| Title of Invention | CODING APPARATUS AND DECODING APPARATUS |
|---|---|
| Abstract | An encoder apparatus capable of encoding spectrum with a high quality at a low bit rate without occurrence of disturbance in the harmonic structure of the spectrum. In the apparatus, an internal status setting part (106) uses a first spectrum S1 (k) to set an internal status of a filtering part (107). A pitch coefficient setting part (109) changes a little by a little and outputs the pitch coefficient T. The filtering part (107) calculates, based on the pitch coefficient T, an estimated value S'2 (k) of a second spectrum S2 (k). A searching part (108) calculates a similarity between S2 (k) and S'2 (k). Then, a pitch coefficient T' having the maximum similarity as calculated is applied to a filter coefficient calculating part (110), which uses the pitch coefficient T' to obtain a filter coefficient β i. |
| Full Text | FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) CODING APPARATUS AND DECODING APPARATUS MATSUSHITA ELECTRIC INDUSTRIAL CO. LTD., a Japanese company of 1006, Oaza Kadoma, Kadoma-shi, Osaka 571-8501, Japan. The following specification particularly describes the invention and the manner in which it is to be performed. 2F04019-PCT DESCRIPTION CODING APPARATUS AND DECODING APPARATUS 5 Technical Field [ 0 001J The present invention relates to a coding apparatus mounted on a radio communication apparatus or the like for coding a voice signal, audio signal or the like and a decoding apparatus for decoding this coded signal. 10 Background Art [0002] A coding technology for compressing a voice signal , audio signal or the like to a low bit rate signal is particularly important from the standpoint of effectively 15 using a transmission path capacity {channel capacity) of radio waves or the like and a recording medium in a mobile communication system. [0 003] Examples of a voice coding scheme for coding a voice signal include schemes likeG726, G729 standardized 20 by the ITU-T {International Telecommunication Union Telecommunication Standardization Sector). These schemes use narrow band signals (300 Hz to 3.4 kHz) as coding targets and can perform high quality coding at bit rates of 8 kbits/s to 32 kbits/s. However, since such 25 a narrow band signal is so narrow that its frequency band is a maximum of 3.4 kHz, the quality thereof is such that it gives the user an impression that a sound is muffled, 2- 2F04019-PCT which results inaproblemthat it lacks a sense of realism. [0004] Furthermore, there is also a voice coding scheme that uses wideband signals {50 Hz to 7 kHz) as coding targets. Typical examples of this are G722, G722.1 of 5 ITU-T and AMR-WB of 3GPP (The 3rd Generation Partnership Project). These schemes can perform coding of wideband voice signals at a bit rate of 6.6 kbits/s to 64 kbits/s. However, when the signal to be coded is voice, although a wideband signal has relatively high quality, it is not 10 sufficient when an audio signal is the target or a voice signal of higher quality with a sense of realism is required. [0005] On the other hand, when a maximum frequency of a signal is generally on the order of 10 to 15 kHz, it 15 is possible to obtain a sense of realism equivalent to FM radio, and when the maximum frequency is on the order of up to 20 kHz, it is possible to obtain quality comparable to that of CD (compact disk) . For such a signal, audio coding represented by the layer III scheme or AAC scheme 20 standardized by MPEG (Moving Picture Expert Group) is appropriate. However, these audio coding schemes have a wide frequency band of a signal to be coded, which results in a problem that the bit rate of a coded signal increases. [0006] Examples of conventional coding technologies 25 include a technology of coding a signal with a wide frequency band at a low bit rate (e.g., see Patent Document 1) . According to this, an input signal is divided into 3 2F04019-PCT a signal of a low-frequency domain and a signal of a high-frequency domain, the spectrum of the signal of the high-frequency domain is replaced by the spectrum of the signal of the low-frequency domain and coded, and the 5 overall bit rate is thereby reduced. [0007] FIG. 1A to FIG, ID show an overview of the above described processing of replacing the spectrum of high-frequency domain by the spectrum of the low-frequency domain. This processing is originally 10 intended to be performed in combinat ion with coding processing, but for simplicity of explanation, a case where the above described processing is performed on an original signal will be explained as an example. [0008] FIG .1A shows a spectrum of an original- signal 15 whose frequency band is restricted to 0Ík 25 [0009] In this technology, a spectrum of the original signal whose frequency band is 0^=k 2F04019-PCT band is 0≤k 10 s adjusted and the spectrum as shown in FIG . ID isobtained. This is the spectrum which is the spectrum obtained by estimating the original signal. Patent Document 1 : National Publication of International 15 Patent Application No.2001-521648 (pp.15, FIG.l, FIG.2) Disclosure of Invention Problems to be Solved by the Invention [0010] Generally, spectra such as voice signal and audio 20 signal are known to have a harmonic structure in which a peak of spectrum appears at every integer multiple of a certain frequency (every predetermined pitch). This harmonic structure is important information to keep the quality of a voice signal, audio signal or the like, and 25 if disturbance occurs in the harmonic structure, a listener perceives deterioration of. the quality. [0011] FIG.2A and FIG.2B are diagrams illustrating 5 2F04019-PCT problems of the conventional technology. [0012] FIG.2A is a spectrum obtained by analyzing the spectrum of an audio signal. As is appreciated from this figure, the original signal has a harmonic structure 5 having an interval T on the frequency axis. On the other hand, FIG.2B shows a spectrum obtained as a result of estimating the spectrum of the original signal according to the above described technology, when these two spectra are compared, it is observed from the spectrum shown in 10 FIG.2B that the harmonic structure is maintained in low-frequency spectrum SI of the replacement source and high-frequency spectrum S2 of the replacement destination, whereas the harmonic structure is collapsed in the connection domain (spectrum S3) between low-frequency 15 spectrum SI and high-frequency spectrum S2. [0013] When this estimated spectrum is converted to a time signal and listened, there is a problem that the listener perceives deterioration in quality due to such disturbance of the harmonic structure. This disturbance 20 of the harmonic structure is caused by the fact that replacement has been performed with no consideration given to the shape of the harmonic structure. [0014] It isanobject of the present invention to provide a coding apparatus capable of- coding a spectrum at a low 25 bit rate and with high quality without producing disturbance in the harmonic structure of the spectrum and a decoding apparatus capable of decoding this coded 6 2F04019-PCT signal. Means for Solving the Problem [0015] The coding apparatus of the present invent ion 5 adopts a configuration comprising an acquisition section that acquires a spectrum divided into two bands of low-frequency band and high- frequency band, a calculation section that calculates a parameter indicating the degree of similarity between the acquired spectrum of the 10 low- frequency band and the acquired spectrum of the high-frequency band based on the harmonic structure of the spectrum and a coding section that encodes the calculated parameter indicating the degree of similarity instead of the acquired spectrum of the high-frequency 15 band. [0016] The decoding apparatus of the present invention adopts a configuration comprising a spectrum acquisition section that acquires the spectrum of the low-frequency band out of the spectrum divided into two bands of 20 low-frequency band and high-frequency band, a parameter acquisition section that acquires a parameter indicating the degree of similarity between the spectrum of the low- frequency band and the spectrum of the high-frequency band and a decoding section that decodes the spectra of 25 the low-frequency band and high-frequency band using the acquired spectrum of the low-frequency band and the parameter. 