CN115696141A - Digital audio removes stable headphone amplifier of shake - Google Patents

Abstract

A stable earphone amplifier for removing jitter from digital audio, including a correction module, which is arranged between the input interface and the amplification module, and is used for correcting the deviation of clock jitter. A storage module, an energy analysis module, a detection module and an amplification control module are also set; the storage module acquires digital audio files from the player and stores them in the storage module; the energy analysis module extracts the audio to be played or is being played from the storage module The waveform vibration curve of the file is analyzed, and the waveform characteristics are extracted and sent to the detection module; the detection module extracts the waveform data from the signal output by the amplification module, and extracts the characteristics of the waveform data; the detection module compares the waveform characteristics sent by the energy analysis module with the The waveform characteristics actually played by the amplification module are compared, and the comparison result is output, which solves the volume change and instability caused by the correction module.

Description

A Stable Headphone Amplifier with Digital Audio Jitter Removal

technical field

The invention relates to the field of digital audio processing, in particular to a stable headphone amplifier capable of removing jitter from digital audio.

Background technique

Clock jitter refers to the short-term change of the clock cycle at a given point, so that the clock cycle may be lengthened or shortened on different cycles. Clock jitter will cause frequency changes, misalignment, instability, etc. when the audio file is played. .

Application number CN202221369584.6 discloses a circuit that uses PLL technology to eliminate clock jitter during digital audio transmission. A digital receiving module is set up to receive input audio, generate LRCK signals, and output them to the phase detection module; digital phase-locked loop The module is used to generate the same frequency signal as the LPCK signal, and output it to the phase detection module; output the audio signal; by processing the phase difference between the digital receiving module and the digital phase locked loop module, it is fed back to the digital phase locked loop module to eliminate the clock shake.

However, when correcting clock jitter, it will lead to a certain degree of misalignment and broadening between the data path signal and the original signal. At the same time, due to the delay in the processing process, the large change in the amount of data, and the unstable temperature of the amplifier will also lead to actual amplification. Sometimes it will cause a certain degree of volume instability.

Contents of the invention

In order to solve the above-mentioned problems, the present invention provides a stable headphone amplifier for removing jitter from digital audio, including an input interface, a correction module, an amplification module, and an output interface; it also includes a storage module, an energy analysis module, a detection module, and an amplification control module;

The input interface is connected to the correction module, the correction module is connected to the amplification module, and the amplification module is connected to the output interface; the digital audio signal input from the input interface is corrected by the correction module for clock jitter, and the corrected audio data is sent to the amplification module for amplification, and through the output interface output;

The storage module obtains the digital audio file from the player and stores it in the storage module; the energy analysis module extracts the waveform vibration curve of the audio file to be played or is being played from the storage module, analyzes it, extracts the waveform characteristics and sends it to the detection module;

The detection module extracts waveform data from the signal output by the amplification module, and extracts the characteristics of the waveform data; the detection module compares the waveform characteristics sent by the energy analysis module with the waveform characteristics actually played by the amplification module, and outputs the comparison result;

The amplification control module is connected with the amplification module, and controls the amplification ratio of the amplification module, thereby controlling the volume of the amplification module.

The storage module is directly connected to the audio source through data through wired or wireless means or connected to the audio source through the input interface; and directly obtains the entire audio file played from the audio source;

The energy analysis module obtains the audio file from the storage module and extracts its vibration curve; the waveform vibration curve is extracted in the energy analysis module; the extracted features include the energy change curve changing with time; Sub-energy change curve.

The method of obtaining the energy change curve is as follows: firstly, the vibration curve of the audio file is divided into multiple audio segments at a time interval T; the frequency domain conversion is performed on the audio segment to obtain the spectrum curve of the audio segment; The frequency is divided into N sections, and then the spectral curves of the same frequency in different audio clips are taken as a group to obtain the spectral curves of N groups of audio clips; the total energy of the spectral curves in each group is transformed with time; The time-varying energy change curve is recorded as the standard energy change curve.

