c may be one or more.

[0097] As used in this application and the appended claims, the term "and" may be interpreted as "when," "once," "in response to determining," or "in response to detecting," depending on the context. Similarly, the phrases "upon determining" or "upon detecting such a condition or event" may be interpreted as "when determined," "in response to determining," "upon detecting such a condition or event," or "upon detecting a described condition or event," depending on the context.

[0098] Additionally, in the specification and claims of this application, the terms "first," "second," "third," etc. are used merely for distinguishing purposes and should not be understood to indicate or imply relative importance.

[0099] References to "one embodiment" or "some embodiments" or the like in the present specification mean that one or more embodiments of the present application include the particular feature, structure, or characteristic described in connection with that embodiment. Thus, "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. appearing in different places in this specification do not necessarily refer to the same embodiment, unless otherwise specified, but rather mean "one or more, but not all, embodiments."

[0100] Finally, the above embodiments are merely for illustrating the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art may still modify the technical solutions described in the above embodiments, or may substitute equivalently for some or all of the technical features therein. These modifications or substitutions will not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. 1. An audio compression method applied to an audio playback device, comprising: obtaining a first audio signal to be processed; filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum to obtain a second audio signal, the target frequency spectrum being related to a distortion band of the audio reproduction device; processing the second audio signal with a predetermined dynamic range compressor DRC to obtain a compression coefficient; and outputting a compressed signal based on the compression coefficient; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: Turning off the frequency spectrum compensation filter and debugging the sound effect processing module, and then detecting the acoustic output threshold curve of the audio playback device; determining a compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of the audio signal output from the sound effects processing module; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter; The step of obtaining the first audio signal to be processed includes: obtaining an original audio signal to be played; inputting the original audio signal to be played into a sound effect processing module for processing to obtain a third audio signal, the third audio signal being the first audio signal, and the sound effect processing module including at least one sound effect processor; The step of outputting a compressed signal based on the compression coefficient includes: an audio compression method comprising compressing the third audio signal based on the compression factor and outputting the compressed signal;

2. The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: Turning off the frequency spectrum compensation filter and debugging the sound effect processing module, and then detecting a distortion band of the audio playback device; determining the target frequency spectrum based on the distortion band; and obtaining the frequency spectrum compensation filter by debugging based on the target frequency spectrum.

2. The audio compression method of claim 1.

3. The first audio signal is an original audio signal to be reproduced, or the first audio signal is an audio signal obtained by attenuating the original audio signal to be reproduced based on a predetermined threshold.

2. The audio compression method of claim 1.

4. 1. An audio compression method applied to an audio playback device, comprising: obtaining a first audio signal to be processed; filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum to obtain a second audio signal, the target frequency spectrum being related to a distortion band of the audio reproduction device; processing the second audio signal with a predetermined dynamic range compressor DRC to obtain a compression coefficient; and outputting a compressed signal based on the compression coefficient; The step of outputting a compressed signal based on the compression coefficient includes: a step of compressing an original audio signal to be reproduced based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: turning off the frequency spectrum compensation filter and testing an acoustic output threshold curve of the audio reproduction device; determining a compression curve based on the acoustic output threshold curve and an original audio signal for debugging; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter. Audio compression method.

5. 1. An audio compression method applied to an audio playback device, comprising: obtaining a first audio signal to be processed; filtering the first audio signal with a frequency spectrum compensation filter based on a predetermined target frequency spectrum to obtain a second audio signal, the target frequency spectrum being related to a distortion band of the audio reproduction device; processing the second audio signal with a predetermined dynamic range compressor DRC to obtain a compression coefficient; and outputting a compressed signal based on the compression coefficient; The step of outputting a compressed signal based on the compression coefficient includes: inputting the original audio signal to be played into a sound effect processing module for processing to obtain a third audio signal, the sound effect processing module including at least one sound effect processor; compressing the third audio signal based on the compression coefficient and outputting the compressed signal; The method of obtaining the target frequency spectrum and the frequency spectrum compensation filter is as follows: detecting an acoustic output threshold curve of the audio playback device after turning off the frequency spectrum compensation filter and the sound effect processing module; determining a compression curve based on the acoustic output threshold curve and an original audio signal for debugging; determining the target frequency spectrum based on the compression curve; Debugging based on the target frequency spectrum to obtain the frequency spectrum compensation filter. Audio compression method.

6. determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging, determining the compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of the original audio signal for debugging; 6. An audio compression method according to claim 4 or 5.

7. determining a compression curve based on the acoustic output threshold curve and the original audio signal for debugging, determining the compression curve based on a difference between the acoustic output threshold curve and a frequency response curve of a fourth audio signal, the fourth audio signal being an audio signal obtained by attenuating the original audio signal for debugging according to a predetermined threshold; 6. An audio compression method according to claim 4 or 5.

8. the sound effects processing module includes an equalizer; 6. The audio compression method according to claim 1, 2 or 5.

9. The DRC debugging method is as follows: performing parameter debugging based on the audio signal output from the frequency spectrum compensation filter; The audio compression method according to any one of claims 1 to 5.

10. The frequency spectrum compensation filter is an infinite impulse response (IIR) filter or a finite impulse response (FIR) filter. The audio compression method according to any one of claims 1 to 5.

11. a processor; Memory and a computer program stored in the memory and executable by the processor; When the processor executes the computer program, the audio compression method according to any one of claims 1 to 5 is realized. Audio playback device.

12. A computer-readable storage medium on which a computer program is stored, When the computer program is executed by a processor, it realizes the audio compression method according to any one of claims 1 to 5. A computer-readable storage medium.

13. When executed by a processor, the method implements the audio compression method according to any one of claims 1 to 5. Computer program.

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