CN101197576A - Audio signal encoding and decoding method - Google Patents
Audio signal encoding and decoding method Download PDFInfo
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- CN101197576A CN101197576A CNA2006101192822A CN200610119282A CN101197576A CN 101197576 A CN101197576 A CN 101197576A CN A2006101192822 A CNA2006101192822 A CN A2006101192822A CN 200610119282 A CN200610119282 A CN 200610119282A CN 101197576 A CN101197576 A CN 101197576A
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Abstract
The invention discloses a method for coding and decoding an audio signal, which comprises a coding step and a decoding step. The method adopts a policy of mixed resolution coding of different frequency resolutions of high and low frequency ranges, so that higher cut-off frequency can be acquired based on not changing the prior broadband frequency spectrum coding framework; because only the high frequency part corresponding to the audio signal is conducted with a processing of reducing the frequency resolution, the coding tone can be furthest guaranteed on the premise of reducing requirement of coding bit, so that the tone effect which is difficult to fulfill for general parameter coding can be received. The invention can be completely applied without changing the coding/decoding architecture, so the invention has the widest general applicability.
Description
Technical field
The present invention relates to the Audio Signal Processing technical field, relate in particular to a kind of audio-frequency signal coding, coding/decoding method.
Background technology
The mode of current audio coding can roughly be divided into parameter coding and based on the spectrum coding of subband.Be mainly used in low code check situation based on parameter coding, then be mainly used in medium or the high code rate situation based on the spectrum coding of subband.Though parameter coding can use low code check to encode, the tonequality loss obviously behind the coding/decoding.The subband spectrum coding method can be compiled out the code stream than high tone quality, but need take higher code check.Because in the wideband encoding process, the shared proportion of the bit that spectrum coding produced (bit) number is maximum, therefore takies in order obviously to reduce coding bit, and it is most possible reducing the spectrum coding occupancy of partly encoding, and also is most pronounced effects.The method that tradition minimizing spectrum coding bit takies mainly is to adopt the method that reduces cut-off frequency.By reducing cut-off frequency, need corresponding can the minimizing of frequency spectrum point number of coding, thereby reach the purpose that reduces coding bit.The way of this reduction cut-off frequency in be feasible under the situation of high code check, this is because people's ear is responsive more then relatively not too responsive to high band to low frequency signal.If but under low code check (below 10kbps) situation, cut-off frequency very low (as 3Khz or lower) when adopting method of coding subband to encode usually, if still adopt the method that reduces cut-off frequency, can have a strong impact on coding back auditory perception, also just directly have influence on the tonequality behind the final coding.Therefore how under low code check situation, the coding techniques that can obtain reasonable effect when significantly reducing coding bit number becomes the target of industry exploration.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of audio-frequency signal coding, coding/decoding method, can be widely used in wideband encoding, under low code check situation, can obtain obviously to be better than the effect of parameter coding when significantly reducing coding bit number especially.
For solving the problems of the technologies described above, the present invention proposes a kind of audio-frequency signal coding, coding/decoding method, comprising: coding step comprises: (a) input audio signal; (b) obtain frequency spectrum below cut-off frequency by normal time domain to the conversion of frequency domain; (c) carry out the down-sampled of high band frequency-region signal,, be adjusted at the resolution of each frequency subband of high band in the cut-off frequency and form new frequency spectrum promptly according to step b gained frequency spectrum; (d) carry out the coding of hybrid frequency resolution frequency spectrum then; (e) at last steps d the is encoded bit stream of gained enrolls code stream; Wherein step c comprises: (1) selects the frequency division point of a high band, and all frequency subbands that are higher than this frequency partly are high band; (2) in high band range, the spectrum value of choosing a plurality of frequency subbands of same number from low frequency toward high frequency successively forms a new spectrum value; (3) repeating step 2 finishes up to cut-off frequency successively.Decoding step comprises: (f) code stream of input step e gained; (g) resolve code stream and obtain the mixed-resolution frequency spectrum; (h) the decode liter sampling of back high band, promptly according to the frequency spectrum of step g gained mixed-resolution frequency spectrum reconfiguration normal resolution, and corresponding with step c; (i) by the conversion of normal frequency domain to time domain, reconstruct obtains the decoded audio frame signal.Abovementioned steps c is down-sampled to be not limited to reduce by one times down-sampled method, and its down-sampled method comprises: directly get the method for average or the method for employing filter; Same abovementioned steps h rises to sample and is not limited to rise the method for sampling that rises that doubles, and also comprise the liter sampling multiple that all and coded portion step c adapt, and its method that rises sampling comprises: directly get the method for average or the method for employing filter.
