BR112016016373B1 - DECODING DEVICE, DECODING METHOD AND NON-TRAINER STORAGE MEDIUM - Google Patents

Abstract

DECODING DEVICE, ENCODING DEVICE, DECODING METHOD AND ENCODING METHOD. The present invention relates to a decoding device that includes: a separation unit that separates first encoded data, a spectrum that includes a baseband spectrum of audio signals that have been encoded, and second encoded data, a spectrum of upper band high-band that was encoded based on the first encoded data; a first decoding unit that decodes the first encoded data and generates a first decoded spectrum; a first amplitude normalizer that divides amplitude of the first decoded spectrum into subbands, which normalizes the spectrum of each subband by the largest amplitude of the first decoded spectrum within each subband, and generates a normalized spectrum; an addition unit that adds noise spectrum to the normalized spectrum and generates a normalized added noise spectrum; a second decoding unit that decodes the second encoded data using the normalized added noise spectrum, and generates a second added noise spectrum; and a converter that performs time-frequency conversion with respect to a coupled spectrum based on the first decoded spectrum and the second spectrum of (...).

Description

BACKGROUND FIELD OF TECHNIQUE

[0001] The present invention relates to decoding and encoding audio signals to reduce musical noise in audio signals and musical signals (hereinafter referred to as audio signals and so on).

DESCRIPTION OF RELATED TECHNIQUE

[0002] Music coding technology that compresses audio signals into a low bit rate is an important technology in the effective use of radio waves and the like in mobile communication. There has been even more demand for higher quality phone call audio in recent years, and there is a desire for a calling service that has a real-life feel. This can be accomplished by encoding audio signals and so on from a wide frequency band at a high bitrate. However, this approach contradicts the effective use of radio waves and frequency bands.

[0003] As for a method for encoding signals of a wide frequency band with high quality at a low bit rate, there is a technology in which the input signal spectrum is a device (unit) in the two spectrums of a portion of low-band and a high-band portion, with the high-band portion being replaced by a duplicate of the low-band portion. That is, the overall bit rate is reduced by replacing the low-band portion with the high-band portion (Japanese Unexamined Patent Application Publication (PCT Application Translation) No. 2001-521648).

[0004] Based on this technology, there is a technology that, in view of the fact that the high-band spectrum has less deviation than the low-band spectrum, the low-band spectrum is normalized (smoothed) for each sub-band, after which correlation with the high-band spectrum is obtained. Consequently, sound quality deterioration can be prevented by copying the low-band spectrum that has high peak features. However, this technology has a disadvantage in that, because the low-band spectrum is expressed as a discrete pulse stream, the envelope of input signals in the method that estimates the envelope of the discrete pulse stream is entirely different from the original envelope. Consequently, a method was proposed instead of this normalization method, in which normalization is performed on the maximum amplitude value of discrete pulses, in each sub-band (International Publication No. 2013/035257).

[0005] Figure 11 is the coding device according to International Publication No. 2013/035257. In this coding device, input signals are converted into frequency region signals by a time-frequency converter 1010 and output as an input signal spectrum, and a low frequency region of the input signal spectrum is encoded into a core encoding unit 1020 and output as core encoded data. The core-coded data is then decoded and a core-coded low-frequency spectrum is generated, which is normalized by the maximum amplitude value in a subband amplitude normalization unit 1030 and a low-band spectrum normalized is generated. The band of the high-band portion in which the correlation value with respect to the normalized low-band spectrum is the greatest, and the gain between the normalized low-band spectrum in that band and the high-band portion of the input spectrum , are obtained, and these are encoded in an extended bandwidth coding unit 1060, and output as extended bandwidth encoded data.

[0006] Figure 12 illustrates a decoding device corresponding to this. The coded data is divided into core coded data and extended band coded data in a separation unit 2010, the core coded data is decoded in a core decoding unit 2020, and a core coded low-band spectrum is generated. The core-encoded low-band spectrum is subjected to the same processing as the coding device side, which is normalization by the largest value of the sample amplitude, thus generating the normalized low-band spectrum data. The normalized low-band spectrum data is then used to decode the extended-band encoded data by an extended-band decoding unit 2040, thereby generating the extended-band spectrum.

[0007] Also disclosed is technology in which the switch is performed between a subband amplitude normalization unit 1030 that performs normalization at the highest value of the sample, and a spectrum envelope normalization unit 7020 that normalizes the envelope of the sample's spectral power, according to the intensity of the peak features, as illustrated in Figure 13.

[0008] The normalization technology at the highest sample value, described in International Publication No. 2013/035257, is effective in a case in which the low-band spectrum is sparse, that is, in a case in which the value of amplitude of only part of the samples is large and the amplitude value of the other samples is almost zero. That is, the technology, according to International Publication No. 2013/035257, suppresses spectra with extremely large amplitude from being generated even for sparse spectra (homogenization), and can yield normalized low-band spectra with uniform features (supplementation). warning).

SUMMARY

[0009] However, spectral holes readily occur when the pulse flow is sparse, and such spectral holes cause noise that is called musical noise. International Publication No. 2013/035257 does not disclose any measures taken against musical noise due to spectral holes when the low-band spectrum is normalized by the highest amplitude of the sample.

[0010] An exemplary and non-limited embodiment provides a decoding device and encoding device capable of decoding high quality audio signals and so on with suppressed musical noise, while reducing the overall bit rate.

[0011] In general terms, the technical characteristics of the disclosed decoding device include:

[0012] a separation unit that separates first coded data, where a spectrum including a low-band spectrum of audio signals was coded, and second coded data where a high-band spectrum of a band higher than the band spectrum - low was encoded, with respect to the first encoded data;

[0013] a first decoding unit that decodes the first encoded data and generates a first decoded spectrum;

[0014] a first amplitude normalizer that divides the amplitude of the first decoded spectrum into a plurality of subbands, normalizes the spectrum of each subband by the largest value of the amplitude of the first decoded spectrum within each subband, and generates a normalized spectrum ; ;

[0015] an addition unit that adds noise spectrum to the normalized spectrum and generates a normalized spectrum of added noise;

[0016] a second decoding unit that decodes the second encoded data using the normalized added noise spectrum, and generates a second added noise spectrum; It is

[0017] a converter that performs frequency-time conversion in relation to a coupled spectrum based on the first decoded spectrum and the second added noise spectrum. According to a decoding device of an embodiment of the present disclosure, high quality audio signals and so on can be decoded with suppressed musical noise.

[0018] It should be noted that general or specific embodiments can be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. Additional benefits and advantages of the described embodiments will become apparent from the specification and drawings. Benefits and/or advantages may be obtained individually through the various embodiments and features of the specification and drawings, which need not be provided in order to obtain one or more of these benefits and/or advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a configuration diagram of a decoding device, according to a first embodiment of the present disclosure.

[0020] Figure 2 is a configuration diagram of a decoding device, according to a second embodiment of the present disclosure.

[0021] Figure 3 is a configuration diagram of another decoding device, according to the second embodiment of the present disclosure.

[0022] Figure 4 is a configuration diagram of a decoding device, according to a third embodiment of the present disclosure.

[0023] Figure 5 is an explanatory diagram of a noise generation unit, according to the third embodiment of the present disclosure.

[0024] Figure 6 is a configuration diagram of a decoding device, according to a fourth embodiment of the present disclosure.

[0025] Figure 7 is an explanatory diagram of an amplitude adjustment unit, according to the fourth embodiment of the present disclosure.

[0026] Figure 8 is a configuration diagram of another decoding device, according to the fourth embodiment of the present disclosure.

[0027] Figure 9 is an explanatory diagram illustrating operations of an amplitude readjustment unit of another decoding device in accordance with the fourth embodiment of the present disclosure.

[0028] Figure 10 is a configuration diagram of a decoding device, in accordance with a fifth embodiment of the present disclosure.

[0029] Figure 11 is a configuration diagram of a coding device, according to the conventional technique.

[0030] Figure 12 is a configuration diagram of a decoding device, according to the conventional technique.

[0031] Figure 13 is a configuration diagram of a coding device, according to the conventional technique.

[0032] Figure 14 is a configuration diagram of a decoding device, according to a sixth embodiment of the present disclosure.

