CN101179278B - Sound system and method for encoding sound signals thereof - Google Patents

Abstract

A sound system and a method for coding sound signals thereof are provided, the sound signal coding system includes a sound signal input terminal, an input buffer unit, a coding unit, an output buffer unit and a sound signal output terminal. The encoding unit further includes an auxiliary operation unit and a main operation unit. The system shares the operation amount of the main operation unit to encode the voice signal with the auxiliary operation unit, and operates the voice signal with the modulation filter bank, the fast Fourier transform, the improved digital cosine transform and the improved digital sine transform, so as to reduce the complexity of the algorithm, improve the efficiency of processing the voice signal, reduce the whole clock pulse rate and save the power consumption.

Description

Sound system and method for encoding sound signals thereof

technical field

The invention relates to an audio device, in particular to an audio system and a method for encoding audio signals thereof.

Background technique

In traditional audio devices, tapes are used as recording media. However, tapes are bulky and difficult to store. The sound quality of recording and playback is easily distorted, and random access is impossible.

In order to solve the shortcomings of the above-mentioned traditional audio devices, digital media such as memory cards, flash drives, and optical discs have been developed on the market as access media for accessing audio signals. Use digital storage media to access audio signals. Digital methods are used for computing and accessing audio signals. For accessing audio signals provided by digital audio sources, undistorted (non-compressed) recordings can be achieved. And undistorted playback, or very little distortion (need to be compressed) recording and very little distortion playback. In addition, audio devices that use digital storage media to access audio signals can have a longer recording time, and in terms of recording speed, if a digital audio source is used as a recording source, as long as the digital audio source can be played at a high speed, the audio device can reach high speed. Double speed recording.

However, in the development of audio devices that use digital storage media to access audio signals, the way to achieve audio signal compression is an important key. Generally speaking, current audio devices use a single digital signal microprocessor (digital signal micro-processor) to perform arithmetic processing on audio signal compression. When the audio device processes real time audio signal compression, if the input rate of the audio signal is too high to exceed the limit of the amount of data processed by the digital signal microprocessor, it is easy to cause insufficient data throughput.

Contents of the invention

The object of the present invention is to provide a sound system and a method for encoding sound signals thereof. The system uses an auxiliary computing unit to share the computational load of the main computing unit for encoding sound signals, and uses modulation filter banks, fast Fourier transform, and improved Digital cosine conversion and improved digital sine conversion are used to calculate the sound signal for further encoding. In this way, the complexity of the algorithm can be reduced, the efficiency of processing the sound signal can be improved, the overall clock rate can be reduced, and power consumption can be saved. .

According to the audio system provided by the present invention, the audio signal encoding system includes an audio signal input end, an input buffer unit, an encoding unit, an output buffer unit and an audio signal output end. The encoding unit further includes an auxiliary operation unit and a main operation unit.

When the audio signal is input to the coding system from the audio signal input port and is a digital signal, the coding system will first buffer the data sequence of the audio signal, and then send it to the coding unit. Then, the auxiliary calculation unit will receive the sound signal, and use the regular cosine modulation filter bank, fast Fourier transform, improved digital cosine transform, etc. to share and calculate the sound signal, and compare the status of the calculation process and the result of the calculation. The sound signal is sent to the main computing unit. The main computing unit will then further encode the sound signal output by the auxiliary computing unit, and provide a control signal to the auxiliary computing unit according to the state of the sound signal calculated by the auxiliary computing unit, so that the auxiliary computing unit can then follow this control signal for further operations. Finally, the output buffer unit buffers the audio signal output by the encoding unit and sends it to the audio signal output terminal.

To achieve the above purpose, the present invention provides an audio device for recording, playing and transcoding an audio signal, which includes: an encoding/decoding unit for encoding or decoding the audio signal, wherein Accelerated computational processing of the sound signal using a cosine modulated filter bank, a fast fourier transform, a modified digital cosine transform and a modified digital sine transform, wherein the fast fourier transform is used to implement the cosine modulated filter row; a digital-to-analog converter for converting the audio signal decoded by the encoding/decoding unit; a digital storage medium for storing the encoded audio signal provided by the encoding/decoding unit , or for providing the audio signal; and a playback unit for amplifying and playing the audio signal converted by the digital-to-analog converter.