The present invention can guarantee coding tonequality to greatest extent owing to only the relative HFS of audio signal is reduced the processing of frequency resolution under the prerequisite that reduces coding bit demand, and then can obtain the acoustical quality that is difficult to arrive than common parameter coding.In addition, because the inventive method can obtain complete application under the situation that does not change the coding/decoding architecture, so method of the present invention has general applicability the most widely.
Description of drawings
Fig. 1 is the schematic flow sheet of coding method of the present invention;
Fig. 2 is the schematic flow sheet of coding/decoding method of the present invention.
Embodiment
The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.
In the wideband encoding process, the shared proportion of bit number that wherein spectrum coding produced is maximum.As previously mentioned, take in order obviously to reduce coding bit, it is most possible reducing the spectrum coding occupancy of partly encoding, and also is most pronounced effects.The method that reduces cut-off frequency with conventional tradition is different, the present invention has adopted complete method inequality, the present invention considers that people's ear is very sensitive to the signal of low frequency part under low code check situation, so the present invention has only carried out special processing to relative HFS, promptly adjust high-band frequency resolution and reach the purpose that reduces coding bit number.
As shown in Figure 1 and Figure 2, be the schematic flow sheet of coding method of the present invention and coding/decoding method respectively.
Fig. 1 coding method comprises: at first obtain frequency spectrum 101 below cut-off frequency by time domain to the conversion of frequency domain, according to this frequency spectrum, be adjusted at the resolution of each frequency subband of high band in the cut-off frequency and form new frequency spectrum 102, carry out the coding 103 of frequency spectrum then, the bit stream of the gained of will encoding at last enrolls final code stream 104; Wherein time domain is changeed conversion process 101 employings and the general duplicate transform method of encoder of frequency domain; The selection of cut-off frequency also is just the same.
Below each step of above-mentioned coding is told about in detail.
102 steps: promptly the adjustment of high-band frequency resolution is a most crucial part of the present invention in the cut-off frequency: at first select the frequency division point of a high band, all frequency subbands that are higher than this frequency partly are the alleged high band of the present invention; In high band range, the spectrum value of choosing several frequency subbands of same number from low frequency toward high frequency successively forms a new spectrum value, and it is wide that the frequency subband bandwidth ratio of this spectrum value correspondence was not adjusted the frequency bandwidth of previous subband correspondence originally; Repeat this process successively until cut-off frequency finishes.Usually, can select per two frequency subbands as a processing unit, also promptly per successively two frequency subbands form a new frequency subband, and the bin width of new like this frequency subband correspondence is original twice just.102 processes also can be understood as a kind of down-sampled to the high-band frequency subband.
With two frequency subband processing units is example, this down-sampled process can further specify as follows: at first determine this down-sampled calculative strategy: the simplest can be the average of two frequency subbands, also can be the output by finite impulse corresponding (FIR) low pass filter; Two subbands in every then interval calculate the spectrum value of a new subband; Utilize these the new spectrum values and the frequency spectrum of original low-frequency range to form the new frequency spectrum of new mixed-resolution at last, and with this frequency spectrum as follow-up spectrum coding.
103 steps: process that hybrid frequency resolution frequency spectrum is encoded and general cataloged procedure are just the same substantially, unique different be that pairing frequency has been counted and obviously reduced in the cut-off frequency scope.The spectrum value number that also promptly needs to encode obviously reduces, and then finally reaches the purpose that reduces coding bit number.
104 steps: form final encoding code stream according to the coding bit stream that forms in 103 processes.
Fig. 2 coding/decoding method comprises: the frequency spectrum 201 that at first obtains mixed-resolution by normal decode procedure, according to the frequency spectrum 202 of the frequency spectrum reconfiguration normal resolution of mixed-resolution, conversion and the reconstruct according to normal frequency domain to time domain subsequently obtains decoded audio frame signal 203 then.
Below each step of above-mentioned decoding is told about in detail.
201 steps: mixed-resolution frequency spectrum decode procedure is just the same with normal decode procedure.
202 steps: promptly the normal resolution frequency spectrum reconfiguration is the most crucial process of decoded portion of the present invention.The entire spectrum restructuring procedure be with cataloged procedure in mixing frequency spectrum acquisition methods corresponding one by one.202 step process also can be understood as a kind of liter sampling.