[0033] Figures 15A and 15B are explanatory diagrams illustrating the operations of a core decoded spectral amplitude adjustment unit, in accordance with the sixth embodiment of the present disclosure.

[0034] Figure 16 is a configuration diagram of a decoding device, according to a first other example of the sixth embodiment of the present disclosure.

[0035] Figure 17 is a configuration diagram of a decoding device, according to a second example of the sixth embodiment of the present disclosure.

[0036] Figure 18 is a configuration diagram of a decoding device, in accordance with a seventh of the present disclosure.

[0037] Figure 19 is a configuration diagram of an amplitude readjustment unit of the decoding device, in accordance with the seventh embodiment of the present disclosure.

DETAILED DESCRIPTION

[0038] Configurations and operations of embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that output signals from the decoding devices and input signals to the encoding devices in the present disclosure cover, in addition to cases of audio signals in the narrower sense, cases of musical signals that also have bandwidth. wider band and even cases in which these coexist.

[0039] It should be noted that, in the present specification, "input signals" is a concept that encompasses not only audio signals, but also musical signals that have wider bandwidth than audio signals, and signals in which audio signals and musical signals coexist.

[0040] "Noise spectrum" is a spectrum in which the amplitude fluctuates irregularly. If the cycle is regular but long enough to be considered as essentially irregular, this is considered to fall under irregular.

[0041] "Generating" a noise spectrum includes causing a noise spectrum to occur and also includes outputting a noise spectrum saved in a storage device or the like in advance.

[0042] Regarding "coupling" and "frequency-time conversion", the first of which is temporarily optional, and can be at the same time per course. It is sufficient that "coupling" and "frequency-time conversion" are performed as a result.

[0043] "Bit allocation information" means information representing the number of bits allocated to a predetermined band of a core decoded spectrum.

[0044] "Sparse information" is information that represents the distribution state of null spectra or non-zero spectra and a core decoded spectrum and, for example, is information that directly or indirectly indicates the proportion of non-zero spectra or null spectra such as total spectra, a predetermined band of a core decoded spectrum.

[0045] "Correlation" represents the similarity of two spectra. This also includes cases where similarity is quantitatively assessed using a correlation index.

[0046] A "terminal device" is a device that the user side uses, examples of which are cell phones, smart phones, karaoke devices, personal computers, television sets, digital voice recorders, and so on.

[0047] A "base station device" is a device that directly or indirectly transmits to a terminal device, or directly or indirectly receives signals from the terminal device. Examples include eNode B, various types of servers, access points, and so on.

[0048] A "non-zero component" (or non-zero content) is a component (or content) in which a pulse is considered to exist. Pulses that are equal to or less than a predetermined intensity in which pulses are not considered to exist are null component (or null content), not non-zero components. That is, not all pulses contained in an original normalized spectrum are necessarily non-zero components.

FIRST MODE

[0049] Figure 1 is a block diagram illustrating the configuration of a decoding device, according to a first embodiment. The decoding device 100 illustrated in Figure 1 includes a separation unit 101, a core decoding unit (first decoding unit) 102, an amplitude normalization unit 103, a noise generating unit 104, a first decoding unit addition 105, an extended band decoding unit (second decoding unit) 106, and a frequency-time converter 107. An antenna A is connected to the separation unit 101.

[0050] Antenna A receives core coded data and extended band coded data. Core coded data (first coded data) is coded data obtained by encoding a low-band spectrum of a predetermined frequency or below into input signals by a coding device. Extended band coded data is coded data obtained by encoding a high-band spectrum of a predetermined frequency or above into input signals. The extended-band coded data (second coded data) is coded based on a core-coded low-band spectrum (first coded spectrum) obtained by decoding core-coded data from a high-band spectrum of a predetermined frequency at input signals.

[0051] As a specific example, delay information which is information that indicates a particular band in which the correlation between a high-band spectrum and a core-coded low-band spectrum is the greatest, and the gain between a core-coded spectrum high-band spectrum and a core-coded low-band spectrum in a particular band. This coding will be described through a specific example in a fifth embodiment. It should be noted that the amplitude band encoded data input into the decoding device in accordance with the present embodiment is not restricted to this specific example.

[0052] The separation unit 101 separates the input core coded data and extended bandwidth coded data. The separation unit 101 outputs the core-encoded data to the core decoding unit 102, and the wide-band encoded data to the wide-band decoding unit 106.

[0053] The core decoding unit 102 decodes the core encoded data and generates a core decoded spectrum. The core decoding unit 102 outputs the core decoded spectrum to the amplitude normalization unit 103 and the time-frequency converter 107.

[0054] The amplitude normalization unit (first amplitude normalization unit) 103 normalizes the core decoded spectrum and generates a normalized spectrum. Specifically, the amplitude normalization unit 103 divides the core decoded spectrum into multiple subbands, and normalizes the spectrum of each subband by the largest amplitude value (absolute value) of the spectrum included in each subband. In this way, the highest spectrum value in each sub-band after normalization is unified between the sub-bands. Consequently, there are no longer any spectra with extremely large amplitude in the normalized spectrum.

[0055] It should be noted that dividing the core decoded spectrum into sub-bands is optional. The subband division method is also optional. For example, the bandwidth of the subbands may be uniform or non-uniform.

[0056] The amplitude normalization unit 103 outputs the normalized spectrum to the first addition unit 105 and the extended band decoding unit 106. The noise generation unit 104 generates a noise spectrum. A noise has a spectrum in which the amplitude fluctuates irregularly. A specific example is a spectrum in which positive/negative is randomly assigned to each frequency component. While positive/negative is random, an amplitude can be a constant value, or it can be a randomly generated amplitude value within a range.

[0057] The method for generating the noise spectrum may be generated as needed based on random numbers, or an arrangement in which a previously generated noise spectrum is saved in a storage device such as memory or the like, and is recalled and output . Multiple noise spectra can be called and added, odd-numbered components and even-numbered components can be combined, and polarity can be randomly assigned when adding or combining. Alternatively, a null spectrum component in the core decoded spectrum can be detected and a noise spectrum generated to fill it. Furthermore, a noise spectrum can be generated according to the characteristics of a core decoded spectrum.

[0058] It should be noted that the noise spectrum is not restricted to one, and that it can be selected and emitted from multiple noise spectra according to predetermined conditions. An example of multiple noise spectra being generated will be described in a third embodiment.

[0059] The noise generation unit 104 outputs the noise spectrum to the first addition unit 105. The first addition unit 105 adds the normalized spectrum and the noise spectrum and generates a normalized added noise spectrum. Consequently, the noise spectrum is added to at least the zero component region of the normalized spectrum. The first addition unit 105 then outputs the normalized noise spectrum added to the extended band decoding unit (second decoding unit) 106.

[0060] In the present embodiment, the noise spectrum is added to the normalized spectrum which is a spectrum after normalization in the amplitude normalization unit 103, and not to the core decoded spectrum which is the input spectrum before normalization in the amplitude normalization unit 103. amplitude normalization 103. The reason for this is as follows.

[0061] The amplitude of the added noise spectrum is often smaller than the amplitude of the core decoded spectrum, and the core decoded spectrum is sparse, so in a case of performing normalization to short sub-bands that are around of 15 samples and so on, many subbands will all be zero. Adding the noise spectrum to the kernel before normalization in such a case has the following problem.

[0062] First, a base level noise spectrum is added to the entirely zero subband. This noise spectrum alone thus becomes the largest value and is normalized to 1, so if there is no peak in the subband, the overall noise is amplified. On the other hand, in a case where there is no peak within the subband, the spectrum of the peak that originally exists is the largest value, so the noise component remains at a low level through normalization or becomes actually smaller due to normalization. Consequently, large-amplitude noise spectra are locally added to subbands that originally have entirely zero components. In contrast, the present embodiment adds the noise spectrum to the following normalization, so that amplification of the noise spectrum due to the normalization can be prevented.