In order to achieve the above object, the present invention also provides a method for coding a sound signal, which includes: inputting a sound signal to a sound signal coding system; utilizing a cosine modulation filter bank, a fast Fourier transform, and an improved digital Cosine transformation and a modified digital sine transformation to divide the sound signal into a plurality of sub-bands, wherein the fast Fourier transform is used to realize the cosine modulation filter bank; according to the state of dividing the sound signal into the sub-bands, a control signal is generated , and generate subsequent sub-bands according to the control signal; and encode these sub-bands.

Through the above technical features, the present invention provides the advantage of using the auxiliary computing unit to share the computing load of the main computing unit in the audio signal coding system.

Another advantage provided by the present invention is that the audio signal is divided into multiple sub-bands for further encoding by using modulation filter bank, fast Fourier transform, modified digital cosine transform and modified digital sine transform.

Yet another advantage provided by the present invention is that the modulated filter bank is implemented using a fast Fourier transform.

Another advantage provided by the present invention is that the modified digital cosine transform and the modified digital sine transform are used to assist the fast Fourier transform to realize the modulated filter bank.

Another advantage provided by the present invention is that the efficiency of processing audio signals can be improved, the overall clock pulse rate can be reduced, and power consumption can be saved by utilizing the sharing of the calculation amount of the main calculation unit.

Description of drawings

Fig. 1 is the schematic block diagram of the sound system of content of the present invention;

2 is a schematic block diagram of an audio signal encoding system of an encoding/decoding unit of the present invention;

Fig. 3 is the coding flowchart of the sound signal of content of the present invention;

Fig. 4 is the flow chart that realizes sound signal coding with cosine modulation filter row of content of the present invention;

FIG. 5 is a flow chart of implementing a cosine modulated filter bank by fast Fourier transform according to the present invention.

Explanation of symbols in the figure

Encoding/decoding unit 10

Audio signal input terminal 110

Input buffer unit 120

Code unit 130

Auxiliary arithmetic unit 131

Main computing unit 133

output buffer unit 140

Audio signal output port 150

Analog to Digital Converter 20

Digital to Analog Converter 30

digital storage media 40

Playback unit 50

Detailed ways

Please refer to FIG. 1 for illustrating the system architecture of the audio device provided by the present invention, wherein FIG. 1 is a schematic block diagram of the audio device of the present invention. The audio device 1 of the present invention comprises an encoding/decoding unit (encoding/decoding unit) 10, an analog-to-digital converter (analogy-to-digital converter, ADC) 20, a digital-to-analog converter 30 (digital-to-analogy converter, DAC), a digital storage medium 40 and a playback unit 50.

Assuming that the audio signal X input to the audio device 1 is a digital signal, the audio device 1 will use the encoding/decoding unit 10 to directly encode the audio signal X, and finally store it in the digital storage medium 40, or convert it into After the analog signal is amplified and output by the playback unit 50 . Assuming that the audio signal X input to the audio device 1 is an analog signal, the audio device 1 will first use the analog-to-digital converter 20 to convert the audio signal X into a digital signal, and then send it to the encoding/decoding unit 10 for encoding. Finally, The encoded audio signal X is stored in the digital storage medium 40 , or converted into an analog signal by the digital-to-analog converter 30 , amplified and output by the playback unit 50 .

When it is desired to play the audio signal X stored in the digital storage medium 40, the audio device 1 will directly extract the audio signal X from the digital storage medium 40, decode it through the encoding/decoding unit 10, and then pass it through digital simulation. The converter 30 converts the digital audio signal X into an analog signal, and finally the audio signal X is amplified and played by the playback unit 50 .

Therefore, it can be known from the above that the digital storage medium 40 can be an optical disc, etc., but the present invention is not limited thereto, and any storage medium capable of storing the audio signal X in a digital format falls within the scope of the present invention.

The present invention further proposes an encoding system in the above-mentioned encoding/decoding unit 10 for illustration, and uses an auxiliary computing unit to assist the encoding structure of digital signal processing, as shown in FIG. 2 , which is the audio signal of the encoding/decoding unit of the present invention. Block diagram of the coding system. The audio signal encoding system includes an audio signal input end 110 , an input buffer unit (input buffer) 120 , an encoding unit 130 , an output buffer unit (output buffer) 140 and an audio signal output end 150 . The encoding unit 130 further includes an auxiliary operating unit (auxiliary operating unit) 131 and a main operating unit (major operating unit) 133 .

