JP2003140692A - Coding device and decoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coding device and a decoding device for realizing coding and decoding of a wide range of digital acoustic signals. SOLUTION: The decoding device 100 is provided with: a 1st coding part 132 for coding a low frequency region among the spectral data obtained by converting an input acoustic signal for a certain time; a 2nd quantization part 133 for generating auxiliary information expressing the features of a high frequency region among the spectral data obtained by converting the input acoustic signal for a certain time; a 2nd coding part 134 for coding the generated auxiliary information; and a stream output part 140 or outputting the data coded by the 1st coding part 132, and the data coded by the 2nd coding part 134.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high quality audio encoding and decoding technique for digital audio data.

[0002]

2. Description of the Related Art Currently, various audio compression methods for compressing and encoding audio data have been developed. MPEG-2 Ad
advanced Audio Coding (hereinafter AA
(Abbreviated as C) is one of the methods. For details of AAC, refer to "ISO / IEC 13818-7 (MPEG-2).
Advanced Audio Coding, AA
C) ”.

First, the conventional encoding and decoding procedure is shown in FIG.
2 is used for the explanation. FIG. 22 shows a conventional MPEG-2.
Encoding device 300 and decoding device 40 based on the AAC method
It is a block diagram which shows the structure of 0. Encoding device 300
Is an apparatus for compressing and encoding an input acoustic signal based on the MPEG-2 AAC encoding method, and is an acoustic signal input unit 310, a conversion unit 320, a quantization unit 331, an encoding unit 332, and a stream output unit. 340.

The acoustic signal input section 310 includes, for example, 44.
At a sampling frequency of 1 kHz, digital audio data as an input signal is cut out for every 1024 continuous samples. The coding unit of 1024 samples is called "frame".

The conversion unit 320 uses the MD of the sample data on the time axis cut out by the acoustic signal input unit 310.
It is converted into spectrum data on the frequency axis by CT. The spectral data of 1024 samples converted at this point is classified into a plurality of groups. Each of the groups is set so that each of the plurality of groups includes one or more samples of spectral data. Also, each of these groups simulates a critical band in human hearing. Each of the groups is called a “scale factor band”.

The quantizer 331 quantizes the spectrum data obtained from the converter 320 with a predetermined number of bits. M
PEG-2 AAC quantizes the spectral data within the scale factor band using one normalization factor for each scale factor band. 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 332 Huffman-encodes the data quantized by the quantization unit 331, that is, each scale factor and the spectrum data quantized using the scale factor into a stream format. At this time, the encoding unit 332 obtains the difference between the scale factors of the scale factor bands adjacent to each other in the front and rear in one frame, and performs the Huffman encoding on the difference and the scale factor of the leading scale factor band.

The stream output unit 340 includes a coding unit 33.
The encoded signal obtained from 2 is converted into an MPEG-2 AAC bitstream and output. Encoding device 300
The bit stream output from is transmitted to the decoding device 400 via a transmission medium, or recorded on a recording medium such as an optical disk such as a CD or a DVD, a semiconductor, a hard disk, or the like.

The decoding device 400 is a device for decoding the bitstream coded by the coding device 300, and comprises a stream input section 410, a decoding section 421,
The inverse quantization unit 422, the inverse conversion unit 430, and the acoustic signal output unit 440 are included.

The stream input section 410 is used by the encoding device 3.
The bit stream coded by "00" is input through the transmission medium or the recording medium after being reproduced, and the coded signal is extracted from the input bit stream. The decoding unit 421 decodes the extracted coded signal from the stream format into quantized data.

The dequantization section 422 dequantizes the quantized data decoded by the decoding section 421. MPEG-2
AAC decodes Huffman-encoded data. The inverse transform unit 430 transforms the spectrum data on the frequency axis obtained by the inverse quantization unit 422 into sample data on the time axis. In MPEG-2 AAC, IMDC
T (Inverse Modified Discre
te CosineTransform). The acoustic signal output unit 440 sequentially combines the sample data on the time axis obtained by the inverse conversion unit 430, and outputs it as digital acoustic data.

In the actual MPEG-2 AAC encoding process, in addition to this, Gain Control and TN are also used.
S (TEMPORAL NOISE SHAPIN
G), psychoacoustic model, M / S Stereo, Int
There are cases in which tools such as energy stereo and prediction are used, and bit reservoirs and the like are used.

In the above system,
In the encoding of audio data, as a measure of how much the sound quality of the input audio data is maintained,
There is a reproduction band after encoding. For example, when the sampling frequency of the input signal is 44.1 kHz, the reproduction band is 22.0.
5 kHz, which corresponds to 22.05 kHz, or 22.
High-quality audio encoding can be achieved by efficiently encoding wideband data close to 05 kHz without degrading it and keeping the amount of information within the transfer rate range. However, the width of the playback band affects the number of spectral data,
The number of spectral data affects the amount of information. For example, when the sampling frequency of the input signal is 44.1 kHz, 10
The spectrum data of 24 samples corresponds to the data of 22.05 kHz, and in order to secure the reproduction band of 22.05 kHz, it is necessary to transmit all the spectrum data of 1024 samples.

However, in consideration of a low transfer rate transmission line such as a mobile phone, it is not realistic to actually transmit all the spectrum data of 1024 samples because the data amount is too large. In other words, if you try to transfer all spectrum data in this playback band with a data amount that matches the transfer rate, the amount of information that can be assigned to each frequency band will be small, and as a result, the effect of quantization noise will increase, Audio quality is deteriorated due to encoding.

For this reason, not only MPEG-2 AAC but also many acoustic signal coding systems perform auditory weighting on spectrum data and do not transmit data with low priority, so that efficient acoustic signal Transmission is realized. According to this, regarding the reproduction band, in order to improve the encoding accuracy of the low-frequency part that has a high auditory priority,
A sufficient amount of data is allocated to the coded information in the low frequency band, and the high frequency band having a low priority has a high probability of being excluded from transmission.

However, in spite of such ingenuity in the MPEG-2 AAC system, further improvement in quality and improvement in compression efficiency are demanded for audio signal encoding. That is, there is an increasing demand for transmitting high-frequency acoustic signals even at low transfer rates.

It is an object of the present invention to provide an encoding device and a decoding device which can realize high-quality encoding of an audio signal and its decoding without significantly increasing the amount of information after encoding. .

[0016]

In order to achieve the above object, an encoding apparatus of the present invention is an encoding apparatus for encoding an input acoustic signal, which converts an input acoustic signal for a fixed time. Of the spectrum data obtained by the above, the first encoding means for encoding the low frequency part of the frequency and the spectrum data obtained by converting the input acoustic signal for a certain time,
Auxiliary information generating means for generating auxiliary information representing the characteristics of the high frequency part of the frequency, second encoding means for encoding the generated auxiliary information, and data encoded by the first encoding means. And output means for outputting the data encoded by the second encoding means. In the above encoding device of the present invention, the auxiliary information generating means generates auxiliary information representing a characteristic of a high frequency part of the spectrum in the spectrum data obtained by converting the input acoustic signal for a certain time, and second. The encoding means encodes the generated auxiliary information.

In order to achieve the above object, the decoding device of the present invention is a decoding device for inputting and decoding the encoded data encoded by the encoding device according to claim 1, wherein the input code is Coded data separation means for separating the data coded by the second coding means from the coded data, and the data coded by the first coding means in the input coded data are decoded to lower the frequency. A first decoding means for outputting spectrum data representing a region, and data that is separated from the input encoded data and encoded by the second encoding means to generate the auxiliary information and generate the auxiliary information. Second decoding means for generating and outputting spectrum data representing a high frequency part of the frequency based on the auxiliary information, and spectrum data output by the first decoding means, Serial converted by synthesizing the output spectral data by the second decoding means, characterized in that it comprises an acoustic signal output means for outputting a sound signal on the time axis. In the above-mentioned decoding device of the present invention, the encoded data separating means receives the second encoded data from the input encoded data.
Separating the data encoded by the encoding means,
The decoding means is separated from the input encoded data,
The data encoded by the second encoding means is decoded to generate the auxiliary information, and the spectrum data representing the high frequency part of the frequency is generated and output based on the generated auxiliary information.