Still be example for 2 times with a liter sampling: owing to do not have the side frequency sub belt energy to concern relevant information in the bit stream, come reconstructed high frequency section spectrum signal so generally can adopt the principle that rises sampling, the simplest a kind of processing method can be directly the energy of adjacent two normal sub-band all is taken as identical, promptly as shown in the formula shown in (1)
Wherein
Be hybrid frequency resolution frequency spectrum, f0 is a high band initial frequency point.
203 steps: the frequency spectrum according to the normal frequency resolution of reconstruct can reconstruct normal time-domain audio frame signal through normal frequency domain to time domain conversion, and this process is just the same with conventional way.
Embodiment:
Specify the process of the present invention of implementing for example in the following cases: the spectral index of (1) high frequency initial frequency point correspondence number is 200, and the spectral index of (2) cut-off frequency correspondence number is 400, and (3) down-sampled multiple is one times.
Coding side then:
1) by be converted to 400 spectrum values cut-off frequency below of normal time domain to frequency-region signal, totally 400;
2) adopt per two Frequency points to average successively and obtain a spectrum value under the low frequency resolution, totally 100;
3) 200 values of low-frequency range and the value of 100 low frequency resolution are formed hybrid frequency resolution frequency spectrum (300 values);
4) carry out normal spectrum coding and form final encoding code stream according to hybrid frequency resolution frequency spectrum.
Decoding end:
1) by normal decode procedure, decoding obtains the frequency spectrum (300 values) under the hybrid frequency resolution;
2) 100 spectrum values of high band expanded successively according to formula (1) be reconstructed into 200 values,
F0=201 wherein, k=0,1,2 ..., 99; 200 values of this reconstruct and 200 values of low-frequency range together are reconstructed into the frequency spectrum of normal frequency under differentiating;
3) promptly obtain the time-domain audio signal of final reconstruct by the conversion restructuring procedure of normal frequency domain to time domain.
In addition, adopt the technology of the present invention, can under the situation that does not increase coding bit demand, improve the cut-off frequency of coding.Specifically can illustrate as follows.
Suppose original frequency spectrum 300 spectrum values of need encoding, adopt the present invention can adopt 200 low frequency spectrum values, add 100 high band low resolution spectrum values again, so just be equivalent to actual coding 200+100 * 2=400 spectrum value (supposing to fall a sampling), and then improved cut-off frequency to a certain extent.
The inventive method is owing to only carried out special processing to the relative HFS of audio signal, and this processing only is a kind of way that reduces frequency resolution, so still can guarantee not losing of main information, can under the prerequisite that reduces coding bit demand, guarantee coding tonequality to greatest extent, and then can obtain the acoustical quality that is difficult to arrive than common parameter coding.In addition, because the pairing technical essential of the inventive method can obtain complete application under the situation that does not change the coding/decoding architecture, so the inventive method has general applicability the most widely, can be widely used in based on sub-band coding the method for especially low code check sub-band coding.
In sum, the inventive method is a kind of can being widely used in based on sub-band coding, the method of especially low code check sub-band coding, the application of the invention can obviously reduce the required code check of sub-band coding, and the tonequality behind the coding is significantly better than the parameter coding effect simultaneously.The present invention can obtain higher cut-off frequency under low code check on the basis that does not change original existing broader frequency spectrum coding framework structure, perhaps obtain lower encoder bit rate under identical cut-off frequency.Under the Low Bit-rate Coding situation, can obtain tonequality significantly better than parameter coding.
Claims (3)
1. an audio-frequency signal coding, coding/decoding method is characterized in that, comprise the steps: coding step, comprising: (a) input audio signal; (b) obtain frequency spectrum below cut-off frequency by normal time domain to the conversion of frequency domain; (c) carry out the down-sampled of high band frequency-region signal,, be adjusted at the resolution of each frequency subband of high band in the cut-off frequency and form new frequency spectrum promptly according to step b gained frequency spectrum; (d) carry out the coding of hybrid frequency resolution frequency spectrum then; (e) at last steps d the is encoded bit stream of gained enrolls code stream; Wherein step c comprises: (1) selects the frequency division point of a high band, and all frequency subbands that are higher than this frequency partly are high band; (2) in high band range, the spectrum value of choosing a plurality of frequency subbands of same number from low frequency toward high frequency successively forms a new spectrum value; (3) repeating step 2 finishes up to cut-off frequency successively;
Decoding step comprises: (f) code stream of input step e gained; (g) resolve code stream and obtain the mixed-resolution frequency spectrum; (h) the decode liter sampling of back high band, promptly according to the frequency spectrum of step g gained mixed-resolution frequency spectrum reconfiguration normal resolution, and corresponding with step c; (i) by the conversion of normal frequency domain to time domain, reconstruct obtains the decoded audio frame signal.