[0063] The extended band decoding unit 106 decodes extended band coded data (second coded data) using the added noise normalized spectrum and normalized spectrum. Specifically, the extended bandwidth decoding unit 106 decodes the extended bandwidth encoded data and obtains delay and gain information. The extended band decoding unit 106 identifies the band of the added noise normalized spectrum to be copied into the extended band that is the high-band portion, based on the delay and normalized spectrum information, and copies a predetermined band of the spectrum. normalized noise added to the extended band. The extended band decoding unit 106 obtains the added noise extended band spectrum by multiplying the copied added noise normalized spectrum by the decoded gain.

[0064] The extended band decoding unit 106 then outputs the added noise extended band spectrum to the frequency-time converter 107. The frequency-time converter 107 couples the core decoded spectrum that produces the bandwidth portion -low and the extended-band spectrum of added noise that produces the high-band portion, thus generating a decoded spectrum. The frequency-time converter 107 then converts the decoded spectrum into time region signals by performing orthogonal transformation on the decoded spectrum, and outputs as output signals. The output signals output from the decoding device 100 pass through a DA converter, amplifier, speaker, and so on, which are omitted from the illustration, and output as audio signals, musical signals, or signals where These coexist.

[0065] Thus, according to the present embodiment, the normalized spectrum is added to the normalized spectrum, so the occurrence of musical noise can be suppressed even in a case where the normalized spectrum is sparse. That is, the present modality yields the advantages in that the homogenization and smoothing advantages that are obtained by normalizing by the highest value of a spectrum can be maintained, while the disadvantages that this normalization method has are compensated.

[0066] The noise spectrum has also been added to the normalized spectrum after normalization in the amplitude normalization unit 103 in the present embodiment, so that excessive amplification of the noise spectrum by normalization can be prevented, thus yielding the advantage it emits signals with high sound quality can be obtained.

SECOND MODE

[0067] In the following, the configuration of a decoding device 200 according to a second embodiment of the present disclosure will be described with reference to Figure 2. Blocks having the same configuration as in Figure 1 are denoted by the same numerical references. The difference between the decoding device 200 according to the present embodiment and the decoding device 100 in the first embodiment is that the decoding device 200 has a second addition unit 201. Other components are basically the same as in the first embodiment, then the description will be omitted.

[0068] The second addition unit 201 adds the noise spectrum generated by the noise generation unit 104 to the core decoded spectrum emitted from the core decoding unit 102, and generates an added noise core decoded spectrum. The second addition unit 201 then outputs the added noise core decoded spectrum to the frequency-time converter 107.

[0069] The frequency-time converter 107 couples the added noise core decoded spectrum that produces the low-band portion and the added noise extended-band spectrum that produces the high-band portion, thus generating a decoded spectrum. The frequency-time converter 107 then converts the decoded spectrum into time region signals by performing orthogonal transformation on the decoded spectrum, and outputs as output signals.

[0070] Thus, according to the present embodiment, the noise spectrum is added not only to the normalized spectrum that produces the high-band portion, but also to the core decoded spectrum that produces the low-band portion, so that the musical noise that occurs from the low-band spectrum, which is for listening, can be suppressed. Obviously, musical noise can be suppressed even in a case of generating output signals using independent core decoded spectrum.

ANOTHER EXAMPLE OF SECOND MODE

[0071] In the following, the configuration of a decoding device 210 which is another example of the second embodiment of the present disclosure will be described with reference to Figure 3. Blocks having the same configuration as Figures 1 and 2 are denoted by the same references numeric. The decoding device 210 according to the present embodiment differs from the decoding device 200 in the second embodiment in that it does not emit the noise spectrum, which is emitted to the first addition unit 105, directly from the generation unit. noise 104, but instead generates the noise spectrum by subtracting the core decoded spectrum from the noise core decoded spectrum added in the subtraction unit 202, and outputs it. Other components are basically the same as in the second embodiment, so the description will be omitted.

[0072] The noise generation unit 104 detects a null spectrum component of the core decoded spectrum, and generates a noise spectrum to fill therein. The second addition unit 201 adds the noise spectrum generated by the noise generation unit 104 to the core decoded spectrum emitted from the core decoding unit 102 and generates an added noise core decoded spectrum. The second addition unit 201 then outputs the added noise core decoded spectrum to the frequency-time converter 107 and a subtraction unit 202.

[0073] The subtraction unit 202 subtracts the core decoded spectrum from the added noise decoded spectrum, and takes this difference as the noise spectrum and outputs it to the first addition unit 105.

[0074] The reason why this processing is carried out will be described below. The processing of adding the noise spectrum to the core decoded spectrum can be performed by detecting a null spectrum component of the core decoded spectrum, and adding a noise spectrum to fill in this, as in the case of the present embodiment, in addition of a case of realizing by adding the independently generated noise spectrum to the core decoded spectrum. In this case, the normalized spectrum is imposed on the core decoded spectrum and immediately becomes integral to the core decoded spectrum, so that the noise spectrum to be emitted for the first addition unit 105 needs to be obtained by a separate method.

[0075] Accordingly, the subtraction unit 202 is provided in the present embodiment, and the core decoded spectrum is subtracted from the added noise core decoded spectrum, thereby extracting the noise spectrum. In this case, the noise generating unit 104, the second addition unit 201, and the subtraction unit 202 together produce the noise generating unit in accordance with the present disclosure.

[0076] Thus, according to the present embodiment, the noise spectrum is not added to spectrums other than a null spectrum of the spectra that produce the core decoded spectrum, so that more accurate decoding can be performed, and signals of High image quality output can be obtained.

THIRD MODE

[0077] In the following, the configuration of a decoding device 300 of a third embodiment in accordance with the present disclosure will be described with reference to Figure 4. Blocks having the same configuration as Figures 1 and 2 are denoted by the same references numeric. The difference between the decoding device 300 according to the present embodiment and the decoding device 200 according to the second embodiment is that the decoding device 300 has a noise generating unit 301 instead of the noise generating unit of noise 104. Other components are basically the same as in the second embodiment, so the description will be omitted.

[0078] The noise generation unit 301 has the ability to generate multiple different noise spectra, and can change the output noise spectra according to the characteristics of the core decoded spectra.

[0079] Figure 5 is a flowchart illustrating the operation of the noise generation unit 301. The noise generation unit 301 receives band norm information from the core decoding unit 102 (average amplitude information bandwidth), bit allocation information, and sparse information (S1). Bit allocation information is information that represents the number of bits allocated to a particular band of the core decoded spectrum. For example, the ITU-T G.722.1 and also G.719 recommendations thereof, standard information of a spectrum (average amplitude value for each band, or information in accordance therewith (scaling coefficient, band energy, etc.)) are encoded, and bit allocation is decided based on this standards information. Sparse information is information that indicates the proportion of non-zero spectra as all spectra in a particular band of the core decoded spectrum (or, conversely, can be defined as the proportion of null spectra).

[0080] Next, the noise generation unit 301 calculates a first noise amplitude adjustment coefficient C1 using bit allocation information (S2). C1 is calculated using a function F(b) of an allocated bit count b, for example. F(b) outputs a fixed value Nb when b = 0, outputs 0 when b > ns, and outputs a value between Nb and 0 when 0 < b < ns, where the closer b is to ns, the closer the value is 0. For example, this is a function like the one illustrated in the following Expression (1).

[0081] where Nb is a constant between 0 and 1.0, and is a value of a noise amplitude adjustment coefficient used in a case where there is no bit allocation, and ns is a constant, which is a count bit required for high-quality quantization of the spectrum.

[0082] The number of bits is the same number as this bit count or more, where quantization can be performed at a level where quantization error is not problematic, so that there is no need to add noise. C1 can be calculated for all bands in which bit allocation is performed, or multiple bands can be grouped, and calculated for the overall grouped bands.

[0083] Additionally, the noise generation unit 301 outputs a second noise amplitude adjustment coefficient C2 using sparse information (S3). C2 is defined as in the following Expression (2) as a proportion of null spectrum Sp in the total number of spectra of the object bands, e.g.

[0084] where Nz represents the number of null spectra, and Lb represents the total number of spectra of the object bands.

[0085] The greater the proportion of null spectra, the greater the value of Sp, which is a variable between 0 and 1.0. The following Expression (3) can be used instead of Expression (2).