The present invention can be realized as a broadcasting system consisting of a transmitting device having the encoding device of the present invention and a receiving device having the decoding device of the present invention, and the features of the encoding device and the decoding device. Can be realized as an encoding method and a decoding method in which specific constituent elements are processing steps, or can be realized as a program that causes a computer to execute those steps. It goes without saying that the program can be distributed via a computer-readable recording medium such as a CD-ROM or a transmission medium such as a communication path.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An encoding apparatus 100 and a decoding apparatus 200 according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the embodiment of the present invention, MPEG-2 AAC will be described as an example of a conventional method. FIG. 1 is a block diagram showing configurations of an encoding device 100 and a decoding device 200 according to an embodiment of the present invention. <Encoding device 100>

The encoding apparatus 100 compresses and encodes the low frequency part of the input acoustic signal based on the MPEG-2 AAC encoding system, and also generates auxiliary information representing the characteristics of the acoustic signal of the high frequency part. A device for compressing and coding it, incorporating it into the coded bit stream of the low-frequency part, and outputting it, which comprises an acoustic signal input section 110, a conversion section 120, and a first section.
The quantization unit 131, the first encoding unit 132, the second quantization unit 133, the second encoding unit 134, and the stream output unit 140.

The acoustic signal input section 110 has a frequency of 44.1.
MP sampled at a sampling frequency of kHz
Digital acoustic data, which is an input signal similar to that of EG-2 AAC, is cut out in a cycle of about 22.7 msec (every 1024 samples) by overlapping 512 samples before and after the same.

The conversion unit 120 converts the sample data on the time axis cut out by the acoustic signal input unit 110 into spectrum data on the frequency axis, as in the conventional case. M
In PEG-2 AAC, MDCT (Modified)
Discrete Cosine Transform
m), the input signal 1024 points are overlapped with the data of 512 samples before and after, and the time axis data of 2048 samples are converted into the spectrum data of 2048 samples. Only one 1024 sample needs to be encoded.

Further, the conversion unit 120 is configured to convert the converted 10
Spectral data of 24 samples is classified into a plurality of scale factor bands each including spectral data of 1 sample or more (practically a multiple of 4). In this scale factor band, the number of samples (spectral data) contained in each scale factor band is defined according to the frequency in this standard. It is divided into a large number to include a large number of samples. In MPEG-2 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, if the sampling frequency is 44.1 kHz,
The number of scale factor bands included in one frame is 49, and spectral data of 1024 samples is included in 49 scale factor bands. On the other hand, of the scale factor bands defined in this way, which scale factor band is to be transmitted is not specified in particular, and it is possible to select the most preferable scale factor band according to the transfer rate of the transmission path and transmit it. Good. For example, the transfer rate of the transmission line is 96k
In the case of bps, only the low band 40 scale factor band (640 samples) of one frame may be selected and transmitted.

In this embodiment, the conversion unit 1
A case where the conversion unit 20 classifies the spectrum data after conversion into the scale factor bands of the division method and the number that are uniquely defined will be described.

The first quantizer 131 receives the spectrum data output from the converter 120, determines the scale factor for each scale factor band in the low frequency band of the input spectrum data, and
The spectrum in the scale factor band is quantized by the determined scale factor, and the quantized value that is the quantized result is output to the first encoding unit 132. For example, in this case, the sampling frequency of the input signal is 44.1 kHz
Therefore, the reproduction band is 22.05 kHz, but the quantization value obtained from the spectrum data in each scale factor is 4 bits or less for the low frequency part of this, for example, the band of 11.025 kHz or less. As represented, the scale factor is calculated, and the spectrum is used to normalize and then quantize each spectrum within the scale factor band.

The first encoding unit 132 has the data quantized by the first quantization unit 131, that is, within all scale factor bands corresponding to 512 samples on the low frequency side of all spectrum data. The quantized value and the scale factor used for the quantization are Huffman-encoded as a first encoded signal and converted into a predetermined stream format.

The second quantizing unit 133 receives the spectrum data output from the converting unit 120 and receives the first quantizing unit 1
Band not quantized at 31, ie 11.02
Only auxiliary information in the high frequency band of 5 kHz or higher is calculated and output.

The auxiliary information is simplified information which is calculated on the basis of the spectrum data of the high frequency band and represents the acoustic signal of the high frequency band which is not transmitted by the conventional method. In other words, it is the information that indicates the characteristics of the high frequency part of the spectrum data obtained by converting the input acoustic signal for a certain period of time. Specifically, it is the absolute maximum within the scale factor band of the high frequency part. The scale factor and its quantized value for each scale factor band that makes the quantized value of the spectral data (spectral data with the maximum absolute value) 1, and the absolute maximum spectrum within each scale factor band It is the position of the data, and is the quantized value of the absolute maximum spectrum data for each scale factor band when the scale factor common to each scale factor band in the high frequency region is defined, and the spectrum at the predetermined position in the high frequency region Is a sign indicating the positive or negative sign of the low frequency band, which is similar to the spectrum of the high frequency band. , Etc. information indicating the copying method when copying the torque representative of the spectrum of the higher frequency band. Furthermore, in the auxiliary information as described above, not only the high-frequency part,
It is also possible to add noise information indicating the amplitude of white noise mixed in from the low-frequency part to the high-frequency part.

The second encoder 134 Huffman-encodes the auxiliary information output from the second quantizer 133 into a predetermined stream format and outputs it as second encoded information.

The stream output unit 140 adds header information and other necessary sub information to the first coded signal output from the first coding unit 132, and MPEG-2 is added.
Convert to an AAC encoded bitstream, and
The second encoded signal output from the encoding unit 134 of
The bit stream is stored in an area which is ignored by the conventional decoding device or whose operation is not specified.

Specifically, the stream output section 140 is
The encoded signal output from the second encoding unit 134 is M
Fill Element and Data Stream in PEG-2 AAC encoded bit stream
Stored in Element. The bit stream output from the encoding device 100 is transmitted to the decoding device 200 via a transmission medium, an optical disc such as a CD or a DVD,
It is recorded on a recording medium such as a semiconductor or a hard disk.

In MPEG-2 AAC, the MDCT conversion length can be changed according to the input acoustic signal. A block having a conversion length of 2048 samples is called a LONG block, a block having a conversion length of 256 samples is called a SHORT block, and these are collectively called a block size.
Although this description is given for the LONG block unless otherwise specified, the same processing can be performed for the SHORT block.

In actual MPEG-2 AAC encoding processing, Gain Control and TNS (T
EMPORAL NOISE SHAPING), psychoacoustic model, M / S Stereo, Intensit
There are cases where tools such as y Stereo and Prediction are used, block size switching, and bit reservoirs are used. <Decoding device 200>

The decoding device 200 is a device which restores wideband acoustic data added with a high frequency part from the input coded bit stream based on the auxiliary information.
Stream input unit 210, first decoding unit 221, first
The inverse quantization unit 222, the second decoding unit 223, the second inverse quantization unit 224, the inverse quantized data combination unit 225, the inverse conversion unit 230, and the acoustic signal output unit 240.

The stream input section 210 reproduces data from a recording medium via a transmission medium and reproduces it from the recording medium.
The first encoded signal stored in the area to be decoded by the conventional decoding device and the operation to be performed by the conventional decoding device are ignored. And the second encoded signal stored in the non-stored area and extracts the first encoded signal and the first encoded signal, respectively.
To the second decoding unit 221 and the second decoding unit 223.