7 2F04019-PCT [0017] The coding method of the present invent ion comprises an acquiring step of acquiring a spectrum divided into two bands of low-frequency band and high-frequency band, a calculating step of calculating 5 a parameter indicating the degree of similarity between the acquired spectrum of the low-frequency band and the acquired spectrum of the high-frequency band based on a harmonic structure of the spectrum and a coding step of coding the calculated parameter indicating the degree 10 of similarity instead of the acquired spectrum of the high-frequency band. [0018] The decoding method of the present invention comprises a spectrum acquiring step of acquiring a spectrum of a low- frequency band out of a spectrum divided 15 into two bands of the low-frequency band and high-frequency band, a parameter acquiring step of acquiring a parameter indicating the degree of similarity between the spectrum of the low-frequency band and the spectrum of the high-frequency band and a decoding step 20 of decoding the spectra of the low-frequency band and high-frequency band using the acquired spectrum of the low-frequency band and the parameter. Advantageous Effect of the Invention 25 [0019] The present invention is capable of performing coding of a spectrum at a low bit rate and with high quality without any collapse of a harmonic structure of the -¥- 8 spectrum. Furthermore, the present invention is also capable of improving sound quality when decoding this coded signal. Brief Description of Drawings [0020] FIG. 1 is a diagram illustrating an overview of a conventional processing of replacing a spectrum of high frequency domain by a spectrum of a low frequency domain; FIG. 1A INTENSITY FREQUENCY FIG.IB INTENSITY FREQUENCY FIG.1C INTENSITY FREQUENCY FIG. ID INTENSITY FREQUENCY FIG. 2 is a diagram illustrating a problem of the conventional technology; FIG.2A INTENSITY FREQUENCY FIG.2B INTENSITY FREQUENCY FIG.3 is a block diagram showing the principal configuration of a radio transmission apparatus according to Embodiment 1; 130 RADIO TRANSMISSION APPARATUS 131 INPUT APPARATUS 132 A/D CONVERSION APPARATUS 120 CODING APPARATUS 133 RF MODULATION APPARATUS FIG. 4 is a block diagram showing internal configuration of a coding apparatus according to Embodiment 1; 120 CODING APPARATUS 122 DOWNSMPLING SECTION 9 123 FIRST LAYER CODING SECTION 124 FIRST LAYER DECODING SECTION 12 5 UPSAMPLING SECTION 12 6 DELAY SECTION 100 SPECTRUM CODING SECTION 127 MULTIPLEXING SECTION FIG. 5 is a block diagram showing the internal configuration of a spectrum coding section according to Embodiment 1; 100 SPECTRUM CODING SECTION 104 FREQUENCY DOMAIN CONVERSION SECTION 105 FREQUENCY DOMAIN CONVERSION SECTION 106 INTERNAL STATE SETTING SECTION 109 PITCH COEFFICIENT SETTING SECTION 107 FILTERING SECTION 108 SEARCH SECTION 110 FILTER COEFFICIENT CALCULATION SECTION FIG. 6 is a diagram illustrating an overview of filtering processing of a filtering section according to Embodiment 1; INTERNAL STATE (FIRST SPECTRUM Sl(k)) ESTIMATED VALUE S'2(k) OF SECOND SPECTRUM FIG.7 is a diagram illustrating how a spectrum of an estimated value of a second spectrum changes as pitch coefficient T changes; FIG.8 is a diagram illustrating how a spectrum of an estimated value of a second spectrum changes as pitch coefficient T changes; FIG. 9 is a flow chart showing an example of a series of algorithms of processes carried out by the filtering section, search section and pitch coefficient setting section according to Embodiment 1; START ST1010 SET T=Train, Amax=0, T'=Tmin ST1020 FILTERING PROCESSING ST1030 CALCULATE DEGREE OF SIMILARITY A ST1070 OUTPUT T' END FIG.10 is a block diagram showing the principal configuration of a radio reception apparatus according to Embodiment 1; 180 RADIO RECEPTION APPARATUS 182 RF DEMODULATION APPARATUS 170 DECODING APPARATUS 184 OUTPUT APPARATUS 10 183 D/A CONVERSION APPARATUS FIG.11 is a block diagram showing the internal configuration of a decoding apparatus according to Embodiment 1; 170 DECODING APPARATUS 172 SEPARATION SECTION 173 FIRST LAYER DECODING SECTION 174 UPSAMPLING SECTION 150 SPECTRUM DECODING SECTION FIG.12 is a block diagram showing the internal configuration of a spectrum decoding section according to Embodiment 1; 150 SPECTRUM DECODING SECTION 154 FREQUENCY DOMAIN CONVERSION SECTION 155 INTERNAL STATE SETTING SECTION 156 FILTERING SECTION 158 TIME DOMAIN CONVERSION SECTION FIG.13 is a diagram illustrating a decoded spectrum generated by a filtering section according to Embodiment 1; DECODING SPECTRUM S' (k) INTERNAL STATE (FIRST SPECTRUM Sl(k)) ESTIMATED VALUE S'2(k) OF SECOND SPECTRUM FIG.14A is a block diagram showing the principal configuration of the transmitting side when the coding apparatus according to Embodiment 1 is applied to a wired communication system; 140 WIRED TRANSMISSION APPARATUS 131 INPUT APPARATUS 132 A/D CONVERSION APPARATUS 120 CODING APPARATUS FIG.14B is a block diagram showing the principal configuration of the receiving side when the decoding apparatus according to Embodiment 1 is applied to a wired communication system; 190 WIRED RECEPTION APPARATUS 191 RECEPTION APPARATUS 170 DECODING APPARATUS 184 OUTPUT APPARATUS 183 D/A CONVERSION APPARATUS FIG.15 is a block diagram showing the principal configuration of a spectrum coding section according to Embodiment 2; 200 SPECTRUM CODING SECTION 104 FREQUENCY DOMAIN CONVERSION SECTION 11 105 FREQUENCY DOMAIN CONVERSION SECTION 106 INTERNAL STATE SETTING SECTION 109 PITCH COEFFICIENT SETTING SECTION 201 FILTERING SECTION 108 SEARCH SECTION FIG.16 is a diagram illustrating an overview of filtering using a filter according to Embodiment 2; INTERNAL STATE (FIRST SPECTRUM Sl(k)) ESTIMATED VALUE S'2(k) OF SECOND SPECTRUM FIG.17 is a block diagram showing the principal configuration of a spectrum coding section according to Embodiment 3; 300 SPECTRUM CODING SECTION 104 FREQUENCY DOMAIN CONVERSION SECTION 105 FREQUENCY DOMAIN CONVERSION SECTION 106 INTERNAL STATE SETTING SECTION 109 PITCH COEFFICIENT SETTING SECTION 107 FILTERING SECTION 108 SEARCH SECTION 301 OUTLINE CALCULATION SECTION 302 MULTIPLEXING SECTION FIG.18 is a block diagram showing the principal configuration of a spectrum coding section according to Embodiment 4; and 550 SPECTRUM CODING SECTION 551 SEPARATION SECTION 154 FREQUENCY DOMAIN CONVERSION SECTION 155 INTERNAL STATE SETTING SECTION 156 FILTERING SECTION 552 SPECTRUM ENVELOPE DECODING SECTION 553 SPECTRUM ADJUSTING SECTION 158 TIME DOMAIN CONVERSION SECTION FIG.19 is a block diagram showing the principal configuration of a spectrum decoding section according to Embodiment 5; 650 SPECTRUM DECODING SECTION 154 FREQUENCY DOMAIN CONVERSION SECTION 155 INTERNAL STATE SETTING SECTION 156 FILTERING SECTION 652 LPC SPECTRUM CALCULATIONS ECTION 553 SPECTRUM ADJUSTING SECTION 159 TIME DOMAIN CONVERSION SECTION 12- Best Mode for Carrying Out the Invention [0021] The inventor focused attention on the characteristics such as voice signal, audio signal or the suchlike {hereinafter, collectively referred to as "acoustic signal"), that is to say, on the fact that an acoustic signal forms a harmonic structure in the frequency axis direction, discovered the possibility of performing coding spectra of the remaining bands using spectra of some bands out of spectra of all frequency bands, and came up with the present invention. [0022] That is, the essence of the present invention is to determine, for example, when coding a signal spectrum divided into two frequency bands of high frequency domain and low frequency domain, the degree of similarity between the spectra of both the high frequency domain and low frequency domain for the spectrum of the high frequency domain and perform coding of a parameter indicating this degree of similarity. [0023] With reference to the accompanying drawings, embodiments of the present invention will be explained in detail below. [0024] (Embodiment 1) FIG. 3 is a block diagram showing the principal configuration of radio transmission apparatus 130 when a radio coding apparatus according to Embodiment 1 of the present invention is mounted on the transmitting side of a radio communication system. [0025] This radio transmission apparatus 130 includes coding apparatus 120, input apparatus 131, A/D conversion apparatus 132, RF modulation apparatus 133 and antenna 134. [0026] Input apparatus 131 converts sound wave Will audible to human ears to an analog signal which is an electric signal and outputs the signal to A/D conversion apparatus 132. A/D conversion apparatus 132 converts this analog signal to a digital signal and outputs the digital signal to coding apparatus 120. Coding apparatus 120 encodes the input digital signal, generates a coded 15 2F04019-PCT signal and outputs the coded signal to RF modulation apparatus 13 3 . RF modulation apparatus 13 3 modulates the coded signal, generates a modulated coded signal and outputs the modulated coded signal to antenna 134. 