The detection module obtains the audio data from the amplifying module, and divides the vibration curve of the acquired audio at a time interval T, and divides it into multiple audio segments; converts the audio segment into the frequency domain to obtain a spectrum curve of the audio segment; divides the audio segment The frequency spectrum of is divided into N sections according to the frequency, and then the spectral curves of the same frequency in different audio segments are taken as a group to obtain the spectral curves of N groups of audio segments; the total energy of the spectral curves in each group is calculated as a function of time; N time-varying energy change curves are recorded as actual energy change curves;

In the detection module, compare the actual energy change curve with the standard energy change curve. The comparison method is:

H _n (t) = F _n (t) - G _n (t);

Where F _n (t) represents the nth actual energy change curve, G _n (t) represents the nth standard energy change curve, H _n (t) represents the nth actual energy change curve and the nth standard energy change curve The difference; n ranges from 1 to N, and t represents the time independent variable; that is, compare the difference between the nth actual energy change curve and the nth standard energy change curve at each moment;

after:

H(t)=k ₁ ·H ₁ (t)+k ₂ ·H ₂ (t)+...+k _n ·H _n (t)+k _N ·H _N (t);

Among them, k ₁ , k ₂ , k ₃ , ..., k _N represent the weights corresponding to different frequency bands;

In the detection module, H(t) is output to the amplification control module; the amplification control module adjusts the amplification ratio of the amplification module according to the positive and negative values of H(t), and the larger the H(t), the corresponding adjustment of the amplification ratio of the amplification module decreases. The smaller the H(t) is, the higher the amplification rate of the amplifying module is adjusted. By this time, the amplifying module is consistent with the original energy change in the sound source, and the volume change caused by the correcting module is reduced.

The correction module includes reference clock, sampling rate input, I2S input, buffer module, frequency synthesis module and output module;

Both the reference module and the sampling rate input are connected to the frequency synthesis module, and the frequency synthesis module locks the sampling rate to the local clock frequency and detects the local clock frequency; calculates the difference between the sampling rate and the I2S input clock and the local clock, and further according to the The difference sets the buffer sequence direction and buffer depth to correct clock skew.

Frequency synthesis module includes mode controller 1, counting window generator 2, counter 3, synchronous frequency divider 4, LUT5, subtractor 6, FIR filter 7, sliding mode filter 8, low noise DAC9, analog loop filter 10 and broadband VCO11;

The reference module outputs a 10MHz high-precision reference clock to the counting window generator 2;

The sampling rate information is sent to the mode controller 1 so that the output frequency switching control parameters are sent to the LUT5. At the same time, the mode of the sliding mode filter 8 is controlled to be fast frequency switching, and the filtered control data is sent to the low-noise DAC9, which passes through the analog loop filter After 10, output to VCO11;

The VCO output is sent to the synchronous frequency divider 4, and then sent to the frequency measuring device composed of the counting window generator 2 and the counter 3 to complete the frequency measurement; the frequency measurement result is sent to the LUT5 and the mode controller 1, and the mode controller 1 controls the loop to control;

The input I2S data is sent to the large-capacity buffer 15, and the mode controller 1 obtains the difference between the sampling rate information and the I2S input clock through the LUT5 unit, and the buffer sequence direction and buffer depth of the FIFO are set by the difference;

The maximum depth of the large-capacity cache 15 can ensure that 74 minutes of CD disc playback is complete without leakage; at the same time, it is equipped with a silent detection module, which is a protection mechanism, and the large-capacity cache 15 is reset in the silent segment; Large-capacity cache 15 can ensure the continuous and stable operation of the system.

The beneficial effects of the present invention are:

The invention includes a correction module, which is arranged between the input interface and the amplification module, and is used for correcting the deviation of the clock jitter. A storage module, an energy analysis module, a detection module and an amplification control module are also set; the storage module acquires digital audio files from the player and stores them in the storage module; the energy analysis module extracts the audio to be played or is being played from the storage module The waveform vibration curve of the file is analyzed, and the waveform characteristics are extracted and sent to the detection module; the detection module extracts the waveform data from the signal output by the amplification module, and extracts the characteristics of the waveform data; the detection module compares the waveform characteristics sent by the energy analysis module with the The waveform characteristics actually played by the amplification module are compared, and the comparison result is output, which solves the volume change and instability caused by the correction module.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative efforts.

Accompanying drawing 1 is a schematic diagram of the overall structure of the present invention;

Accompanying drawing 2 is the schematic diagram of connection structure of correction module of the present invention;

Accompanying drawing 3 is the schematic diagram of circuit structure of the present invention.

