CN101587711B - Pitch post-treatment method, filter and pitch post-treatment system - Google Patents
Pitch post-treatment method, filter and pitch post-treatment system Download PDFInfo
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Abstract
The invention discloses a pitch post-treatment method. The pitch post-treatment method comprises that an energy ratio of a current frame and a post frame of a decoded pitch synthesis signal is compared with a preset threshold value to confirm pitch post-treatment; the pitch post-treatment comprises the filter treatment of the pitch synthesis signal; and the filter treatment comprises the followingsteps: obtaining at least two gain control values corresponding to at least two partial adjustment factors according to the gain of the pitch synthesis signal and the partial adjustment factors; and combining the gain control values and the partial adjustment factors to obtain a filter function. Accordingly, the invention also discloses a filter and a pitch post-treatment system. The invention reduces the accessing and shifting operations of registers, removes the design of a low-pass filter in the prior art and greatly lowers the complexity.
Description
Technical Field
The present invention relates to a speech processing technology, and in particular, to a pitch post-processing method, a filter, and a pitch post-processing system.
Background
With the rise of 3G technology, higher requirements are put on digital audio coding technology. Due to the expansion of multimedia services, not only higher coding efficiency and real-time performance are required, but also the coding bandwidth of audio needs to be further expanded, or relatively good coding and decoding performance can be realized at a lower code rate.
AMR-WB + can have excellent coding quality under low Code Rate by adopting the technologies of an Adaptive Multi-Rate Wideband (AMR-WB +) having mixed Algebraic Codebook Excited Linear Prediction (ACELP)/Transform Excited coding (TCX) model, bandwidth extension, stereo coding and the like. However, since the code rate is low, when encoding the required parameters, some fine structure information of speech has to be compressed in the code stream due to insufficient bit number allocation, so that although correct decoding can be performed and intelligibility reaches the general level required by a listener, the perceptual quality of the decoded signal is not satisfactory due to various decoding noises caused thereby, and further post-processing is still required in terms of the perceptual quality of audio.
The purpose of post-processing is to enhance information related to the perceptual quality in the synthesized sound signal or to reduce or remove interfering information that degrades the perceptual quality. In the prior art, a pitch post-processing method is used as a common method of the post-processing technology.
In AMR-WB +, pitch post-processing is a band-selectable pitch enhancement post-processing algorithm. As shown in fig. 1, the decoded synthesized sound signal is divided into two sub-bands, which may be a low sub-band and a non-low sub-band, wherein the low sub-band is first passed through a gain adaptive pitch enhancer, which mainly attenuates the noise between the low frequency end tone harmonics to an appropriate degree, and then passed through a low pass filter to filter out the spectral tilt and some other undesired frequency components; while the non-low sub-bands pass directly through the high-pass filter; and finally, summing the signals of the sub-bands after the respective processing to obtain a synthetic sound signal after the fundamental tone enhancement.
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art:
the pitch post-processing technology in the prior art needs a large amount of shifting and state updating operations on a register, and is complex to implement.
Disclosure of Invention
The embodiment of the invention provides a pitch post-processing method, a filter and a pitch post-processing system for reducing implementation complexity.
The pitch post-processing method of the embodiment of the invention comprises the following steps:
comparing the energy ratio of the current frame and the previous frame of the decoded fundamental tone synthetic signal with a preset threshold value, and determining to perform fundamental tone post-processing;
the pitch post-processing includes filtering the pitch synthesized signal, where the filtering includes obtaining at least two gain control values corresponding to the local adjustment factors according to the gain of the pitch synthesized signal and the at least two local adjustment factors, and combining the gain control values and the local adjustment factors to obtain a filter function.
A filter of an embodiment of the present invention includes:
an input unit configured to input the decoded pitch synthesis signal;
a filtering unit, configured to obtain at least two gain control values corresponding to the local adjustment factors according to the gain of the pitch synthesized signal and the at least two local adjustment factors, combine the gain control values and the local adjustment factors to obtain a filtering function, and perform filtering processing on the pitch synthesized signal input by the input unit by using the filtering function;
and the output unit is used for outputting the fundamental tone synthesis signal after the filtering processing of the filtering unit.
