JP2003228399A - Encoding device, decoding device, and sound data distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoding device which can efficiently encode a sound signal over a wide band. <P>SOLUTION: A sound data input part 310 of the encoding device 300 cuts 4096 pieces of successive sound data out of a sound data sequence and a conversion part 320 converts the cut sound data into spectrum data on the frequency axis. A data separation part 330 separates the spectrum data into a low-frequency part and a high-frequency part based upon 11.025 kHz (f1) as a border. The low-frequency part spectrum data are quantized and encoded by a 1st quantization part 340 and an encoding part 350 as usual. A 2nd encoding part 355 generates auxiliary information showing a feature of a high-frequency part frequency spectrum and a 2nd encoding part 355 encodes the auxiliary information. A stream output part 390 puts together and output the code obtained by the 1st encoding part 350 and the code obtained by the 2nd encoding part 355. Here, f1 is less than a half of the sampling frequency f2 when the sound data sequence was generated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-quality sound compression encoding and decompression decoding technique for acoustic signals.

[0002]

2. Description of the Related Art In recent years, various techniques for high-quality compression coding and decompression decoding of audio signals such as voice and musical sound have been developed, and "MPEG-2 Advanced A" is developed.
audio Coding "(hereinafter referred to as" MPEG-2 A
"AC" or "AAC") is also one of the methods (see Non-Patent Document 1).

[0003]

[Non-Patent Document 1] M. Bosi et al., "IS 1381.
8-7 (MPEG-2 Advanced Audio)
Coding, AAC) ", April 1997 FIG. 24 is a block diagram showing a functional configuration of a conventional AAC encoding device and decoding device.

The encoding apparatus 1000 is an apparatus for compression-encoding the input acoustic signal based on the AAC encoding method, and includes an A / D converter 1050 and an acoustic data input unit 11.
00, conversion unit 1200, quantization unit 1400, encoding unit 1
500 and a stream output unit 1900.

The A / D converter 1050 samples the input acoustic signal at a sampling frequency of 22.05 kHz, for example, and converts the analog acoustic signal into a digital acoustic data string. Acoustic data input unit 1100
Every time 1024 samples (the 1024 samples are referred to as “frames” below) of the acoustic data sequence that is the input signal are read, 50% of the samples of the frame and adjacent frames before and after the frame (51
A total of 2048 samples of acoustic data trains obtained by overlapping 2) are cut out. The conversion unit 1200 uses the MDCT
(Modified Discrete Cosine
Transform), the acoustic data input unit 1
Data of 2048 samples on the time axis cut out by 100 is converted into spectrum data on the frequency axis. It should be noted that the spectrum data of 1024 points, which is half of the data obtained by the conversion, represents a reproduction band of 11.025 kHz or less, which is half the sampling frequency, and is classified into a plurality of groups. Each group is set such that each of the plurality of groups includes one or more points of spectrum data. Also, each of these groups simulates a critical band in human hearing. Each of the groups is called a “scale factor band”. The quantization unit 1400 uses one normalization coefficient for each scale factor band to convert the conversion unit 12
The spectrum data in the scale factor band obtained from 00 is quantized into a predetermined number of bits. This normalization coefficient is called "scale factor". In addition, the result of quantizing each spectrum data with each scale factor is referred to as a “quantized value”. The encoding unit 1500 Huffman-encodes the data quantized by the quantization unit 1400, that is, each scale factor and the spectrum data quantized using the scale factor. Stream output unit 19
00 represents the encoded signal obtained from the encoding unit 1500,
It is converted into the stream format of the AAC bit stream and output. The bitstream output from the encoding device 1000 is transmitted to the decoding device 2000 via a transmission medium or a recording medium.

The decoding device 2000 is the same as the encoding device 100.
A device for decoding a bitstream encoded by 0, which comprises a stream input unit 2100 and a decoding unit 2
200, an inverse quantization unit 2300, an inverse conversion unit 2800, an acoustic data output unit 2900, and a D / A converter 2950.

The stream input unit 2100 inputs the bit stream encoded by the encoding device 1000 via a transmission medium or a recording medium, and extracts an encoded signal from the input bit stream. The decoding unit 2200
The Huffman-encoded coded signal is decoded into quantized data. The dequantization unit 2300 dequantizes the quantized data decoded by the decoding unit 2200 using a scale factor. The inverse transform unit 2800 uses IMDCT (In
Verse Modified Discrete C
The Transform spectrum) is used to convert the spectrum data of 1024 points on the frequency axis obtained by the dequantization unit 2300 into acoustic data of 1024 samples on the time axis. The acoustic data output unit 2900 sequentially combines the acoustic data of 1024 samples on the time axis obtained by the inverse conversion unit 2800 and outputs the acoustic data of 1024 samples one by one in time order. D / A converter 2950
Converts from digital audio data to analog audio signals at a sampling frequency of 22.05 kHz.

According to the encoding device 1000 and the decoding device 2000 according to the conventional AAC standard as described above,
The compression rate can be increased to 1 bit or less at each point,
Moreover, half of the sampling frequency 11.025 kHz
Represents the following playback bands, and the low-frequency part 1 has a high auditory priority.
Since the 024 points of spectrum data are encoded, it is possible to reproduce an acoustic signal with relatively high sound quality.

[0009]

However, the encoding apparatus 1000 and the decoding apparatus 20 of the conventional AAC system are used.
00 (conventional example 1), the sampling frequency is 2
Since it is 2.05 kHz, the spectral data to be encoded does not include any band exceeding 11.25 kHz. For this reason, there is a problem in that it is not possible to meet the demand for higher quality in which the user wants to view the band exceeding 11.25 kHz.

In order to solve such a problem, FIG.
A / of the encoding device 1000 and the decoding device 2000
The sampling frequency applied to the D converter 1050 and the D / A converter 2950 is twice as high as 22.05 kHz, 44.1.
It is possible to increase the frequency to kHz (this method will be
Also referred to as "conventional example 2". ).

However, the sampling frequency is set to 4
When it is set to 4.1 kHz, the compression ratio is maintained at 11.0.
Although it is possible to encode the spectrum data of 512 points in the high frequency part exceeding 25 kHz, the spectrum data of the low frequency part having a high auditory priority is halved to 512 points. That is, there is a trade-off relationship between the sampling frequency and the number of spectra in the low frequency band, and the conventional AAC
Then both cannot be raised at the same time. Therefore, another problem occurs that the sound quality as a whole is rather deteriorated.

Such a situation is caused by another method (for example, M
The same applies to the encoding device and the decoding device of P3, AC3, etc.). The present invention has been made to solve the above technical problems, and an encoding device and a decoding device that can realize high-quality reproduction of an audio signal without significantly increasing the amount of information after encoding. It is to provide a device and the like.

[0013]

In order to solve the above-mentioned problems, an encoding apparatus according to the present invention is an encoding apparatus for encoding acoustic data, wherein a certain number of consecutive acoustics are extracted from an acoustic data string. Cutting-out means for cutting out data, converting means for converting the cut-out acoustic data into spectrum data on the frequency axis, spectrum data obtained by the conversion is lower than the f1 Hz spectrum data and higher than f1 Hz Separation means for separating the high-frequency part spectrum data, low-frequency part coding means for quantizing and coding the separated low-frequency part spectrum data, and the high-frequency part from the separated high-frequency part spectrum data Auxiliary information generating means for generating auxiliary information indicating the characteristics of the frequency spectrum, high-band part coding means for coding the generated auxiliary information, and the low-band part code Output means for synthesizing and outputting the code obtained by the means and the code obtained by the high band encoding means, and the f1 is the sampling frequency f2 when the acoustic data string is created. It is characterized by being less than half.

Here, the f1 is f2 / 4, the conversion means converts the acoustic data into spectrum data of 0 to 2 × f1 Hz, and the separation means 0 to f1H.
It is characterized in that it is separated into low-frequency spectrum data of z and high-frequency spectrum data of f1 to 2 × f1 Hz, and the low-frequency spectrum data up to f1 Hz is n.
Of the spectrum data, the cut-out means cuts out the acoustic data of the number necessary to generate the 2 × n spectrum data, and the conversion means cuts the cut-out acoustic data of 2 × n pieces. It is characterized in that it is converted into spectrum data, and the separating means separates into n pieces of low band spectrum data and n pieces of high band spectrum data, and the cutting means is a unit of coding.
2 × n pieces of spectrum data, which is a combination of n pieces of sound data corresponding to a frame and n / 2 pieces of sound data belonging to each of two frames adjacent to the frame, are cut out, and the conversion means cuts out the spectrum data. The above-mentioned conversion is performed on 2 × n acoustic data obtained by MDCT,
0 to 2 × f1 Hz consisting of 2 × n spectrum data
The spectrum may be converted into a spectrum of

Further, a decoding device according to the present invention is a decoding device for decoding coded data input via a recording medium or a transmission medium, and a low frequency part coding included in the coded data. Extraction means for respectively extracting the data and the high frequency band encoded data, and the low frequency band spectrum of frequency f1 or less by decoding and dequantizing the low frequency band encoded data extracted by the extraction means. Low-frequency part dequantizing means for outputting data, and auxiliary-information decoding means for decoding auxiliary data extracted by the extracting means to generate auxiliary information representing characteristics of the high-frequency spectrum data. A high-frequency part inverse quantization means for outputting spectrum data of a high-frequency part based on the auxiliary information generated by the auxiliary information decoding means; and a low-frequency part inverse quantization means. Synthesis means for synthesizing the high-frequency spectrum data and the high-frequency spectrum data output by the high-frequency inverse quantization means, and the spectrum data synthesized by the high-frequency spectrum inverse conversion to the acoustic data on the time axis. And an acoustic data output means for outputting the acoustic data inversely transformed by the inverse transformation means in chronological order.

The present invention can be realized as a communication system comprising the above-mentioned encoding device and decoding device, or a code having steps as characteristic means constituting the above-mentioned encoding device, decoding device and communication system. Encryption method, decryption method,
It can be realized as a communication method, or can be realized as an encoding program or a decoding program that causes a CPU to execute the characteristic means or steps that configure the encoding device or the decoding device, or can be read by a computer in which these programs are recorded. Needless to say, it can be realized as any recording medium.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a case where an embodiment of the present invention is applied to a broadcasting system as an acoustic data distribution system will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of the broadcasting system according to the present embodiment. A broadcasting system 1 according to the present embodiment shown in the figure is provided in a broadcasting station, and is an encoding device 300 that encodes an input acoustic signal.
And a decoding device 400 that is provided in the user terminal and that decodes the bitstream acoustic signal encoded by the encoding device 300.

(Encoder 300) Encoder 300
Is an encoding device that encodes an input acoustic signal, and includes an A / D converter 305 and an acoustic data input unit 310.
A conversion section 320, a data separation section 330, first and second quantization sections 340 and 345, first and second encoding sections 350 and 355, and a stream output section 390.

The A / D converter 305 converts the input acoustic signal into a sampling frequency 4 which is twice as high as that of the conventional example 1, for example.
Sampling is performed at 4.1 kHz, an analog acoustic signal is converted into digital acoustic data (for example, 16 bits), and an acoustic data string on a time axis is generated.

The acoustic data input unit 310 receives the acoustic data sequence generated by the A / D converter 305 in 2048 samples (2 frames) each cycle (approximately 45.
4 msec), that is, in a slow cycle in which the time is extended twice as long as that of the conventional example 2, 204 of these two frames
An acoustic data string in which 8 samples overlap with 1024 samples, which is 50% of adjacent frames before and after these frames, that is, twice as many as the conventional one (4096
20) to extract the acoustic data string of
A counter 311 for detecting the cutout timing each time 48 samples are received, and a FIFO buffer 312 for temporarily storing a sound data string of 4096 samples are provided.

The conversion unit 320 includes an acoustic data input unit 310.
The acoustic data of 4096 samples for two frames cut out by is converted into spectrum data on the frequency axis, and the acoustic data of 4096 samples on the time axis is converted to spectrum data on the frequency axis of 4096 points. MDCT 321 and grouping unit 3 for grouping spectral data into scale factor bands
And 22.

The MDCT 321 is specifically 4096
The acoustic data on the time axis of the sample is converted into 4096 points of spectral data (16 bits).
Since it becomes the spectrum data of the group, only the spectrum data of one of the 2048 samples is to be encoded and the other is discarded.

As described above, the A / D converter 305, the acoustic data input unit 310, and the conversion unit 32 of the encoding device 300.
When the configuration of 0 is compared with that of the encoding device 1000 of the above-mentioned conventional example 1, the sampling frequency in the A / D converter 305 is increased to twice the frequency (44.1 kHz), and the cutout length in the acoustic data input unit 310 is increased. Is doubled (4096 samples) and the MD of the conversion unit 320 is increased.
This is a big difference in that the coding unit in CT321 is doubled (4096 samples).

Further, the encoding device 10 of the above-mentioned conventional example 2
Compared with the configuration of No. 00, although the sampling frequency in the A / D converter 305 is the same, the cutout length in the acoustic data input unit 310 is doubled (4096 samples), and the coding unit in the MDCT 321 of the conversion unit 320 is increased. This is a big difference in that the number is doubled (coding unit: 4096 samples).