5 Antenna 134 transmits the modulated coded signal as radio wave W12. [0027] FIG. 4 is a block diagram showing the internal configuration of above described coding apparatus 120. Here, a case where hierarchical coding {scalable coding) 10 is performed will be explained as an example. [0028] Coding apparatus 120 includes input terminal 121, down sampling section 122, first layer coding section 123, first layer decoding section 124, up sampling section 125, delay section 126, spectrum coding section 100, 15 multiplexing section 127 and output terminal 128. [0029] A signal having an effective frequency band of 0^ k 25 First layer decoding section 124 generates a decoded signal of a first layer based on the code. Upsampling section 125 increases the sampling rate of the decoded 14 2F04019-PCT signal of first layer coding section 123. [0030] On the other hand, delay section 126 provides a delay of a predetermined length to the signal input via input terminal 121. Suppose the length of this delay has 5 the same value as a time delay produced when the signal is passed through down sampling section 122, first layer coding section 123, first layer decoding section 124 and up sampling section 125. Spectrum coding section 100 performs spectrum coding using the signal output from 10 up sampling section 125 as a first signal and the signal output from del ay section 126 as a second signal and outputs the generated code to multiplexing section 127. Multiplexing section 127 multiplexes the code obtained from first layer coding section 123 with the code obtained 15 from spectrum coding section 100 and outputs the multiplexed parameter as an output code via output terminal 128. This output code is given to RF modulation apparatus 133. [0031] FIG. 5 is a block diagram showing the internal 20 configuration of above described spectrum coding section 100. [0032] Spectrum coding section 100 includes input terminals 102, 103, frequency domain conversion sections 104, 105, internal state setting section 106, filtering 25 section 107, search section 108, pitch coefficient sett ing section 109, filter coefficient calculation section 110 and output terminal 111. 15 2F04019-PCT [0033] The first signal is input from up sampling section 125 to input terminal 102. This first signal is a signal which is decoded by first layer decoding section 124 using a coded parameter coded by first layer coding section 5 123 and has an effective frequency band of 0 ^ k frequency band of 0^k 15 S2(k). Here, the frequency conversion method applies a discrete Fourier transform (DFT), discrete cosine transform (DCT), modified discrete cosine transform (MDCT) or the like are used. [0035] Internal state setting section 106 sets the 20 internal state of a filter used in filtering section 107 using first spectrum SI(k) having an effective frequency band of 0Sk 16 2F04019-PCT [0037] Filtering section 107 performs filtering of the second spectrum based on the internal state of the filter set by internal state setting section 106 and pitch coefficient T output from pitch coefficient setting 5 section 109 and calculates estimated value S'2(k) of the first spectrum. Details of this filtering processing which will be described later. [0038] Search section 108 calculates a degree of similarity which is a parameter indicating similarity 10 between second spectrum S2(k} output from frequency domain conversion section 105 and estimated value S' 2 (k) of the second spectrum output from filtering section 107 . This degree of similarity will be described in detail later. Calculation processing of this degree of 15 similarity is performed every time pitch coefficient T is given from pitch coefficient setting section 109 and pitch coefficient T' (range of Tmin to Tmax) whereby the calculated degree of similarity becomes a maximum is given to filter coefficient calculation section 110. 20 [0039] Filter coefficient calculation section 110 calculates filter coefficient £i using pitch coefficient T' given from search section 108 and outputs the filter coefficient via output terminal 111 . At this time, pitch coefficient T' is also output via output terminal 111 25 simultaneously. [0040] Next, specific operations of the principal components of spectrum coding section 100 will be 17 2F04019-PCT explained in detail using mathematical expressions below. [0041] FIG. 6 illustrates an overview of filtering processing of filtering section 107. [0042] Here, suppose spectra of all frequency bands 5 (0≤k In this equation, z denotes a z conversion variable, T denotes a coefficient given from pitch coefficient 10 setting section 109 and suppose M=l. [0043] As shown in this figure, first spectrum Sl{k) is stored in band 0^k 20 nearby spectrums S(k-T-i) separated by i centered on the spectrum S(k-T) having a frequency lower than k by T by predetermined weighting factor Pi. 18 2F04019-PCT At this time, suppose the input signal given to this filter is zero. That is, (Equation 2) expresses a zero input response of (Equation 1) . Estimated value S' 2(k) of the second spectrum in FL≤k 15 similarity performed by search section 108 and derivation processing of optimum pitch coefficient T will be explained. [004 7] First, there are various definitions of the degree of similarity. Here, a case where the degree of 20 similarity defined by the following equation based on a least square error method is used assuming that filter coefficients [3-! and p^ are 0 will be explained as an example. 19 2F04019-PCT In the case where this degree of similarity is used, filter coefficient Pi is determined after optimum pitch coefficient T is calculated. Here, E denotes a square error between S2(k) and S'2(k) . In this equation, the 5 first term of the right side becomes a fixed value which is irrelevant to pitch coefficient T, and therefore pitch coefficient T for generating S'2(k) which makes a maximum of the second term of the right side is searched. The second term of the right side of this equation will be 10 called a "degree of similarity." [0048] FIG. 7A to FIG. 7E are diagrams illustrating how the spectrum of estimated value S'2(k) of the second spectrum changes as pitch coefficient T changes. [0049] FIG. 7A is a diagram illustrating the first 15 spectrum having a harmonic structure stored as an internal state. Furthermore, FIG. 7B to FIG. 7D are diagrams illustrating spectra of estimated values S'2(k) of the second spectrum calculated by performing filtering using three types of pitchcoefficientsT0, Ti, T2. FIG. 7E shows 20 second spectrum S2{k) to be compared with the spectrum of estimated value S'2(k} . [0050] In the example shown in this figure, the spectrum shown in FIG. 7C is similar to the spectrum shown in FIG. 7E, and therefore it is real i zed that the degree of similarity 25 calculated using T]. shows the highest value. That is, Tn is an optimum value as pitch coefficient T whereby the harmonic structure can be maintained. 