An embodiment of the present invention provides a pitch post-processing system, which includes:
and the full-zero post-filter is used for obtaining at least two parts of gain control values corresponding to the local adjustment factors according to the gain of the decoded fundamental tone synthetic signal and the at least two local adjustment factors, combining the gain control values and the local adjustment factors to obtain a filter function, and filtering the fundamental tone synthetic signal by using the filter function.
By implementing the pitch post-processing method, the filter and the pitch post-processing system provided by the embodiment of the invention, the filter provided by the embodiment of the invention is utilized for pitch post-processing, so that the quantization noise among harmonics is eliminated, the perceptual quality of the decoded sound is improved, the access and shift operations of a register are reduced, the design of a low-pass filter in the prior art is eliminated, and the complexity is greatly reduced. And the coefficients of the filter used for pitch post-processing may be adaptively adjusted to track changes in the output signal.
Drawings
Fig. 1 is a schematic diagram of a system architecture of a pitch post-processing in the prior art;
fig. 2 is a flow chart of a pitch post-processing method according to an embodiment of the present invention;
FIG. 3 is a flow chart before step S1 of the method of FIG. 2;
FIG. 4 is a detailed flowchart of step S2 of the method of FIG. 2;
FIG. 5 is a block diagram of a first embodiment of a pitch post-processing system according to the invention;
FIG. 6 is a schematic diagram of a first embodiment of a filter according to the present invention;
FIG. 7 is a block diagram of a second embodiment of a pitch post-processing system of the present invention;
FIG. 8 is a schematic diagram of a second embodiment of a filter according to the present invention;
fig. 9 is a schematic structural diagram of a determining unit according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of the energy ratio acquisition module of FIG. 9;
fig. 11 is a schematic structural diagram of a filtering unit according to an embodiment of the present invention;
FIG. 12 is a block diagram of a third embodiment of a pitch post-processing system of the present invention;
FIG. 13 is a diagram of the spectral response of a prior art AMR-WB + filter for pitch post-processing;
fig. 14 is a diagram illustrating the spectral response of a filter according to an embodiment of the present invention.
Detailed Description
The following describes in detail a technical solution of a pitch post-processing method, a filter and a pitch post-processing system according to embodiments of the present invention with reference to the accompanying drawings.
Referring to fig. 2, a flowchart of a pitch post-processing method according to an embodiment of the present invention is shown. As can be seen from fig. 2, the pitch post-processing method includes:
s1, according to the energy ratio E of the current frame and the previous frame of the decoded pitch synthesis signalcomAnd a preset threshold value EthrWhether the post-processing is required or not is judged,in particular, the amount of the solvent to be used,
when said E iscomGreater than a predetermined EthrIf so, the step S2 is executed if it is determined that the post-processing is necessary, otherwise, the process goes to step S4.
And S2, filtering the pitch synthesis signal. In this embodiment, the filtering process includes obtaining at least two portions of gain control values corresponding to the local adjustment factors according to the gain of the pitch synthesis signal and the at least two local adjustment factors, and combining the gain control values and the local adjustment factors to obtain a filter function, which is represented by h (z), and specifically, the filter function h (z) is obtained by summing a first portion and a second portion, where the first portion is a first gain control value G1Multiplied by a first base value, the second part being a second gain control value G2Multiplying by a second base value, said first base value being obtained by multiplying a first local adjustment factor lambda1And z-TIs then summed with 1, the second base value being obtained by first adjusting a second local adjustment factor lambda2And z-TSum of the product of (a) with 1, and then with z-1Obtaining a product, wherein T represents a pitch period, and may be specifically expressed as formula (1):
H(z)＝G1(1+λ1z-T)+G2(1+λ2z-T)z-1，(1)
G1representing a first gain control value, G2Representing a second gain control value, λ1Denotes a first local adjustment factor, λ2Denotes the second local adjustment factor and T denotes the pitch period.
And S3, outputting the signal after the filtering processing, and ending the process.
And S4, directly outputting the fundamental tone synthesis signal, and ending the process.
The filter provided by the embodiment of the invention is used for pitch post-processing, the perceptual quality of the decoded sound is improved, and the filter coefficient can be adaptively adjusted to track the change of an output signal.