The audio signal input terminal 110 is connected to the auxiliary operation unit 131 in the encoding unit 130 through the input buffer unit 120 . The main operation unit 133 in the encoding unit 130 is connected to the audio signal output terminal 150 through the output buffer unit 140 . The auxiliary calculation unit 131 is mainly used to assist the main calculation unit 133 in calculation, and share the calculation amount (computon) of the main calculation unit 133 in calculating and processing the sound signal X. The main computing unit 133 is mainly used for encoding the audio signal X, and provides a control signal to the auxiliary computing unit 131 for further computing according to the state of the audio signal X computed by the auxiliary computing unit 131 .

Please refer to FIG. 3 , which is a flow chart of the audio signal encoding in the present invention. When the audio signal X is input to the coding system in the encoding/decoding unit 10 from the audio signal input terminal 110, and is a digital signal, as in step S310, the encoding system will first buffer the data sequence of the audio signal X, as in step S320, and then and then sent to the encoding unit 130.

The auxiliary operation unit 131 in the encoding unit 130 receives the sound signal X, and uses a cosine modulated filter bank (cosine modulated filter bank), fast Fourier transform (FFT), and improved digital cosine Transform (modified digital cosine transform, MDCT) etc. to apportion the calculation of the sound signal X, and send the state of the calculation process and the calculated sound signal X to the main calculation unit 133, as in step S330.

The main calculation unit 133 will then further encode the sound signal X output by the auxiliary calculation unit 131, and provide a control signal to the auxiliary calculation unit 131 according to the state of the sound signal X calculated by the auxiliary calculation unit 131, so that the auxiliary calculation unit The 131 can perform further operations according to the control signal, such as step S340. Finally, the output buffer unit 140 buffers the audio signal X output by the encoding unit 130, as in step S350, and sends it to the audio signal output terminal 150 for output, as in step S360.

Therefore, it can be seen from the above that the main computing unit 133 can be a digital signal processor (digital signal processing, DSP), etc., and the auxiliary computing unit 131 can be a virtual device designed by a program, but the present invention is not limited thereto , any mechanism that can achieve processing and computing the sound signal X is within the scope of the present invention.

In order to further illustrate the encoding method of the present invention, the present invention proposes an action of utilizing a cosine modulation filter bank to realize the compression of the sound signal X in the encoding of the sound signal X, as shown in FIG. The flow chart of changing the filter bank to realize the coding of the sound signal.

When the audio signal X is input to the encoding unit 130 in FIG. 3, since the audio signal X has multiple output points, the output points of the audio signal X are first divided into multiple data vectors, respectively X[1] to X[N ], as in step S410.

Then, the data vectors X[1] to X[N] of these sound signals X are respectively analyzed by modified cosine transform (MDCT) and modified digital sine transform (MDST) to generate cosine transform function Y1 and the sine transfer function Y2, as in step S420.

After the encoding unit 130 completes converting the data vectors X[1] to X[N] of the sound signal X into the cosine transformation function Y1 and the sine transformation function Y2, the cosine transformation function Y1 is used again to multiply the vectors generated by the cosine transformation function Y1 to generate the cosine multiplication function W1, and use the second look-up table to make the sine conversion function Y2 generate the effect of vector multiplication to generate the sine multiplication function W2, as in step S430. Wherein, the first comparison table is a comparison table of a sine function, the second comparison table is a comparison table of a cosine function, and the cosine multiplication function W1 is the multiplication of the cosine conversion function Y1 and the first comparison table, which can be regarded as a As a matrix function, the sine multiplication function W2 is the multiplication of the sine transfer function Y2 and the second comparison table, which can also be regarded as a matrix function.

Finally, add the cosine multiplication function W1 and the sine multiplication function W2 to generate the modulation function Z, as in step S440, and further output to the main computing unit 133 for encoding, as in step S450. Since the cosine multiplication function W1 and the sine multiplication function W2 are both matrix functions, the modulation function Z is also a matrix function, and is an integration of the cosine multiplication function W1 and the sine multiplication function W2, which can be divided into multiple frequency band vectors Z[1] to Z[N].