Detailed ways

Example 1:

Referring to Figures 1-3, the present invention provides a stable headphone amplifier for digital audio jitter removal, including an input interface, a correction module, an amplification module, and an output interface; it also includes a storage module, an energy analysis module, a detection module, and an amplification control module;

The input interface is connected to the correction module, the correction module is connected to the amplification module, and the amplification module is connected to the output interface; the digital audio signal input from the input interface is corrected by the correction module for clock jitter, and the corrected audio data is sent to the amplification module for amplification, and through the output interface output;

The storage module obtains the digital audio file from the player and stores it in the storage module; the energy analysis module extracts the waveform vibration curve of the audio file to be played or is being played from the storage module, analyzes it, extracts the waveform characteristics and sends it to the detection module;

The detection module extracts waveform data from the signal output by the amplification module, and extracts the characteristics of the waveform data; the detection module compares the waveform characteristics sent by the energy analysis module with the waveform characteristics actually played by the amplification module, and outputs the comparison result;

The amplification control module is connected with the amplification module, and controls the amplification ratio of the amplification module, thereby controlling the volume of the amplification module.

The storage module is directly connected to the audio source through data through wired or wireless means or connected to the audio source through the input interface; and directly obtains the entire audio file played from the audio source;

The energy analysis module obtains the audio file from the storage module and extracts its vibration curve; the waveform vibration curve is extracted in the energy analysis module; the extracted features include the energy change curve changing with time; Sub-energy change curve.

The method of obtaining the energy change curve is as follows: firstly, the vibration curve of the audio file is divided into multiple audio segments at a time interval T; the frequency domain conversion is performed on the audio segment to obtain the spectrum curve of the audio segment; The frequency is divided into N sections, and then the spectral curves of the same frequency in different audio clips are taken as a group to obtain the spectral curves of N groups of audio clips; the total energy of the spectral curves in each group is transformed with time; The time-varying energy change curve is recorded as the standard energy change curve.

The detection module obtains the audio data from the amplifying module, and divides the vibration curve of the acquired audio at a time interval T, and divides it into multiple audio segments; converts the audio segment into the frequency domain to obtain a spectrum curve of the audio segment; divides the audio segment The frequency spectrum of is divided into N sections according to the frequency, and then the spectral curves of the same frequency in different audio segments are taken as a group to obtain the spectral curves of N groups of audio segments; the total energy of the spectral curves in each group is calculated as a function of time; N time-varying energy change curves are recorded as actual energy change curves;

In the detection module, compare the actual energy change curve with the standard energy change curve. The comparison method is:

H _n (t) = F _n (t) - G _n (t);

Where F _n (t) represents the nth actual energy change curve, G _n (t) represents the nth standard energy change curve, H _n (t) represents the nth actual energy change curve and the nth standard energy change curve The difference; n ranges from 1 to N, and t represents the time independent variable; that is, compare the difference between the nth actual energy change curve and the nth standard energy change curve at each moment;

after:

H(t)=k ₁ ·H ₁ (t)+k ₂ ·H ₂ (t)+...+k _n ·H _n (t)+k _N ·H _N (t);

Among them, k ₁ , k ₂ , k ₃ , ..., k _N represent the weights corresponding to different frequency bands;

In the detection module, H(t) is output to the amplification control module; the amplification control module adjusts the amplification ratio of the amplification module according to the positive and negative values of H(t), and the larger the H(t), the corresponding adjustment of the amplification ratio of the amplification module decreases. The smaller the H(t) is, the higher the amplification rate of the amplifying module is adjusted. By this time, the amplifying module is consistent with the original energy change in the sound source, and the volume change caused by the correcting module is reduced.

The correction module includes reference clock, sampling rate input, I2S input, buffer module, frequency synthesis module and output module;

Both the reference module and the sampling rate input are connected to the frequency synthesis module, and the frequency synthesis module locks the sampling rate to the local clock frequency and detects the local clock frequency; calculates the difference between the sampling rate and the I2S input clock and the local clock, and further according to the The difference sets the buffer sequence direction and buffer depth to correct clock skew.

Frequency synthesis module includes mode controller 1, counting window generator 2, counter 3, synchronous frequency divider 4, LUT5, subtractor 6, FIR filter 7, sliding mode filter 8, low noise DAC9, analog loop filter 10 and broadband VCO11;

The reference module outputs a 10MHz high-precision reference clock to the counting window generator 2;

The sampling rate information is sent to the mode controller 1 so that the output frequency switching control parameters are sent to the LUT5. At the same time, the mode of the sliding mode filter 8 is controlled to be fast frequency switching, and the filtered control data is sent to the low-noise DAC9, which passes through the analog loop filter After 10, output to VCO11;

The VCO output is sent to the synchronous frequency divider 4, and then sent to the frequency measuring device composed of the counting window generator 2 and the counter 3 to complete the frequency measurement; the frequency measurement result is sent to the LUT5 and the mode controller 1, and the mode controller 1 controls the loop to control;

The input I2S data is sent to the large-capacity buffer 15, and the mode controller 1 obtains the difference between the sampling rate information and the I2S input clock through the LUT5 unit, and the buffer sequence direction and buffer depth of the FIFO are set by the difference;

The maximum depth of the large-capacity cache 15 can ensure that 74 minutes of CD disc playback is complete without leakage; at the same time, it is equipped with a silent detection module, which is a protection mechanism, and the large-capacity cache 15 is reset in the silent segment; Large-capacity cache 15 can ensure the continuous and stable operation of the system.