20 2F04019-PCT [0051] FIG.8A to FIG.8E domain also figures similar to FIG.7Ato FIG.7E, but here the phase of the first spectrum stored as the internal state is different from that of FIG.7A to FIG.7E. However, in the example shown in this 5 figure, pitch coefficient T whereby the harmonic structure is maintained is also Ti . [0052] Thus, changing pitch coefficient T and finding T of a maximum degree of similarity is equivalent to finding out apitch (or an integer multiple thereof) of the harmonic 10 structure of the spectrum on a try-and-error basis . The coding apparatus of this embodiment calculates estimated value S'2(k) of the second spectrum based on the pitch of this harmonic structure, and there fore the harmonic structure does not collapse in the connection area between 15 the first spectrum and estimated spectrum. This is easily understandable considering that estimated value S'2(k) of the connection section when k = FL is calculated based on the first spectrum separated by pitch {or an integer multiple thereof) T of the harmonic structure. 20 [0053] Furthermore, pitch coefficient T expresses an integer multiple (integer value) of the frequency interval of the spectrum data. However, the pitch of the actual harmonic structure is often a non-integer value. Therefore, by selecting appropriate weighting factor Pi 25 and applying a weighted addition to M neighboring data centered on T, it is possible to express a pitch of the harmonic structure of a non-integer value within a range 19- 2F04019-PCT from T-M to T+M. [0054] FIG. 9 is a flowchart showinganexample of a series of algorithms of processes performed by filtering section 107, search section 108 and pitch coefficient setting 5 section 109 . An overview of these processes has already been explained, and therefore detailed explanations of the flow will be omitted. [0055] Next, the calculation processing of a filter coefficient by filter coefficient calculation section 10 110 will be explained. [0056] Filter coefficient calculation section 110 determines filter coefficient β that minimizes square distortion E in the following equation using pitch coefficient T" given from search section 108. 15 Filter coefficient calculation section 110 holds a combination of a plurality of pi ( i = -1, 0, 1) as a data table beforehand, determines a combination of pi(i = -l,0,l) that minimizes square distortion E of above described (Equation 4) and outputs an index thereof. [005 7] Thus, for the spectrum of an input signal divided into two parts of a low-frequency domain (0≤k 2F04019-PCT includes the low-frequency spectrum as the internal state, encodes and outputs a parameter indicating the filter characteristic of filtering section 107 instead of the high-frequency spectrum, and therefore, it is possible 5 to perform coding of the sectrum at a low bit rate and with high quality. [0058] Furthermore, in the above described configuration, when filtering section 107 estimates the shape of the high-frequency spectrum using the 10 low-frequency spectrum, pitch coefficient setting section 109 changes the frequency difference between the low-frequency spectrum which serves as a reference for estimation and the high-frequency spectrum, that is, pitch coefficient T, in various ways and outputs the 15 frequency difference, and search section 108 detects T corresponding to a maximum degree of similarity between the low-frequency spectrum and high-frequency spectrum. Therefore, it is possible to estimate the shape of the high- frequency spectrum based on the pitch of the harmonic 20 structure of the overal 1 spectrum and perform coding while maintaining the harmonic structure of the overall spectrum. [0059] Furthermore, there is no need for setting the bandwidth of the low-frequency spectrum based on the pitch 25 of the harmonic structure. That is, it is not necessary to match the bandwidth of the low-frequency spectrum to the pitch of the harmonic structure (or an integer multiple 2F04019-PCT thereof) , and it is possible to set a bandwidth arbitrarily. This is because the above described configuration allows spectra to be connected smoothly in the connection section between the low-frequency spectrum and high-frequency 5 spectrum without matching the bandwidth of the low-frequency spectrum to the pitch of the harmonic structure. [0060] This embodiment has explained the case where M=l in (Equation 1) as an example, but M is not limited to 10 this and an integer {natural number) of 0 or greater can also be used. [0061] Furthermore, this embodiment has explained the coding apparatus that performs hierarchical coding (scalable coding) as an example, but above described 15 spectrum coding section 100 can also be mounted on a coding apparatus that performs coding based on other schemes. [0062] Furthermore, this embodiment has explained the case where spectrum coding section 100 includes frequency domain conversion sections 104, 105. These are 20 components necessary when a time domain signal is used as an input signal, but the frequency domain conversion section is not necessary in a structure in which the spectrum is directly input to spectrum coding section 100 25 [0063] Furthermore, this embodiment has explained the case where the high-frequency spectrum is coded using the low-frequency spectrum, that is, using the 24 2F04019-PCT low-frequency spectrum as a reference for coding, but the method of setting the spectrum which serves as a reference is not limited to this, and it is also possible to perform coding of the low-frequency spectrum using 5 the high-frequency spectrum or perform coding of the spectra of other regions using the spectrum of an intermediate frequency band as a reference for coding though these are not desirable from the standpoint of effectively using energy. 10 [0064] FIG.10 is a block diagram showing the principal configuration of radio reception apparatus 18 0 that receives a signal transmitted from radio transmission apparatus 130. [0065] This radio reception apparatus 180 includes 15 antenna 181, RF demodulation apparatus 182, decoding apparatus 170, D/A conversion apparatus 183 and output apparatus 184 . [0066] Antenna 181 receives a digital coded acoustic signal as radio wave W12, generates a digital received 20 coded acoustic signal which is an electric signal and provides it to RF demodulation apparatus 182. RF demodulation apparatus 182 demodulates the received coded acoustic signal from antenna 181, generates the demodulated coded acoustic signal and provides it to 25 decoding apparatus 170. [0067] Decoding apparatus 170 receives the digital demodulated coded acoustic signal from RF demodulation 2F04019-PCT apparatus 182, performs decoding processing, generates a digital decoded acoustic signal and provides it to D/A conversion apparatus 183. D/A conversion apparatus 183 converts the digital decoded voice signal from decoding 5 apparatus 170, generates an analog decoded voice signal and provides it to output apparatus 184. Output apparatus 184 converts the analog decoded voice signal which is an electric signal to air vibration and outputs it as sound wave W13 so as to be audible to human ears. 10 [0068] FIG.11 is a block diagram showing the internal configuration of above described decoding apparatus 170 . Here, a case where a signal subjected to hierarchical coding is decoded will be explained as an example. [0069] This decoding apparatus 170 includes input 15 terminal 171, separation section 172, first layer decoding section 173, up sampling section 174, spectrum decoding section 150 and output terminals 176, 177. [0 070] RF demodulation apparatus 182 inputs digital demodulated coded acoustic signal to input terminal 171 . 20 Separation section 172 separates the demodulated coded a cousticsignal input via input terminal 171 and generates a code for first layer decoding section 173 and a code for spectrum decoding section 150. First layer decoding section 173 decodes the decoded signal having signal band 25 0^k 2F04019-PCT terminal 176. This allows, when the first layer decoded signal generated by first layer decoding section 173 needs to be output, the first layer decoded signal can be output via this output terminal 176. 5 [0071] Upsampling section 174 increases the sampling first layer decoding section 17 3. Spectrum decoding section 150 is given the code separated by separation section 172 and the up sampled first layer decoded signal 10 generated by up sampling section 174. Spectrum decoding section 150 performs spectrum decoding which will be described later, generates a decoded signal having signal band 0^k [0072] According to this configuration, when the first layer decoded signal generated by first layer decoding 20 section 173 needs to be output, the first layer decoded signal can be output from output terminal 176. Furthermore, when an output signal of higher quality of spectrum decoding section 150 needs to be output, the output signal can be output from output terminal 177. 