2. audio-frequency signal coding according to claim 1, coding/decoding method is characterized in that, described step c is down-sampled to be not limited to reduce by one times down-sampled method; Described step h rises sampling and is not limited to rise the method for sampling that rises that doubles, and also comprises the liter sampling multiple that all and coded portion step c adapt.
3. audio-frequency signal coding according to claim 2, coding/decoding method is characterized in that, described down-sampled method comprises: directly get the method for average or the method for employing filter; The method of described liter sampling comprises: directly get the method for average or the method for employing filter.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101615395B (en) * | 2008-12-31 | 2011-01-12 | 华为技术有限公司 | Methods, devices and systems for encoding and decoding signals |
| CN102099856B (en) * | 2008-07-17 | 2012-11-07 | 弗劳恩霍夫应用研究促进协会 | Audio encoding/decoding method and device having a switchable bypass |
| CN102985969A (en) * | 2010-12-14 | 2013-03-20 | 松下电器产业株式会社 | Coding device, decoding device, and methods thereof |
| CN105374362A (en) * | 2010-01-08 | 2016-03-02 | 日本电信电话株式会社 | Encoding method, decoding method, encoder apparatus, decoder apparatus and program |
| WO2021204015A1 (en) * | 2020-04-09 | 2021-10-14 | 于江鸿 | Data processing method and system |
| CN113870872A (en) * | 2018-06-05 | 2021-12-31 | 安克创新科技股份有限公司 | Voice tone enhancement method, device and system based on deep learning |
| US11503306B2 (en) | 2020-04-09 | 2022-11-15 | Jianghong Yu | Image and video data processing method and system |
| US11528488B2 (en) | 2020-04-09 | 2022-12-13 | Jianghong Yu | Image and video data processing method and system |
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- 2006-12-07 CN CNA2006101192822A patent/CN101197576A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102099856B (en) * | 2008-07-17 | 2012-11-07 | 弗劳恩霍夫应用研究促进协会 | Audio encoding/decoding method and device having a switchable bypass |
| US8712763B2 (en) | 2008-12-31 | 2014-04-29 | Huawei Technologies Co., Ltd | Method for encoding signal, and method for decoding signal |
| CN101615395B (en) * | 2008-12-31 | 2011-01-12 | 华为技术有限公司 | Methods, devices and systems for encoding and decoding signals |
| CN105374362A (en) * | 2010-01-08 | 2016-03-02 | 日本电信电话株式会社 | Encoding method, decoding method, encoder apparatus, decoder apparatus and program |
| CN105374362B (en) * | 2010-01-08 | 2019-05-10 | 日本电信电话株式会社 | Coding method, coding/decoding method, code device, decoding apparatus and recording medium |
| US9373332B2 (en) | 2010-12-14 | 2016-06-21 | Panasonic Intellectual Property Corporation Of America | Coding device, decoding device, and methods thereof |
| CN102985969B (en) * | 2010-12-14 | 2014-12-10 | 松下电器（美国）知识产权公司 | Coding device, decoding device, and methods thereof |
| CN102985969A (en) * | 2010-12-14 | 2013-03-20 | 松下电器产业株式会社 | Coding device, decoding device, and methods thereof |
| CN113870872A (en) * | 2018-06-05 | 2021-12-31 | 安克创新科技股份有限公司 | Voice tone enhancement method, device and system based on deep learning |
| WO2021204015A1 (en) * | 2020-04-09 | 2021-10-14 | 于江鸿 | Data processing method and system |
| US11503306B2 (en) | 2020-04-09 | 2022-11-15 | Jianghong Yu | Image and video data processing method and system |
| US11528488B2 (en) | 2020-04-09 | 2022-12-13 | Jianghong Yu | Image and video data processing method and system |
| US11677960B2 (en) | 2020-04-09 | 2023-06-13 | Jianghong Yu | Image and video processing methods and systems |
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