Example 2:

Referring to Figure 2-3, the circuit example specifically includes mode controller 1, counting window generator 2, counter 3, synchronous frequency divider 4, LUT5, subtractor 6, FIR filter 7, sliding mode filter 8, low noise DAC9, analog loop filter 10 and wideband VCO11; also includes silence detection 13, FIFO control 14, large-capacity buffer FIFO15, I2S timing generation 12.

Among them, the I2S timing and data input are divided into 3 routes, one route enters the silence detection 13 and then enters the FIFO control 14, the second route enters the large-capacity buffer FIFO 15, and the third route enters the counter 3; input I2S_MCLK enters the counter 3;

The 10MHz high-precision reference clock enters the counting window generator 2, and then enters the counter 3; the sampling rate enters the mode controller 1, and then enters the counting window generator 2, LUT5 and sliding mode filter 8 (FIR+IIR);

The mode controller is connected to FIFO control 14, LUT5, and sliding mode filter 8 (FIR+IIR);

Counter 3 outputs to LUT5 and subtractor 6, LUT5 outputs to subtractor and sliding mode filter 8 (FIR+IIR), and subtractor outputs to FIR filter 7,;

The sliding mode filter 8 (FIR+IIR) is output to the low-noise DAC9 and then output to the analog loop filter 10 and then output to the broadband VCO 11;

Wideband VCO output to synchronous frequency divider 4, I2S timing generation 12 and MCLK output;

The I2S timing generation 12 is output to the FIFO control 14 and the I2S output; the FIFO control 14 is connected to the large-capacity buffer FIFO15; the large-capacity buffer FIFO15 is connected to the I2S timing generation 12.

The description thus far of the foregoing embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and used in a selected embodiment, even if not specifically shown or described. In many respects, the same elements or features may also be varied. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous details are set forth, such as examples of specific parts, devices and methods, in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and no limitation is intended. As used herein, the singular forms "a" and "the" may be meant to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprising" and "having" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements and/or components, but do not exclude the presence or additional presence of one or more other features , as a whole, steps, operations, elements, components and/or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring performance in the specific order discussed and illustrated, unless an order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be employed.

Claims (7)