[0086] Finally, the noise generation unit 301 uses the first and second noise amplitude adjustment coefficients C1 and C2 to calculate a noise amplitude LN based on the following Expression (4) (S4),

[0087] where |E(i)| is the band norm information (band average amplitude information) for band i and b and Sp represents the bit allocation count and space information with respect to band i.

[0088] Although both C1 and C2 have been described as being used in the present embodiment, LN can be obtained using only one or the other.

[0089] Thus, in the present embodiment, the noise generation unit 301 decides the amplitude of the noise spectrum to be generated, based on band norm information, bit allocation information and sparse information. Consequently, the noise spectrum can be adaptively added based on the quantization roughness, thus yielding the advantage that noise deterioration due to the addition of too much noise where fine quantization was performed can be avoided.

[0090] Although an example has been described in the present embodiment in which bit allocation information and sparse information are output from the core decoding unit 102, this is not restrictive. For example, an arrangement may be made in which the core decoded spectrum is input to the noise generating unit 301, the noise generating unit 301 analyzes the core decoded spectrum, and obtains the band norm information, bit allocation and space information on its own.

[0091] It should be noted that an arrangement has been described in which the noise generating unit 104 in the second embodiment is replaced by the noise generating unit 301, but the noise generating unit 104 according to the first embodiment can be replaced by the noise generating unit 301.

[0092] Although the present embodiment describes LN as being calculated and applied for each band i, multiple bands can be grouped and calculated and adapted, or the average LN value calculated for each i can be applied as a uniform LN for all bands .

FOURTH MODE

[0093] In the following, the configuration of a decoding device 400 in accordance with a fourth embodiment of the present disclosure will be described with reference to Figure 6. Blocks having the same configuration as Figures 1, 2, and 4 are denoted with the same numerical references. The difference between the decoding device 400 according to the present embodiment and the decoding device 200 according to the second embodiment is that the decoding device 400 according to the present embodiment includes a amplitude normalization unit. noise (second amplitude normalization unit) 401 and an amplitude adjustment unit 402. Other components are basically the same as in the second embodiment, so the description will be omitted.

[0094] The noise amplitude normalization unit 401 normalizes the normalized spectrum generated in the noise generation unit 104 and generates a normalized noise spectrum. The operations of the noise amplitude normalization unit 401 are the same as the operations of the amplitude normalization unit 103, but may be different. For example, in a case where processing is performed in the amplitude normalization unit 103 to set the spectral components below a threshold value to zero in order to make sparse, that threshold value may be set to a threshold value low in the noise amplitude normalization unit 401 to make the degree of scarcity as small as the noise spectrum.

[0095] The noise amplitude normalization unit 401 then outputs the normalized noise spectrum to the amplitude adjustment unit 402. The amplitude adjustment unit 402 adjusts the amplitude of the normalized noise spectrum that the normalization unit of noise amplitude 401 emitted. The normalized noise spectrum of which the amplitude has been adjusted is then output to the first addition unit 105. The details of operations of the amplitude adjustment unit 402 are described later.

[0096] The first addition unit 105 adds the normalized spectrum and the normalized noise spectrum of which the amplitude was adjusted, thereby generating a normalized added noise spectrum. The first addition unit 105 then outputs the normalized noise spectrum added to the extended band decoding unit 106.

[0097] Figure 7 is a flowchart illustrating the operations of the amplitude adjustment unit 402. The amplitude adjustment unit 402 receives the core decoded spectrum X(j), band norm information |E(i) |, bit allocation information and sparse information, output from the core decoding unit 102 (S1). The amplitude adjustment unit 402 then analyzes the core decoded spectrum band |E(i)|, and obtains the difference between an average amplitude |XE(i)| calculated from the core decoded spectrum X(j) and the band norm information |E(i)| (band norm information). The ratio between the obtained error and the decoded norm (band norm information) is used to calculate a noise amplitude adjustment coefficient according to the following Expression (5) (S2).

[0098] where i represents the band node, j represents the spectrum node included in band i and α is an adjustment coefficient that takes a value between 0 and 1.0.

[0099] The amplitude adjustment unit 402 then calculates the noise amplitude adjustment coefficient C1 according to Expression (1), in the same manner as the third embodiment, using the bit allocation information (S3 ).

[00100] The amplitude adjustment unit 402 further calculates the noise amplitude adjustment coefficient C2 according to Expression (2), in the same way as the third embodiment, using the sparse information of the normalized spectrum (S4).

[00101] Finally, the amplitude adjustment unit 402 calculates the LN noise amplitude by the following Expression (6) based on the results of (S2), (S3), and (S4), and adjusts the amplitude of the normalized spectrum of noise (S5).

[00102] Although all of C0, C1 and C2 are used in the present embodiment, LN can be obtained using at least one. Also, although sparse information from the normalized spectrum is used as the sparse information of obtaining C2 in the present embodiment, the sparse information obtained from the core decoded spectrum can be used, or both can be used together.

[00103] Additionally, an arrangement can be made, in which the amplitude ratio of the core decoded spectrum and the noise spectrum added to the decoded spectrum is a noise amplitude adjustment coefficient C3, and the noise amplitude LN is obtained from the following Expression (7) based on C3. Obviously, C3 can be obtained independently, and LN can be obtained using at least one of C0, C1, C2 and C3.

[00104] It should be noted that LN is preferably smoothed between frames, for interframe noise level stability. An expression such as LN(f) = μ x LN (f - 1) + (1 - μ) x LN(f) can be used for smoothing. Here, LN(f) is LN in the frame at f, and μ is a smoothing coefficient. μ takes on a value between 0 and 1.

[00105] According to the present embodiment, the core decoded spectrum is normalized in the amplitude normalization unit 103, while the noise spectrum is normalized in the noise amplitude normalization unit 401, so that spectra having a nature common are rendered (e.g., the amplitude of the spectra is generally uniform) by the core decoded spectrum and noise spectrum passing through the corresponding paths, so that both signals can be made as signals that can be handled at the same stage.

[00106] Also according to the present embodiment, the noise spectrum added to the high-band portion (normalized noise spectrum) is output through the noise amplitude normalization unit 401 and amplitude adjustment unit 402, while the Noise spectrum added to the low-band portion does not go through the noise amplitude normalization unit 401 nor the amplitude adjustment unit 402, so the characteristics are made to differ between the noise spectrum added to the high-band portion. (normalized noise spectrum) and the noise spectrum added to the low-band portion. Consequently, the correlation can be reduced between the low-band portion and the high-band portion, whereby a noise spectrum with more random characteristics can be generated.

[00107] According to the present embodiment, the normalized noise spectrum has the amplitude adjusted in the amplitude adjustment unit 402, thereby yielding the advantage that deterioration due to the addition of too much noise can be avoided.

[00108] Although an example has been described in the present embodiment in which bit allocation information and sparse information are output from the core decoding unit 102, this is not restrictive. For example, an arrangement may be made in which the core decoded spectrum is input into the amplitude adjustment unit 402, the amplitude adjustment unit 402 analyzes the core decoded spectrum and obtains the band norm information, allocation information bit bit and space information on its own.

[00109] It should be noted that an arrangement has been described in which the noise amplitude normalization unit 401 and the amplitude adjustment unit 402 are added to the configuration of the second modality, they can be added to the first modality or the third modality .

ANOTHER EXAMPLE OF THE FOURTH MODE

[00110] In the following, the configuration of another decoding device 410 according to the fourth embodiment of the present disclosure will be described with reference to Figure 8. Blocks having the same configuration as in Figure 6 are denoted by the same numerical references . The difference between the decoding device 410 and the decoding device 400 according to the fourth embodiment is that the decoding device 410 according to the present embodiment has an amplitude readjustment unit 403. Other components are basically the same as in fourth modality, then the description will be omitted.

[00111] The amplitude readjustment unit 403 generates an extended band using the core decoded spectrum to which the noise is added and then readjusts the amplitude of the added noise component. This readjustment can be performed as illustrated in Figure 9. In Figure 9, (a) represents the normalized spectrum emitted from the amplitude normalization unit 103, and (b) represents the normalized spectrum of added noise emitted from the first unit of addition 105. As indicated by (c), the normalized spectrum of added noise is switched to an extended band based on delay information, thereby generating an extended band spectrum multiplying by the gain. In (b), only band i which is the lowest band in the extended band is illustrated. E(i), in this drawing, represents the band norm information (band energy) of band i, and the portion surrounded by the dotted line (d) is the normalized spectrum of added noise specified by delay information (specified by the extended bandwidth decoding unit 106). A matched extended band (the i band, here) is multiplied by a suitable copied gain G. The portion surrounded by the dotted line (e) is the extended band. The amplitude readjustment of the added noise component is performed as follows.