25 Decoding apparatus 170 outputs either one of signals output from terminal 176 or output terminal 177 and provides the signal to D/A conversion apparatus 183. 2F04019-PCT Which signal is to be output depends on the setting of the application or judgment of the user. [0073] FIG.12 is a block diagram showing the internal configuration of above described spectrum decoding 5 section 150. [0074] This spectrum decoding section 150 includes input terminals 152, 153, frequency domain conversion section 154, internal state setting section 155, filtering section 156, time domain conversion section 158 and output 10 terminal 159. [0075] A filter coefficient indicating a code obtained by spectrum coding section 100 is input to input terminal 152 via separation section 172. Furthermore, a first signal having an effective frequency band of 0^k the frequency of the time domain signal input from input 20 terminal 153 and calculates first spectrum Sl(k). As the frequency conversion method, a discrete Fourier transform (DFT) , discrete cosine transform (DCT) , modified discrete cosine transform (MDCT) or the like is used. [0077] Internal state setting section 155 sets the 25 internal state of a filter used in filtering section 156 using first spectrum Sl{k) . [0078] Filtering section 156 performs filtering of the 18 2F04019-PCT first spectrum based on the internal state of the filter set by internal state setting section 155 and pitch coefficient T' and filter coefficient (3 provided from input terminal 152 and calculates estimated value S'2{k) 5 of the second spectrum. In this case, filtering section 156 uses the filter function described in (Equation 1). [0079] Time domain conversion section 158 converts decoded spectrum S'(k) obtained from filtering section 156 toa time domain signal and outputs the decoded spectrum 10 via output terminal 159. Here, processing such as appropriate windowing and overlapped addition is performed as required to avoid discontinuation that may occur between frames. {0080] FIG.13 shows decoded spectrum S' (k) generated by 15 filtering section 156. [0081] As shown in this figure, decoded spectrum S' (k) having frequency band 0^k [0082] Thus, the decoding apparatus of this embodiment has the configuration corresponding to the coding method according to this embodiment, and therefore, it is possible to decode a coded acoustic signal efficiently 25 with fewer bits and output an acoustic signal of high quality. [0083] Here, the case where the coding apparatus or 29 2F04019-PCT decoding apparatus according to this embodiment i s applied to a radio communication system has been explained as an example, but the coding apparatus or decoding apparatus according to this embodiment is also applicable 5 to a wired communication system as shown below. [0084] FIG.14A is a block diagram showing the principal configuration of the transmitting side when the coding apparatus according to this embodiment is applied to a wired communication system. The same components as those 10 shown in FIG.3 are assigned the same reference numerals and explanations thereof will be omitted. [0085] Wired transmission apparatus 140 includes coding apparatus 120, input apparatus 131 and A/D conversion apparatus 132 and an output thereof is connected to network 15 Nl . [0086] The input terminal of A/D conversion apparatus 132 is connected to the output terminal of input apparatus 131. The input terminal of coding apparatus 120 is connected to the output terminal of A/D convers ion 20 apparatus 132. The output terminal of coding apparatus 120 is connected to network Nl. [0087] Input apparatus 131 converts sound wave Will audible to human ears to an analog signal which is an electric signal and provides it to A/D conversion 25 apparatus 132. A/D conversion apparatus 132 converts the analog signal to a digital signal and provides the digital signal to coding apparatus 12 0. Coding apparatus 12 0 - 30 2F04019-PCT encodes the input digital signal, generates a code and outputs the code to network Nl. [0088] FIG-14B is a block diagram showing the principal configuration of the receiving side when the decoding 5 apparatus according to this embodiment is applied to a wired communication system. The same components as those shown in FIG.10 are assigned the same reference numerals and explanations thereof will be omitted. [0089] Wired reception apparatus 190 includes reception 10 apparatus 191 connected to network Nl, decoding apparatus 170, D/A conversion apparatus 183 and output apparatus 184 . [0090] The input terminal of reception apparatus 191 is connected to network Nl . The input terminal of decoding 15 apparatus 170 is connected to the output terminal of reception apparatus 191- The input terminal of D/A conversion apparatus 183 is connected to the output terminal of decoding apparatus 170. The input terminal of output apparatus 184 is connected to the output terminal 20 of D/A conversion apparatus 183. [0091] Reception apparatus 191 receives a digital coded acoustic signal from network Nl, generates a digital received acoustic signal and provides the signal to decoding apparatus 170 . Decoding apparatus 17 0 receives 25 the received acoustic signal from reception apparatus 191, performs decoding processing on this received acoustic signal, generates a digital decoded acoustic 31 2F04019-PCT signal and provides it to D/A conversion apparatus 183. D/A conversion apparatus 183 converts the digital decoded voice signal from decoding apparatus 170, generates an analog decoded voice signal and provides it to output 5 apparatus 184. Output apparatus 184 converts the analog decoded acoustic signal which is an electric signal to air vibration and outputs it as sound wave W13 audible to human ears. [0092] Thus, according to the above described 10 configuration, it is possible to provide a wired transmission/reception apparatus having operations and effects similar to those of the above described radio transmission/reception apparatus. 15 [00 93] (Embodiment 2} FIG.15 is a block diagram showing the principal configuration of spectrum coding section 200 in a coding apparatus according to Embodiment 2 of the present invention. This spectrum coding section 200 has a basic 20 configuration similar to that of spectrum coding section 100 shown in FIG.5 and the same components are assigned the same reference numerals and explanations thereof will be omitted. [0094] A feature of this embodiment is to make a filter 25 function used in the filtering section simpler than that in Embodiment 1 . [0095] For the filter function used in filtering section 32- 2F04019-PCT 201, a simplified one as shown in the following equation . is used. This equation corresponds to a filter function assuming 5 M=0, po=l in (Equation 1). [0096] FIG. 16 illustrates an overview of filtering using the above described filter. [0097] Estimated value S'2(k) of a second spectrum is obtained by sequentially copying low-frequency spectra 10 separated by T. Furthermore, search section 108 determines optimum pitch coefficient T' by searching for pitch coefficient T which minimizes E of (Equation 3) as in the case of Embodiment 1. Pitch coefficient T' obtained in this way is output via output terminal 111. 15 In this configuration, the characteristic of the filter is determined only by pitch coefficient T. [0098] Note that the filter of this embodiment is characterized in that it operates in a way similar to an adaptive codebook, one of components of a CELP 20 (Code-Excited Linear Prediction) scheme which is a representative technology of low-rate voice coding. [0099] Next, the spectrum decoding section that decodes a signal coded by above described spectrum coding section 200 will be explained (not shown). 