1. A stable headphone amplifier for removing jitter from digital audio, comprising an input interface, a correction module, an amplification module and an output interface; it is characterized in that: it also includes a storage module, an energy analysis module, a detection module and an amplification control module; The input interface is connected to the correction module, the correction module is connected to the amplification module, and the amplification module is connected to the output interface; the digital audio signal input from the input interface is corrected by the correction module for clock jitter, and the corrected audio data is sent to the amplification module for amplification, and through the output interface output; The storage module obtains the digital audio file from the player and stores it in the storage module; the energy analysis module extracts the waveform vibration curve of the audio file to be played or is being played from the storage module, analyzes it, extracts the waveform characteristics and sends it to the detection module; The detection module extracts waveform data from the signal output by the amplification module, and extracts the characteristics of the waveform data; the detection module compares the waveform characteristics sent by the energy analysis module with the waveform characteristics actually played by the amplification module, and outputs the comparison result; The amplification control module is connected with the amplification module, and controls the amplification ratio of the amplification module, thereby controlling the volume of the amplification module. 2. the stable earphone amplifier that a kind of digital audio frequency according to claim 1 removes jitter is characterized in that: The storage module is directly connected to the audio source through data through wired or wireless means or connected to the audio source through the input interface; and directly obtains the entire audio file played from the audio source; The energy analysis module obtains the audio file from the storage module and extracts its vibration curve; the waveform vibration curve is extracted in the energy analysis module; the extracted features include the energy change curve changing with time; Sub-energy change curve. 3. a kind of digital audio frequency according to claim 2 removes the stable headphone amplifier of jitter, it is characterized in that: The method of obtaining the energy change curve is as follows: firstly, the vibration curve of the audio file is divided into multiple audio segments at a time interval T; the frequency domain conversion is performed on the audio segment to obtain the spectrum curve of the audio segment; The frequency is divided into N sections, and then the spectral curves of the same frequency in different audio clips are taken as a group to obtain the spectral curves of N groups of audio clips; the total energy of the spectral curves in each group is transformed with time; The time-varying energy change curve is recorded as the standard energy change curve. 4. the stable earphone amplifier that a kind of digital audio frequency according to claim 3 removes jitter is characterized in that: The detection module obtains the audio data from the amplifying module, and divides the vibration curve of the acquired audio at a time interval T, and divides it into multiple audio segments; converts the audio segment into the frequency domain to obtain a spectrum curve of the audio segment; divides the audio segment The frequency spectrum of is divided into N sections according to the frequency, and then the spectral curves of the same frequency in different audio segments are taken as a group to obtain the spectral curves of N groups of audio segments; the total energy of the spectral curves in each group is calculated as a function of time; N time-varying energy change curves are recorded as actual energy change curves; In the detection module, compare the actual energy change curve with the standard energy change curve. The comparison method is: H _n (t) = F _n (t) - G _n (t); Where F _n (t) represents the nth actual energy change curve, G _n (t) represents the nth standard energy change curve, H _n (t) represents the nth actual energy change curve and the nth standard energy change curve The difference; n ranges from 1 to N, and t represents the time independent variable; that is, compare the difference between the nth actual energy change curve and the nth standard energy change curve at each moment; after: H(t)=k ₁ "H ₁ (t)+k ₂ "H ₂ (t)+...+k _n "H _n (t)+k _N "H _N (t); Among them, k ₁ , k ₂ , k ₃ , ... k _n ..., k _N represent the weights corresponding to different frequency bands; In the detection module, H(t) is output to the amplification control module; the amplification control module adjusts the amplification ratio of the amplification module according to the positive and negative values of H(t), and the larger the H(t), the corresponding adjustment of the amplification ratio of the amplification module decreases. The smaller the H(t) is, the higher the amplification rate of the amplifying module is adjusted. By this time, the amplifying module is consistent with the original energy change in the sound source, and the volume change caused by the correcting module is reduced. 5. a kind of digital audio frequency according to claim 4 removes the stable headphone amplifier of jitter, it is characterized in that: The correction module includes reference clock, sampling rate input, I2S input, buffer module, frequency synthesis module and output module; Both the reference module and the sampling rate input are connected to the frequency synthesis module, and the frequency synthesis module locks the sampling rate to the local clock frequency and detects the local clock frequency; calculates the difference between the sampling rate and the I2S input clock and the local clock, and further according to the The difference sets the buffer sequence direction and buffer depth to correct clock skew. 6. a kind of digital audio frequency according to claim 5 removes the stable headphone amplifier of jitter, it is characterized in that: The frequency synthesis module includes a mode controller (1), a counting window generator (2), a counter (3), a synchronous frequency divider (4), a LUT (5), a subtractor (6), an FIR filter (7), Sliding mode filter (8), low noise DAC (9), analog loop filter (10), and wideband VCO (11); The reference module outputs a 10MHz high-precision reference clock to the counting window generator (2); The sampling rate information is sent to the mode controller (1) so that the output frequency switching control parameters are sent to the LUT (5). At the same time, the mode of the sliding mode filter (8) is controlled for fast frequency switching, and the filtered control data is sent to the low-noise DAC. (9), output to the VCO (11) after passing through the analog loop filter (10); The VCO output is sent to the synchronous frequency divider (4), and then sent to the frequency measuring device composed of the counting window generator (2) and the counter (3) to complete the frequency measurement; the frequency measurement result is sent to the LUT (5) and the mode controller ( 1), the loop is controlled by the mode controller (1); The input I2S data is sent into the large-capacity buffer (15), and the mode controller (1) obtains the difference between the sampling rate information and the I2S input clock through the LUT (5) unit, and sets the buffer sequence direction and buffer depth of the FIFO through the difference; The maximum depth of the large-capacity cache (15) can ensure that 74 minutes of CD disc playback is complete without leakage; at the same time, it is equipped with a silence detection module, which is a protection mechanism and resets the large-capacity cache (15) in the silent segment ; By resetting the large-capacity cache (15), the system can be guaranteed to work continuously and stably. 7. a kind of digital audio frequency according to claim 3 removes the stable headphone amplifier of jitter, it is characterized in that: The value of T is 50ms to 100ms.

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