In practical implementation, as shown in fig. 3, before step S1, the method further includes:
s101, extracting a gain value gain from the fundamental tone synthesis signal;
s102, obtaining a ratio of the pitch synthesis signal amplitudes in the two pitch periods, wherein the value of the ratio can be obtained by calculation according to formula (2) by using a calculation module,
wherein T represents a pitch period, and syn _ in represents the pitch synthesized signal;
s103, comparing the gain value with the ratio value, and taking the smaller value of the gain value and the ratio value as EcomThen, the routine proceeds to step S1 to perform determination processing.
In a specific implementation, as shown in fig. 4, step S2 specifically includes:
s201, obtaining a first gain control value G according to the gain1And a second gain control value G2In particular, the G1By first passing lambda1The product of the sum and gain is summed with 1, and the sum is inverted to obtain G2By first passing lambda2The product with gain is summed with 1, and the sum is inverted to obtain the sum, which is expressed as formula (3) and formula (4), respectively:
the value range of lambda is generally between 0 and 1, the value of lambda determines the weighting degree between signals separated by one pitch period, and the optimal value in the embodiment of the invention is lambda1＝λ20.1, of course, in practical implementation, λ is determined according to practical conditions1，λ2Are not necessarily all the same.
S202, using G1And G2To configure the filter function, specifically, G is calculated in step S2011And G2Is substituted into equation (1) to configure the filter function.
S203, performing filtering processing on the pitch synthesized signal, specifically, performing convolution processing on the pitch synthesized signal and the impulse response function of h (z), and outputting the signal after the convolution processing, where the processing may be represented as: <math><mrow>
<mi>syn</mi>
<mo>_</mo>
<mi>out</mi>
<mo>=</mo>
<mi>syn</mi>
<mo>_</mo>
<mi>in</mi>
<mo>⊗</mo>
<mi>h</mi>
<mo>,</mo>
</mrow></math> where h is an impulse response function of h (z), syn _ in represents a pitch synthesized signal decoded by the pitch decoder, and syn _ out represents a signal output after filtering.
In the implementation, the preset determination threshold E in step S1 isthr0.4 to 0.8. When E isthrWhen the signal is 0.8, few signals pass through the post-processing module; when E isthrWhen the signal is 0.4, a plurality of signals pass through the post-processing module; preferably, EthrWhen the gain is 0.6, the optimal post-filtering effect can be realized under the condition that the gain is not overflowed.
According to the pitch post-processing method provided by the embodiment of the invention, the full zero post-filter is used for pitch post-processing, so that quantization noise among harmonics is eliminated, the perceptual quality of decoded sound is improved, the access and shift operations of a register are reduced, the design of a low-pass filter in the prior art is eliminated, and the complexity is greatly reduced. And the coefficients of the filter used for pitch post-processing may be adaptively adjusted to track changes in the output signal.
Based on the above-mentioned pitch post-processing method, an embodiment of the present invention provides a pitch post-processing system, and the following describes the pitch post-processing system in detail with reference to the accompanying drawings.
Referring to fig. 5, fig. 5 is a block diagram of a first embodiment of a pitch post-processing system according to the present invention. As shown in fig. 5, the pitch post-processing system comprises a full zero post-filter 3 and a pitch decoder 1.
In this embodiment, the all-zero-point post-filter 3 is configured to obtain at least two gain control values corresponding to at least two local adjustment factors according to a gain of a pitch synthesized signal decoded by the pitch decoder 1 and the at least two local adjustment factors, combine the gain control values and the local adjustment factors to obtain a filter function, and perform filtering processing on the decoded pitch synthesized signal by using the filter function, where the filter function of the all-zero-point post-filter 3 is:
H(z)＝G1(1+λ1z-T)+G2(1+λ2z-T)z-1，
G1representing a first gain control value, G2Representing a second gain control value, λ1Denotes a first local adjustment factor, λ2Denotes the second local adjustment factor and T denotes the pitch period.
The full zero filter provided by the embodiment of the invention is utilized to carry out fundamental tone post-processing, the perceptual quality of the decoded sound is improved, the access and shift operations of a register are reduced, the design of a low-pass filter in the prior art is eliminated, and the complexity is greatly reduced. And the coefficients of the filter used for pitch post-processing may be adaptively adjusted to track changes in the output signal.
In the embodiment of the present invention, as shown in fig. 6, the structure of the all-zero post-filter shown in fig. 5 is the same as that of the filter provided by the present invention, and includes an input unit 301, a filtering unit 302, and an output unit 303.