As a result, the conversion unit 320 outputs 11.0.
The spectrum data belonging to the low frequency band of 25 kHz or less (hereinafter referred to as “low frequency spectrum data”) is 102.
A total of 2048 pieces of spectrum data are output, which is 1024 pieces of spectrum data (hereinafter, referred to as “spectrum data of high band portion”) belonging to the high band portion exceeding 11.025 kHz.

The grouping unit 322 of the conversion unit 320 is
One of the 2048 samples of the spectral data that is the target of encoding is converted into one or more samples (practically 4
Multiple scale factor bands containing spectral data of multiples of.

This scale factor band corresponds to this A
In the AC standard, the number of samples (spectral data) included in each scale factor band is determined according to the frequency. In the low frequency region, each sample is divided into a small number of samples. Largely separated to include. In AAC, the number of scale factor bands corresponding to the spectrum data of one frame is also determined according to the sampling frequency. For example, the sampling frequency is 44.1.
In the case of kHz, the number of scale factor bands included in one frame is 49, and the spectrum data of 1024 samples is included in the 49 scale factor bands. On the other hand, of the scale factor bands determined in this way, which scale factor band is to be transmitted is not specified by the AAC, and the most preferable scale factor band is selected according to the transfer rate of the transmission path. All you have to do is transmit. For example, when the transfer rate of the transmission path is 96 kbps, only the low band 40 scale factor band (640 samples) of one frame may be selected and transmitted.

On the other hand, in the present embodiment,
Spectral data of 2 frames (1024 low band spectral data, high band spectral data 102
4) is twice as long as the conventional cycle (about 45.4 msec)
Is output from the MDCT 321. Therefore, if the transfer rate of the transmission path is 96 kbps, even if all the scale factor bands (1024 samples) in the lower frequency band of the two frames are to be transmitted, compared to the data transfer for two frames by the conventional method, AAC 2 times (640
X2 = 1280 samples), a sufficient margin is created in the transfer rate. Therefore, in the present embodiment, a case will be described in which grouping section 322 classifies the converted spectrum data into scale factor bands of a partitioning method and number that are uniquely determined.

The data separating section 330 separates the 2048 spectrum data output from the converting section 320 into low-frequency spectrum data (1024) and high-frequency spectrum data (1024). Then, the data separating unit 330 separates the separated spectrum data (1
024) to the first quantizer 340, high-band spectrum data (1024) to the second quantizer 345,
Output each.

The first quantizer 340 includes a data separator 3
The spectrum data in the low-frequency part transferred from 30 is determined for each scale factor band, and the scale factor is determined for each scale factor band, and the spectrum in the scale factor band is quantized. The head of the determined scale factor and the difference between the scale factors are output to the first encoding unit 350, and the scale factor calculating unit 341 is provided. Scale factor calculation unit 341
For example, according to the formula, for each scale factor band, one normalization coefficient (scale factor, 8 bits) is calculated so that the spectral data in the band fits within a predetermined number of bits, and the scale factor is used. Each spectrum in the scale factor band is quantized, and the scale factor difference is calculated.

The first encoding unit 350 encodes the data quantized by the first quantization unit 340 and the scale factor for each scale factor band into a predetermined stream format. , Huffman coding table 351 for further compressing each quantized data and each scale factor and the like.
Specifically, Huffman coding is performed so that each data quantized using the Huffman coding table 351 and each scale factor are transmitted at a low bit rate.

The second quantizing section 345 uses the auxiliary information based on the spectrum that is not quantized by the first quantizing section 340, that is, the spectrum data of the high frequency band of 11.025 kHz or higher output from the data separating section 330. Is output and the auxiliary information generation unit 346 for generating auxiliary information is provided. Here, the auxiliary information is simplified information which is calculated based on the spectrum data of the high frequency band and which briefly represents the characteristics of the spectrum data of the high frequency band with a small amount of information. In other words, of the spectrum data obtained by converting the input acoustic data for a certain period of time, it is the information representing the characteristics of the high frequency part of the frequency, and one specific example is the absolute value within the scale factor band of the high frequency part. It is an optimum scale factor for each scale factor band and its quantized value such that the quantized value of the maximum spectral data (spectral data having the maximum absolute value) is set to "1".

The second encoding unit 355 encodes the auxiliary information output from the second quantization unit 345 into a predetermined stream format and outputs it as second encoded information. A Huffman coding table 356 for coding is provided.

The stream output unit 390 adds header information and other necessary sub-information to the first coded signal output from the first coding unit 350 and adds the AAC coded bit stream as usual. And stores the second encoded signal output from the second encoding unit 355 in an area in the bitstream that is ignored by the conventional decoding device or its operation is not specified. . Specifically, the stream output unit 390 outputs the encoded signal output from the second encoding unit 355 to Fill Elem in the encoded bit stream of AAC.
Stored in nt or Data Stream Element.

However, as the information indicating the sampling frequency of the bit stream stored in the header information, a value that is half the sampling frequency of the acoustic data is stored.
That is, the sampling frequency of the acoustic data is 44.1.
For kHz, half the actual size is 22.05 kHz in the header
Information is stored. Then, the information indicating the actual sampling frequency of 44.1 kHz may be stored in the area or the like in which the auxiliary information is stored.

The bit stream output from the encoding device 300 is transmitted to the decoding device 400 via a transmission medium such as the Internet formed by radio waves, light or metal.

As described above, in the encoding device 300, when the spectrum data on the frequency axis obtained by the conversion unit 320 is quantized and encoded, the data separation unit 330 causes the spectrum data of the low frequency band (1024 points). ) And high-frequency spectrum data (1024 points), the low-frequency spectrum data is quantized and encoded by the same method as the conventional method, and the high-frequency spectrum data is different from the conventional method. Quantization of spectrum data is that the output is performed by quantizing and encoding with (generating auxiliary information and encoding auxiliary information), incorporating the encoded bit stream of the high frequency band into the encoded bit stream of the low frequency band, and outputting. , Coding device 10 of the related art for performing coding in the same manner over the entire band
It is very different from 00.

As a result, it is possible to encode a high-quality acoustic signal within the range in which the total amount of information does not increase significantly compared to the conventional one. In addition, the sampling frequency 2 in the header
Since the information of 2.05 kHz is stored, there is an effect that the conventional decoding device 2000 can also decode the bit stream generated by the encoding device 300 according to the present embodiment.

(Decoding Device 400) Decoding device 400 according to the present embodiment performs an acoustic signal on the time axis by performing a process substantially opposite to that of encoding device 300 on the bit stream output from encoding device 300. (Playback upper limit frequency 22.05
a stream input unit 4
10, the first and second decoding units 420 and 425,
The first and second dequantization units 430 and 435, the dequantized data combination unit 440, the deconversion unit 480, the acoustic data output unit 490, and the D / A converter 495 are provided.

The stream input section 410 is used by the encoding device 3.
00 is input via a transmission medium, and a first encoded signal stored in an area used by a conventional decoding device from the input bit stream and a conventional decoding device , And the second encoded signal stored in the area where the operation is not defined is extracted and output to the first decoding unit 420 and the second decoding unit 425, respectively.

The first decoding section 420 receives the first coded signal output from the stream input section 410 and decodes it from the stream format into quantized data. Huffman decoding table 421.

The first dequantization unit 430 dequantizes the quantized data decoded by the first decoding unit 420, and outputs spectrum data. The quantized data is output based on the formula. A processing unit 431 for inverse quantization is provided. Here, the number of samples of the spectrum data output by the first dequantization unit 430 is 1024, and these are 1
It represents a reproduction band of 1.025 kHz or less.

The second decoding unit 425 inputs the second coded signal output from the stream input unit 410 and decodes the auxiliary information, and a Huffman decoding table for decoding the auxiliary information. 426.

The second dequantization section 435 is for generating high frequency band spectrum data based on the auxiliary information, and includes a spectrum data generation section 436. Here, the number of samples of the spectrum data output by the second dequantization unit 435 is 1024, and these are 11.02.
Represents a playback band above 5 kHz.

The spectrum data generation unit 436 generates noise according to a predetermined procedure based on the spectrum data output from the first dequantization unit 430, and the second
The noise is shaped on the basis of the auxiliary information output from the decoding unit 425 of FIG.
This noise includes white noise, pink noise, and the like, as well as spectrum data obtained by copying a part or all of the low-frequency spectrum data.

Specifically, the spectrum data generator 43
6 is, for example, the spectrum data of the low frequency band output by the first dequantization unit 430 is copied to the high frequency band, and the spectrum copied into the band for each scale factor band of the high frequency band. Each spectral data in the band is a coefficient of the ratio between the absolute maximum value of the data and the value obtained by dequantizing the quantized value “1” using the scale factor value corresponding to the band described in the auxiliary information. The spectrum of the high frequency band is restored by multiplying by.

The dequantized data synthesizing unit 440 synthesizes the spectrum data output from the first dequantization unit 430 and the spectrum data output from the second dequantization unit 435. Here, the number of samples of the spectrum data output by the dequantized data synthesis unit 440 is 2048, which represents a reproduction band of 0 to 22.05 kHz.

As described above, the decoding device 400 includes the first (low-frequency band) code stored in the area used by the conventional decoding device from the bitstream coded by the coding device 300. The encoded signal and the second (high frequency band) coded signal stored in the area where the conventional decoding device ignores or does not specify the operation are separated, and the first (low frequency band) code is separated. Only the encoded signal is decoded and dequantized by the same method as the conventional method, and the second (high frequency band) encoded signal is decoded and dequantized by a method different from the conventional method,
Decoding device 2000 of Conventional Examples 1 and 2 that performs decoding and dequantization of a bit stream in the same system over the entire band in that the low band spectrum data and the high band spectrum data are combined and output. And the composition is very different.

As a result, it is possible to decode a significantly increased amount of information as compared with the conventional one, from the same small amount of information as the conventional one, and it is possible to decode a high-quality sound signal.
The inverse transform unit 480 converts the spectrum data on the frequency axis output from the inverse quantized data synthesis unit 440 into the IMDCT.
Is used to convert to 2048 samples (2 frames) of acoustic data on the time axis.

The acoustic data output unit 490 is the inverse conversion unit 48.
The sound data of 2048 samples on the time axis obtained at 0 are sequentially combined, and the sound data of 2048 samples are output one by one in time order.

The D / A converter 495 converts digital audio data into analog audio signals at a sampling frequency of 44.1 kHz. In this way, the decoding device 40
In the case of 0, the inverse transform unit in the inverse transform unit 480 is double (20
48 samples), and the acoustic data output unit 49
The frame length at 0 is doubled (2048 samples) and the sampling frequency at the D / A converter 495 is doubled (44.1 kHz). The configuration thereof is largely different from that of the digitalization device 2000.

As a result, the D / A converter 495 outputs 1
Spectrum data (1
024) and spectrum data of high frequency band (1024
In the high band (0 to 22.05 kHz),
Moreover, a high quality acoustic signal is output.

As described above, according to the functional configuration of the present embodiment, the low-frequency portion is subjected to the conventional encoding while the high-frequency portion is extremely controlled while being based on the information amount in the range that does not increase significantly compared with the conventional one. By encoding with a small amount of information, a high quality acoustic signal can be encoded and decoded.

Further, the coding device 3 in the present embodiment
00 and the decoding device 400 are similar to those of the conventional encoding device 1000 except that the data separation unit 330 and the second quantization unit 34 are used.
5 and the second encoding unit 355, and the second decoding unit 425, the second dequantization unit 435, and the dequantized data synthesis unit 440 are added to the conventional decoding device 2000. Therefore, there is an effect that the existing encoding device 1000 and the decoding device 2000 can be realized without significantly changing the configurations.

Further, the coding device 3 according to the present embodiment
The bit stream generated by 00 has an effect that it can be decoded by the conventional decoding device 2000.
Next, the encoding process of each unit of the encoding device 300 in the broadcasting system 1 will be specifically described.

FIG. 2 is a diagram showing a state change of the acoustic signal processed in the acoustic data input unit 310 and the conversion unit 320 of the encoding device 300 shown in FIG. In particular, FIG. 2A is a waveform diagram showing 2048 sample data on the time axis cut out by the acoustic data input unit 310 shown in FIG. 1, and FIG. 2B shows the sample data on the time axis. 3 is a waveform diagram showing spectrum data on the frequency axis after being converted by the MDCT 321 of the conversion unit 320 shown in FIG. In addition, in FIG. 2A and FIG. 2B, the sample data and the spectrum data are shown as analog waveforms, but in reality, both are digital signals. The same applies to the following waveform diagrams.

The sound data input unit 310 has 44.1k
The acoustic data sampled at Hz is input. The acoustic data input unit 310 outputs 1024 samples before and after the input of 2048 samples of this acoustic data.
The sample is overlapped and cut out, and the conversion unit 32 is used.
Output to 0.