In order to further illustrate the steps of the improved cosine transform and the improved sine transform to decompose the data signal X into a cosine transform function Y1 and a sine transform function Y2 in the present invention, the present invention proposes a method of using fast Fourier transform to realize cosine modulation filtering The action of the filter bank is shown in FIG. 5 , which is a flow chart of implementing the cosine modulation filter bank by fast Fourier transform in the present invention.

First, reorder the output points of the data signal X input into the encoding unit 130 in FIG. 2 , that is, reorder the output points in the data vectors X[1] to X[N] of the data signal X, as in step S510. Sort the output points of the data signal X as follows:

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&equiv;</span>\left\{\begin{array}{cc}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>& \frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right.$

and

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$

Among them, k represents the kth output point of the data signal X, N represents the N data vectors of the data signal X, I represents the ith data vector of the data signal X, and F(i) is the Fourier transform of f(k) formula.

Make F(2i+1)=F(N-2i-2) by variable transformation, and combine the output points of the data signal X to generate complex functions f1 and f2, as in step S520.

$\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H061E3945420061114E000011.png,H061E3945420061114E000041.png"\; state="\{\{state\}\}">f</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$

$\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$

Among them, f1 is a complex function of an even function, and f2 is a complex function of an odd function.

并取复数函数f1、f2的共轭复数，形成共轭函数f1^*及f2^*，如步骤S530。to rotate

And take complex conjugate functions f1 and f2 to form conjugate functions f1 ^* and f2 ^* , as in step S530.

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H061E3945420061114E000011.png,H061E3945420061114E000041.png"\; state="\{\{state\}\}">f</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H061E3945420061114E000011.png,H061E3945420061114E000041.png"\; state="\{\{state\}\}">f</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;j</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; )</span>}$

${\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;j</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; )</span>}$

The fast Fourier transform is used for calculation to generate transfer functions F1 and F2, as in step S540.

F _i =(FFT(f ^* )) ^*

产生还原转移函数F1^*、F2^*，如步骤S550。Again take the complex conjugate and rotate

Generate reduction transfer functions F1 ^* , F2 ^* , as in step S550.

${\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;j</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; )</span>}$

Sort the calculation results to generate the cosine transfer function Y1 and the sine transfer function Y2, as in step S560.

$\mathrm{<span\; class="notranslate">\; Y</span>}\mathrm{<span\; class="notranslate">\; 1</span>}\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ~</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$

$\mathrm{<span\; class="notranslate">\; Y</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; (</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ~</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$

From the above, it can be seen that by using the fast Fourier transform to realize the cosine modulation filter bank, when the number of sub-bands of the sound signal X increases, resulting in a significant increase in the amount of calculation, the sound signal coding system of the present invention can reduce the sound signal calculation. The complexity of the algorithm applied by X, in addition, because of the sharing of the calculation load, can improve the efficiency of processing audio signals, reduce the overall clock pulse rate, and save power consumption.

The drawings shown are provided for reference and illustration only, and are not intended to limit the present invention. The above is only a preferred feasible embodiment of the present invention, and does not limit the patent scope of the present invention. Therefore, all equivalent structural changes made by using the description of the present invention and the contents of the icons are all included in the scope of the present invention. Within the scope, agree with Chen Ming.

Claims (14)