In this embodiment, the input unit 301 is configured to input the decoded pitch synthesis signal.
The filtering unit 302 is configured to obtain at least two gain control values corresponding to at least two local adjustment factors according to the gain of the pitch synthesis signal input by the input unit 301 and the at least two local adjustment factors, combine the gain control values and the local adjustment factors to obtain a filtering function, and perform filtering processing on the pitch synthesis signal by using the filtering function, where the filtering function adopted by the filtering unit 302 is represented as:
H(z)＝G1(1+λ1z-T)+G2(1+λ2z-T)z-1，
wherein G is1Representing a first gain control value, G2Representing a second gain control value, λ1Denotes a first local adjustment factor, λ2Denotes the second local adjustment factor and T denotes the pitch period.
The output unit 303 is configured to output the pitch synthesized signal after being filtered by the filtering unit 302.
In another embodiment of the present invention, as shown in fig. 7, a block diagram of a second embodiment of a pitch post-processing system according to the present invention further includes a determining unit 2. In this embodiment, the judging unit 2 is configured to determine the energy ratio E of the current frame to the previous frame of the pitch synthesis signal according to the pitch decoded by the pitch decoder 1comAnd a preset judgment threshold value EthrAnd judging whether post-processing is needed or not, and sending the fundamental tone synthetic signal to the all-zero filter 3 for processing when judging that the post-processing is needed, or directly outputting the fundamental tone synthetic signal when judging that the post-processing is not needed.
It should be noted that the determining unit 2 may also be carried on the full-zero post-filter 3 as an assembly, where the structure of the full-zero post-filter 3 is the same as that of the filter according to the embodiment of the present invention, as shown in fig. 8, the filter further includes the determining unit 2.
In this embodiment, the judging unit 2 is configured to determine the energy ratio E of the current frame to the previous frame of the pitch synthesis signal input by the input unit 301comAnd a preset judgment threshold value EthrWhether post-processing is needed or not is judged, and when the post-processing is judged to be needed, the pitch synthesized signal input by the input unit 301 is sent to the filtering unit 302 for processing and then output by the output unit 303, or when the post-processing is judged to be not needed, the pitch synthesized signal input by the input unit 301 is directly output by the output unit 303.
In a specific implementation, as shown in fig. 9, the determining unit 2 includes an energy ratio obtaining module 201, a threshold configuring module 202, a comparing module 203, and a result executing module 204.
In this embodiment, the energy ratio obtaining module 201 is configured to obtain an energy ratio E between a current frame and a previous frame of the pitch synthesis signalcom。
The threshold configuration module 202 is used for obtaining a judgment threshold EthrThe judgment threshold value Ethr0.4 to 0.8.
The comparison module 203 is used for comparing the E acquired by the energy ratio acquisition module 201comE obtained by the threshold configuration module 202thrTo perform comparison processing.
The result execution module 204 is coupled to the comparison module 201 for executing the result when EcomGreater than EthrIf not, the pitch synthesized signal input by the input unit 301 is output through the output unit 303.
As shown in fig. 10, the energy ratio obtaining module 201 includes a gain value obtaining module 2011, an amplitude ratio calculating module 2012 and an energy ratio determining module 2013.
In this embodiment, the gain value obtaining module 2011 is configured to extract a gain value gain from the pitch synthesis signal.
The amplitude ratio calculation module 2012 is arranged to calculate the ratio of the amplitudes of the pitch synthesized signal over two pitch periods,
wherein, <math><mrow>
<mi>ration</mi>
<mo>=</mo>
<msqrt>
<mfrac>
<mrow>
<mn>0.01</mn>
<mo>+</mo>
<munderover>
<mi>Σ</mi>
<mrow>
<mi>i</mi>
<mo>=</mo>
<mn>0</mn>
</mrow>
<mi>T</mi>
</munderover>
<mi>syn</mi>
<mo>_</mo>
<msup>
<mi>in</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>i</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<mn>0.01</mn>
<mo>+</mo>
<munderover>
<mi>Σ</mi>
<mrow>
<mi>i</mi>
<mo>=</mo>
<mn>0</mn>
</mrow>
<mi>T</mi>
</munderover>
<mi>syn</mi>
<mo>_</mo>
<msup>
<mi>in</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>i</mi>
<mo>+</mo>
<mi>T</mi>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
</msqrt>
<mo>,</mo>
</mrow></math> t denotes the pitch period and syn _ in denotes the pitch synthesized signal.