25 [0100] This spectrum decoding section has a configuration similar to that of spectrum decoding 33 2F04019-PCT section 150 shown in FIG.12, and therefore detailed explanations thereof will be omitted, and it has the following features. That is, when filtering section 156 calculates estimated value S ' 2 (k) of the second spectrum, 5 it uses the filter function described in (Equation 5) instead of the filter function described in (Equation 1) . It is only pitch coefficient T' that is provided from input terminal 152. That is, which of the filter function described in (Equation 1) or (Equation 5) should be used 10 is determined depending on the type of the filter function used on the coding side and the same filter function used on the coding side is used. [0101] Thus, according to this embodiment, the filter function used in the filtering section is made simpler, 15 which result in eliminating the necessity for installing a filter coefficient calculation section. Therefore, it is possible to estimate the second spectrum (high-frequency spectrum) with a smaller amount of calculation and also reduce the circuit scale. 20 [0102] (Embodiment 3) FIG.17 is a block diagram showing the principal configuration of spectrum coding section 300 in a coding apparatus according to Embodiment 3 of the present 25 invention. This spectrum coding section 300 has a basic configuration similar to that of spectrum coding section 100 shown in FIG.5 and the same components are assigned 34 2F04019-PCT the same reference numerals and explanations thereof will be omitted. [0103] A feature of this embodiment is to further comprise outline calculation sect ion 301 and multiplexing 5 sect ion 302 and perform coding of envelope information about a second spectrum after estimating the second spectrum. [0104] Search section 108 outputs optimum pitch coefficient T' to multiplexing section 302 and outputs 10 estimated value S'2(k) of the second spectrum generated using this pitch coefficient T' to outline calculation section 3 01. Outline calculation section 3 01 calculates envelope information about second spectrum S2(k) based on second spectrum S2{k) provided from frequency domain 15 conversion section 105. Here, a case where this envelope in format ion is expressed by spectrum power for each subband and frequency band FL S k In this equation, BMj) denotes a minimum frequency of the jth subband, BH{j) denotes a maximum frequency of the j th subband. The subband information of the second 25 spectrum obtained in this way is regarded as the spectrum envelope information about the second spectrum. £3- 35 2F04019-PCT [0105] In a similar fashion, subband information B' (j) of estimated value S'2(k) on the second spectrum is calculated according to the following equation, 5 and amount of variation V (j } for each subband is calculated according to the following equation. [0106] Next, outline calculation section 301 encodes amount of variation V(j), obtains the coded amount of 10 variation V(j) and outputs the index thereof to multiplexing section 302. Multiplexing section 302 multiplexes optimum pitch coefficient T' obtained from search section 108 and an index of amount of variation V(j} output from outline calculation section 301 and 15 outputs the multiplexing result via output terminal 111 . [0107] Thus , this embodiment makes it possible to improve an accuracy of the estimated value of the high-frequency-spectrum since the envelope information about the high-frequency spectrum is further coded after a 20 high-frequency spectrum is estimated. [0108] (Embodiment 4) FIG.18 is a block diagram showing the principal configuration of spectrum decoding section 550 according 25 to Embodiment 4 of the present invention. This spectrum 2F04019-PCT decoding section 550 has a basic configuration similar to that of spectrum decoding section 150 shown in FIG. 12, and therefore the same components are assigned the same reference numerals and explanations thereof will be 5 omitted. [0109] A feature of this embodiment is to further comprise separation section 551, spectrum envelope decoding section 552 and spectrum adjusting section 553 . This allows spectrum coding section 300 or the like shown 10 in Embodiment 3 to perform decoding of a code resulting from coding of envelope information as well as coding of an estimated spectrum of a high-frequency spectrum. {0110] Separation section 551 separates a code input via input terminal 152, provides information about a 15 filtering coefficient to filtering section 156 and provides information about a spectrum envelope to spectrum envelope decoding section 552. [0111] Spectrum envelope decoding section 552 decodes amount of variation Vq(j) obtained by coding amount of 20 variation V(j) from the spectrum envelope information given from separation section 551. [0112] Spectrum adjusting section 553 multiplies decoded spectrum S'(k) obtained from filtering section 156 by decoded amount of variation Vq{j) for each subband 25 obtained from spectrum envelop decoding section 552 according to the following equation, S3(k) = S'(k)-V!I {j) {BL{j) 2F04019-PCT adjusts a spectral shape in frequency band FL ^ k 5 to a time domain signal. [0113] Thus, according to this embodiment, it is possible to decode a code including envelope information. [0114] This embodiment has explained the case where the spectrum envelope information provided from separation 10 section 551 is value Vq(j ) obtained by coding amount of variation V{j) for each subband shown in (Equation 8) as an example, but the spectrum envelope information is not limited to this. 15 [0115] (Embodiment 5} FIG.19 is a block diagram showing the principal configuration of a spectrum decoding section 650 in a decoding apparatus according to Embodiment 5 of the present invent ion. This spectrum decoding section 650 20 has a basic configuration similar to that of spectrum decoding section 550 shown in FIG.18, and therefore the same components are assigned the same reference numerals and explanations thereof will be omitted. [0116] A feature of this embodiment is to further 25 comprise LPC spectrum calculation section 652, use an LPC spectrum calculated with an LPC coefficient as spectrum envelope information, estimate a second spectrum, 38 2F04019-PCT and then multiply the second spectrum by the LPC spectrum to obtain a more accurate estimated value of the second spectrum. [0117] LPC spectrum calculation section 652 calculates 5 LPC spectrum env(k) from LPC coefficient a (j ) input via input terminal 651 according to the following equation. Here, NP denotes the order of the LPC coefficient. Furthermore, it is also possible to calculate LPC spectrum 10 ``env(k) using variable Y(0 15 Here, Y m&Y De defined as a fixed value or may also take a value which is variable from one frame to another. LPC spectrum env(k) calculated in this way is output to spectrum adjusting section 553. [0118} Spectrum adjusting section 553 multiplies 20 decoded spectrum S' (k) obtained from filtering section 156 by LPC spectrum env(k) obtained from LPC spectrum 39- 2F04019-PCT calculation section 6 52 according to the following equation, S3(k) = S'(k)env(k) (FL adjusts the spectrum in frequency band FL^ k to time domain conversion section 158 and converted to a time domain signal . [0119] Thus, according to this embodiment, using an LPC 10 spectrum as spectrum envelope information makes it possible to obtain a more accurate estimated value of the second spectrum. [012 0] The coding apparatus or decoding apparatus according to the present invention can be mounted on a 15 communication terminal apparatus and base station apparatus in a mobile communication system, and therefore, it is possible to provide a communication terminal apparatus and base station apparatus having operations and effects similar to those described above. 