The conversion section 320 performs MDCT on a total of 4096 samples of data, but since the spectrum obtained by MDCT has a bilaterally symmetrical waveform, half of that is 20.
The spectrum data corresponding to the 48 samples as shown in FIG. 2B is output.

In the spectrum data shown in FIG. 2B, the vertical axis represents the value of the frequency spectrum, that is, the amount (magnitude of the frequency component of the acoustic data represented by the voltage value of 2048 samples in FIG. 2A). Is represented by 2048 points corresponding to the number of samples. Also, the encoding device 3
Sound signal input to the sampling frequency 44.
Since the A / D conversion is performed at 1 kHz, the reproduction band of the spectrum data is 22.05 kHz. Furthermore, the spectrum obtained by MDCT 321 is shown in FIG.
Since it may take a negative value as shown in (b), MD
When encoding the spectrum obtained by CT321, it is necessary to also encode the positive and negative signs of the spectrum. In the following, in order to avoid confusion with the encoding code, the information indicating the positive and negative signs of the spectrum data is referred to as “sign information”.

The spectral data and sine information output from the conversion unit 320 are processed by the data separation unit 330 into a low frequency band of 0 to 11.025 kHz and 11.025.
The spectrum data and the like in the low frequency band are output to the first quantization unit 340, and the spectrum data and the like in the high frequency band are output to the second quantization unit 345.

FIG. 3 shows the first quantizer 34 shown in FIG.
It is a flowchart which shows operation | movement in the scale factor determination process of 0. The first quantizer 340 first
As an initial value of the scale factor, a scale factor common to each scale factor band is determined (S9
1) Using the scale factor, all low-frequency spectrum data to be transmitted as one frame (1024 samples) of acoustic data are quantized, and the difference before and after the obtained scale factor is calculated, and the difference is calculated. And the scale factor at the beginning and each quantized value are Huffman-encoded (S92). Since the quantization and the encoding here are performed only for counting the number of bits, it is assumed that only data is performed and information such as a header is not added in order to simplify the process.

Next, the first quantizer 340 determines whether or not the number of bits of the Huffman-encoded data exceeds a predetermined number of bits (S93). If the number of bits exceeds the predetermined number, the initial value of the scale factor is determined. (S101), the value of the scale factor is used, and quantization and Huffman coding are performed again for the same low-frequency spectrum data (S).
92), it is determined whether or not the number of bits of the low-frequency part encoded data for one frame after Huffman encoding exceeds a predetermined number of bits (S93), and this process is repeated until the number of bits is equal to or less than the predetermined number of bits. .

If the number of bits of the low frequency band encoded data does not exceed the predetermined number of bits, the first quantizer 340
The following process is repeated for each scale factor band to determine the scale factor of each scale factor band (S94). First, each quantized value in the scale factor band is inversely quantized (S95), and the difference between the respective absolute values of the respective inverse quantized values and the corresponding original spectrum data is obtained and summed (S96). Further, it is determined whether or not the calculated sum of the differences is a value within the allowable range (S97), and if it is within the allowable range, the above process is repeated for the next scale factor band (S94 to S98). .

On the other hand, if the allowable range is exceeded, the value of the scale factor is increased to quantize the spectrum data of the scale factor band (S10).
0), the quantized values are inversely quantized (S95), and the absolute value differences between the inverse quantized values and the corresponding spectrum data are summed (S96). Further, it is judged whether the total of the differences is within the allowable range (S97), and if it exceeds the allowable range,
The scale factor is sequentially increased until it is within the allowable range (S100), and the above processing (S95 to S97 and S
100) is repeated.

The first quantizer 340 determines that, for all scale factor bands, the sum of the difference between the values obtained by dequantizing the quantized values in the scale factor bands and the original spectrum data is within the allowable range. When such a scale factor is determined (S98), the low frequency band spectrum data for one frame is quantized again using the determined scale factor, and the difference between each scale factor, the leading scale factor and each quantization are performed. The value and Huffman coding are performed to determine whether or not the number of bits of the low frequency band encoded data exceeds a predetermined number of bits (S99).
If the number of bits of the low-frequency part encoded data exceeds the predetermined number of bits, the initial value of the scale factor is reduced until it becomes less than or equal to the predetermined number of bits (S101), and then the scale within each scale factor band is reduced. The process of determining the factor (S94 to S98) is repeated. If the number of bits of the low frequency band encoded data does not exceed the predetermined number of bits (S99), the value of each scale factor at that time is
Determine the scale factor of each scale factor band.

The first quantizer 340 quantizes the low-frequency spectrum data using the scale factor determined in this way, and quantizes the quantization value, the start of the determined scale factor, and the scale factor. The difference and the signature information received from the data separation unit 330 are used together with the first information.
To the encoding unit 350.

It should be noted that whether the sum of the difference between the dequantized value of the quantized value in the scale factor band and the original spectral data is within the allowable range is determined by
It is performed based on data such as a psychoacoustic model.

Further, here, the initial value of the scale factor is set to a relatively large numerical value, and when the number of bits of the low-frequency part coded data after Huffman coding exceeds a predetermined number of bits, sequentially, The scale factor is determined by a method of lowering the initial value of the scale factor, but it is not always necessary to do this. For example, set the initial value of the scale factor to a low value in advance,
The initial value is gradually increased, and when the total number of bits of the low-frequency part encoded data first exceeds the predetermined number of bits, the initial value of the scale factor set immediately before is used for each The scale factor of the scale factor band may be determined.

Further, here, the scale factor of each scale factor band is determined so that the total number of bits of the low-frequency part encoded data for one frame does not exceed a predetermined number of bits, but this need not always be the case. . For example, in each scale factor band, the scale factor may be determined so that each quantized value in the scale factor band does not exceed a predetermined number of bits. The operation of the first quantizer 340 in this process will be described below with reference to FIG.

FIG. 4 shows the first quantizer 34 shown in FIG.
It is a flowchart which shows the operation | movement in the other scale factor determination processing of 0. The first quantization unit 340 calculates scale factors for all scale factor bands in the low frequency band to be encoded by the following procedure (S1). Also, the first quantizer 340
Calculates the scale factor for all spectral data in each scale factor band by the following procedure (S2).

First, the first quantizer 340 quantizes the spectrum data with a predetermined scale factor value based on the formula (S3), and the quantized value is given to represent the quantized value. It is determined whether the number of bits has exceeded, for example, 4 bits (S4).

If the result of determination is that the quantized value exceeds 4 bits, the value of the scale factor is adjusted (S8),
The same spectrum data is quantized with the adjusted scale factor value (S3). The first quantization unit 340 determines whether the obtained quantization value exceeds 4 bits (S
4) The adjustment of the scale factor (S8) and the quantization with the adjusted scale factor (S3) are repeated until the quantized value of the spectrum data becomes a value of 4 bits or less.

If the result of determination is that the quantized value is 4 bits or less, the next spectrum data is quantized with a predetermined scale factor value (S3). When the quantized values of all the spectrum data in one scale factor band are 4 bits or less (S5), the first quantizer 340 sets the value of the scale factor at that time to the scale factor of the scale factor band. (S6).

Further, when the first quantizing section 340 determines the scale factors for all the scale factor bands (S7), it ends the process. Through the above processing, one scale factor is determined for each scale factor band in the low frequency band to be encoded. The first quantizer 340 quantizes the spectrum data in the low frequency band by using the scale factor determined in this way, and quantizes the 4-bit quantized value and the 8-bit scale factor. And the scale factor difference, the data separation unit 3
The signature information received from 30 is output to the first encoding unit 350.

The quantized value, scale factor, etc. output to the first encoding unit 350 are Huffman encoded and output to the stream output unit 390 as a first encoded signal equivalent to the case of downsampling. .

On the other hand, the second quantizing unit 345 generates auxiliary information based on the spectrum data of the high frequency band and the like.
FIG. 5 is a spectrum waveform diagram showing a specific example of the auxiliary information (scale factor) generated by the second quantizing unit 345 shown in FIG. 1, and FIG. 6 is the second quantizing unit shown in FIG. It is a flowchart which shows operation | movement in the auxiliary information (scale factor) calculation processing of 345.

In FIG. 5, the divisions on the frequency axis of the low frequency band are the divisions of the scale factor bands defined in the present embodiment. Also, in the high frequency part, the delimiter indicated by the broken line in the frequency direction is
The division of the scale factor band in the high frequency band defined in the present embodiment is shown. The same applies to the following waveform diagrams.

Of the spectrum data output from the conversion unit 320, the reproduction band 11.0 shown by the solid waveform in FIG.
The low frequency band below 25 kHz is output to the first quantizer 340 and quantized as usual. On the other hand, the high-frequency part up to the reproduction band 22.05 kHz exceeding the reproduction band 11.0525 kHz shown by the broken line waveform in FIG.
It is represented by the auxiliary information (scale factor) calculated by 45.

The calculation procedure of the auxiliary information (scale factor) of the second quantizer 345 will be described below with reference to the flowchart of FIG. 6 using the specific example of FIG. The second quantization unit 345 sets the quantization value of the absolute maximum spectrum data in each scale factor band to “1” for all scale factor bands in the high band up to the reproduction band 22.05 kHz that exceeds the reproduction band 11.0525 kHz. The optimum scale factor for "" is calculated according to the following procedure (S11).

The second quantizer 345 has a reproduction band of 11.
Absolute maximum spectral data (peak) in the first scale factor band in the high band above 025 kHz
Is specified (S12). In the specific example of FIG. 5, it is assumed that the position of the peak specified in the first scale factor band is and the value of the peak at that time is “256”.

The second quantizing section 345 applies the peak value "256" and the scale factor value of the initial value to the formula for calculating the quantized value, in the same manner as the procedure shown in the flowchart of FIG. The value of the scale factor sf at which the quantized value obtained from the formula is "1" is calculated (S13). For example, in this case, the value of the scale factor sf that sets the quantized value of the peak value “256” to “1”,
For example, sf = 24 is calculated.

For the first scale factor band, when the scale factor value sf = 24 for setting the peak quantized value to "1" is obtained (S14), the second quantizer 345 determines that the next scale factor band For, the peak of the spectrum data is specified (S12). For example, the position of the specified peak is and its value is "31.
2 ”, the value of the scale factor sf at which the quantized value of the peak value“ 312 ”becomes“ 1 ”, for example, sf
= 32 is calculated (S13).

Similarly, the second quantizing section 345, for the third scale factor band in the high frequency band, sets the value of the scale factor sf that makes the quantized value of the peak value "288""1", For example, sf = 26 is calculated, and the value of the scale factor sf that makes the quantized value of the peak value “203” “1”, for example, sf = 18 is calculated for the fourth scale factor band.

In this way, when the scale factor that makes the quantized value of the peak value "1" is calculated for all scale factor bands in the high frequency region (S1
4), the second quantization unit 345 calculates the scale factor of each scale factor band obtained by the calculation,
The data is output to the second encoding unit 355 as the auxiliary information of the high frequency band, and the process ends.

As described above, the auxiliary information (scale factor) is generated by the second quantizing unit 345. This auxiliary information (scale factor) is 1024.
If the high frequency part represented by the spectral data of the points is represented by the value of each scale factor from 0 to 255, each scale factor band in the high frequency part (here, 4
Each) can be represented by 8 bits. Further, if the difference of each scale factor is Huffman-encoded, the data amount may be further reduced. On the other hand, if the spectrum data of 1024 points in the high frequency band is quantized and Huffman-encoded by the conventional method as in the low frequency band, the data amount is expected to be at least about 300 bits. Therefore, this auxiliary information shows only one scale factor for each scale factor band in the high frequency band,
It can be seen that the data amount is significantly reduced as compared with the case where the high frequency part is quantized according to the conventional method.

Further, this scale factor shows a value which is almost proportional to the peak value (absolute value) in each scale factor band, and it is the spectrum data which has a constant value at 1024 points in the high frequency region or the spectrum in the low frequency region. It can be said that the spectrum data obtained by multiplying a part or the whole copy of the data by the scale factor roughly restores the spectrum data obtained based on the input acoustic signal. Also, for each scale factor band, the coefficient between the absolute maximum value of the spectral data copied in the band and the value obtained by dequantizing the quantized value “1” using the scale factor value corresponding to that band is used as a coefficient. As a result, the spectrum data can be restored more accurately by multiplying each spectrum data in the band. Further, since the difference in the waveform in the high frequency band is not as clearly audibly discriminated as in the low frequency band, the auxiliary information thus obtained is sufficient as information representing the waveform in the high frequency band. Can be said.

Here, the quantized value of the spectrum data in each scale factor band in the high frequency band is "1".
Although the scale factor is calculated so that it does not have to be “1”, it may be set to another value.

The auxiliary information generated by the second quantizer 345 is Huffman coded by the second encoder 355, and the stream output unit 390 decodes it as a second coded signal in the conventional decoding in the bit stream. It is stored in an area that is ignored by the computer or whose operation is not specified.

FIG. 7 shows the stream output unit 3 shown in FIG.
FIG. 9 is a diagram showing a position in a bitstream in which auxiliary information is stored by 90. In FIG. 7, the auxiliary information representing the spectrum of the high frequency band is coded and then stored as a second coded signal in an area in the bitstream that is not recognized as an acoustic coded signal.