1. An audio device for recording, playing and transcoding a sound signal, characterized in that it includes: An encoding/decoding unit for encoding or decoding the sound signal, wherein a cosine modulation filter bank, a fast Fourier transform, a modified digital cosine transform and a modified digital sine transform are used to accelerate the operation processing the sound signal, wherein the fast Fourier transform is used to implement the cosine modulated filter bank; a digital-to-analog converter for converting the audio signal decoded by the encoding/decoding unit; a digital storage medium for storing the encoded audio signal provided by the encoding/decoding unit, or for providing the audio signal; and A playing unit is used to amplify and play the audio signal converted by the digital-to-analog converter. 2. The audio device according to claim 1, wherein the audio signal is a digital signal. 3. The audio device as claimed in claim 1, further comprising an analog-to-digital converter for converting an analog signal to generate the audio signal. 4. The audio device according to claim 1, wherein the encoding/decoding unit comprises: an auxiliary operation unit for receiving the sound signal and performing a preliminary operation on the sound signal to generate a status signal; and a main computing unit, which is used to provide a control signal to the auxiliary computing unit according to the state signal, and encode the sound signal after preliminary computing; Wherein, after receiving the control signal, the auxiliary operation unit performs further operation on the sound signal according to the control signal. 5. The audio device according to claim 4, wherein the encoding/decoding unit further comprises: an input buffer unit for buffering the audio signal for further operation and encoding; and An output buffer unit is used for buffering the audio signal provided by the main computing unit for further output. 6. The audio device according to claim 1, wherein the digital storage medium is an optical disc, a built-in memory device or an external memory device. 7. The audio device according to claim 4, wherein after receiving the sound signal, the auxiliary computing unit uses the cosine modulation filter bank, the fast Fourier transform, the improved digital cosine transform and The improved digital sine conversion divides the sound signal into multiple sub-bands to generate the state signal, and generates subsequent state signals according to the control signal; and the main computing unit receives the sent from the auxiliary computing unit The state signal and the audio signal after preliminary calculation are generated, and the control signal is generated according to the state signal and sent back to the auxiliary computing unit, and the sub-frequency bands are coded. 8. The audio device according to claim 7, wherein the auxiliary computing unit divides the sound signal into the frequency sub-bands, and uses the improved digital cosine transform and the improved digital sine transform to analyze the sound signal , to generate a cosine transfer function and a sine transfer function and calculate the cosine transfer function and the sine transfer function respectively according to a first comparison table and a second comparison table to generate a cosine multiplication function and a sine multiplication The function then integrates the cosine multiplication function and the sine multiplication function to divide the sound signal into these sub-bands. 9. The audio device according to claim 8, wherein the auxiliary computing unit generates the cosine transfer function and the sine transfer function by reconfiguring a plurality of output points of the sound signal and utilizing the improved digital cosine transformation and the improved digital sine transformation to combine these output points to generate a plurality of complex functions; then the auxiliary operation unit takes the conjugate complex numbers of these complex functions after rotating these complex functions respectively to form a plurality of conjugate function, and use the fast Fourier transform to operate these conjugate functions to generate the transfer functions corresponding to these conjugate functions; then the auxiliary operation unit takes the conjugate complex numbers of these transfer functions, and rotates the joint of these transfer functions yoke complex numbers to generate a plurality of restored transfer functions; the auxiliary operation unit reorders the restored transfer functions to generate the cosine transfer function and the sine transfer function. 10. The audio device according to claim 8, wherein the first lookup table is a sine function lookup table, and the second lookup table is a cosine function lookup table. 11. A method for coding an audio signal, comprising: Inputting an audio signal into an audio signal encoding system; splitting the sound signal into frequency subbands using a cosine modulation filter bank, a fast fourier transform, a modified digital cosine transform, and a modified digital sine transform, wherein the fast fourier transform is used to effectuate the cosine modulation filter bank; generating a control signal based on the division of the sound signal into the sub-bands, and generating subsequent sub-bands based on the control signal; and These subbands are encoded. 12. The method for coding an audio signal as claimed in claim 11, wherein the step of dividing the audio signal into these sub-frequency bands comprises: analyzing the sound signal using the improved digital cosine transform and the improved digital sine transform to generate a cosine transform function and a sine transform function; calculating the cosine transfer function and the sine transfer function respectively according to a first comparison table and a second comparison table to generate a cosine multiplication function and a sine multiplication function; The cosine multiplication function and the sine multiplication function are integrated to generate the frequency subbands. 13. The method for coding an audio signal according to claim 12, wherein the step of generating the cosine transfer function and the sine transfer function comprises: Reconfigure multiple output points of the audio signal; combining the output points using the modified digital cosine transform and the modified digital sine transform to generate a plurality of complex functions; After rotating these complex functions respectively, take conjugate complex numbers to form multiple conjugate functions; Using the fast Fourier transform to operate these conjugate functions to generate transfer functions corresponding to these conjugate functions; After taking the complex conjugates of the transfer functions, rotating the complex conjugates to produce a plurality of reduced transfer functions; and The reduced transfer functions are sorted to generate the cosine transfer function and the sine transfer function. 14. The method for coding an audio signal according to claim 12, wherein the first lookup table is a sine function lookup table, and the second lookup table is a cosine function lookup table.

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