The first decoding unit 221 inputs the first coded signal output from the stream input unit 210, and decodes the Huffman-coded data from the stream format into quantized data. First dequantizer 222
Dequantizes the quantized data decoded by the first decoding unit 221, and outputs low-frequency spectrum data. Here, the number of samples of the spectrum data output by the first dequantization unit 222 is 512 samples (the maximum number of samples is 1024), and these are 11.025 kHz.
Represents the reproduction band of.

The second decoding unit 223 receives the second coded signal output from the stream input unit 210, decodes the input second coded signal, and outputs auxiliary information.
The second dequantization unit 224 uses a predetermined procedure based on the spectrum data output from the first dequantization unit 222 to copy noise, for example, a part or all of the low-frequency part spectrum data. , Or white noise or pink noise, and the second decoding unit 2
The above noise is shaped based on the auxiliary information output by 23, and the spectrum data of the high frequency band is output.

Specifically, the second inverse quantizer 224 is
The spectrum data of the low frequency band output by the first dequantization unit 222 is copied to the high frequency band, and the absolute maximum value of the spectrum data copied into the band for each scale factor band of the high frequency band. By multiplying each spectrum data in the band by using as a coefficient the ratio of the quantized value “1” to the value inversely quantized using the scale factor value corresponding to the band described in the auxiliary information. Restore the spectrum of the region. Further, the second dequantization unit 224 generates white noise having a predetermined amplitude in advance, adjusts the amplitude according to the noise information in the auxiliary information, adds it to the restored spectrum, and adds it to the high-frequency part. Output the spectrum data of.

The dequantized data synthesizing unit 225 synthesizes the spectrum data output from the first dequantization unit 222 and the spectrum data output from the second dequantization unit 224. The inverse transform unit 230 transforms the spectrum data on the frequency axis output from the dequantized data synthesis unit 225 into sample data of 1024 samples on the time axis using IMDCT according to MPEG-2 AAC. The acoustic signal output unit 240 sequentially combines the sample data on the time axis obtained by the inverse conversion unit 230, and outputs it as digital acoustic data.

As described above, 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, so that the total information amount is It is possible to encode a high-quality acoustic signal in a range that does not significantly increase compared to the above.

Further, the encoding device 10 according to the present embodiment
0 and the configuration of the decoding device 200 are the same as those of the conventional encoding device 3
00 to the second quantizer 133 and the second encoder 134.
And the second decoding unit 223 and the second dequantization unit 224 are added to the conventional decoding device 400. Therefore, the existing coding device 300 and decoding device 40
There is an effect that it can be realized without significantly changing the configuration of 0.

Further, the coding device 3 in the present embodiment
The bit stream generated by 00 can be decoded by the conventional decoding device 400. Although the present embodiment has been described by taking MPEG-2 AAC as an example, it is obvious that the present invention can be applied to other acoustic coding schemes and to new acoustic coding schemes that do not exist.

Further, in the present embodiment, the input data in the second quantizing unit 133 is only the spectrum data output from the converting unit 120, but it is not limited to this, and the first data is not limited to this. A value obtained by dequantizing the output of the quantizing unit 131 may be input separately. FIG. 2 is a block diagram showing the configurations of encoding apparatus 101 and decoding apparatus 200, which are another configuration example of the present embodiment. Since the same configuration as that in FIG. 1 has already been described, the same reference numerals as those in FIG.

The encoding device 101 is different from the encoding device 100 in that it additionally includes an inverse quantization unit 135. In this encoding device 101, the first quantization unit 1
51 quantizes all the 1024-point spectrum data output by the conversion unit 120, outputs the quantized result to the inverse quantization unit 152, and outputs the quantized result of the low-frequency part 512 points of the first quantized result. It outputs to the encoding unit 132.

The inverse quantizer 152 is the first quantizer 15
Dequantize the quantized quantized value once by 1,
The spectrum data that is the result of the inverse quantization is output to the second quantization unit 153. The second quantizing unit 153 includes a converting unit 12
The inverse quantization unit 15 does not input the spectrum data from 0.
The spectrum data which is the dequantization result of 2 is input, and the auxiliary information of the high frequency part is generated based on the input spectrum data.

Although the second quantizing unit 153 does not input the spectrum data from the transforming unit 120 here, it generates the auxiliary information in the high frequency band based on the spectrum data from the inverse quantizing unit 152. The present invention is not limited to this example, and the second quantizing unit 153 inputs the spectral data from the transforming unit 120 for a certain portion and the spectral data from the inverse quantizing unit 152 for a certain portion. You may.

FIG. 3 is a diagram showing changes in the state of the acoustic signal processed by the coding apparatus 100 shown in FIG.
FIG. 3A is a waveform diagram showing 1024 sample data on the time axis cut out by the acoustic signal input unit 110 shown in FIG. FIG. 3B is a waveform diagram showing spectrum data on the frequency axis after the sample data on the time axis is converted by the MDCT of the conversion unit 120 shown in FIG. Note that, in FIGS. 3A and 3B, 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 acoustic signal input section 110 has 44.1 kHz
The digital audio signal sampled by z is input. The acoustic signal input unit 110 outputs the input signal every 10
At the timing of cutting out 24 samples, 512 samples before and after that are overlapped and cut out, and the conversion unit 120
Output to. The conversion unit 120 performs MDCT on a total of 2048 samples of data, but since the spectrum obtained by MDCT has a bilaterally symmetric waveform, half of that is 10
Spectral data as shown in FIG. 3B corresponding to 24 samples is generated.

In the spectrum data shown in FIG. 3B, the vertical axis represents the value of the frequency spectrum, that is, the amount (the magnitude) of the frequency component of the acoustic signal represented by the voltage value of 1024 samples in FIG. 3A. Is represented by 1024 points corresponding to the number of samples. Also, the encoding device 10
Since the sampling frequency of the digital audio signal input to 0 is 44.1 kHz, the reproduction band of the spectrum data is 22.05 kHz. Furthermore, MD
Since the spectrum obtained by CT may take a negative value as shown in FIG. 3B, when the spectrum obtained by MDCT is encoded, the positive and negative signs of the spectrum are also encoded. There is a need. 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”.

FIG. 4 shows the stream output unit 1 shown in FIG.
FIG. 4 is a diagram showing a position in a bitstream in which auxiliary information is stored by 40. In the figure, after the auxiliary information representing the spectrum of the high frequency band is encoded, it is stored as a second encoded signal in a region in the bitstream that is not recognized as an acoustic encoded signal.

The shaded portion in FIG. 4A 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 400 does not recognize the encoded signal to be decoded and ignores it.

Further, the hatched portion in FIG. 4B 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 MPEG-2 AAC standard for future expansion. Similar to the Fill Element, this area is either ignored by the conventional decoding device 400 or read even if the data is read, even if auxiliary information representing the spectrum of the high frequency part is stored here. This is an area where the operation of the decoding device 400 for data 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 400 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. 4C, the second coded signal may be incorporated discontinuously in the header information and the first coded information.

FIG. 5 shows the stream output unit 1 shown in FIG.
It is a figure which shows the other example in case 40 stores auxiliary information. FIG. 5A shows stream 1 in which only the first coded signal is continuously stored for each frame. FIG. 5B 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 140 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 in 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.

Coding apparatus 100 configured as described above
The operation of the decoding apparatus 200 will be described below with reference to FIG. 6, FIG. 7, FIG. 9, FIG. 11, FIG.
~ It demonstrates using the flowchart of FIG.