20 [0121] The case where the present invention is constructed by hardware has been explained as an example so far, but the present invention can also be implemented by software. [0122) The present application is based on Japanese 25 Patent Application No.2003-323658 filed on September 16, 2003, entire content of which is expressly incorporated by reference herein. A_)0 2F04019-PCT Industrial Applicability [0123] The coding apparatus and decoding apparatus according to the present invent ion have the effect of 5 performing coding at a low bit rate and is also applicable to a radio communication system or the like. 39- 2F04019-PCT CLAIMS 1. A coding apparatus comprising: an acquisition section chat; acquires a spectrum divided into two bands of low-frequency band and 5 high-frequency band; a calculation section that calculates a parameter indicating the degree of similarity between said acquired spectrum of the low-frequency band and said acquired spectrum of the high-frequency band based on the harmonic 10 structure of said spectrum,- and a coding section that encodes said calculated parameter indicating a degree of similarity instead of said acquired spectrum of the high-frequency band. 15 2. The coding apparatus according to claim 1, wherein said calculation section comprises: a generation section that generates a similar spectrum of said spectrum of the high- frequency band based on said spectrum of the low- frequency band separated from 20 said spectrum of the high-frequency band by an integer multiple of a pitch of a harmonic structure on a frequency axis; and a detection section that detects a parameter indicating a characteristic of said similar spectrum when 25 said similar spectrum is the most similar to said spectrum of the high-frequency band. 2F04019-PCT 3. The coding apparatus according -c claim 1, wherein said coding section also encodes information about an envelope of said acquired spectrum of the high-frequency band . 5 4. The coding apparatus according co claim 1, wherein said calculation section comprises: an estimation section that estimates said acquired spectrum of the high-frequency band using a filter having said acquired spectrum of the low-frequency band as an internal state; and an output section that outputs a parameter indicating a characteristic of said filter, wherein a filter function of said filter is expressed by the following equation, and said estimation section performs said estimation using a zero input response of said filter. where, P(z): Filter function z . z conversion variable M: Order of filter multiplied 1/2-fold p: Weighting factor T: Pitch coefficient 2F04019-PCT 5. The coding apparatus according to claim 4, wherein M= 0 and p : = 1 in said filter function. . 5 6. The coding apparatus according to claim 1, wherein-said spectrum of the low-frequency band is obtained from a signal decoded after being coded in a lower layer through hierarchical coding. 10 7. A transmission/reception apparatus comprising the coding apparatus according to claim 1. 8. A decoding apparatus comprising: a spectrum acquisition section that acquires a 15 spectrumofalow- frequency band out of a spectrum divided into two bands of low-frequency band and high-frequency band; a parameter acquisition section that acquires a parameter indicating a degree of similarity between said 20 spectrum of the low- frequency band and said spectrum of the high- frequency band,- and a decoding section that decodes said spectra of the low-frequency band and high-frequency band using said acquired spectrum of the low-frequency band and said 25 parameter. 9. The decoding apparatus according to claim 8, further 44 2F04019-PCT comprising an envelope information acquisition seccior. chat acquires information about an envelope of said spectrum of the high-frequency band, wherein said decoding section performs said decoding also using 5 information about said acquired envelope. 10 . The decoding apparatus according to claim 8 , wherein said decoding section comprises an estimation section that includes said acquired spectrum of the low-frequency 10 band as an internal state and estimates said spectrum of the high-frequency band using a filter having said acquired parameter as a filter characteristic, a filter function of said filter is expressed by the following equation, and said estimation section performs said 15 estimation using a zero input response of said filter. where, P(z): Filter function z : z conversion variable M: Order of filter multiplied 1/2 – fold 20 :β Weighting factor T: Pitch coefficient 11. The decoding apparatus according to claim 10 wherein M=0 and p0 = 1 in said filter function. 2F04019-FCT 11 . The decoding apparatus according to claim 8 , wherein said spectrum of the low-frequency band is generated from a signal decoded in a lower layer through hierarchical 5 coding. 13. A transmission/reception apparatus comprising the decoding apparatus according to claim 8. 10 14. A coding method comprising: an acquiring step of acquiring a spectrum divided into two bands of low-frequency band and high-frequency band; a calculating step of calculating a parameter indicating a degree of similarity between said acquired 15 spectrum of the low-frequency band and said acquired spectrum of the high-frequency band based on a harmonic structure of said spectrum,- and a coding step of encoding said calculated parameter indicating the degree of similarity instead of said 20 acquired spectrum of the high-frequency band. 15. A decoding method comprising: a spectrum acquiring step of acquiring a spectrum of a low-frequency band out of a spectrum divided into 25 two bands of low-frequency band and high-frequency band; a parameter acquiring step of acquiring a parameter indicating the degree of similarity between said spectrum 45 ■ 2F04019-PCT of. the low-frequency band and said spectrum of the high-frequency band; and a decoding step of decoding said spectra of the low-frequency band and high-frequency band using said 5 acquired spectrum of the low-frequency band and said parameter. 5 16. (Added) A spectrum coding apparatus that encodes a spectrum including a first band and a second band, comprising: an acquisition section that acquires information about a spectrum similar to a spectrum of said second 10 band from a spectrum of said first band based on a harmonic structure,- and a coding section that encodes said information instead of the spectrum of said second band. 15 17. (Added) The spectrum coding apparatus according to claim 16, wherein said information is shape information about a spectrum similar to the spectrum of said second band . 20 18. (Added) The spectrum coding apparatus according to claim 16, wherein said acquisition section generates an estimated spectrum similar to the spectrum of said second band based on a harmonic structure of said spectrum and acquires information about said estimated spectrum. 25 19. (Added) A coding, apparatus comprising: an acquisition section that acquires a spectrum 46 2F04 019-PCT having a low frequency band and a high frequency band; a generation section char generates a parameter indicating a degree of similarity between said spectrum of the low frequency band and said spectrum of the high 5 frequency band based on a harmonic structure of said spectrum; and a coding section that encodes said parameter indicating the degree of similarity instead of said spectrum of the high frequency band. 10 20. (Added) The coding apparatus according to claim 19, wherein said generation sect ion comprises: a spectrum generation section that generates a spectrum similar to said spectrum of the high frequency 15 band based on said spectrum of the low frequency band separated by an integer multiple of apitch of saidharmonic structure from said spectrum of the high frequency band; and an output section that outputs a parameter 20 indicating a characteristic of said similar spectrum as said parameter indicating the degree of similarity. 21. (Added) The coding apparatus according to claim 20, wherein said spectrum generation section generates said 25 similar spectrum using a filter, said filter comprises said spectrum of the low frequency band separated by an integer multiple of a pitch 48 2F04019-PCT of said harmonic structure from said spectrum of the high frequency band as an in snarl state, and said output section outputs a filter coefficient of said filter as a parameter indicating said degree of 5 similarity. 22. (Added) The coding apparatus according to claim 19, wherein said coding section also encodes envelope information about said spectrum of the high frequency 10 band. 23. (Added) The coding apparatus according to claim 19, wherein said coding sect ion also encodes information about a power ratio between said spectrum of the low 15 frequency band and said spectrum of the high frequency band . 