The energy ratio determining module 2013 is configured to compare the gain obtained by the gain obtaining module 2011 with the amplitudeThe ratio calculated by the ratio calculation module 2012 is compared and the smaller value of the two is taken as Ecom。
In practical implementation, the filtering unit 302 according to the embodiment of the present invention specifically includes a first gain control calculating module 3021, a second gain control calculating module 3022, a filter coefficient configuring module 3023, and a filter processing module 3024.
In this embodiment, the first gain control calculation module 3021 is configured to obtain the first gain control value G according to the gain obtained by the gain value obtaining module 20111， <math><mrow>
<msub>
<mi>G</mi>
<mn>1</mn>
</msub>
<mo>≈</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>1</mn>
<mo>+</mo>
<msub>
<mi>λ</mi>
<mn>1</mn>
</msub>
<mo>*</mo>
<mi>gain</mi>
</mrow>
</mfrac>
<mo>.</mo>
</mrow></math>
The second gain control calculating module 3022 is configured to obtain the second gain control value G according to the gain obtained by the gain value obtaining module 20112， <math><mrow>
<msub>
<mi>G</mi>
<mn>2</mn>
</msub>
<mo>≈</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>1</mn>
<mo>+</mo>
<msub>
<mi>λ</mi>
<mn>2</mn>
</msub>
<mo>*</mo>
<msub>
<mi>E</mi>
<mi>com</mi>
</msub>
</mrow>
</mfrac>
<mo>.</mo>
</mrow></math>
A filter coefficient configuration module 3023 for configuring the filter coefficient according to the G1And G2And configuring a filter function of the filter unit.
The filtering module 3024 is configured to filter the pitch synthesis signal according to the filtering function configured by the filtering coefficient configuration module 3023, and specifically, to combine the pitch synthesis signal with the h (z)The impulse response function performs convolution processing to output the signal after the convolution processing, which can be expressed as: <math><mrow>
<mi>syn</mi>
<mo>_</mo>
<mi>out</mi>
<mo>=</mo>
<mi>syn</mi>
<mo>_</mo>
<mi>in</mi>
<mo>⊗</mo>
<mi>h</mi>
<mo>,</mo>
</mrow></math> where h is the impulse response function of the all-zero post-filter h (z), syn _ in represents the pitch synthesized signal decoded by the pitch decoder, and syn _ out represents the signal processed and output by the all-zero post-filter.
Referring to fig. 12, a block diagram of a third embodiment of a pitch post-processing system of the present invention is illustrated. On the basis of the above embodiment, the system further comprises a pitch tracker 4 and a pitch enhancer 5.
In this embodiment, the pitch tracker 4 is configured to extract a pitch period T and a gain value gain from a pitch synthesis signal at the encoding end.
The pitch enhancer 5 is configured to perform pitch enhancement processing on the pitch synthesized signal decoded by the pitch decoder according to the pitch period and the gain value extracted by the pitch tracker 4.
In summary, by implementing the pitch post-processing method, the filter and the pitch post-processing system according to the embodiments of the present invention, the filter proposed in the embodiments of the present invention is used for pitch post-processing, so as to eliminate quantization noise between harmonics and improve perceptual quality of decoded voice, as shown in fig. 13 and 14, fig. 13 is a schematic diagram of a spectral response of an AMR-WB + filter used for pitch post-processing in the prior art, and fig. 14 is a schematic diagram of a spectral response of a filter proposed in an embodiment of the present invention. Comparing fig. 13 and fig. 14, the embodiment of the present invention also realizes the emphasis of low frequency components, does not need to use a subband filter in AMR-WB + to perform high and low frequency band decomposition on the decoded signal, reduces the access and shift operations of a register, greatly reduces the complexity, and can adaptively adjust the coefficients of the filter for the pitch post-processing to track the change of the output signal.