The shaded portion in FIG. 7A is, for example, a region (Fill Element) filled with "0" to match the data length of the bit stream.
However, even if the auxiliary information representing the spectrum of the high frequency band, that is, the second coded signal is stored in this area,
The conventional decoding device 2000 does not recognize the coded signal to be decoded and ignores it.

Further, the hatched portion in FIG. 7B is, for example, the Data Stream Element.
The area (DSE) is an area in which only the physical structure such as the bit length is defined by the AAC standard for future expansion. This area is Fill
Similar to the Element, even if the auxiliary information indicating the spectrum of the high frequency part is stored here, the conventional decoding device 2
000 or the decoding device 20 for the read data even if the data is read
00 is an area in which the operation is not defined.

In the above description, the second coded signal is stored in the area in the bit stream which is ignored by the conventional decoding apparatus 2000 according to the MPEG-2 AAC standard. The information may be incorporated at a predetermined position, the second encoded signal may be incorporated at a predetermined position in the first encoded signal, or may be incorporated over both of them. Further, since the second coded signal is stored in the bit stream, it is not necessary to secure a continuous area in the header and the first coded signal. That is, as shown in FIG. 7C, the second coded signal may be discontinuously incorporated in the header information and the first coded information.

FIG. 8 shows the stream output unit 3 shown in FIG.
It is a figure which shows the other example in case 90 stores auxiliary information. FIG. 8A shows the stream 1 in which only the first coded signal is continuously stored for each frame. FIG. 8B shows stream 2 in which only the second encoded signal in which the auxiliary information is encoded is continuously stored for each frame corresponding to stream 1.

The stream output section 390 may store the second coded signal in the stream 2 which is completely different from the stream 1 which is the bit stream storing the first coded signal. For example, stream 1 and stream 2 are
It is a bitstream transmitted on different channels.

As described above, by transmitting the first coded signal and the second coded signal by completely different bit streams, the low frequency part representing the basic information of the input acoustic signal is transmitted or accumulated in advance. In addition, there is an effect that the high frequency band information can be added later if necessary.

In the formats shown in FIGS. 7 and 8, the information indicating the sampling frequency of the bit stream stored in the header stores 22.05 kHz which is half the actual sampling frequency. deep. Thereby, the decoding device 20 of the first conventional example
Even with 00, a bit stream in the 0 to 11.025 kHz band can be decoded and reproduced in the same manner as in the case of downsampling.

Next, the difference between the system of the coding device 300 according to the embodiment of the present invention and the system of the coding device 1000 of the first conventional example will be described with reference to FIG. FIG. 9 is a diagram showing a comparison between the method according to the embodiment and the method (down-sampling method) according to the conventional example 1, and in particular, FIG.
FIG. 9 is a diagram showing a system according to the embodiment, and FIG. 9B is a diagram showing a system according to Conventional Example 1.

In the system according to the present embodiment, the sampling frequency is set to 44.1 kHz,
An acoustic data string is acquired every 2.7 μsec, and 2048 pieces included in the frame to be encoded and 10 pieces before and after that are included.
A total of 4096 pieces of 24 pieces are cut out and MDCT to obtain 2048 pieces of spectrum data. The reproduction band of this spectrum data is 22.05k
Represents Hz. The 2048 pieces of spectrum data are separated into spectrum data (1024 pieces) in the low band part and spectrum data (1024 pieces) in the high band part at the boundary of 11.025 kHz. The low-band spectrum data (1024 pieces) is subjected to normal quantization and coding to obtain a first coded signal of high quality and low bit rate equivalent to down sampling. Moreover, 1024 pieces of spectrum data have been acquired also in the high frequency region. If this is subjected to normal quantization / encoding, a low bit rate cannot be realized. Therefore, in the method according to the present embodiment, the second coded signal is obtained by generating auxiliary information from 1024 spectrum data in the high frequency band and encoding only the auxiliary information. Therefore, it is possible to encode a high-quality acoustic signal within a range in which the total amount of information does not increase significantly.

On the other hand, in the conventional downsampling method of the first example, the sampling frequency is set to 2
By setting the frequency to 2.05 kHz, an acoustic data string every 45 μsec is acquired, and 1024 pieces included in the frame to be coded and 512 pieces before and after the total of 204 pieces are included in total.
Eight pieces are cut out and MDCT is performed to obtain 1024 pieces of spectrum data. The reproduction band of this spectrum data represents 11.025 kHz. Normal quantization / encoding is performed on the 1024 pieces of spectrum data. Therefore, although a high-quality coded signal can be obtained for 11.025 kHz or less,
Since there is no spectrum data in the high frequency band exceeding 11.025 kHz, the encoded signal in the high frequency band cannot be acquired.

Next, the difference between the system of the coding device 300 according to the embodiment of the present invention and the system of the coding device 1000 of the second conventional example will be described with reference to FIG. FIG. 10 is a diagram showing a comparison between the method according to the embodiment and the method according to the conventional example 2, and particularly FIG. 10A is a diagram showing the method according to the embodiment, and FIG. 8] is a diagram showing a method according to Conventional Example 2. [FIG. Since the method according to the present embodiment has been described above, its explanation is omitted.

In the sampling system of the second conventional example, 22.7 μsec is set by setting the sampling frequency to 44.1 kHz as in the case of the present embodiment.
While obtaining the acoustic data sequence for each, 2048 pieces of 1024 pieces included in the frame to be encoded and 512 pieces before and after that are cut out, and MDCT is performed to obtain 1024 pieces of spectrum data. . The reproduction band of this spectrum data represents 22.05 kHz. Normal quantization / encoding is performed on the 1024 pieces of spectrum data. That is, every half time (about 22.7 msec) of the present embodiment, 1024 pieces of spectrum data (512 in the low frequency band below 11.025 kHz and 51 in the high frequency band over 11.025 kHz).
2) have been acquired.

Here, in the encoding apparatus 1000 of the conventional example 2, as in the embodiment of the present invention, 11.025-2.
It is assumed that the auxiliary information is generated from the high-frequency spectrum data of 2.05 kHz. In this case, about 2
The number of bits that can be used for quantization is n every 2.7 msec.
And the number of bits that can be used as auxiliary information is m1, it is necessary to quantize 512 samples in the low frequency band (0 to 11.025 kHz) with (n-m1) bits. On the other hand, in the case of the embodiment of the present invention, if the number of bits that can be used in quantization for each approximately 45.4 msec is 2 × n and the number of bits that can be used as auxiliary information is m2, the low band (0 to 0 11.025kHz) 1024 samples (2
Xn-m2) bits may be quantized.

By the way, in AAC, it is generally known that high coding efficiency cannot be obtained unless a certain number of samples (threshold value) are collected.
In the case of 12 samples, the threshold value is not reached, and in the case of 1024 samples of the present embodiment, the threshold value is sufficiently exceeded.

Therefore, it is better to quantize 1024 samples with (2 × n-m2) bits as in the present embodiment than to quantize 512 samples with (n-m1) bits as in Conventional Example 2. , Higher coding efficiency is obtained.
Further, as a result of higher coding efficiency being obtained in the present embodiment, m2 can be made larger (m2> 2 × m1), and it becomes possible to improve the sound quality in the high frequency range.

FIG. 11 shows the coding method of this embodiment,
It is the figure which compared the spectrum data and the characteristic with the encoding system of the prior art examples 1 and 2. In this embodiment,
Sampling frequency is 44.1kHz and frame length is 2
The number is 048. Therefore, in the spectrum data, 1024 pieces of spectrum data in the low frequency band of 0 to 11.025 kHz and auxiliary information based on 1024 pieces of spectrum data in the high frequency band of 11.25 to 22.05 kHz are acquired. . As a result, in the present embodiment, the band is substantially the same as that of Conventional Example 2, but is wider than that of Conventional Example 1. Further, in the present embodiment, in terms of sound quality, the quality is the same in the low frequency range of 0 to 11.025 kHz as compared with the conventional example 1, but 11.025 to 22.0.
Since there is auxiliary information in the high-frequency part of 5 kHz, the quality is high as a whole, which is 11.025 to the conventional example 2.
Since there is auxiliary information in the high frequency part of 22.05 kHz, it is possible to obtain substantially the same quality, and 0 to 11.02.
The low-frequency part of 5 kHz has high quality because the number of spectrum data is doubled, and therefore the quality is high as a whole.

On the other hand, in the conventional example 1, the sampling frequency is 22.05 kHz, the frame length is 1024, and the spectrum data is 0 to 11.025 kHz.
In this band, 1024 pieces of spectrum data are acquired. As a result, in Conventional Example 1, the band is halved and narrowed as compared with the present embodiment. Therefore, in terms of sound quality, the same quality is obtained in the low frequency band of 0 to 11.025 kHz, but there is no spectrum data in the high frequency band of 11.025 to 22.05 kHz, which is bad.
It becomes low as a whole.

In the conventional example 2, the sampling frequency is 44.1 kHz and the frame length is 1024.
In the spectrum data, 1024 pieces of spectrum data are acquired in the entire band of 0 to 22.05 kHz. As a result, in Conventional Example 2, the band is the same as that of the present embodiment, but in terms of sound quality, 11.025 to 22.0.
In the high frequency band of 5 kHz, the spectrum data is coded so that the quality is high, but the band 0 to 11.025.
Since the number of spectrum data is halved in the low frequency part of kHz, the quality is deteriorated and the quality is deteriorated as a whole.

Therefore, according to this embodiment, the low-frequency part is encoded by the conventional method, and the high-frequency part is encoded by an extremely small amount of information. It is possible to encode a high quality acoustic signal within a range that does not increase significantly.

Next, the encoding process of each unit of the decoding device 400 in the broadcasting system 1 will be concretely described. The first coded signal output from the stream input unit 410 is decoded into quantized data and the like by the first decoding unit 420, and coded into low-frequency spectrum data by the first dequantization unit 430. Be converted. On the other hand, the stream input unit 4
The second decoded signal output from 10 is decoded into auxiliary information by the second decoding unit 425. The second dequantization unit 435 generates spectrum data in the high frequency band based on the auxiliary information. The processing in the second dequantization unit 435 will be described in detail.

FIG. 12 is a flow chart showing a procedure for copying the low frequency band 1024 spectrum in the forward direction to the high frequency band by the second dequantization unit 435 shown in FIG.
Such copying of the spectrum data of the low frequency band is executed when generating the spectrum data of the high frequency band.

In FIG. 12, inv_spec1
[I] indicates the value of the i-th spectrum in the output data of the first dequantization unit 430, and inv_spec2
[J] indicates the value of the j-th spectrum in the input data of the second inverse quantization unit 435.

First, since the second dequantization unit 435 inputs the 0th spectrum to the 1023nd spectrum in the same direction, the initial values of the counters i and j for counting the number of spectra are respectively set to "0". Set to (S
71). Next, the second dequantization unit 435 checks whether or not the value of the counter i is less than “1024” (S7
2) If the value of the counter i is less than “1024”, the value of the i-th (0th in this case) spectrum of the low-frequency part of the first dequantization unit 430 is set to the second dequantization unit. The value is input as the value of the jth (0th in this case) spectrum of the high frequency band 435 (S73). After this, the second dequantization unit 43
5 increments the values of the counters i and j by "1" (S74), and the value of the counter i is "1024".
It is checked whether it is less than (S72).

The second inverse quantizer 435 repeats the above process while the value of the counter i is less than "1024".
When the value of the counter i becomes "1024" or more, the processing ends.

As a result, the entire spectrum of the 0 to 1023th low frequency band, which is the result of the inverse quantization by the first dequantization unit 430, is directly used as the high frequency band spectrum of the second dequantization unit 435. To be copied.

The spectrum data thus copied is the auxiliary information decoded by the second decoding unit 425, that is, the spectrum data copied according to the value of the scale factor for setting the peak value to "1". The amplitude is adjusted and output as high-frequency spectrum data. Note that the amplitude is adjusted for each scale factor band by dequantizing the quantized value “1” using the absolute maximum value of the spectrum data copied in the band and the scale factor value corresponding to that band. This is achieved by multiplying each spectrum data in the band by using the ratio of and as a coefficient. Here, the maximum number of samples of the spectrum data output by the second dequantization unit 435 is 1024, which represents a reproduction band exceeding 11.025.

In FIG. 12, the low frequency band 1024
Although the procedure of copying the spectrum to the high frequency part in the forward direction of the frequency axis direction is shown, it may be copied in the reverse direction as shown in FIG.

FIG. 13 is a flow chart showing a procedure for copying the low frequency band 1024 spectrum to the high frequency band in the direction opposite to the frequency axis direction by the second dequantization unit 435 shown in FIG. Similar to FIG. 12, inv.
_Spec1 [i] indicates the value of the i-th spectrum in the output data of the first dequantization unit 430, and inv
_Spec2 [j] represents the value of the j-th spectrum in the input data of the second inverse quantization unit 435.