[00112] First, a threshold value Th is decided. Th is a value that is half the largest amplitude of the normalized spectrum, for example. In a case where the amplitude of the normalized spectrum is restricted to a particular amplitude or above, the smallest amplitude value of the normalized spectrum may be Th. Alternatively, an average amplitude value of normalized spectra that have a value may be used. Again, an average amplitude value of the added noise spectra can be used. Additionally, these values can be values multiplied by a constant and adjusted.

[00113] Th and its amplitude in a case where the smallest amplitude of the normalized spectrum is used as Th are illustrated in (b) by a dashed line of two points. Components that have an amplitude smaller than this Th are defined as noise components. Next, the gain G obtained by decoding the extended band encoded data is multiplied by Th and G^Th is calculated.

[00114] Next, with respect to the i-band spectrum generated by band extension, a spectrum that has an amplitude smaller than the threshold value G^Th is selected and defined as the noise component, and the noise component energy of band i is calculated (defined as EN(i)).

[00115] Next, a SEN(i), which is EN(i) smoothed in the axial time direction by the following Expression (8) is obtained.

[00116] where α represents a smoothing coefficient that is a constant from 0 to 1 and close to 1, and pSEN(i) represents SEN(i) from another previous frame.

[00117] The noise component is then multiplied by ^SEN(i)/ ^EN(i), so that the energy of the noise spectrum of band i is SEN(i).

[00118] In the same way, amplitude readjustment is performed on the noise components of the bands of other extended bands. Additionally, in a case where there is a variance in the SEN(i) bands of other extended bands, amplitude readjustment to eliminate that variance can be performed. Specifically, an average AEN value of EN(i) across all bands of the extended band is obtained, the noise component of each band is multiplied by AEN/EN(i) so that EN(i) of all bands is equal to AEN and after that interframe smoothing processing is performed.

[00119] It should be noted that the order in which the noise component energy alignment processing in each band and the interframe smoothing processing are optional, and that only one or the other can be performed.

FIFTH MODE

[00120] The modalities of the decoding devices were described from the first to the fourth modality. The present disclosure is also applicable to encoding devices. Further, the configuration of a coding device 500 in accordance with a fifth embodiment of the present disclosure will be described with reference to Figure 10.

[00121] Figure 10 is a block diagram illustrating a coding device according to a fifth embodiment. A coding device 500 illustrated in Figure 10 is configured to include a time-frequency converter 501, a core coding unit 502, an amplitude normalization unit 503, a noise generation unit 504, a normalization unit of noise amplitude 505, an amplitude adjustment unit 506, a first addition unit 507, a band search unit 508, a gain calculation unit 509, an extended band coding unit 510, a multiplexer 511, and a delay search position candidate storage unit 512. An antenna A is connected to the multiplexer 511.

[00122] The time-frequency converter 501 converts input signals, which are time-region audio signals and so on, into region-frequency signals, and outputs the obtained input signal spectrum to the coding unit of core 502, band search unit 508 and gain calculation unit 509.

[00123] The core coding unit 502 encodes the low-band spectrum of the input signal spectrum and generates core coded data. An example of encoding is CELP encoding and transformation encoding. The core coding unit 502 outputs the core coded data to the multiplexer 511. The core coding unit 502 decodes the core coded data and outputs the obtained core decoded spectrum to the amplitude normalization unit 503.

[00124] The operations of the amplitude normalization unit 503, the noise generation unit 504, and the noise amplitude normalization unit 505, and the amplitude adjustment unit 506 are the same as those described in the third and fourth embodiments, then the description will be omitted.

[00125] The delay search position candidate storage unit 512 stores positions (frequencies) of components in which the amplitude of the normalized spectrum is non-zero, as candidate positions for band search. The delay search position candidate storage unit 512 then outputs the stored candidate position information to the bandwidth search unit 508.

[00126] The first addition unit 507 adds the normalized spectrum and the normalized noise spectrum of which the amplitude was adjusted, and generates a normalized added noise spectrum. The first addition unit 507 then outputs the normalized noise spectrum added to the band search unit 508 and the gain calculation unit 509.

[00127] The band search unit 508, the gain calculation unit 509 and the extended band coding unit 510 perform high-band spectrum coding processing of the input signal spectrum.

[00128] The band search unit 508 searches for a particular band in which the correlation between the high-band spectrum and the normalized spectrum of added noise is the greatest in the input signal spectrum. The search is performed by selecting candidates from the input of candidate positions from the delay search position candidate storage unit 512 in which the correlation is the largest. The band search unit 508 then outputs the delay information, which is information indicating a particular search band, to the gain calculation unit 509 and the extended band coding unit 510.

[00129] The gain calculation unit 509 calculates the gain between the high-band spectrum in a particular band and the normalized spectrum of added noise, and outputs it to the extended band coding unit 510.

[00130] The extended bandwidth coding unit 510 encodes the delay and gain information, and generates extended bandwidth encoded data. The wideband coding unit 510 then outputs the wideband coded data to the multiplexer 511. The multiplexer 511 multiplexes the core coded data and the wideband coded data, and transmits the same via antenna A.

[00131] Thus, according to the present embodiment, the search (delay search, similarity search) of a high-band spectrum is performed using an added noise spectrum and component, so that the matching accuracy spectrum shape can be improved.

[00132] It should be noted that while Figure 10 illustrating the present embodiment shows a configuration in which the third modality and the fourth modality, which are modalities of a decoding device, have been combined, in which the configuration may correspond to the first, second, third or fourth modalities. Additionally, the configuration may correspond to a sixth embodiment described later.

SIXTH MODE

[00133] In the following, the configuration of a decoding device 600 according to a sixth embodiment of the present disclosure will be described with reference to Figure 14. Blocks having the same configuration as those of the decoding device 400 in Figure 6 which illustrate the fourth modality are denoted by the same numerical references. The difference between the decoding device 600 according to the present embodiment and the decoding device 400 is that the anomaly detection processing request signal of decoding device 600 includes a threshold value calculation unit 601 and a core decoded spectrum amplitude adjustment unit 602. Additionally, the amplitude adjustment unit 402 was replaced by a noise spectrum amplitude adjustment unit (second amplitude adjustment unit) 603.

[00134] The decoding device 600 according to the present embodiment additionally has a noise generation and addition unit 604 and the subtraction unit 202 instead of the noise generation unit 104; This is a configuration for generating and adding the noise spectrum to fill in the null spectrum component of the core decoded spectrum described in the other example of the second embodiment. Other components are basically the same as in the fourth embodiment, so the description will be omitted.

[00135] The threshold value calculation unit 601 uses sparse information from the normalized spectrum to calculate the threshold value Th of the intensity spectrum, to distinguish between the noise component and the non-noise component. A specific calculation method will be described later. It should be noted that sparse information from the kernel decoded spectrum can be used instead of sparse information from the normalized spectrum.

[00136] The threshold value calculation unit 601 then outputs the threshold value to the core decoded spectrum amplitude adjustment unit 602 and the noise spectrum amplitude adjustment unit 603.

[00137] The core decoded spectrum amplitude adjustment unit 602 adjusts the amplitude of the normalized spectrum so that the non-zero component of the normalized spectrum is greater than the threshold value. Specifically, the overall normalized spectrum is raised by providing each spectrum with a certain offset, or amplifying by a certain rate, such that the smallest value of the non-zero component in the normalized spectrum is greater than the threshold value, as illustrated in Figure 15(a).

[00138] An example of an amplification method is scaling by Y = aX + Th in which the amplitude after amplification is Y, before amplification is X, and the threshold value is Th (it should be noted that a = (Xmax - Th)/Xmax, where Xmax is the largest value that X can assume).