FIG. 6 is a flow chart showing the operation in the scale factor determination process of the first quantizer shown in FIG. The first quantization unit 131 first determines a scale factor common to each scale factor band as an initial value of the scale factor (S91), and should be transmitted as one frame of acoustic data using the scale factor. The low-pass spectrum data is all quantized, the difference before and after the obtained scale factor is obtained, and the difference, the leading scale factor, 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 the data is added and the information such as the header is not added in order to simplify the processing. Next, the first quantization unit 131 determines whether or not the number of bits of the Huffman-encoded data has exceeded a predetermined number of bits (S93). If the number of bits has exceeded, the initial value of the scale factor is lowered ( S101), using the value of the scale factor, the quantization and Huffman coding are performed again for the same low frequency band spectrum data (S9).
2) 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 quantizing unit 131
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 absolute value difference between each inverse quantized value and the corresponding original spectrum data is obtained and summed (S96). further,
It is judged whether or not the obtained sum of the differences is within the allowable range (S97), and if it is within the allowable range, the above process is repeated for the next scale factor band (S9).
4 to S98). On the other hand, if it exceeds the allowable range, the value of the scale factor is increased to quantize the spectrum data of the scale factor band and (S1
00), the quantized values are inversely quantized (S95), and the differences between the absolute values of 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-described processing (S95 to S97 and S100) is repeated.

The first quantizer 131, for all scale factor bands, sums the difference between the absolute values of the dequantized values of the quantized values in the scale factor bands and the original spectrum data 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 part encoded data does not exceed the predetermined number of bits (S
99), the value of each scale factor at that time is determined as the scale factor of each scale factor band.

Incidentally, whether or not the sum of the absolute differences between the dequantized values of the quantized values in the scale factor band and the original spectrum data is within the allowable range is determined by data such as a psychoacoustic model. It is done based on.

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 131 in this process will be described below with reference to FIG. 7.

FIG. 7 shows the first quantizer 13 shown in FIG.
It is a flow chart which shows operation in other scale factor decision processing of No. 1. The first quantization unit 131 calculates scale factors for all scale factor bands in the low frequency band to be encoded by the following procedure (S1). In addition, the first quantizer 131
Calculates the scale factor for all spectral data in each scale factor band by the following procedure (S2).

First, the first quantizer 131 quantizes the spectral 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 quantizer 131 determines whether or not the obtained quantized 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 become 4 bits or less (S5), the first quantizer 131 sets the scale factor value at that time to the scale factor of that scale factor band. (S6).

Furthermore, when the first quantizing unit 131 determines the scale factors for all 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 131 quantizes the low-frequency spectrum data using the scale factor thus determined, and quantizes the 4-bit quantized value and the 8-bit scale factor. And are output to the first encoding unit 132.

FIG. 8 shows the second quantizing unit 13 shown in FIG.
Auxiliary information (scale factor) generated by 3
3 is a spectrum waveform diagram showing a specific example of FIG. In FIG. 8, the divisions on the frequency axis of the low frequency band indicate the divisions of the scale factor bands defined in this embodiment. Further, in the high frequency part, the division indicated by the broken line in the frequency direction indicates the division of the scale factor band in the high frequency part defined in the present embodiment. The same applies to the following waveform diagrams.

Of the spectrum data output from the conversion unit 120, the reproduction band 11.0 shown by the solid line waveform in FIG.
The low frequency band of 25 kHz or less is output to the first quantization unit 131 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 auxiliary information (scale factor) calculated by 33. The calculation procedure of the auxiliary information (scale factor) of the second quantization unit 133 will be described below with reference to the flowchart of FIG. 9 using the specific example of FIG.

FIG. 9 shows the second quantizing unit 13 shown in FIG.
It is a flow chart which shows operation in auxiliary information (scale factor) calculation processing of No. 3. Second quantizer 13
3 is a reproduction band 2 exceeding a reproduction band of 11.05 kHz.
For all scale factor bands in the high frequency band up to 2.05 kHz, the optimum scale factor for setting the quantized value of the absolute maximum spectrum data in each scale factor band to "1" is calculated according to the following procedure (S11). .

The second quantizer 133 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. 8, it is assumed that the position of the peak specified in the first scale factor band is, and the peak value at that time is “256”.

The second quantizer 133 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 133 determines 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 unit 133, for the third scale factor band in the high frequency region, the value of the scale factor sf that sets the quantized value of the peak value “288” to “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 133 calculates the scale factor of each scale factor band obtained by the calculation,
The data is output to the second encoding unit 134 as 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 133. This auxiliary information (scale factor) is included in the high-frequency part represented by the spectral data of 512 points. If the value of each scale factor is represented by a value from 0 to 255, each scale factor band (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 spectral data of 512 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 150 bits. Therefore, this auxiliary information shows only one scale factor for each scale factor band in the high frequency band, but the amount of data is greatly reduced as compared with the case of quantizing the high frequency band according to the conventional method. You can see that it is done.

Further, this scale factor shows a value almost proportional to the peak value (absolute value) in each scale factor band, and the spectrum data having a constant value at 512 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 spectrum 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.

Although only the scale factor is encoded as the auxiliary information here, the present invention is not limited to this. The quantization value, the characteristic spectral position information, the sign information representing the positive and negative signs of the spectrum, and noise. The generation method and the like may be encoded together. Also, two or more of these may be combined and coded. In this case, it is particularly effective to encode the coefficient indicating the ratio of amplitude, the position of the absolute maximum spectrum data and the like in the auxiliary information in combination with the scale factor.

FIG. 10 shows the second quantizer 1 shown in FIG.
It is a spectrum waveform diagram which shows the specific example of the auxiliary information (quantization value) produced | generated by 33. In addition, FIG.
Auxiliary information (quantized value) of the second quantizer 133 shown in
It is a flow chart which shows operation in calculation processing.

The second quantizer 133 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 133 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. 10, it is assumed that the position of the peak specified in the first scale factor band is and the peak value at that time is “256”.

The second quantizing unit 133 applies the 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 133 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 133, for the third scale factor band in the high frequency part, quantizes the peak value "288" with the scale factor value "18" to "9". 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 133 outputs the quantized value of each scale factor band obtained by the calculation to the second encoding unit 134 as auxiliary information of the high frequency band, and ends the process.

As described above, the auxiliary information (quantization value) is generated by the second quantizing unit 133, and this auxiliary information (quantization value) is high, which is represented by the spectral data of 512 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 spectral data of a constant value at 512 points in the high frequency band or the spectral data of 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. Also, for each scale factor band, the ratio between the absolute maximum value of the spectrum 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.

Here, the scale factor value corresponding to the quantized value transmitted as the second encoded information is
Although predetermined, the optimum scale factor value may be calculated and added to the second encoded information for transmission. 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, so that the amount of information required to transmit the quantized value is smaller. .

Although only the quantized value or only the quantized value and the scale factor is encoded as the auxiliary information,
It does not have to be limited to this, scale factor,
The characteristic spectrum position information, the signature information of the spectrum data, the noise generation method, and the like may be encoded. Also, two or more of these may be combined and coded.

FIG. 12 shows the second quantizer 1 shown in FIG.
FIG. 23 is a spectrum waveform diagram showing a specific example of auxiliary information (positional information) generated by 33. In addition, FIG.
Auxiliary information (positional information) of the second quantizer 133 shown in FIG.
It is a flow chart which shows operation in calculation processing.

The second quantizer 133 has a reproduction band of 11.
The position of the absolute maximum spectrum data in each scale factor band is specified in accordance with the following procedure for all scale factor bands in the high frequency range exceeding 025 kHz and up to 22.05 kHz in the reproduction band (S3
1).

The second quantizer 133 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. 12, the position of the peak specified 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 quantization unit 133 uses the specified peak position “22nd spectrum data from the beginning of the scale factor band”.
Is held (S33).

For the first scale factor band, when the position of the peak is specified and held (S3
4), the 2nd quantization part 133 specifies the peak of spectrum data about the following 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 133
Holds the position of the identified peak "60th spectral data from the beginning of the scale factor band" (S33).