Through the above description of the embodiments, those skilled in the art will clearly understand that the present invention may be implemented by software plus a necessary hardware platform, and may also be implemented by hardware entirely. With this understanding in mind, all or part of the technical solutions of the present invention that contribute to the background can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods according to the embodiments or some parts of the embodiments of the present invention.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (18)
1. A method of pitch post-processing, comprising:
comparing the energy ratio of the current frame and the previous frame of the decoded fundamental tone synthetic signal with a preset threshold value, and determining to perform fundamental tone post-processing;
the pitch post-processing includes filtering the pitch synthesized signal, where the filtering includes obtaining at least two gain control values corresponding to the local adjustment factors according to the gain of the pitch synthesized signal and the at least two local adjustment factors, and combining the gain control values and the local adjustment factors to obtain a filtering function used by the filtering.
2. The method of claim 1, wherein the filter function is represented by h (z) and is obtained by summing a first portion and a second portion, wherein the first portion is a first gain control value G1Multiplied by a first base value, the second part being a second gain control value G2Multiplying by a second base value, said first base value being obtained by multiplying a first local adjustment factor lambda1And z-TIs then summed with 1, the second base value being obtained by first adjusting a second local adjustment factor lambda2And z-TSum of the product of (a) with 1, and then with z-1The product is obtained and T represents the pitch period.
3. The method according to claim 1 or 2, wherein the step of comparing the energy ratio of the current frame and the previous frame of the decoded pitch synthesis signal with a preset threshold value and determining to perform the pitch post-processing specifically comprises:
and when the energy ratio of the current frame to the previous frame is larger than a preset threshold value, judging that post-processing is needed, otherwise, directly outputting the fundamental tone synthesis signal.
4. The method according to claim 1 or 2, wherein before the step of comparing the energy ratio of the current frame to the previous frame of the decoded pitch synthesis signal with a preset threshold value, determining to perform the pitch post-processing comprises:
extracting a gain value gain from the pitch synthesis signal;
obtaining the ratio of the pitch synthesis signal amplitudes in the two pitch periods;
and comparing the value of gain with the value of the ratio, and taking the smaller value of the two as the energy ratio.
5. The method according to claim 4, wherein the step of performing filtering processing on the pitch synthesized signal when it is determined that post-processing is necessary comprises:
obtaining a first gain control value G according to the gain1And a second gain control value G2；
Using G1And G2To configure the filter function;
and carrying out filtering processing on the fundamental tone synthesis signal according to the filtering function.
6. The method of claim 5, wherein G is1By first locally adjusting a factor lambda1The product of the sum and gain is summed with 1, and the sum is inverted to obtain G2By first adjusting the second local adjustment factor lambda2The product of gain is summed with 1 and the sum is inverted.
7. The method according to claim 5, wherein the step of filtering the pitch synthesis signal according to the filter function is specifically:
and convolving the pitch synthesis signal with an impulse response function of a filter function H (z), and outputting the convolved signal.
8. The method of claim 1, wherein the predetermined threshold is 0.4 to 0.8.
9. A filter, comprising:
an input unit configured to input the decoded pitch synthesis signal;
a filtering unit, configured to obtain at least two gain control values corresponding to the local adjustment factors according to the gain of the pitch synthesis signal input by the input unit and the at least two local adjustment factors, combine the gain control values and the local adjustment factors to obtain a filtering function, and perform filtering processing on the pitch synthesis signal input by the input unit by using the filtering function;
and the output unit is used for outputting the fundamental tone synthesis signal after the filtering processing of the filtering unit.
10. The filter of claim 9, wherein the filter function is represented by h (z) and is obtained by summing a first portion and a second portion, wherein the first portion is a first gain control value G1Multiplied by a first base value, the second part being a second gain control value G2Multiplying by a second base value, said first base value being obtained by multiplying a first local adjustment factor lambda1And z-TIs then summed with 1, the second base value being obtained by first adjusting a second local adjustment factor lambda2And z-TSum of the product of (a) with 1, and then with z-1The product is obtained and T represents the pitch period.
11. The filter of claim 9, further comprising:
and the judging unit is used for judging whether post-processing is needed according to the energy ratio of the current frame and the previous frame of the pitch synthesis signal input by the input unit and a preset threshold, and when the judgment result shows that the post-processing is needed, the pitch synthesis signal input by the input unit is sent to the filtering unit for processing and then output by the output unit, or when the judgment result shows that the post-processing is not needed, the pitch synthesis signal input by the input unit is output by the output unit.