First, since the second dequantization unit 435 inputs the 0th spectrum to the 1023th spectrum in the reverse direction, the initial value of the counter i for counting the number of spectra is set to "0". The initial value of j is "1023"
(S81). Then, the second inverse quantizer 4
35 checks whether the value of the counter i is less than "1024" (S82), and if the value of the counter i is less than "1024", the i-th low-frequency part of the first dequantization unit 430 is checked. The value of the (0th in this case) spectrum is input as the value of the jth (1023th in this case) spectrum in the high-frequency part of the second dequantization unit 435 (S83). After that, the second dequantization unit 435 increments the value of the counter i by "1", decrements the value of j by "1" (S84), and the value of the counter i becomes "102".
It is checked whether it is less than 4 "(S82).

The second inverse quantizer 435 repeats the above process while the value of the counter i is less than "1024",
When the value of the counter i becomes "1024" or more, the processing ends.

As a result, the entire spectrum of the 0 to 1023th low frequency band, which is the result of dequantization by the first dequantization unit 430, becomes 1023 to 0 of the high frequency band of the second dequantization unit 435.
The second spectrum is copied in the reverse direction.

Also in this case, the copied spectrum data is the spectrum data copied according to the auxiliary information decoded by the second decoding unit 425, that is, the value of the scale factor for setting the peak value to "1". Is adjusted and output as high-frequency spectrum data. Note that the amplitude is adjusted for each scale factor band by dequantizing the quantized value “1” using the absolute maximum value of the spectrum data copied in the band and the scale factor value corresponding to that band. This is achieved by multiplying each spectrum data in the band by using the ratio of and as a coefficient. Here, the second dequantization unit 435
The maximum number of samples of spectrum data output by is 102
4, which represents a playback band above 11.025.

The second inverse quantizer 435 copies all the spectrum data in the low frequency band to the high frequency band, but may copy only a part of the spectrum data. In addition, as a procedure for copying the entire high-frequency part and the low-frequency part at a time, FIG.
Although the case of No. 3 has been described as an example, it may be partially copied as shown in FIG. 12 and partially copied as shown in FIG.

Further, a part or all of them may be copied by inverting the positive and negative signs. Furthermore, these copying procedures may be determined in advance, changed according to the data in the low frequency band, or transmitted as auxiliary information.

Further, here, the spectrum data on the low frequency band side is copied as the spectrum data on the high frequency band side, but the present invention is not limited to this, and the spectrum data on the high frequency band side is only the second coding information. May be generated from

Further, in the present embodiment, as the noise generation in the second dequantization unit 435, the case where the spectrum data obtained from the first dequantization unit 430 is mainly copied has been described. Not limited, spectral data with a constant value in each scale factor band in the high frequency band, white noise,
The second dequantization unit 435 may uniquely generate pink noise or the like, or may generate it in accordance with the auxiliary information.

1 output from the second inverse quantizer 435
The 024 pieces of spectrum data are combined with the spectrum data (1024 pieces) output from the first inverse quantization section 430 in the inverse quantized data combination section 440, and IMDC
The audio signal in the reproduction band of 0 to 22.05 kHz is reproduced by being inversely converted into acoustic data on the time axis by being T-converted and being D / A converted at the sampling frequency of 44.1 kHz.

As described above, according to the present invention, the MDCT and IMDCT having the double conversion length of the conventional method are used to obtain 204
The conventional coding was performed on only the first 1024 samples of the spectrum data of 8 samples, and the remaining 1024 samples of the latter half were coded with a smaller amount of information as compared with the conventional method, and they were combined at the time of decoding.

Since the amount of information required to encode the spectrum data of 1024 samples in the latter half can be reduced, the first half 10
It was possible to increase the amount of information required for encoding the spectrum data of 24 samples, and it was possible to perform wideband encoding while improving the accuracy of the original signal in the low frequency band.

The bit stream generated by the coding apparatus in this embodiment can also be decoded by the conventional decoding apparatus. Next, various modifications of the auxiliary information and its decoding will be described.

FIG. 14 shows the second quantizer 3 shown in FIG.
It is a spectrum waveform diagram which shows the specific example of the other auxiliary information (quantization value) produced | generated by 45. In addition, FIG.
9 is a flowchart showing an operation in another auxiliary information (quantized value) calculation process of the second quantizer 345 shown in FIG. 1.

The second quantizer 345 has a reproduction band of 11.
A scale factor value common to all scale factor bands in the high band up to a reproduction band of 22.05 kHz exceeding 025 kHz, for example, "18" is set in advance, and the scale factor value "18" is used. Each time, the quantized value of the absolute maximum spectrum data (peak) in the scale factor band is calculated (S21).

The second quantizer 345 has a reproduction band of 11.
Absolute maximum spectral data (peak) in the first scale factor band in the high band above 025 kHz
Is specified (S22). In the specific example of FIG. 14, it is assumed that the position of the peak specified in the first scale factor band is, and the value of the peak at that time is “256”.

The second quantizing unit 345 applies a predetermined common scale factor value "18" and the peak value "256" to the formula for calculating the quantized value, and calculates the quantized value ( S23). For example, in this case, when the peak value “256” is quantized with the scale factor value “18”, the quantized value “6” is calculated.

When the quantized value "6" of the peak value "256" is obtained for the first scale factor band (S24), the second quantizing unit 345 causes the peak of the spectral data for the next scale factor band. (S22), for example, when the position of the specified peak is and its value is “312”, the quantized value of the peak value “312” having the scale factor value of “18”, for example, "10" is calculated (S23).

Similarly, the second quantizing unit 345, with respect to the third scale factor band in the high frequency part, quantizes the value "9" of the peak value "288" having the scale factor value "18". Is calculated, and the quantized value “5” of the peak value “203” having the scale factor value of “18” is calculated for the fourth scale factor band.

In this way, for all scale factor bands in the high frequency band, when the quantized values of the peak values when the scale factor is fixed to "18" are calculated (S24), the second quantization is performed. The unit 345 outputs the quantized value of each scale factor band obtained by the calculation to the second encoding unit 355 as auxiliary information of the high frequency band, and ends the process.

As described above, the auxiliary information (quantized value) is generated by the second quantizer 345. This auxiliary information (quantized value) is high, which is represented by the spectrum data of 1024 points. The region is represented by a 4-bit quantized value for each of the four scale factor bands.
On the other hand, in the above-mentioned auxiliary information (scale factor), the high frequency part is represented by the scale factor of 8 bits for each of the four scale factor bands, so by comparison with this, the amount of data in the high frequency part is It is more reduced. In addition, this quantized value roughly represents the amplitude of the peak value (absolute value) in each scale factor band, and is one of the spectrum data that has a constant value at 1024 points in the high frequency band or the spectrum data in the low frequency band. It can be said that the spectrum data obtained based on the input acoustic signal is roughly restored even if the spectrum data is obtained by simply multiplying a copy of all or part of the copy. In addition, for each scale factor band, the ratio between the absolute maximum value of the spectral data copied in the band and the value obtained by dequantizing the quantized value corresponding to that band using a predetermined scale factor value. By multiplying each spectrum data in the band by using as a coefficient, the spectrum data can be restored more accurately.

In this embodiment, the scale factor value corresponding to the quantized value transmitted as the second coded information is set in advance, but the optimum scale factor value is calculated and It may be added to the second encoded information and transmitted. For example, if the scale factor is selected so that the maximum quantized value is 7, the number of bits representing the quantized value is 3 bits, and therefore the amount of information required to transmit the quantized value is smaller. .

FIG. 16 is a block diagram of the second quantizer 3 shown in FIG.
It is a spectrum waveform diagram which shows the specific example of the other auxiliary information (positional information) produced | generated by 45. In addition, FIG.
9 is a flowchart showing an operation in another auxiliary information (positional information) calculation process of the second quantizer 345 shown in FIG. 1.

The second quantizer 345 has a reproduction band of 11.
The position of the absolute maximum spectrum data in each scale factor band is specified according to the following procedure for all scale factor bands in the high band up to a reproduction band of 22.05 kHz exceeding 025 kHz (S3
1).

The second quantizer 345 has a reproduction band of 11.
Absolute maximum spectral data (peak) in the first scale factor band in the high band above 025 kHz
Is specified (S32). In the specific example of FIG. 16, the position of the identified peak in the first scale factor band is, and is 2 from the beginning of this scale factor band.
It is assumed that it is the second spectrum data. The second quantizer 345 determines the position of the identified peak “22nd spectrum data from the beginning of the scale factor band”.
Is held (S33).

For the first scale factor band, when the peak position is specified and held (S3
4), the second quantization unit 345 identifies the peak of the spectrum data for the next scale factor band (S32). For example, it is assumed that the identified peak position is and is the 60th spectrum data from the beginning of the scale factor band. Second quantizer 345
Holds the position of the identified peak "60th spectral data from the beginning of the scale factor band" (S33).

In the same manner, the second quantizing section 345 will be described below.
Specifies and holds the peak position "spectral data at the beginning of the scale factor band" for the third scale factor band in the high frequency region, and holds the peak position "scale factor band" for the fourth scale factor band. 25 from the beginning of
Th spectral data "is specified and retained.

In this way, when the peak positions are specified and held for all scale factor bands in the high frequency band (S34), the second quantizer 345 is used.
The second coding unit 35 uses the held peak position of each scale factor band as auxiliary information in the high frequency band.
5 is output, and the process ends.

As described above, the auxiliary information (positional information) is generated by the second quantizing unit 345. This auxiliary information (positional information) is in the high-frequency part represented by the spectrum data of 1024 points. Are represented by 6-bit position information for each of the four scale factor bands.

In this case, in decoding apparatus 400, second dequantization section 435 received part or all of the spectrum data of 1024 samples in the low frequency band from second decoding section 425. It is copied as 1024 sample data on the high frequency side according to the auxiliary information (positional information).
The copying procedure is to extract similar data from the spectrum data output from the first dequantization unit 430 based on the peak information of the spectrum data in one or more scale factor bands, and partially or entirely. It is achieved by copying. In addition, the second dequantization unit 43
In 5, the amplitude of the copied spectrum data is adjusted if necessary. The adjustment of the amplitude is achieved by setting each spectrum data as a predetermined coefficient, for example, “0.5”, and multiplying this coefficient. This coefficient may be a fixed value, may be changed for each band or for each scale factor band, or may be changed by the first dequantization unit 43.
You may change according to the spectrum data output from 0.

Although a predetermined coefficient is used in the above, the value of this coefficient may be added to the second coded information as auxiliary information. Alternatively, a scale factor value as a coefficient may be added to the second encoded information, or a quantized value of a peak in the scale factor band may be added as a coefficient to the second encoded information. The amplitude adjusting method is not limited to this, and other methods may be used.

In this embodiment, only the position information or only the position information and the coefficient information is encoded as the auxiliary information, but the auxiliary information is not limited to this, and the scale factor, the quantized value, and the spectrum The sign information and the noise generation method may be encoded. In addition, these 2
You may encode in combination of one or more.

Further, although the spectrum data on the low frequency band side is copied as the spectrum data on the high frequency band side, the present invention is not limited to this, and the spectrum data on the high frequency band side is generated only from the second coded information. May be.

FIG. 18 is a block diagram of the second quantizer 3 shown in FIG.
It is a spectrum waveform diagram which shows the specific example of the other auxiliary information (sign information) produced | generated by 45. In addition, FIG.
6 is a flowchart showing an operation in another auxiliary information (sign information) calculation process of the second quantizer 345 shown in FIG. 1.

The second quantizer 345 has a reproduction band of 11.
For all scale factor bands in the high band up to the reproduction band 22.05 kHz exceeding 025 kHz, the signature information of the spectrum data at a predetermined position of each scale factor band, for example, the center of the scale factor band, is specified according to the following procedure. (S41).

The second quantizer 345 has a reproduction band of 11.
The sign information of the spectrum data at the center position of the first scale factor band in the high frequency band exceeding 025 kHz is checked (S42), and the value is held. For example, the sine code of the spectral data at the center of the first scale factor band is "+". The second quantizer 345 assigns this code “+” to the 1-bit value “1”.
And hold it. If this code is "-", it is represented by "0" and held.

For the first scale factor band, when the signature information of the spectrum data at the center position of the scale factor band is held (S43),
The second quantizer 345 checks the sign of the spectrum data at the center position for the next scale factor band (S42). For example, the checked code is "+"
Then, the second quantization unit 345 holds “1” as the signature information of the spectrum data at the center position of the second scale factor band.

In the same manner, the second quantizer 345 is also used.
Examines the sign "+" of the spectrum data at the center position of the third scale factor band in the high frequency region, holds the sign information "1", and holds the sign "1" of the spectrum data at the center position of the fourth scale factor band ""+" Is checked and the signature information "1" is held.

In this way, when the sign information of the spectral data at the center position is held for all scale factor bands in the high frequency band (S43), the second quantizing unit 345 holds each of them. The sign information of the scale factor band is output to the second encoding unit 355 as auxiliary information of the high frequency band, and the process ends.