[00139] Alternatively, the smallest of a spectrum that has a certain intensity or greater (called the "zero threshold value") can be made to be greater than the threshold value, as illustrated in Figure 15B. For example, in a case where the range of a normalized spectrum is normalized from 0 to 10, the zeroing threshold value is set to 0.95, and the lowest of a spectrum that is 0.95 or higher can be made larger than the threshold value Th. In this case, spectra smaller than 0.95 are set to zero. That is, in this case, spectra of the zeroing threshold value or higher are non-zero components, and spectra lower than the zeroing threshold value are null components.

[00140] While fixed values can be used as the zeroing threshold value as described above, a variable value that varies according to other variables can be used as the zeroing threshold value. For example, the zeroing threshold value = threshold value Th x α (where α is a constant, α = 1/4, for example) can be used. Also, an upper limit value or lower limit value can be used together as the zeroing threshold value. For example, in a case where the zeroing threshold value is 0.9 or lower, 0.9 can be used as the zeroing threshold value. The normalized spectrum of which the amplitude was adjusted is then output to the first addition unit 105.

[00141] The noise spectrum amplitude adjustment unit 603 adjusts the amplitude of the normalized noise spectrum so that the largest value of the normalized noise spectrum is equal to or less than the threshold value. Specifically, in a case where the largest value of the normalized noise spectrum is less than the threshold value, the largest value of the normalized spectrum is set to the threshold value or smaller by giving each spectrum a certain shift, or amplifying for a certain fee. In a case where the highest value of the normalized noise spectrum is greater than the threshold value, a negative shift is applied, which is equivalent to saying that a subtraction (cut), or amplification by a negative rate, i.e., attenuation, is performed. This adjustment is synonymous with normalizing the normalized noise spectrum by a threshold value.

[00142] The normalized noise spectrum of which the amplitude was adjusted is output to the first addition unit 105. The first addition unit 105 adds the normalized spectrum in which the amplitude was adjusted and the normalized noise spectrum in which the amplitude was adjusted. adjusted, and outputs the same to the extended band decoding unit 106 as a normalized spectrum of added noise.

[00143] Below is a method to obtain the threshold value. The threshold value serves to separate between the noise component and the non-noise component. The threshold value Th can be obtained by the following Expression (9), using the scarcity Sp in Expression (2). The a is a constant, and is set to 4, for example, in the present embodiment.

[00144] It should be noted that the threshold value Th can be obtained using the following Expression (10) instead of Expression (9) using Nz.

[00145] where Np represents the number of spectra that are not zero.

[00146] Also, an upper limit or lower limit can be used together with these as the threshold value Th. That is, according to Expression (9), the greater the scarcity Sp, that is, the more discrete the flow of pulse with more null component, the lower is the noise property and lower is the threshold value Th. In contrast, the smaller the Sp scarcity, i.e., the denser the pulse flow with less null component, the higher is the noise property and higher is the threshold value Th.

[00147] When the shortage Sp is large (the threshold value Th is low), the noise spectrum amplitude adjusted in the noise spectrum amplitude adjustment unit 603 is suppressed to a low level, and a noise spectrum with a small amplitude is added in the addition unit 105. That is, the noise property of the normalized spectrum signals is low, so the amplitude of the added noise spectrum is small to maintain this property.

[00148] In contrast, when the sparseness Sp is small (the threshold value Th is high), the noise spectrum amplitude adjusted in the noise spectrum amplitude adjustment unit 603 is large, and a noise spectrum with a Large amplitude is added in addition unit 105. That is, the noise property of the normalized spectrum signals is high, so the amplitude of the added noise spectrum is large to maintain this property.

[00149] It should be noted that a threshold value was used in common in the present embodiment between the core decoded spectrum amplitude adjustment unit (first amplitude adjustment unit) 602 and the noise spectrum amplitude adjustment unit (second amplitude adjustment unit) 603. However, the core decoded spectrum amplitude adjustment unit 602 and the noise spectrum amplitude adjustment unit 603 may use different threshold values. This is due to the fact that, while the threshold value serves to separate the noise component and non-noise component, the noise property that the low-band spectrum originally included in the normalized spectrum has, and the noise property that The generated noise spectrum may have different properties, and using independent patterns for each rather than using the same pattern for both can improve image quality in such cases. For example, setting the threshold used with the core decoded spectrum amplitude adjustment unit 602 to be higher than the threshold used with the noise spectrum amplitude adjustment unit 603 enables the component contained in the normalized spectrum, which is the original signal, be more accentuated.

[00150] Although only sparsity was used in Expression (9) to obtain the threshold value, band norm information and bit allocation information can be combined, or used independently, as in the third and fourth embodiments. modality. For example, using bit allocation information together is conceivable in the following case.

[00151] Increasing the bit allocation allows the number of pulses to be increased, so lower amplitude pulses are also encoded, and the number of quantized pulses increases. As a result, shortages decrease. That is, scarcity depends not only on the characteristics of the signals to be encoded, but also on the allocated bit count. Consequently, in a case where the number of allocated bits changes greatly, the relationship between scarcity and the threshold value can be adjusted to correct the influence due to the change in bit allocation.

[00152] While the configuration in the other example of the second embodiment was used for the noise generating and adding unit 604 in the present embodiment, the noise generating unit 104 of the first embodiment, the noise generating unit 104 and the second unit addition unit 201 of the second embodiment, and the noise generating unit 301 and the second addition unit 201 of the third embodiment may be used instead.

[00153] According to the above-described decoding device 600, the amplitude of both the normalized spectrum and the normalized noise spectrum can be adjusted, with respect to the amplitude of the normalized spectrum and the amplitude of the normalized noise spectrum, and these can be adjusted synchronously, so that optimal noise can be added according to the normalized spectrum property, and as a result, the sound quality of output signals can be improved.

[00154] More specifically, the noise property of the normalized spectrum is enhanced, and a spectrum suitable for expressing a high-band frequency spectrum can be created, so that the sound quality of the signals output from the decoding device based on the bandwidth extension model can be improved.

FIRST ANOTHER EXAMPLE OF THE SIXTH MODE

[00155] In the following, the configuration of a decoding device 610 according to a first another example of the sixth embodiment of the present disclosure will be described with reference to Figure 16. Blocks having the same configuration as in Figure 14 are denoted by the same numeric references. The difference between the decoding device 610 and the decoding device 600 according to the present embodiment relates primarily to the operations of the threshold value calculation unit 601.

[00156] The threshold value calculation unit 601 of the decoding device 610 according to the present embodiment takes the input sparse information as the sparse information of the core decoded spectrum, obtains the threshold value Th in the threshold value calculation unit threshold value 601 using Expression (9) and Expression (10) based on this sparse information, and the zero-down threshold value is also obtained using this threshold value Th, using a computation such as the value zero threshold value = threshold value Th x α, for example.

[00157] The threshold value calculation unit 601 then outputs the threshold value Th to the core decoded spectrum amplitude adjustment unit 602 and the noise spectrum amplitude adjustment unit 603, and outputs the value zero reduction threshold for the amplitude normalization unit (first amplitude normalization unit) 103.

[00158] The amplitude normalization unit 103 normalizes the core decoded spectrum, and sets spectra less than the zeroing threshold value, or equal to or less than the zeroing threshold value, to zero (performs reduction to zero). zero), and outputs them.

[00159] Although the present embodiment has been described with the zeroing block as the amplitude normalization unit 103, but a separate zeroing block may be provided upstream or downstream of the amplitude normalization unit 103, or this may be performed in the core decoded spectrum amplitude adjustment unit 602. In this case, the output destination of the zeroing threshold value may be the block that performs this zeroing.

ACCORDING TO ANOTHER EXAMPLE OF THE SIXTH MODE

[00160] In the following, the configuration of a decoding device 620 according to a second another example of the sixth embodiment of the present disclosure will be described with reference to Figure 17. Blocks having the same configuration as in Figure 16 are denoted by the same numeric references. The difference between the decoding device 620 according to the present embodiment and the decoding device 600 or decoding device 610 is that a noise generating and adding unit 605 has been provided.