Similarly, the second quantizer 133
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 133 is used.
Uses the position of the peak of each scale factor band held therein as the auxiliary information of the high frequency band in the second encoding unit 13
4 is output, and the process ends.

As described above, the auxiliary information (positional information) is generated by the second quantizing unit 133. This auxiliary information (positional information) is in the high-frequency part represented by the spectral data of 512 points. Are represented by 6-bit position information for each of the four scale factor bands.

In this case, in the decoding apparatus 200, the second dequantization unit 224 inputs a part or all of the spectral data of 512 samples in the low frequency band from the second decoding unit 223. It is copied as 512 sample data on the high frequency side according to the auxiliary information (positional information). The copy procedure is to extract similar data from the spectrum data output from the first dequantization unit 222 based on the peak information of the spectrum data in one or more scale factor bands, and extract a part or all of the similar data. Achieved by copying.

Further, in the second inverse quantizer 224,
If necessary, adjust the amplitude of the copied spectral data. 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 according to the spectrum data output from the first dequantization unit 222.

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.

Here, 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. The generation method or the like may be encoded. Also, two or more of these may be combined and coded. 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 the second data.
It may be generated only from the encoded information of.

FIG. 14 is a block diagram of the second quantizer 1 shown in FIG.
FIG. 33 is a spectrum waveform diagram showing a specific example of auxiliary information (sign information) generated by 33. Further, FIG. 15 is a flowchart showing the operation in the auxiliary information (sign information) calculation processing of the second quantizer 133 shown in FIG.

The second quantizer 133 has the reproduction band 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 ( S
41).

The second quantizer 133 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 quantization unit 133 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 quantization unit 133 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 133 holds “1” as the signature information of the spectrum data at the center position of the second scale factor band.

Similarly, the second quantizer 133
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 central position is held for all scale factor bands in the high frequency band (S43), the second quantizing unit 133 holds each of the held information. The sign information of the scale factor band is output to the second encoding unit 134 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 133, and this auxiliary information (sign information) is in the high frequency part represented by the spectral data of 512 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 200, second dequantization section 224 copies a part or all of the spectral data of 512 samples in the low frequency band as the high frequency band 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 223.

Here, the sign information representing the code at the center position of each scale factor band in the high frequency part is used as the auxiliary information (sign information), but the sign information 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 22.
2 may be changed according to the output of No. 2, or position information indicating at which position the sign information of each scale factor band is the sign information may be added to the second encoded information and transmitted. .

Further, in the second inverse quantizer 224,
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 by the first dequantization unit 222.
It may be changed depending on the spectrum data output. The amplitude adjusting method is not limited to this, and other methods may be used.

Although a predetermined coefficient is used here, 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, here, only the sign information, the sign information and the coefficient information, the sign information and the position information only, or the sign information, the position information and the coefficient information are coded as the auxiliary information. However, the quantization value, scale factor, characteristic spectral position information, noise generation method, and the like may be encoded. Also, two or more of these may be combined and coded.

In this embodiment, 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 the second code. It may be generated only from the activation information.
In addition, in the above, this code "+" is a 1-bit value "1".
, And the code “−” is expressed by “0”, but the way of expressing the code in the auxiliary information (sign information) is not limited to this and may be expressed by another value.

FIG. 16 shows the second quantizer 1 shown in FIG.
FIG. 13 is a spectrum waveform diagram showing an example of a method of creating auxiliary information (copy information) generated by 33. FIG.
(A) is a waveform diagram showing a spectrum in the first scale factor band in the high frequency region. Figure 16 (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). In addition, FIG. 17 is a flowchart showing the operation in the auxiliary information (copy information) calculation processing of the second quantization unit 133 shown in FIG.

The second quantizer 133 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 (the 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 has a value closest to n is specified according to the following procedure (S51).

The second quantizer 133 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. 16A, it is assumed that the identified peak position is and its spectrum is n = 22 spectrum data of this scale factor band.

The second quantizing unit 133 specifies the position 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). Then, the second quantizer 1
33 is for all peaks identified in the low range,
Search the scale factor band whose position from the peak to the beginning of the scale factor band is closest to n,
The number N of the scale factor band, the direction of the search, and the sign information of the peak are specified (S54).

More specifically, the second quantizing unit 133, for all the specified peaks (both positive and negative), sequentially from the peak on the low frequency side, and the position from that 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. 16 (b). Since the waveform in which the peak position in the high frequency band and the peak position in the low frequency band are inverted left and right (in the frequency axis direction) within the scale factor band 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 move vertically (in the vertical axis direction) as shown in FIG. 16B. 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.

If the peak specified in the low frequency band has a positive value, the second quantizing unit 133 specifies the low frequency band in the search directions of (1) and (2). 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 spectrum in the low frequency band as shown in (2) of FIG. 16B.
18 is specified, similarly, in the search direction (3), an error of “4” occurs in the scale factor band corresponding to the spectrum of the low frequency band as shown in (3) of FIG. 16B. 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 133
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 133 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 band, the peak position from the beginning of the scale factor band is n, and the peak position from the beginning of the scale factor band is the closest to n. 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 quantizing unit 133 causes each scale factor band of the specified high frequency band to be identified. 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 134 as auxiliary information (copy information) in the high frequency band, and the process ends.

In this case, when the decoding apparatus 200 decodes the first coded signal according to the conventional procedure, 512 samples of spectrum data on the low frequency side are obtained. In the second dequantization unit 224, the second decoding unit 22
A part or all of the spectrum data corresponding to the scale factor band number output from 3 is copied as the high frequency side spectrum. In addition, the second dequantization unit 224
In step 1, the amplitude of the copied spectral data is adjusted if necessary. The adjustment of the amplitude can be achieved by multiplying each spectrum by a predetermined coefficient, for example, its value is “0.5”.

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 222.

Although a predetermined coefficient is used for adjusting the amplitude here, 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.

Here, in addition to the scale factor band number N, the sign information and the search direction information are extracted as the auxiliary information (copy information) in the high frequency range.
The sign information and the search direction information may be omitted depending on the amount of information that can be transmitted in the high frequency band. The sign information is "1" if the sign of the peak in the low frequency band is "+",
If it is "-", it is set to "0", and the search direction information is "1" when searching in the direction of the lower frequency from the peak, and "0" when searching in the direction of the higher frequency from the peak. However, the method of expressing the sign of the peak of the low frequency band in the sign information and the search direction of the search direction information is not limited to these, and may be expressed by other values.

Further, here, the head of the scale factor band whose distance is the closest value to n is searched from the position of each peak specified in the low frequency band, but the present invention is not limited to this example. It is also possible to search for a peak whose distance from the beginning of each scale factor band in the low frequency band is a value closest to n.

FIG. 18 is a block diagram of the second quantizer 1 shown in FIG.
FIG. 16 is a spectrum waveform diagram showing a second example of a method of creating auxiliary information (copy information) generated by 33. FIG. 19
6 is a flowchart showing an operation in a second calculation process of the auxiliary information (copy information) of the second quantizing unit 133 shown in FIG. 1.

The second quantizer 133 has a reproduction band 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 that take the difference from the high band in the low band is equal to the number of spectra in the scale factor band of the high band,
The number N of the specified scale factor band is the number of the scale factor band at the beginning of the spectrum.

The second quantizing unit 133 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. 18, if the first scale factor band in the high frequency band is the scale factor band with the number of spectral data = 48, the second quantizing unit 133 causes the low frequency band 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 unit 133 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 133 specifies 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 are shown by a dashed line in the high frequency region of FIG. 18 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 unit 133 specifies the number N of the low-frequency band scale factor band for which the spectrum difference is the minimum, with respect to the high-frequency band scale factor band, the number N of the specified scale factor band is specified. 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 134 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 the decoding apparatus 200 are as follows.
This is the same as the case of the auxiliary information (copy information) described with reference to FIGS. 16 and 17.