As described above, the auxiliary information (sign information) is generated by the second quantizing unit 345. This auxiliary information (sign information) is in the high-frequency part represented by the spectrum data of 1024 points. Are represented by 1-bit sign information for each of the four scale factor bands, and a spectrum in the high frequency band can be represented with a very short data length.

In this case, in decoding apparatus 400, second dequantization section 435 copies part or all of the spectrum data of 1024 samples in the low frequency band as the high frequency band side spectrum, and outputs the second spectrum. The code of the spectrum data at a predetermined position is determined according to the sign information input from the decoding unit 425.

Here, the sign information representing the code at the center position of each scale factor band in the high frequency band is used as the auxiliary information (sign information), but it is not limited to the center position of the scale factor band. It may be the signature information at the peak position, the signature information at the beginning of the scale factor band, or any other predetermined position.

Also, here, the position of the spectrum data corresponding to the code (sign information) to be transmitted is predetermined, but this is the first dequantization unit 43.
It may be changed according to the output of 0, or position information indicating the position of the sign information of each scale factor band may be added to the second encoded information and transmitted. .

Further, in the second inverse quantizer 435,
If necessary, adjust the amplitude of the copied spectral data. The amplitude can be adjusted by multiplying each spectrum data by a predetermined coefficient, for example, its value is “0.5”.

This coefficient may be a fixed value, may be changed for each band or for each scale factor band, or may be changed according to the spectrum data output from the first dequantization unit 430. Good. The amplitude adjusting method is not limited to this, and other methods may be used.

Although a predetermined coefficient is used in this embodiment, the value of this coefficient may be added to the second coded information as auxiliary information. Also, a scale factor value as the coefficient may be added to the second encoded information, or a quantized value as the coefficient may be added to the second encoded information.

Further, only the signature information as auxiliary information,
Alternatively, only the sign information and the coefficient information, or only the sign information and the position information, or only the sign information, the position information, and the coefficient information are coded, but the present invention is not limited to this.
Quantization values, scale factors, characteristic spectral position information, noise generation methods, etc. may be encoded. Also, two or more of these may be combined and coded.

Further, in the present embodiment, the spectrum data on the low frequency band side is copied as the spectrum data on the high frequency band side, but not limited to this, the spectrum data on the high frequency band side is the second. It may be generated only from the encoded information.

Further, in the above description, the sign "+" is represented by the 1-bit value "1" and the sign "-" is represented by "0". However, the sign of the sign in the auxiliary information (sign information) is ,
The value is not limited to this, and may be represented by another value.

FIG. 20 shows the second quantizer 3 shown in FIG.
FIG. 16 is a spectrum waveform diagram showing an example of a method of creating other auxiliary information (copy information) generated by 45. Figure 20
(A) is a waveform diagram showing a spectrum in the first scale factor band in the high frequency region. FIG. 20 (b)
FIG. 6 is a waveform diagram showing an example of a spectrum waveform of a low frequency region specified by auxiliary information (copy information). Further, FIG. 21 is a flowchart showing an operation in another auxiliary information (copy information) calculation process of the second quantizer 345 shown in FIG.

The second quantizer 345 has a reproduction band of 11.
For all scale factor bands in the high band up to the reproduction band 22.05 kHz exceeding 025 kHz, the peak position n from the beginning of the scale factor band
In contrast to (nth from the beginning), the number N of the scale factor band in which the peak position from the beginning of the scale factor band in the low frequency part is the value closest to n is specified according to the following procedure (S51).

The second quantizer 345 has a reproduction band of 11.
Absolute maximum spectral data (peak) in the first scale factor band in the high band above 025 kHz
The position n of is specified (S52). As a result, for example, as shown in FIG. 20A, it is assumed that the identified peak position is and its spectrum is the spectrum data of n = 22 in this scale factor band.

The second quantizing section 345 specifies the positions of all peaks (both positive and negative) of the spectrum in the low frequency band where the frequency of the spectrum is 11.025 kHz or less in the reproduction band (S53).

Next, the second quantizing unit 345 searches for a scale factor band whose position from the peak to the beginning of the scale factor band is closest to n for all the peaks specified in the low frequency band, and then the scale factor band is searched. The number N of the factor band, the direction of the search, and the sign information of the peak are specified (S54).

Specifically, the second quantizing unit 345, for all the specified peaks (both positive and negative), sequentially from the peak on the low frequency side, the position from the peak is closest to n. Search for the beginning of the factor band. There are two search directions: a case (1) in which a search is performed in the direction of a lower frequency from the peak and a case (2) in which a search is performed in the direction of a higher frequency from the peak. Also, regarding the peak in the low frequency band where the positive and negative signs are inverted from the peak in the high frequency band, when searching in the direction of the lower frequency from the peak (3), the direction of the high frequency from the peak is further pursued. There are two ways to search (4).

Of these, when the search directions are (2) and (4), when the low-frequency spectrum waveform is copied based on this peak information, as shown in FIG. Since the waveform in which the position of the high-frequency peak and the position of the low-frequency peak are horizontally inverted in the scale factor band (frequency axis direction) is copied, for example, (1)
The search direction of (3) and (3) is the forward direction, and (2) and (4)
It is necessary to attach information indicating forward and backward of the search direction, with and as the reverse direction. When the search directions are (3) and (4), the peak position in the high frequency band and the peak position in the low frequency band are vertically (vertical axis direction) as shown in FIG. Since the inverted waveform is copied, it is necessary to attach information indicating whether the positive and negative signs of the peak value in the high frequency band and the peak value in the low frequency band are inverted.

The second quantizer 345 specifies the low-frequency part in the search directions of (1) and (2) if the peak specified in the low-frequency part has a positive value. If the peak has a negative value, a search is performed in four directions including (3) and (4), and in the search results, the scale factor band whose position from the peak is closest to n is selected. Identify the number. In this case, the error range with respect to n is set in advance to a predetermined value, for example, “5”, and the scale factor band whose position from the peak is closest to n is selected from the four search results. , Specify the scale factor band number N. At the same time, sign information indicating whether the positive and negative signs of the peak value of the high frequency band and the peak value of the low frequency band are inverted,
The information indicating the reverse of the search direction is specified.

For example, in the search direction (1), FIG.
It is assumed that the scale factor band number N = 3 is specified by the position error “1” from the peak corresponding to the spectrum in the low frequency band as shown in (1) of (b). Also,
In the search direction (2), the position factor from the peak is “5” and the scale factor band number N = corresponding to the low frequency band spectrum as shown in (2) of FIG.
18 is specified. Similarly, in the search direction (3), the error of “4” occurs in the scale factor band corresponding to the spectrum of the low frequency band as shown in (3) of FIG. With the number N = 12 and the search direction (4), FIG.
It is assumed that the scale factor band number N = 10 is specified by the error “2” corresponding to the spectrum in the low frequency band as shown in (4) of (b). Second quantizer 345
Selects the number N = 3 of the scale factor bands whose position error from the peak is “1” and whose position from the peak is closest to n, out of the four identified scale factor band numbers. At the same time, the sign information "1" indicating the sign "+" of the peak in the low frequency band and the search direction information "1" indicating that the search is further performed from the peak toward the lower frequency are generated. In this case, if the sign of the peak is "-", the sign information is "1", and if the search is performed in the higher frequency direction from the peak, the search direction information is "0".

When the scale factor band number N = 3, the sign information "1", and the search direction information "1" are specified for the first scale factor band in the high frequency band (S55), the second quantization is performed. Similarly to the above, the unit 345 specifies the scale factor band number N, its sign information, and its search direction information for the next scale factor band.

In this way, for all scale factor bands in the high frequency region, the peak position from the beginning of the scale factor band is the value closest to n with respect to the peak position n from the beginning. When the number N of the scale factor band in the low frequency band, its sign information, and its search direction information are specified (S55), the second quantization unit 345 determines that each scale factor band of the specified high frequency band. The scale factor band number N, the sign information, and the search direction information corresponding to the low frequency band are output to the second coding unit 355 as auxiliary information (copy information) in the high frequency band, and the process ends.

In this case, decoding apparatus 400 decodes the first coded signal according to the conventional procedure to obtain spectrum data of 1024 samples on the low frequency side. The second dequantization unit 435 copies a part or all of the spectrum data corresponding to the scale factor band number output from the second decoding unit 425 as the high frequency band spectrum. Further, the second dequantization unit 435 adjusts the amplitude of the copied spectrum data as needed. To adjust the amplitude, a predetermined coefficient for each spectrum, for example, its value is set to "0.
5 ”and can be achieved by multiplying by the coefficient.

This coefficient may be a fixed value, or for each band,
It may be changed for each scale factor band, or may be changed according to the spectrum data output from the first dequantization unit 430.

In this embodiment, a predetermined coefficient is used for adjusting the amplitude, but the value of this coefficient may be added to the second coded information as auxiliary information. Further, a scale factor value as a coefficient may be added to the second coded information, or a quantized value as a coefficient may be added to the second coded information. The amplitude adjusting method is not limited to this, and other methods may be used.

Further, the sign information and the search direction information in addition to the scale factor band number N were extracted as auxiliary information (copy information) in the high frequency band, but depending on the amount of information that can be transmitted in the high frequency band. The sign information and the search direction information may be omitted. Further, the sign information is "1" if the sign of the peak in the low frequency band is "+", and "0" if it is "-", and the search direction information is from the peak toward the lower frequency direction. The search is represented as "1", and the search from the peak toward higher frequencies is represented as "0". However, the sign of the low-frequency peak in the sign information and the search direction in the search direction information are expressed as follows. However, each is not limited to these values, and may be represented by other values.

Further, the beginning of the scale factor band whose distance is closest to n from the position of each peak specified in the low frequency band is searched, but the present invention is not limited to this example, and each scale in the low frequency band is searched. You may search for the peak whose distance from the head of the factor band is the closest to n.

FIG. 22 shows the second quantizer 3 shown in FIG.
FIG. 16 is a spectrum waveform diagram showing a second example of a method of creating other auxiliary information (copy information) generated by 45. FIG. 23 is a flowchart showing the operation in the second calculation process of the other auxiliary information (copy information) of the second quantizer 345 shown in FIG.

The second quantizer 345 has a reproduction band of 11.
For all scale factor bands in the high band up to a reproduction band of 22.05 kHz above 025 kHz, the difference (energy difference) between the spectrum and all spectra in that scale factor band is the minimum in the low band scale factor band. The number N is specified according to the following procedure (S61). However, the number of spectra in the low-frequency part that is different from that in the high-frequency part is equal to the number of spectra in the scale-factor band of the high-frequency part, and the number N of the specified scale factor band is
It is the scale factor band number at the beginning of the spectrum.

The second quantizing section 345 determines, for all scale factor bands in the low frequency band (S62), from the same number of spectrum data as the spectrum data in the scale factor band in the high frequency band from the beginning of the scale factor band. Then, the difference between the spectrum of the high frequency band and the spectrum of the low frequency band is calculated with the width of the frequency (S63). For example, in the waveform diagram shown in FIG. 22, if the first scale factor band of the high frequency band is the scale factor band of the number of spectrum data = 48, the second quantizing unit 345 determines that the number N of the low frequency band is N. For the 48 spectral data from the beginning of the scale factor band of = 1, the difference between the spectra of the high frequency band and the low frequency band is sequentially calculated.

The second quantizing section 345 obtains the difference in spectrum between the high frequency band and the low frequency band for the same number of spectrums as the scale factor band in the high frequency band (S6).
5) Hold that value, and from the beginning of the scale factor band of the next low frequency band, the width of the frequency of the spectrum data of the same number as the spectrum in the scale factor band of the high frequency band, the high frequency spectrum and the low frequency band. The difference with the partial spectrum is obtained (S64). For example, when the spectrum difference is obtained within the width of 48 pieces of spectrum data from the beginning of the scale factor band with the number N = 1 of the low frequency portion, the value of the obtained difference is held and the low frequency portion The difference of the spectrum is obtained with the width of 48 pieces of spectrum data from the head of the scale factor band of number N = 2. Similarly, the scale factor band of the number N = 3 in the low frequency band,
The scale factor band of number N = 4, ..., The scale factor band of number N = 28 (the end of the low frequency band), such that all the scale factor bands in the low frequency band are sequentially arranged in the high frequency band and the low frequency band. The difference between the spectrum data is obtained by summing the differences between the 48 spectrum data with the region.

For all scale factor bands in the low frequency band, from the beginning of the scale factor band, the width of the spectrum data is the same as the number of spectrum data in the scale factor band in the high frequency band, and the high frequency band spectrum and the low frequency band are When the difference from the spectrum is obtained (S6
4), the second quantization unit 345 identifies the number N of the scale factor band that minimizes the obtained difference (S65). For example, it is assumed that the scale factor band of number N = 8 in the low frequency band is specified in the spectrum waveform diagram shown in FIG. This means that the spectrum of the shaded part in the low frequency band has the smallest difference from the spectrum of the shaded part in the high frequency band, and the energy difference between the spectra is the smallest. That is, the 48 spectral data from the beginning of the scale factor band of number N = 8 is shown by a dashed line in the high frequency region of FIG. 22 when copied to the first scale factor band in the high frequency region starting from 11.25 kHz. It becomes a waveform, and the energy in the scale factor band of the high frequency part can be approximately represented with respect to the original spectrum.