24. (Added) The coding apparatus according to claim 19, wherein said generation section comprises: 20 an estimation section that estimates said spectrum of the high frequency band using a filter having said spectrum of the low frequency band as an internal state; and an output section that outputs a parameter 25 indicating a characteristic of said filter, wherein a filter function of said filter is expressed by the following equation, and 2F04019-PCT said estimation sect ion performs said estimation using a zero input response of said filter. where, 5 P(z): Filter function z: z conversion variable 2M+1: Order of filter £: Weighting factor T: Pitch coefficient 10 25. (Added) The coding apparatus according to claim 24, wherein M = 0 and p"0-l in said filter function. 26. (Added) The coding apparatus according to claim 19, 15 wherein said spectrum of the low frequency band is obtained from a signal decoded after being coded in a lower layer through hierarchical coding. 2 7. (Added) A communication terminal apparatus comprising 20 the coding apparatus according to claim 19. 28 . (Added) A scalable coding apparatus that encodes a voice signal or audio signal separated into a low frequency band and high frequency band, comprising: 50 ' 2F04019-PCT a first coding section that encodes a low-frequency band signal of said voice signal or said audio signal; and a second coding section that encodes a 5 high-frequency band signal of said voice signal or said audio signal using said low-frequency band signal, where in said second coding section comprises: a first spectrum generation section that performs frequency domain conversion on said low-frequency band 10 signal and generates a spectrum of the low frequency band; a second spectrum generation section that performs frequency domain conversion on said voice signal or said audio signal and generates a spectrum having the low frequency band and high frequency band,- and 15 the coding apparatus of claim 19 wherein said acquisition sect ion acquires spectra generated by said first and second spectrum generation sections. 29. (Added) A communication terminal apparatus comprising 20 the scalable coding apparatus according to claim 28. 3 0. (Added) A decoding apparatus comprising: a spectrum acquisition section that acquires a spectrum of a low frequency band out of a spectrum having 25 a low frequency band and high frequency band; a parameter acquisition section that acquires a parameter-indicating a degree of similarity between said 51 2F04019-PCT spectrum of the low frequency band and said spectrum of the high frequency band; and a decoding section that decodes said spectrum of the low frequency band and said spectrum of the high 5 frequency band using said spectrum of the low frequency band and said parameter. 31. (Added) The decoding apparatus according to claim 30, further comprising an envelope information 10 acquisition sect ion that acquires envelope information of said spectrum of the high frequency band, wherein said decoding section performs said decoding using also said envelope information. 15 32. (Added)' The decoding apparatus according to claim 3 0 , wherein said decoding sect ion comprises an estimation section that includes said spectrum of the low frequency band as an internal state and estimates said spectrum of the high frequency band using a filter having said 20 parameter as a filter characteristic, a filter function of said filter is expressed by the following equation, and said estimation section performs said estimation using a zero input response of said filter. 52 2F04019-P where, P{z): Filter function z: z conversion variable 5 2M+1: Order of filter (3: β Weighting factor T: Pitch coefficient 33. (Added) The decoding apparatus according to claim 10 32, wherein M=0 and J30 = l in said filter function. 3 4. (Added) The decoding apparatus according to claim 30, wherein said spectrum of the low frequency band is generated from a signal decoded in a lower layer through 15 hierarchical coding. 3 5 . {Added) A communication terminal apparatus comprising the decoding apparatus according to claim 30. 20 36. (Added) A coding method comprising the steps of: acquiring a spectrum having a low frequency band and a high frequency band ,- generating a parameter indicating a degree of similarity. between said spectrum of the low frequency 53 band and said spectrum of the high-frequency band based on a harmonic structure of said spectrum, and encoding said parameter indicating the similarity instead of said spectrum of the high frequency band. 37. (Added) a decoding method comprising the steps of: acquiring a spectrum having a low frequency band out of a spectrum having a low frequency band and high frequency band; acquiring a parameter indicating a degree of similarity between said spectrum of the low frequency band and said spectrum of the high frequency band; and decoding said spectrum of the low frequency band and said spectrum of the high frequency band using said spectrum of the low frequency band and said parameter. 38. A coding, decoding, transmission/reception apparatus; a coding and decoding, a spectrum coding apparatus and communication terminal apparatus; a scalable coding apparatus; a coding and decoding method such as herein described with reference to the accompanying drawings. Dated this 16th day of March 2006. 54 ABSTRACT An encoder apparatus capable of encoding spectrum with a high quality at a low bit rate without occurrence of disturbance in the harmonic structure of the spectrum. In the apparatus, an internal status setting part (106) uses a first spectrum S'2(k) to set an internal status of a filtering part (107). A pitch coefficient setting part (109) changes a little by a little and outputs the pitch coefficient T. The filtering part (107) calculates, based on the pitch coefficient T, an estimated value S'2(k) of a second spectrum S2k). A searching part (108) calculates a similarity between S2k). 55 |
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318-mumnp-2006-abstract(complete)-(21-3-2006).pdf
318-mumnp-2006-abstract(granted)-(7-6-2010).pdf
318-mumnp-2006-cancelled pages(11-6-2010).pdf
318-MUMNP-2006-CLAIMS(AMENDED)-(16-4-2010).pdf
318-mumnp-2006-claims(complete)-(21-3-2006).pdf
318-mumnp-2006-claims(granted)-(7-6-2010).pdf
318-MUMNP-2006-CORRESPONDENCE(16-1-2009).pdf
318-MUMNP-2006-CORRESPONDENCE(30-4-2010).pdf
318-mumnp-2006-correspondence(9-8-2006).pdf
318-mumnp-2006-correspondence(ipo)-(10-6-2010).pdf
318-mumnp-2006-correspondence-received.pdf
318-MUMNP-2006-DECLARATION BY THE TRANSLATOR(16-1-2009).pdf
318-mumnp-2006-description (complete).pdf
318-mumnp-2006-description(complete)-(21-3-2006).pdf
318-mumnp-2006-description(granted)-(7-6-2010).pdf
318-MUMNP-2006-DRAWING(16-4-2010).pdf
318-mumnp-2006-drawing(complete)-(21-3-2006).pdf
318-mumnp-2006-drawing(granted)-(7-6-2010).pdf
318-MUMNP-2006-ENGLISH TRANSLATION(11-6-2010).pdf
318-MUMNP-2006-FORM 1(11-6-2010).pdf
318-mumnp-2006-form 1(3-4-2006).pdf
318-mumnp-2006-form 13(16-1-2009).pdf
318-mumnp-2006-form 2(complete)-(21-3-2006).pdf
318-mumnp-2006-form 2(granted)-(7-6-2010).pdf
318-MUMNP-2006-FORM 2(TITLE PAGE)-(11-6-2010).pdf
318-mumnp-2006-form 2(title page)-(complete)-(21-3-2006).pdf
318-mumnp-2006-form 2(title page)-(granted)-(7-6-2010).pdf
318-MUMNP-2006-FORM 26(16-1-2009).pdf
318-mumnp-2006-form 26(3-4-2006).pdf
318-MUMNP-2006-FORM 3(16-4-2010).pdf
318-MUMNP-2006-OTHER DOCUMENT(16-4-2010).pdf
318-MUMNP-2006-PETITION UNDER RULE 137(16-4-2010).pdf
318-MUMNP-2006-REPLY TO EXAMINATION REPORT(16-4-2010).pdf
318-MUMNP-2006-TRANSLATED COPY OF PRIORITY DOCUMENT(30-4-2010).pdf
| Patent Number | 240870 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 318/MUMNP/2006 | ||||||||
| PG Journal Number | 24/2010 | ||||||||
| Publication Date | 11-Jun-2010 | ||||||||
| Grant Date | 07-Jun-2010 | ||||||||
| Date of Filing | 21-Mar-2006 | ||||||||
| Name of Patentee | PANASONIC CORPORATION | ||||||||
| Applicant Address | 1006, Oaza Kadoma. Kadoma-shi, Osaka, 57l850, Japan. | ||||||||
Inventors:
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| PCT International Classification Number | G10L19/00 | ||||||||
| PCT International Application Number | PCT/JP2004/013455 | ||||||||
| PCT International Filing date | 2004-09-15 | ||||||||
PCT Conventions:
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