Further, in the flow chart of FIG. 19, 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. The present invention is not limited to this, and as described with reference to FIGS. 16 and 17, any one of the following three methods may be used to calculate the energy difference between the high frequency region and the low frequency region. 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.

FIG. 20 is a flowchart showing a procedure in which the second dequantization unit 224 shown in FIG. 1 copies the low band 512 spectrum to the high band in the forward direction. 20, inv_spec1 [i] represents the value of the i-th spectrum in the output data of the first dequantization unit 222, and inv_spec2 [j] is the input data of the second dequantization unit 224. The value of the j-th spectrum is shown.

First, since the second dequantization unit 224 inputs the 0th spectrum to the 511th 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". "(S7
1). Then, the second inverse quantizer 224 uses the counter i
It is checked whether the value of is less than "512" (S72),
If the value of the counter i is less than “512”, the value of the i-th (lowest in this case) spectrum of the low-frequency part of the first dequantization unit 222 is set to the high-value of the second dequantization unit 224. The value is input as the value of the j-th region (0 in this case) spectrum (S73). After that, the second dequantization unit 224 increments the values of the counters i and j by "1" (S74), and checks whether the value of the counter i is less than "512" (S72). .

The second inverse quantizer 224 repeats the above process while the value of the counter i is less than "512", and ends the process when the value of the counter i becomes "512" or more. As a result, the entire spectrum of the 0-511th low frequency band which is the result of dequantization by the first dequantization unit 222 is copied as it is as the high frequency band spectrum of the second dequantization unit 224. .

FIG. 21 is a flow chart showing a procedure in which the second dequantization unit 224 shown in FIG. 1 copies the low band 512 spectrum to the high band in the direction opposite to the frequency axis direction. 21, inv_
Spec1 [i] indicates the value of the i-th spectrum in the output data of the first dequantization unit 222, and inv_
Spec2 [j] represents the value of the j-th spectrum in the input data of the second dequantization unit 224.

First, since the second dequantizer 224 inputs the 0th spectrum to the 511th 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 set to "511" (S81). Then, the second inverse quantizer 224
Checks whether the value of the counter i is less than "512" (S82), and if the value of the counter i is less than "512", the i-th low-frequency part of the first dequantization unit 222 ( In this case, the value of the (0th) spectrum is set to the second dequantization unit 2
It is input as the value of the jth (in this case, the 511th) spectrum of 24 high-frequency parts (S83). After that, the second dequantization unit 224 increments the value of the counter i by “1” and decrements the value of j by “1” (S
84), and it is checked whether or not the value of the counter i is less than "512" (S82).

The second inverse quantizer 224 repeats the above process while the value of the counter i is less than "512", and ends the process when the value of the counter i becomes "512" or more. As a result, the entire spectrum of the 0-511th low-frequency part, which is the result of the inverse quantization by the first inverse quantizer 222, becomes the second
Are inversely copied as the 511th to 0th spectra in the high frequency band of the inverse quantization unit 224 of FIG.

Although the second dequantization unit 224 copies all the spectrum data in the low frequency band to the high frequency band here, it may copy only a part of the spectrum data. 20 and 21 are taken as an example of the procedure for copying the entire high-frequency part and the low-frequency part at one time, but a part of the process is copied as shown in FIG. May be. Also,
Further, some or all of them may be copied with the positive and negative signs reversed.

The copy procedure may be determined in advance, may be changed according to the data in the low frequency band, or may be transmitted as auxiliary information. It should be noted that, here, the spectrum data on the low frequency band side is copied as the spectrum data on the high frequency band side, but the invention is not limited to this, and the spectrum data on the high frequency band side is generated only from the second encoded information. Good.

In the present embodiment, 512 samples on the low frequency side of all spectrum data are coded as the first coded signal, and the rest are coded as the second coded signal. It is not limited to this. In the present embodiment, the second dequantization unit 2
As the noise generation in 24, the case where the spectrum data obtained from the first dequantization unit 222 is mainly copied has been described, but the present invention is not limited to this and has a constant value in each scale factor band in the high frequency band. The second dequantization unit 224 may independently generate the spectrum data, the white noise, the pink noise, or the like, or may generate them in accordance with the auxiliary information.

In the present embodiment, one side information is encoded in each scale factor band as the second encoded signal, but one side information is encoded in each of two or more scale factor bands. You can turn it into
Two or more pieces of auxiliary information may be encoded in one scale factor band. The auxiliary information in the present embodiment may be encoded for each channel,
One side information may be encoded for two or more channels.

In the present embodiment, the number of quantization units and the number of coding units in coding device 100 are two, but the number of quantization units and the number of coding units are not limited to this, and three or more quantization units and decoding units are provided. May be provided. In the present embodiment, the number of decoding units and dequantization units in decoding apparatus 200 is two, but the number of decoding units and dequantization units is not limited to this, and three or more decoding units and dequantization units may be provided. You may prepare.

In this embodiment, the conversion unit 1
20 has described the case where the spectrum data after conversion is classified into the scale factor band of the division method and the number that are independently determined, but the encoding device of the present invention is not limited to this, and the conversion unit converts the spectrum data after conversion. MPE spectral data
It may be classified into a scale factor band according to the G-2 AAC standard. By thus classifying into scale factor bands according to the standard, even in the conventional decoding device 400, the encoding device 10 of the present invention is also used.
The bit stream coded by 0 can be decoded without any problem, and the conventional digital audio output data can be obtained.

The above processing is performed by hardware as well as
It may be realized by software, or one part may be realized by hardware and the rest may be realized by software. In this embodiment, the sampling frequency is set to 44.1 kHz and one frame is described as digital audio data of 1024 samples, but the encoding device and the decoding device of the present invention are not limited to this, and the sampling frequency May be any Hz.

[0152]

The coding apparatus of the present invention is a coding apparatus for coding an input acoustic signal, and has a low frequency among spectral data obtained by converting an input acoustic signal for a fixed time. First encoding means for encoding the high frequency part, and auxiliary information generating means for generating auxiliary information representing the characteristics of the high frequency part of the frequency in the spectrum data obtained by converting the input acoustic signal for a fixed time. Output means for outputting the second encoding means for encoding the generated auxiliary information, the data encoded by the first encoding means, and the data encoded by the second encoding means. And is provided. In the above encoding device of the present invention, the auxiliary information generating means generates auxiliary information representing a characteristic of a high frequency part of the spectrum in the spectrum data obtained by converting the input acoustic signal for a certain time, and second. The encoding means encodes the generated auxiliary information.

Therefore, according to the coding apparatus of the present invention, the spectral data in the high frequency band is not directly quantized and coded, but the auxiliary information representing the characteristics of the high frequency band is coded. There is an effect that the spectrum in the high frequency part of the frequency can be encoded with a very small amount of data. Further, in the conventional MPEG-2 AAC, since the audio signals in the entire band are encoded by the same method, it is difficult to transmit the high frequency part at a low transfer rate. According to this, since it is possible to transmit information in the high frequency band without significantly increasing the amount of information after encoding, a decoding device that decodes this information is richer in the high frequency band than a conventional decoding device. There is an effect that it is possible to decode a high quality sound signal.

Further, in the encoding device of the present invention, the auxiliary information generating means is a value obtained by quantizing the spectrum data which becomes a peak in each group in the high frequency band for the spectrum data divided into a plurality of groups. Is calculated to be a constant value, and the calculated normalization coefficient is generated as the auxiliary information. Further, the auxiliary information generating means is a high frequency band for the spectrum data divided into a plurality of groups. The spectral data having a peak in each group of parts is quantized by using a normalization coefficient common to each group, and the quantized value is generated as the auxiliary information.