When the second quantizing section 345 specifies the number N of the low-range scale factor band for which the spectrum difference is the minimum for the high-frequency scale factor band, it specifies the number N of the specified scale factor band. In the same manner as described above, the number N of the corresponding scale factor band is specified for the next scale factor band in the high frequency band (S66). Hereinafter, this process is sequentially repeated for each scale factor band in the high frequency region, and when the number N of the low frequency region scale factor band in which the spectrum difference is the smallest among all the high frequency region scale factor bands is specified, The number N of the scale factor band in the low frequency section that has been held is output to the second encoding unit 355 as auxiliary information (copy information) in the high frequency section, and the processing ends.

In this case, the method of copying the low frequency side spectrum and the method of adjusting the amplitude in decoding apparatus 400 are the same as the case of the auxiliary information (copy information) described with reference to FIGS. 20 and 21.

Further, in the flow chart of FIG. 23, when calculating the energy difference between the high band part and the low band part, the same sign and the same direction on the frequency axis are used. However, the coding apparatus of the present invention Without being limited to this, as described with reference to FIGS. 20 and 21, the energy difference between the high band part and the low band part may be calculated using any of the following three methods. The value of each spectrum data of the high band part and the low band part has the same sign, and for the high band part spectral data sequentially selected from the low frequency side to the high frequency side, the low band scale factor band With respect to the same number of spectrum data as the high frequency part from the head, the spectrum data is sequentially selected from the high frequency side to the low frequency side (that is, in the opposite direction on the frequency axis), and the difference is calculated. The sign of the low-pass spectrum is inverted (multiplied by minus), and calculation is performed in the same direction on the frequency axis. The sign of the low-pass spectrum is inverted (multiplied by minus), and calculation is performed in the opposite direction on the frequency axis. Moreover, after performing the calculation by all of these four methods, the number N of the scale factor band of the low-pass spectrum of which the energy difference is the smallest may be used as the auxiliary information. In this case, in order to correctly copy the low frequency band spectrum with the minimum energy difference to the high frequency band, information indicating the relationship between the codes of the low frequency band spectrum and the high frequency band spectrum and the low frequency band in the high frequency band are used. Information indicating the direction on the frequency axis where the partial spectrum is copied is included in the auxiliary information for each scale factor band. The information indicating the relationship between the codes of the low-frequency band spectrum and the high-frequency band spectrum is, for example, 1 bit when the difference is taken with the same code and “0” when the difference is taken with the opposite code. expressed. In addition, the information indicating the direction on the frequency axis when copying the low frequency band spectrum to the high frequency band is, for example, when copying in the forward direction, that is, the spectrum data is selected in the high frequency band and the low frequency band. If the direction is the forward direction, it is "1", and if it is copied in the reverse direction, that is, if the direction of selecting the spectrum data in the high band part and the low band part is the reverse direction, it is set to "0" and 1 bit expressed.

Although the case where the example of the audio data distribution system according to the above embodiment is applied to the broadcasting system has been described, the audio data distribution from the server to the terminal via the transmission medium such as the Internet in a bit stream is performed. It may be applied to a data distribution system, and the bit stream output from the encoding device 300 may be a CD or a DV.
The data is temporarily recorded on a recording medium such as an optical disc such as D, a semiconductor, a hard disk, etc., and the decoding device 40 is passed through this recording medium.
It may be applied to an audio data distribution system in which 0 is reproduced.

In the above embodiment, the LONG block is used, but the SHORT block may be used, and the same processing as that performed in the LONG block may be performed in this SHORT block.

Further, in the encoding process, Gain Con
troll and TNS (TEMPORAL NOISE S
HAPING), psychoacoustic model, M / S Stereo
o, Intensity Stereo, Predic
You may use tools, such as tion, and switching of a block size, a bit reservoir, etc.

Further, in the above embodiment, the auxiliary information is generated based on the spectrum data of the high frequency band separated by the data separation unit 330, but the value obtained by dequantizing the output of the first quantization unit 340 is used. May be used as the spectrum data of the high frequency band, and the auxiliary information may be generated based on the spectrum data of the high frequency band.

Further, as auxiliary information, a scale factor and a quantized value such that the quantized value of the spectrum data in each scale factor band in the high frequency part becomes "1",
Although the characteristic position information of the spectrum and the sine information indicating the positive and negative signs of the spectrum are used, a combination of two or more of these may be used as the auxiliary information. in this case,
It is particularly effective if the auxiliary information is encoded by combining the coefficient indicating the ratio of the amplitude, the position of the absolute maximum spectrum data and the like with the scale factor. Further, in the present embodiment, as the second encoded signal, one side information is encoded in each scale factor band, but one side information is encoded in each of two or more scale factor bands. Alternatively, two or more pieces of auxiliary information may be encoded in one scale factor band.
In addition, as the auxiliary information in the present embodiment, the auxiliary information may be encoded for each channel, or one auxiliary information may be encoded for two or more channels.

Further, in the present embodiment, the number of quantization units and the number of encoding units in encoding apparatus 300 are 2 respectively.
However, the present invention is not limited to this, and three or more quantization units and decoding units may be provided.

In the present embodiment, the decoding device 400 has two decoding units and two dequantization units, but the number of decoding units and dequantization units is not limited to two. A quantizer may be provided.

Further, the above-mentioned processing can be realized not only by hardware but also by software, and a configuration may be such that a part is realized by hardware and the rest is realized by software. Further, in the above embodiment, the sampling frequency is 44.1 kHz, but it is 32 kHz, 48 kHz.
Etc., and the frequency of the boundary to be separated in the data separation unit 330 may be changed to a frequency other than 11.025 kHz.

Further, although AAC is carried out in the above embodiment, other systems (eg MP3, AC3, etc.) are used.
The same may be applied to the encoding device, the decoding device, and the like.

The encoding device may be constructed as follows. That is, an encoding device that encodes acoustic data, and cut-out means that continuously cuts out a number m2 of acoustic data that exceeds the requested number m1 from an acoustic data string.
(M2-m1) conversion means for converting the acoustic data cut out by the cutting-out cutting means into spectrum data on the frequency axis, m2 spectrum data obtained by the conversion, and m1 low-frequency spectrum data (m2-m1) )
Separation means for separating into individual high-frequency spectrum data,
Low frequency band encoding means for quantizing and encoding the separated low frequency band spectrum data, and auxiliary information for generating auxiliary information indicating the characteristics of the high frequency band frequency spectrum from the separated high frequency band spectrum data. Generating means, high band encoding means for coding the generated auxiliary information, code obtained by the low band encoding means and code obtained by the high band encoding means are combined. It may be characterized in that it is provided with an output means for outputting.

In this case, the auxiliary information generating means, for the spectral data divided into a plurality of groups,
In each group of the high frequency part, a configuration is characterized in that a value obtained by quantizing the spectrum data that becomes a peak is calculated as a constant value, and the calculated normalization coefficient is generated as the auxiliary information. can do.

Further, the auxiliary information generating means uses the normalization coefficient common to each group for the spectrum data divided into a plurality of groups, and sets the spectrum data having a peak in each group in the high frequency band. The configuration may be characterized in that quantization is performed and the quantized value is generated as the auxiliary information.

Further, the auxiliary information generating means is characterized in that, with respect to the spectrum data divided into a plurality of groups, the frequency position of the spectrum data having a peak in each group of the high frequency band is generated as the auxiliary information. It can be configured to.

Further, the spectrum data is an MDCT coefficient, and the auxiliary information generating means, for the spectrum data divided into a plurality of groups, gives a sign indicating whether the spectrum data is positive or negative at a predetermined frequency position in the high frequency band. It can be configured to be generated as the auxiliary information.

Further, the auxiliary information generating means specifies, for each of the high band parts, the low band part spectrum which is most approximate to the spectrum in the high band part of the spectrum data divided into a plurality of groups. Can be generated as the auxiliary information. In this case, the auxiliary information generating means is a distance on the frequency axis from the group delimiter to the peak of the high frequency band spectrum in the group, and a frequency from the group delimiter of the low frequency band to the peak of the low frequency band spectrum. It is possible to adopt a configuration characterized in that the low-frequency band spectrum having the smallest difference from the axial distance is specified. Further, the auxiliary information generating means is characterized by specifying a spectrum in a low frequency band portion having a minimum difference value when an energy difference is obtained in the same frequency width as a spectrum in the group in the high frequency band portion. It can be configured. In addition, the information that specifies the spectrum of the low frequency band is a number that specifies the group of the specified low frequency band spectrum.

[0206] Further, the auxiliary information generating means may be characterized in that a predetermined coefficient representing an amplification ratio of the amplitude of the high frequency band spectrum is generated as the auxiliary information.

Further, the output means further converts the data coded by the low frequency band coding means into a coded audio stream defined in a predetermined format, and a region in the coded audio stream. In addition, a stream output unit that stores and outputs the data encoded by the high frequency encoding unit is provided in an area whose use is not restricted by the encoding protocol. it can. In this case, the stream output unit may be configured to write information indicating f1 Hz as a sampling frequency.

Further, the output means further converts the data coded by the low frequency band encoding means into a coded audio stream defined in a predetermined format and the high frequency band coding means. A configuration may be provided that includes a second stream output unit that stores encoded data in a stream different from the encoded acoustic stream and outputs the stream.

An encoding method and a communication method which are realized as a communication system composed of the encoding device and the decoding device of this modified example, or which have the characteristic means constituting the encoding device and the communication system as steps are described. Or as
The characteristic means and steps constituting the above-mentioned encoding device are C
It can be realized as an encoding program to be executed by the PU,
It goes without saying that it can be realized as a computer-readable recording medium in which these programs are recorded.

[0210]

As is apparent from the above description, the encoding device according to the present invention is an encoding device for encoding acoustic data, and a continuous fixed number of acoustic data is cut out from an acoustic data string. Cutting-out means, converting means for converting the cut-out acoustic data into spectrum data on the frequency axis, and the spectrum data obtained by the conversion in the f
Separation means for separating low-band spectrum data up to 1 Hz and high-band spectrum data higher than f1 Hz, low-band coding means for quantizing and coding the separated low-band spectrum data, From the separated high frequency band spectrum data, auxiliary information generation means for generating auxiliary information indicating the characteristics of the high frequency band spectrum, high frequency band encoding means for coding the generated auxiliary information, and And output means for synthesizing and outputting the code obtained by the high frequency area encoding means and the code obtained by the high frequency area encoding means,
The f1 is less than half the sampling frequency f2 when the acoustic data string is created.

In the encoding apparatus of the present invention, the converting means outputs a large number of low-frequency spectrum data of f1 or less from the acoustic data string cut out by the cutting-out means and at the same time outputs high-frequency spectrum data exceeding f1. To do. Then, the spectrum data of the low frequency band separated by the separating means is quantized and encoded, and the spectrum data of the high frequency band is encoded into auxiliary information representing the characteristics of the high frequency band of the frequency, and the high frequency band. The encoding means encodes the generated auxiliary information.

Therefore, within a range in which the total amount of information does not increase significantly, it is possible to encode the acoustic signal with high quality in the low frequency region equivalent to the down sampling and in the high frequency region reproducible.

Here, f1 is f2 / 4, the conversion means converts the acoustic data into spectrum data of 0 to 2 × f1 Hz, and the separation means 0 to f1H.
It is characterized in that it is separated into low-frequency spectrum data of z and high-frequency spectrum data of f1 to 2 × f1 Hz, and the low-frequency spectrum data up to f1 Hz is n.
Of the spectrum data, the cut-out means cuts out the acoustic data of the number necessary to generate the 2 × n spectrum data, and the conversion means cuts the cut-out acoustic data of 2 × n pieces. It is characterized in that it is converted into spectrum data, and the separating means separates into n pieces of low band spectrum data and n pieces of high band spectrum data, and the cutting means is a unit of coding.
2 × n pieces of spectrum data, which is a combination of n pieces of sound data corresponding to a frame and n / 2 pieces of sound data belonging to each of two frames adjacent to the frame, are cut out, and the conversion means cuts out the spectrum data. The above-mentioned conversion is performed on 2 × n acoustic data obtained by MDCT,
0 to 2 × f1 Hz consisting of 2 × n spectrum data
The spectrum may be converted into a spectrum of

Further, the decoding apparatus according to the present invention is a decoding apparatus for decoding coded data input via a recording medium or a transmission medium, and is a low frequency part coding included in the coded data. Extraction means for respectively extracting the data and the high frequency band encoded data, and the low frequency band spectrum of frequency f1 or less by decoding and dequantizing the low frequency band encoded data extracted by the extraction means. Low-frequency part dequantizing means for outputting data, and auxiliary-information decoding means for decoding auxiliary data extracted by the extracting means to generate auxiliary information representing characteristics of the high-frequency spectrum data. A high-frequency part inverse quantization means for outputting spectrum data of a high-frequency part based on the auxiliary information generated by the auxiliary information decoding means; and a low-frequency part inverse quantization means. Synthesis means for synthesizing the high-frequency spectrum data and the high-frequency spectrum data output by the high-frequency inverse quantization means, and the spectrum data synthesized by the high-frequency spectrum inverse conversion to the acoustic data on the time axis. And an acoustic data output means for outputting the acoustic data inversely transformed by the inverse transformation means in chronological order.