12. The filter of claim 11, wherein the decision unit comprises:
an energy ratio obtaining module, configured to obtain an energy ratio of a current frame and a previous frame of the pitch synthesis signal;
the threshold configuration module is used for acquiring a preset threshold;
the comparison module is used for comparing the energy ratio acquired by the energy ratio acquisition module with the preset threshold acquired by the threshold configuration module;
and the result execution module is coupled with the comparison module and used for judging that post-processing is needed when the energy ratio is greater than a preset threshold value, and sending the fundamental tone synthetic signal input by the input unit into the filtering unit for processing, otherwise, outputting the fundamental tone synthetic signal input by the input unit through the output unit.
13. The filter of claim 12, wherein the energy ratio acquisition module comprises:
a gain value obtaining module, configured to extract a gain value gain from the pitch synthesis signal;
a magnitude ratio calculation module for calculating a ratio of the magnitudes of the pitch synthesis signals in the two pitch periods;
and the energy ratio determining module is used for comparing the gain acquired by the gain value acquiring module with the ratio calculated by the amplitude ratio calculating module, and taking the smaller value of the gain acquired by the gain value acquiring module and the ratio calculated by the amplitude ratio calculating module as the energy ratio.
14. The filter of claim 13, wherein the filtering unit comprises:
a first gain control calculation module for obtaining a first gain control value G according to the gain1；
A second gain control calculation module for obtaining a second gain control value G according to the gain2；
A filter coefficient configuration module for configuring the filter coefficient according to the G1And G2Configuring a filter function of the filter unit;
and the filtering processing module is used for carrying out filtering processing on the fundamental tone synthesis signal according to the configured filtering function of the filtering coefficient configuration module.
15. A pitch post-processing system, comprising:
and the full zero post-filter is used for obtaining at least two parts of gain control values corresponding to the local adjustment factors according to the gain of the decoded fundamental tone synthetic signal and the at least two local adjustment factors, combining the gain control values and the local adjustment factors to obtain a filter function, and filtering the decoded fundamental tone synthetic signal by using the filter function.
16. The pitch post-processing system of claim 15, further comprising:
a judging unit for judging the energy ratio E of the current frame and the previous frame of the fundamental tone synthesis signalcomAnd a preset judgment threshold value EthrAnd judging whether post-processing is needed or not, and sending the fundamental tone synthesized signal into the full-zero post-filter for processing when judging that the post-processing is needed, or outputting the fundamental tone synthesized signal when judging that the post-processing is not needed.
17. The pitch post-processing system according to claim 16, wherein the decision unit is carried as a component on the all-zero post-filter.
18. The pitch post-processing system according to any one of claims 15 to 17, wherein the system further comprises:
the pitch tracker is used for extracting a pitch period and a gain value from a pitch synthesis signal at a coding end;
and the pitch enhancer is used for carrying out pitch enhancement processing on the pitch synthesized signal decoded by the pitch decoder according to the pitch period and the gain value extracted by the pitch tracker.
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| CN1154173A (en) * | 1994-04-29 | 1997-07-09 | 乔纳森·爱德华·谢尔曼 | A pitch post-filter |
| CN1256000A (en) * | 1998-01-26 | 2000-06-07 | 松下电器产业株式会社 | Method and device forr emphasizing pitch |
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| US4969192A (en) * | 1987-04-06 | 1990-11-06 | Voicecraft, Inc. | Vector adaptive predictive coder for speech and audio |
| JP3483998B2 (en) * | 1995-09-14 | 2004-01-06 | 株式会社東芝 | Pitch enhancement method and apparatus |
| JP2974059B2 (en) * | 1996-07-18 | 1999-11-08 | 日本電気株式会社 | Pitch post filter device |
| CN101303858B (en) * | 2007-05-11 | 2011-06-01 | 华为技术有限公司 | Method and apparatus for implementing fundamental tone enhancement post-treatment |
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| CN1154173A (en) * | 1994-04-29 | 1997-07-09 | 乔纳森·爱德华·谢尔曼 | A pitch post-filter |
| CN1256000A (en) * | 1998-01-26 | 2000-06-07 | 松下电器产业株式会社 | Method and device forr emphasizing pitch |
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