[00161] In the decoding device 600 and the decoding device 610, the noise generation and addition unit 604 generates and adds the noise spectrum to fill in the null spectrum component of the core decoded spectrum. That is, the configuration adds noise only to positions corresponding to the null spectrum component of the core decoded spectrum, so that it ultimately has no noise addition to the spectral portions subsequently cleared by the amplitude normalization unit 103 or the like. .

[00162] Accordingly, the noise generation and addition unit 605 is provided in the present embodiment to add noise to the spectral portions that have been cleared. The noise generation and addition unit 605 detects a null spectrum in the normalized spectrum of added noise emitted from the first addition unit 105 and generates and adds random noise to fill in this. The largest value of the amplitude to be added is controlled as described above, so that the threshold value generated by the threshold value calculation unit 601 can be output to the noise generation and addition unit 605, this threshold value is used to decide the largest amplitude value. An upper limit value can be used together, separately from the threshold value.

[00163] It should be noted that instead of detecting zero spectra in the added noise normalized spectrum, an arrangement can be made in which zeroed spectra information is received from blocks that perform zero reduction, e.g. the unit of amplitude normalization 103, in which noise is added to the positions of zeroed spectra.

[00164] Also, although the description has been made in the present embodiment in which the noise generation and addition unit 605 is provided downstream of the first addition unit 105, an arrangement can be made in which the noise generation and addition unit noise 605 is provided between the noise spectrum amplitude adjustment unit 603 and the first addition unit 105, or between the noise amplitude normalization unit 401 and the noise spectrum amplitude adjustment unit 603. In this case , information about the zeroed spectra is received from the block that performed the reduction to zero, and noise is added to the positions of the zeroed spectra.

SEVENTH MODE

[00165] Next, the configuration of a decoding device 700 according to a seventh embodiment of the present disclosure will be described with reference to Figure 18. The decoding device 700 according to the present embodiment is the decoding device 620 according to the second other example of the sixth embodiment, in which the amplitude readjustment unit 403 described in the other example of the fourth embodiment has been added. Accordingly, the threshold value Th calculated in the threshold value calculation unit 601 is also output to the amplitude readjustment unit 403. Other settings are the same as the second other example of the sixth embodiment, so the description will be omitted.

[00166] The normalized spectrum of added noise generated in the extended band decoding unit 106 is output to the amplitude readjustment unit 403. The operations of the amplitude readjustment unit 403 are basically the same as those in the other example of the fourth embodiment , then the description will be made below primarily with respect to the second other example of the sixth embodiment. The amplitude readjustment unit 403 will be described in blocks, according to each function. The amplitude readjustment unit 403 is made of a noise energy calculation unit 701, an interframe smoothing unit 702, and an amplitude adjustment unit 703, as illustrated in Figure 19.

[00167] The noise energy calculation unit 701 calculates the energy of the added noise spectrum for each sub-band. The added noise spectrum can be detected and separated using the threshold value Th according to the sixth embodiment. The extended band decoding unit 106 multiplies the normalized spectrum of added noise identified by delay information decoded from the extended band encoded data, by the gain decoded from the same extended band encoded data, thereby generating a spectrum of extended band of added noise. Consequently, the value obtained by multiplying the threshold value Th in the sixth modality by the gain is the threshold value for determining the noise component in the extended band spectrum of added noise. That is, the threshold value obtained by the threshold value calculation unit 601 is multiplied by the gain to obtain the noise component determination threshold value, and components less than (equal to or less than) the determination threshold value of noise component are determined as noise component in each sub-band. The gain is encoded for each sub-band, so that the noise component determination threshold value is calculated for each sub-band.

[00168] The noise spectrum energy of each sub-band is then output to the interframe smoothing unit 702. The interframe smoothing unit 702 uses the noise spectrum energy for each sub-band that was received to perform smoothing processing, so that the change in energy of noise spectra is smooth between sub-bands. Smoothing processing can be performed using known interframe smoothing processing.

[00169] For example, interframe smoothing processing can be performed according to the following Expression (11)

[00170] where Esc represents the energy of the noise spectrum after smoothing processing, Ec represents the energy of the noise spectrum before smoothing processing, EScp represents the energy of the noise spectrum after smoothing processing in the previous frame, and α represents a smoothing coefficient (0 < α < 1). The closer the α value is to 0, the stronger the smoothing. About 0.15 is adequate.

[00171] In the case where signals from the current frame have been suddenly attenuated compared to signals from the previous frame, applying strong smoothing will result in a high level of noise being maintained in an area where signal levels should be lower, which is problematic. In order to deal with such a situation, in a case where the sub-band energy information that is encoded separately is smaller than the sub-band energy of the noise spectrum after smoothing processing in the previous frame (i.e. EScp), the value of α is brought closer to 1 to make the smoothing processing weaker. For example, in a case where the EScp is less than 80% of the decoded subband energy in the current frame, α is set to 0.15 to perform strong smoothing processing, while in a case where the EScp is 80 % of the decoded subband energy in the current frame or greater (i.e., the decoded subband energy in the current frame is not large enough compared to the smoothed noise spectrum subband energy in the previous frame), α is set to 0.8 to perform weak smoothing processing.

[00172] The amplitude adjustment unit 703 readjusts the amplitude of the noise portion of the input added noise extended band spectrum using the ESc calculated by the interframe smoothing unit 702. The readjustment method is the same as described in the other example of the fourth modality. That is, (^ESc/^Ec) is multiplied as a scaling coefficient, as described in the other example of the fourth embodiment.

[00173] In the case where the change in energy due to scaling is large, there is a possibility that the energy of the overall decoded signals that include another other than the noise component has deviated noticeably from the original magnitude. In this case, having a scaling coefficient of \(\ESc/\Ec) enables the change in the scaling coefficient to be suppressed non-linearly, so that adverse effects on the energy of the overall decoded signals due to scaling can be reduced.

[00174] According to the present embodiment described above, the noise component of high-band signals composed of band extension processing is smoothed in the temporal direction, and processing to suppress the change in amplitude change is performed, so that the level of the noise component of the decoded signals is stabilized, and the image quality for listening can be improved. Using this in combination with the added noise normalized spectrum generation method in accordance with the present embodiment with the need to separate the coding and transmission of noise component determination information, the addition and stabilization of noise component effective noise can be realized.

IN CONCLUSION

[00175] The decoding device and the encoding device, according to the present disclosure, have been described with reference to the first to the seventh embodiment. The decoding device and the encoding device according to the present disclosure are concepts that may be in the form of half-complete products or at the level of parts, such as system boards or semiconductor devices, or at the level of having the form of complete products such as terminal devices or base station devices. In a case where the decoding device and encoding device according to the present disclosure are in the form of half-complete products or at the level of parts, they can be made as at the level d to be in the form of complete products by combining with an antenna, DA/AD converter, amplifier, speaker, microphone and so on.

[00176] The block diagrams of Figures 1 to 8, Figure 10, Figure 14, and Figures 16 to 19 represent dedicated design hardware configurations and operations (methods), and also include cases in which programs that perform the operations (method) of predefined development are installed on the general hardware and executed by a processor. Examples of electronic calculators that serve as general-purpose hardware include personal computers, various types of mobile information terminals such as smart phones, cell phones, and the like.

[00177] Dedicated design hardware is not restricted to the complete product level such as cell phones and landline telephones (consumer electronics), and includes those in the form of half-complete products or at the part level such as system boards, semiconductor devices and so on.

[00178] The decoding device and encoding device according to the present disclosure is applicable to devices with respect to recording, transmitting and reproducing audio signals and musical signals.