Therefore, according to the coding apparatus of the present invention, in each group in the high frequency band, one normalization coefficient or a quantized value of spectrum data that is a peak is generated as auxiliary information. Even if a certain number of bits, for example, 8 bits, are assigned to represent the quantization coefficient or the quantized value, the amount of auxiliary information data is small, and the amount of auxiliary data is small for each high frequency group (scale factor band). The peak amplitude of the spectrum data can be represented. As a result, according to the encoding device of the present invention, even in the case of a transmission line having a low transfer rate in a narrow band, an acoustic signal having the same bandwidth as the low frequency part can be obtained with a slight increase in the transmission amount compared with the conventional case. Can be transmitted also in the high frequency range, so that a decoding device for decoding this can restore an acoustic signal that is more faithful to the original sound.

Further, in the encoding device of the present invention, the auxiliary information generating means, with respect to the spectrum data divided into a plurality of groups, determines the frequency position of the spectrum data having a peak in each group of the high frequency band as the auxiliary information. It is generated as information, and the spectrum data is MDC.
For the T coefficient, the auxiliary information generating means may generate, as the auxiliary information, a sign indicating the positive or negative sign of the spectrum data at a predetermined frequency position in a high frequency part, for the spectrum data divided into a plurality of groups. Is characterized by.

Therefore, according to the encoding device of the present invention, the positive and negative signs of the spectrum data at the frequency position of the spectrum data at the peak or the predetermined frequency position of the high frequency region are used to reduce each data in the high frequency region with a small amount of data. There is an effect that it is possible to represent a rough spectrum shape in a group (scale factor band).

Further, in the encoding device of the present invention, the auxiliary information generating means, for each of the spectrum data divided into a plurality of groups, in each group of the high frequency part, the low frequency which is the closest to the spectrum in the group. It is characterized in that information for specifying the spectrum of the region is generated as the auxiliary information.

Therefore, according to the encoding apparatus of the present invention, when a spectrum having a shape similar to that of the high frequency band is present in the low frequency band, the spectrum of the low frequency band is only specified. There is an effect that the high frequency band spectrum can be represented more faithfully with a small amount of data.

[Brief description of drawings]

FIG. 1 is a block diagram showing configurations of an encoding device and a decoding device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing configurations of an encoding apparatus and a decoding apparatus that are another configuration example of the present embodiment.

FIG. 3 is a diagram showing a state change of an acoustic signal processed in the encoding device shown in FIG.

FIG. 4 is a diagram showing a position in a bitstream in which auxiliary information is stored by the stream output unit shown in FIG.

FIG. 5 is a diagram showing another example in which the stream output unit shown in FIG. 1 stores auxiliary information.

FIG. 6 is a flowchart showing an operation in a scale factor determination process of the first quantizer shown in FIG.

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

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

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

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

FIG. 11 is a flowchart showing an operation in auxiliary information (quantized value) calculation processing of the second quantization unit shown in FIG. 1.

FIG. 12 is a spectrum waveform diagram showing a specific example of auxiliary information (positional information) generated by the second quantizer shown in FIG.

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

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

FIG. 15 is a flowchart showing an operation in auxiliary information (sign information) calculation processing of the second quantizer shown in FIG.

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

FIG. 17 is a flowchart showing an operation in auxiliary information (copy information) calculation processing of the second quantization unit shown in FIG. 1.

FIG. 18 is a spectrum waveform diagram showing a second example of a method of creating auxiliary information (copy information) generated by the second quantizer shown in FIG. 1.

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

20 is a flowchart showing a procedure of copying a low-frequency band 512 spectrum to a high-frequency band in the forward direction by the second dequantization unit shown in FIG.

FIG. 21 is a flowchart showing a procedure in which the second dequantization unit shown in FIG. 1 copies the low-frequency band 512 spectrum to the high-frequency band in the direction opposite to the frequency axis direction.

[Fig. 22] Fig. 22 is a block diagram illustrating a configuration of an encoding device and a decoding device according to a conventional MPEG-2 AAC system.

[Explanation of symbols]

100 encoder 110 Acoustic signal input section 120 converter 131 First Quantizer 132 first encoding unit 133 second quantizer 134 Second Encoding Unit 140 stream output section 200 Decoding device 210 Stream input section 221 First Decoding Unit 222 First dequantization unit 223 second decoding unit 224 Second dequantization unit 225 Dequantized Data Synthesis Unit 230 Inverse converter 240 Acoustic signal output section 152 inverse quantizer

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[Procedure amendment]

[Submission date] January 10, 2003 (2003.1.1
0)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

In the above system,
In the encoding of audio data, as a measure of how much the sound quality of the input audio data is maintained,
There is a reproduction band after encoding. For example, when the sampling frequency of the input signal is 44.1 kHz, the reproduction band is 22.0.
5 kHz, which corresponds to 22.05 kHz, or 22.
Wideband data close to 05 kHz is efficiently encoded without deterioration, and all encoded data is transferred.
By transferring to the decryption device within the range of
It is possible to obtain a high-quality sound signal in the decoding device.
It In other words, achieving a high-quality coding at the coding apparatus side
You can do it . However, the width of the reproduction band affects the number of spectrum data, and the number of spectrum data affects the amount of information. For example, if the sampling frequency of the input signal is 4
At 4.1 kHz, the spectrum data of 1024 samples corresponds to the data of 22.05 kHz, which is 22.05.
In order to secure the reproduction band of kHz, it is necessary to transmit all spectrum data of 1024 samples.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

In order to achieve the above object, an encoding apparatus of the present invention is an encoding apparatus for encoding an input acoustic signal, which converts an input acoustic signal for a fixed time. from the spectral data divided into a plurality of groups obtained Te, the spectral data in said each group
The normalization coefficient to be normalized, and the normalization coefficient
Obtained by quantizing each spectral data in each group
Quantization value and the sign of each spectrum data
Positive or negative sign and frequency of each spectrum data
First encoding means for encoding the low frequency band data of the frequency represented by four types of information including the position on the several axis, and the spectrum data in each of the groups of the high frequency band.
Information that identifies the approximated low-frequency spectrum data and
For shaping the specified low-frequency spectrum data
As information, the characteristics of the high frequency spectrum data are described in the above 4
Represented by one or more types of information and three or less types of information
Auxiliary information generating means for generating auxiliary information including information for shaping, second encoding means for encoding the generated auxiliary information, and data encoded by the first encoding means. And output means for outputting the data encoded by the second encoding means. In the encoding device of the present invention, the auxiliary information generating means, among the spectral data divided into a plurality of groups obtained by converting the input acoustic signal for a certain time,
Express the characteristics of the high frequency part with less information than the low frequency part
Generating the auxiliary information, the second encoding means encodes the generated auxiliary information.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

In order to achieve the above object, the decoding apparatus of the present invention is obtained by converting an input acoustic signal for a fixed time.
From the spectral data divided into multiple groups,
For normalizing the spectral data in each group
A normalization coefficient and each of the groups using the normalization coefficient
Quantization obtained by quantizing each of the spectrum data of
Value and positive or negative indicating the positive or negative of each spectrum data
And the position of each spectrum data on the frequency axis
The low-frequency part of the frequency represented by four types of information including and
The first encoded data obtained by encoding the data and the frequency
In the spectral data in each of the groups of the region
Information that identifies the approximated low-frequency spectrum data and
For shaping the specified low-frequency spectrum data
As information, the characteristics of the high frequency spectrum data are described in the above 4
Represented by one or more types of information and three or less types of information
Obtained by encoding auxiliary information, including information for
Input encoded data including the second encoded data
A decoding device for decoding, comprising encoded data separating means for separating the second encoded data from input encoded data, and decoding the first encoded data in the input encoded data to reduce the frequency. decodes the first decoding means for outputting the spectral data representative of the frequency band, the second encoded data separated from the input encoded data, said auxiliary information
Based on the information for specifying the low-frequency spectrum data in the spectrum, the spectrum output by the first decoding means is output.
Specified low frequency spectrum data
Data to each of the groups in the high frequency range, and the auxiliary information
Based on the information for shaping in
Second decoding means for generating and outputting spectrum data representing the high frequency part of the frequency by shaping the spectrum data, the spectrum data output by the first decoding means, and the second decoding means. An acoustic signal output means for synthesizing and converting the outputted spectrum data and outputting as an acoustic signal on the time axis is provided. In the above-mentioned decoding device of the present invention, the encoded data separating means converts the input encoded data into the second code.
Separating the data, the second decoding means, minute separated the said
The second encoded data is decoded to obtain the low-frequency part spectrum data.
The auxiliary information including the information for specifying the data and the information for shaping is generated, and based on the generated auxiliary information, the spectrum data representing the high frequency part of the frequency is generated and output.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