In the decoding apparatus of the present invention, the extracting means extracts the low band encoded data and the high band encoded data from the input encoded data, and the low band inverse quantizing means It outputs the spectrum data of the low frequency part of the frequency f1 or less. The auxiliary information decoding means decodes the auxiliary information, and the high frequency part inverse quantization means outputs the spectrum data of the high frequency part based on the auxiliary information. Therefore, it is possible to decode a significantly increased amount of information as compared with the related art from a little amount of information that is almost the same as that of the related art, and it is possible to decode an audio signal of high sound quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a broadcasting system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state change of an acoustic signal processed by the encoding device shown in FIG.

3 is a flowchart showing an operation in a scale factor determination process of a first quantizer shown in FIG.

FIG. 4 is a flowchart showing another operation in the scale factor determination processing of the first quantizer shown in FIG.

5 is a spectrum waveform diagram showing a specific example of auxiliary information (scale factor) generated by the second quantization unit shown in FIG.

FIG. 6 is a flowchart showing an operation in auxiliary information (scale factor) calculation processing of the second quantization unit shown in FIG. 1.

FIG. 7 is a diagram showing a position in a bitstream where auxiliary information is stored by the stream output unit shown in FIG.

FIG. 8 is a diagram showing another example in which the stream output unit shown in FIG. 1 stores auxiliary information.

FIG. 9 is a diagram showing a comparison between the processes of the encoding device shown in FIG. 1 and the conventional example 1;

FIG. 10 is a diagram showing a comparison between the processes of the encoding device shown in FIG. 1 and the conventional example 2;

FIG. 11 is a diagram comparing and comparing spectrum data and characteristics of the encoding device shown in FIG. 1 and conventional examples 1 and 2.

FIG. 12 is a flowchart showing a procedure in which a low frequency band 1024 spectrum is forwardly copied to a high frequency band by the second dequantization unit shown in FIG. 1.

FIG. 13 is a flowchart showing a procedure in which the second dequantization unit shown in FIG. 1 copies the low frequency band 1024 spectrum to the high frequency band in the direction opposite to the frequency axis direction.

FIG. 14 is a spectrum waveform diagram showing a specific example of other auxiliary information (quantization value) generated by the second quantization unit shown in FIG. 1.

FIG. 15 is a flowchart showing an operation in another auxiliary information (quantized value) calculation process of the second quantizer shown in FIG. 1.

16 is a spectrum waveform diagram showing a specific example of other auxiliary information (positional information) generated by the second quantizer shown in FIG.

17 is a flowchart showing an operation in another auxiliary information (positional information) calculation process of the second quantizer shown in FIG.

18 is a spectrum waveform diagram showing a specific example of other auxiliary information (sign information) generated by the second quantization unit shown in FIG.

19 is a flowchart showing an operation in another auxiliary information (sign information) calculation process of the second quantizer shown in FIG.

20 is a spectrum waveform diagram showing an example of a method of creating other auxiliary information (copy information) generated by the second quantization unit shown in FIG.

FIG. 21 is a flowchart showing an operation in another auxiliary information (copy information) calculation process of the second quantizer shown in FIG.

22 is a spectrum waveform diagram showing a second example of a method of creating other auxiliary information (copy information) generated by the second quantizer shown in FIG. 1. FIG.

23 is a flowchart showing an operation in a second calculation process of another auxiliary information (copy information) of the second quantizer shown in FIG. 1.

[Fig. 24] Fig. 24 is a block diagram illustrating configurations of a conventional AAC encoding device and decoding device.

[Explanation of symbols]

1 broadcasting system 300 encoding device 305 A / D converter 310 Sound data input section 320 converter 330 Data Separator 340 First quantizer 345 Second quantizer 350 First Encoding Unit 355 Second Encoding Unit 390 stream output section 400 Decoding device 410 Stream input section 420 First decoding unit 425 second decoding unit 430 First dequantization unit 435 Second inverse quantizer 440 Dequantized data synthesizer 480 Inverse converter 490 Acoustic data output section 495 D / A converter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mineo Tsushima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Naoya Tanaka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5D045 DA20                 5J064 AA02 BA16 BC02 BC06 BC07                       BC15 BC16 BC29 BD02

Claims (27)

[Claims] 1. A coding device for coding acoustic data, comprising: a cutting-out means for cutting out a continuous fixed number of acoustic data from an acoustic data string; and converting the cut-out acoustic data into spectrum data on a frequency axis. Converting means for separating the spectrum data obtained by the conversion into low-frequency spectrum data up to f1 Hz and high-frequency spectrum data higher than f1 Hz, and separated low-frequency spectrum data A low-band part encoding means for quantizing and coding the high-band part, auxiliary information generating means for generating auxiliary information indicating the characteristics of the high-band frequency spectrum from the separated high-band spectrum data, and the generated auxiliary part. A high band encoding means for coding information, a code obtained by the low band encoding means and a code obtained by the high band encoding means. Above f1 and output means for outputting the encoding device, wherein the acoustic data string is less than half the sampling frequency f2 when it is created. 2. The f1 is f2 / 4, the conversion means converts the acoustic data into spectrum data of 0 to 2 × f1 Hz, and the separation means includes low frequency band spectrum data of 0 to f1 Hz. And the high-frequency spectrum data of f1 to 2 × f1 Hz are separated from each other. 3. The low-frequency part spectrum data up to f1 Hz is composed of n pieces of spectrum data, and the cut-out means cuts out the acoustic data of the number necessary to generate 2 × n spectrum data. The converting means converts the cut-out acoustic data into 2 × n spectrum data, and the separating means separates into n low-frequency spectrum data and n high-frequency spectrum data. The encoding device according to claim 2, wherein 4. The cut-out means includes n pieces of acoustic data corresponding to one frame which is a unit of encoding, and n / 2 belonging to each of two frames adjacent to the frame.
2 × n spectrum data combined with each piece of acoustic data is cut out, and the conversion means performs the conversion on the cut out 2 × n sound data by MDCT to obtain 2 × n spectrums. 4. The encoding device according to claim 3, wherein the encoding device converts the data into a spectrum of 0 to 2 * f1 Hz. 5. The normalization coefficient, wherein the auxiliary information generating means, with respect to the spectrum data divided into a plurality of groups, a value obtained by quantizing the peak spectrum data is a constant value in each group in the high frequency band. The encoding apparatus according to claim 1, wherein the encoding coefficient is calculated, and the calculated normalization coefficient is generated as the auxiliary information. 6. The auxiliary information generating means, with respect to the spectral data divided into a plurality of groups, spectral data having a peak in each group in a high frequency region,
Quantize using a normalization coefficient common to each group,
The coding apparatus according to claim 1, wherein the quantized value is generated as the auxiliary information. 7. The auxiliary information generating means generates, as the auxiliary information, the frequency position of the spectrum data having a peak in each group in the high frequency region for the spectrum data divided into a plurality of groups. The encoding device according to claim 1. 8. The spectrum data is an MDCT coefficient, and the auxiliary information generating means, for the spectrum data divided into a plurality of groups, assigns a sign indicating whether the spectrum data is positive or negative at a predetermined frequency position in a high frequency band. The encoding device according to claim 1, wherein the encoding device is generated as the auxiliary information. 9. The auxiliary information generating means, for the spectrum data divided into a plurality of groups, information for specifying a spectrum of a low frequency band which is most approximate to a spectrum in the high frequency band in each group of the high frequency band. The encoding device according to claim 1, wherein is generated as the auxiliary information. 10. The auxiliary information generating means includes the distance on the frequency axis from the group delimiter to the high band spectrum peak in the group, and the low band group delimiter to the low band spectrum peak. 10. The encoding apparatus according to claim 9, wherein the low-frequency band spectrum having the smallest difference from the distance on the frequency axis of is specified. 11. The auxiliary information generating means specifies a spectrum in a low frequency band portion having a minimum difference value when a difference in energy is taken in the same frequency width as a spectrum in the group in the high frequency band portion. The encoding device according to claim 9, which is characterized in that 12. The encoding apparatus according to claim 9, wherein the information for specifying the low-frequency band spectrum is a number for specifying the group of the specified low-frequency band spectrum. 13. The encoding apparatus according to claim 1, wherein the auxiliary information generating means generates a predetermined coefficient representing the amplification ratio of the amplitude of the high frequency band spectrum as the auxiliary information. 14. The output means further converts the data coded by the low frequency band coding means into a coded audio stream defined in a predetermined format, and a region in the coded audio stream. 2. A stream output unit for storing and outputting the data encoded by the high band encoding unit in an area of which the use is not restricted by an encoding rule. Encoding device. 15. The encoding apparatus according to claim 14, wherein the stream output unit writes information representing f2 / 2 Hz as a sampling frequency. 16. The output means further converts the data coded by the low frequency band encoding means into a coded acoustic stream defined in a predetermined format, and the high frequency band coding means. The encoding device according to claim 1, further comprising a second stream output unit that stores encoded data in a stream different from the encoded audio stream and outputs the stream. 17. A decoding device for decoding coded data input via a recording medium or a transmission medium, the low-band part coded data and the high-band part coded data included in the coded data. And a low-band inverse quantum that outputs low-band spectral data of a frequency f1 Hz or less by decoding and dequantizing the low-band encoded data extracted by the extracting unit. The auxiliary information decoding means for generating auxiliary information representing the characteristics of the high frequency band spectrum data by decoding the high frequency band data extracted by the extraction means, and the auxiliary information decoding means. A high-frequency part inverse quantization means for outputting high-frequency part spectrum data based on the generated auxiliary information; and a low-frequency part spectrum data output by the low-frequency part dequantization means. A synthesizing means for synthesizing the high frequency band spectrum data outputted by the high frequency band inverse quantizing means, and an inverse transforming means for inversely transforming the spectral data synthesized by the synthesizing means into acoustic data on a time axis, A decoding device comprising: acoustic data output means for outputting acoustic data inversely transformed by the inverse transformation means in chronological order. 18. The normalization coefficient, wherein the auxiliary information is calculated so that, when the peak value in each group in the high frequency region is quantized for the spectral data divided into a plurality of groups, the value becomes a constant value. The high-frequency part inverse quantization means uses the normalization coefficient in the generated auxiliary information, is a constant value common to each group of the high-frequency part, and is a predetermined value in each group. Dequantize the quantized value corresponding to the frequency spectrum data,
18. The decoding apparatus according to claim 17, wherein the spectrum data as a result of the inverse quantization generates high frequency band spectrum data that is a peak of each group. 19. The auxiliary information is obtained by quantizing spectral data having a peak in each group in a high frequency part of the spectral data divided into a plurality of groups using a normalization coefficient common to each group. Is a quantized value obtained by, the high-frequency part inverse quantization means, the quantized value in the generated auxiliary information, using a normalization coefficient common to each group of the high-frequency part 18. The inverse-quantized spectrum data as a result of the inverse-quantization to generate high-frequency part spectrum data that is a peak of each group.
Decoding device as described. 20. The auxiliary information is a frequency position of spectrum data having a peak in each group of a high frequency part in the spectrum data divided into a plurality of groups, and the high frequency part inverse quantization means generates 18. The decoding apparatus according to claim 17, wherein the frequency position in the generated auxiliary information generates high frequency band spectrum data having a peak in each high frequency band group. 21. The auxiliary information is a sign indicating whether the spectrum data divided into a plurality of groups is positive or negative at a predetermined frequency position in a high frequency band, and the high frequency band inverse quantization means is a high 18. The decoding device according to claim 17, wherein the spectrum data at a predetermined frequency position in the high frequency band generates high frequency band spectrum data having the code in the generated auxiliary information. 22. The auxiliary information is information that specifies, for each of the high frequency band groups, the low frequency band spectrum that is the closest to the spectrum in the group, with respect to the spectrum data divided into a plurality of groups. The high frequency part inverse quantization means, based on the auxiliary information,
The decoding device according to claim 17, wherein predetermined noise is generated in each group of the high frequency band and is added to the spectrum data to generate high frequency band spectrum data. 23. An audio data distribution system for distributing, via a recording medium or a transmission medium, acoustic data compressed and encoded into a low bit rate bit stream, and the encoding device according to claim 1. Item 17. An audio data distribution system comprising the decoding device according to Item 17. 24. A program used in an encoding device for encoding an input acoustic signal, the program causing a computer to function as each unit included in the encoding device according to claim 1. 25. A program used in a decoding device for decoding encoded data input via a recording medium or a transmission medium, the computer functioning as each unit included in the decoding device according to claim 17. Program to let. 26. A computer-readable recording medium in which the program according to claim 24 is recorded. 27. A computer-readable recording medium recording the program according to claim 25.