Claims (18)

1. Decoding device (600, 610, 620, 700), characterized in that it comprises a separation unit (101) that separates first encoded data, where a spectrum including a low-band spectrum of audio signals has been encoded , and second coded data, where a high-band spectrum of a band higher than the low-band spectrum was coded, based on the first coded data; a first decoding unit (102) that decodes the first encoded data and generates a first decoded spectrum; a first amplitude normalizer (103) that divides the amplitude of the first decoded spectrum into a plurality of subbands, normalizes the spectrum of each subband by the largest value of the amplitude of the first decoded spectrum within each subband, and generates a spectrum normalized; a first adjustment unit configured to adjust an amplitude of a normalized noise spectrum such that a greater value of the normalized noise spectrum is equal to or less than a threshold value, or configured to adjust an amplitude of a normalized noise spectrum using scaling a maximum amplitude of the normalized noise spectrum using a threshold; an amplitude adjustment unit (603) configured to adjust an amplitude of the normalized spectrum relative to a non-zero content of the normalized spectrum by removing non-zero content less than a threshold value, or configured to adjust the first decoded spectrum or the spectrum normalized by removing a low amplitude using threshold; an addition unit (105) that adds an adjusted noise spectrum to an adjusted normalized spectrum or an adjusted decoded spectrum and generates a normalized added noise spectrum; a second decoding unit (106) that decodes the second encoded data using the normalized added noise spectrum and generates a second added noise spectrum; and a converter (107) that performs frequency-time conversion with respect to a spectrum generated by concatenating a spectrum based on the first decoded spectrum and a spectrum based on the second added noise spectrum. 2. Decoding device (600, 610, 620, 700) according to claim 1, characterized by the fact that the converter (107) performs frequency-time conversion in relation to a spectrum generated by concatenation of a spectrum based on a first added noise decoded spectrum obtained by adding the noise spectrum to the first decoded spectrum, and the second added noise spectrum. 3. Decoding device (600, 610, 620, 700) according to claim 1, characterized in that the amplitude of the noise spectrum is based on at least one bit allocation information of the first decoded spectrum, and information sparse indicating a degree of sparsity of the first decoded spectrum. 4. Decoding device (600, 610, 620, 700) according to claim 1, characterized in that the amplitude adjustment unit (603) resets the non-zero content of the normalized spectrum based on a threshold value of zeroing to obtain a null content separate from the non-zero content of the normalized spectrum, the zeroing threshold value being calculated using the threshold value. 5. Decoding device (600, 610, 620, 700) according to claim 4, characterized in that it further comprises a noise addition unit (605) that adds the noise spectrum to a position of the null content that was reset. 6. Decoding device (600, 610, 620, 700) according to claim 1, characterized in that it further comprises an amplitude readjustment unit (403) that applies a smoothing process to a noise component of the second added noise spectrum. 7. Decoding device (600, 610, 620, 700) according to claim 6, characterized in that the amplitude readjustment unit (403) smoothes an energy exchange between frames of the second added noise spectrum using a energy of the noise component of the second added noise spectrum calculated based on a threshold value, and adjusts an amplitude of the noise component of the second added noise spectrum using a scaling coefficient that represents a relationship between an energy of the noise component of the noise component of the second added noise spectrum and an energy of the noise component of the second added noise spectrum to be obtained after smoothing. 8. Decoding method, characterized by the fact that it comprises separating first encoded data, where a spectrum including a low-band spectrum of audio signals was encoded, and second encoded data, where a high-band spectrum of a band upper than low-band spectrum was encoded, based on the first encoded data; decoding the first encoded data and generating a first decoded spectrum; dividing the amplitude of the first decoded spectrum into a plurality of subbands, normalizing the spectrum of each subband by the largest value of the amplitude of the first decoded spectrum within each subband, and generating a normalized spectrum; adjusting an amplitude of a normalized noise spectrum so that a maximum value of the normalized noise spectrum is equal to or less than a threshold value, or adjusting an amplitude of a normalized noise spectrum by scaling a maximum amplitude of the noise spectrum normalized using a threshold; adjusting an amplitude of the normalized spectrum with respect to a non-zero content of the normalized spectrum by removing the non-zero content less than a threshold value, or adjusting the first decoded spectrum or the normalized spectrum by removing a low amplitude using the threshold; adding an adjusted noise spectrum to an adjusted normalized spectrum or an adjusted decoded spectrum and generating an added noise normalized spectrum; decoding the second encoded data using the normalized added noise spectrum, and generating a second added noise spectrum; and performing frequency-time conversion with respect to a spectrum generated by concatenating a spectrum based on the first decoded spectrum and a spectrum based on the second added noise spectrum. 9. Decoding method according to claim 8, characterized in that the frequency-time conversion is carried out with respect to a spectrum generated by concatenating a spectrum based on a first decoded spectrum of added noise obtained by adding the spectrum of noise to the first decoded spectrum, and the second noise spectrum added. 10. Decoding method according to claim 8, characterized by the fact that the amplitude of the noise spectrum is based on at least one of the bit allocation information of the first decoded spectrum, and sparse information indicating a degree of sparsity of the first decoded spectrum. 11. Decoding method according to claim 8, characterized by the fact that a null content of the normalized spectrum is obtained by zeroing based on a zero threshold value to separate the null content and a non-zero content of the spectrum normalized, the zero-down threshold value being calculated using the threshold value. 12. Decoding method according to claim 11, characterized by the fact that it further comprises adding the normalized noise spectrum adjusted to a position of the null content that has been zeroed. 13. Decoding method according to claim 8, characterized by the fact that it further comprises applying a smoothing process to a noise component of the second added noise spectrum. 14. The decoding method of claim 13, wherein an energy exchange is smoothed between frames of the second added noise spectrum using an energy of the noise component of the second added noise spectrum calculated based on a value limit, and an amplitude of the noise component of the second added noise spectrum is adjusted using a scaling coefficient that represents a ratio between an energy of the noise component of the noise component of the second added noise spectrum and an energy of the noise component of the second added noise spectrum to be obtained after smoothing. 15. Non-transitory storage medium, characterized by the fact that it has a method, as defined in claim 8. 16. Decoding device, characterized in that it comprises a separation unit (101) that separates first encoded data, where a spectrum including a low-band spectrum of audio signals has been encoded, and second encoded data, where a spectrum high-band spectrum from a band higher than the low-band spectrum was encoded, based on the first encoded data; a first decoding unit (102) that decodes the first encoded data and generates a first decoded spectrum; a first amplitude normalizer (103) that divides the amplitude of the first decoded spectrum into a plurality of subbands, normalizes the spectrum of each subband by the largest value of the amplitude of the first decoded spectrum within each subband, and generates a spectrum normalized; an addition unit (105) that adds a noise spectrum to the normalized spectrum and generates a normalized added noise spectrum; a second decoding unit (106) that decodes the second encoded data using the normalized added noise spectrum and generates a second added noise spectrum; an amplitude readjustment unit (403) that applies a smoothing process to a noise component of the second added noise spectrum, wherein the amplitude readjustment unit (403) is configured to smooth an energy exchange between frames of the second added noise spectrum using an energy of the noise component of the second added noise spectrum calculated based on a threshold value, and to adjust an amplitude of the noise component of the second added noise spectrum using a scaling coefficient representing a relationship between a noise component energy of the noise component of the second added noise spectrum and a noise component energy of the second added noise spectrum to be obtained after smoothing; and a converter (107) that performs frequency-time conversion with respect to a spectrum generated by concatenating a spectrum based on the first decoded spectrum and a spectrum based on the second added noise spectrum. 17. Coding method, characterized in that it comprises separating first coded data, where a spectrum including a low-band spectrum of audio signals was encoded, and second coded data, where a high-band spectrum of a higher band the low-band spectrum was encoded, based on the first encoded data; decoding the first encoded data and generating a first decoded spectrum; dividing the amplitude of the first decoded spectrum into a plurality of subbands, normalizing the spectrum of each subband by the largest value of the amplitude of the first decoded spectrum within each subband, and generating a normalized spectrum; adding a noise spectrum to the normalized spectrum and generating a normalized added noise spectrum; decoding the second encoded data using the normalized added noise spectrum and generating a second added noise spectrum; applying a smoothing process to a noise component of the second added noise spectrum, the application comprising smoothing an energy exchange between frames of the second added noise spectrum using an energy of the noise component of the second added noise spectrum calculated with based on a threshold value, and adjust an amplitude of the noise component of the second added noise spectrum using a scaling coefficient that represents a relationship between an energy of the noise component of the noise component of the second added noise spectrum and an energy of the noise component of the second added noise spectrum to be obtained after smoothing; and performing a frequency-time conversion with respect to a spectrum generated by concatenating a spectrum based on the first decoded spectrum and a spectrum based on the second added noise spectrum. 18. Non-transitory storage medium, characterized by the fact that it has a method, as defined in claim 17.