The second quantizing unit 133 receives the spectrum data output from the converting unit 120 and receives the first quantizing unit 1
Band not quantized at 31, ie 11.02
Only the auxiliary information in the high frequency band exceeding 5 kHz is calculated and output.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

The first decoding unit 221 inputs the first coded signal output from the stream input unit 210, and decodes the Huffman-coded data from the stream format into quantized data. First dequantizer 222
Dequantizes the quantized data decoded by the first decoding unit 221, and outputs low-frequency spectrum data. Here, the number of samples of the spectrum data output by the first dequantization unit 222 is 512 samples (the maximum number of samples is 1024), and these are 11.025 kHz.
Represents the reproduction band (maximum reproduction band 22.05 kHz) .

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

The encoding device 101 is different from the encoding device 100 in that an inverse quantizing unit 152 is newly provided. In this encoding device 101, the first quantization unit 1
51 quantizes all the 1024-point spectrum data output by the conversion unit 120, outputs the quantized result to the inverse quantization unit 152, and outputs the quantized result of the low-frequency part 512 points of the first quantized result. It outputs to the encoding unit 132.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0123

[Correction method] Change

[Correction content]

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 spectrum in the low frequency band as shown in (2) of FIG. 17B.
18 is specified. Similarly, in the search direction (3), the error is "4" and the scale factor band of the scale factor band corresponds to the spectrum of the low frequency band as shown in (3) of FIG. 17B. In the case of 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 133
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 " 0 ", and if the search is performed in the higher frequency direction from the peak, the search direction information is "0".

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0135

[Correction method] Change

[Correction content]

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 133 specifies 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, when the 48 spectral data from the beginning of the scale factor band of number N = 8 are copied to the first scale factor band in the high frequency region starting from 11.025 kHz, the high frequency region in FIG. The waveform becomes as shown, and the energy in the scale factor band of the high frequency part can be approximately represented with respect to the original spectrum.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0152

[Correction method] Change

[Correction content]

[0152] coding apparatus of the present invention, the input audio signal a coding apparatus for coding, from the spectral data divided into a plurality of groups obtained by converting the input acoustic signal of a predetermined time period , Spect within each group
Normalization coefficient to normalize the normal data and the normalization coefficient
Quantify each of the spectral data within each of the groups using
Quantized value obtained by subdividing and each spectrum data
Of the positive or negative sign of the
It is represented by four types of information including the position of the data on the frequency axis
A first encoding means for encoding low frequency band data of a different frequency, and the spectrum in each group of the high frequency band.
To identify low-pass spectral data that is close to
Information and the specified low-frequency spectrum data
As the information for shaping, the characteristics of the high frequency band spectrum data are defined by one or more and three or less of the above four types of information.
Auxiliary information generating means for generating auxiliary information including information for shaping represented by the information, second encoding means for encoding the generated auxiliary information, and encoding by the first encoding means. Output means for outputting the encoded data and the data encoded by the second encoding means. In the encoding device of the present invention,
The auxiliary information generating means has a characteristic in which a high frequency part of the frequency has less characteristics than a low frequency part of the spectrum data divided into a plurality of groups obtained by converting the input acoustic signal for a certain time.
The auxiliary information represented by the second information, and the second encoding means
The generated auxiliary information is encoded.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0153

[Correction method] Change

[Correction content]

Therefore, according to the coding apparatus of the present invention, the spectral data of the high frequency band is not directly quantized and coded, but the characteristic of the high frequency band is smaller than that of the low frequency band.
Since encoding auxiliary information expressed in free parameters, low
There is an effect that it is possible to encode the spectrum of the high frequency part with a very small amount of data compared to the high frequency part. Further, in the conventional MPEG-2 AAC, since the audio signals in the entire band are encoded by the same method in the low frequency band and the high frequency band, it is difficult to transmit the high frequency band at a low transfer rate. However, according to the encoding device of the present invention, it is possible to transmit high frequency band information without significantly increasing the amount of information after encoding. Therefore, it is possible to decode an acoustic signal with high sound quality that is richer in the high frequency range than that of the digitalization device.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0154

[Correction method] Change

[Correction content]

Further, in the encoding apparatus of the present invention, the auxiliary information generating means quantizes the spectrum data which becomes a peak in each of the high band parts of the spectrum data divided into a plurality of groups. When
Then, the normalization coefficient calculated to have a constant value may be generated as the information for shaping .
Yes. The auxiliary information generating means, for each said spectral data divided into a plurality of groups, the spectral data as a peak in the <br/> each group of the high frequency band,
Quantize using a normalization coefficient common to each group,
Then generate the quantized value as the information for the shaping
You may .

[Procedure Amendment 13]

[Document name to be amended] Statement

[Name of item to be corrected] 0155

[Correction method] Change

[Correction content]

[0155] Therefore, according to the encoding device of the present invention, One to each group of the high frequency band (scale factor band)
In this case , one normalization coefficient or a quantized value of the spectrum data that becomes a peak is generated as auxiliary information, so a certain number of bits, for example, 8 bits, are assigned to represent one normalization coefficient or quantized value. as well, the data amount of the supplementary information is Ru slightly der. Thus, for each group of higher frequency band with a small amount of data it can represent a rough maximum amplitude of the spectral data. As a result, according to the encoding device of the present invention, even in a low-transfer-rate transmission path, a high-frequency-range acoustic signal having the characteristics of the original sound can be generated with a slight increase in the transmission amount compared to the conventional one. Suta
Information can be transmitted, so that a decoding device for decoding the information can restore an acoustic signal that is more faithful to the original sound.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Name of item to be corrected] 0156

[Correction method] Change

[Correction content]

Further, in the coding apparatus of the present invention, the auxiliary information generating means determines the frequency position of the peak spectrum data in each group belonging to the high frequency band for the spectrum data divided into a plurality of groups. It may be generated as information for the shaping . Well
Further, the spectrum data is an MDCT coefficient, and the auxiliary information generating means performs, on the spectrum data divided into a plurality of groups, a sign indicating the positive or negative sign of the spectrum data at a predetermined frequency position in a high frequency band .
It may be generated as information for .

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0157

[Correction method] Change

[Correction content]

[0157] Therefore, according to the encoding device of the present invention, the frequency location of the spectral data as the peak, or by positive or negative sign of the spectral data at a predetermined frequency position of the high frequency portion, a small amount of data of the higher frequency band It is possible to represent the general spectral shape of each group (scale factor band), so
The spectrum data more accurately approximates the spectrum in the high frequency range.
The effect is that it can be shaped to resemble .

[Procedure Amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0158

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Further, in the encoding device of the present invention, the auxiliary information generating means, for each of the spectrum data divided into a plurality of groups, in each group of the high frequency part, the low frequency which is the closest to the spectrum in the group. Information for identifying the spectrum of the low frequency band is supplied to the low frequency band spectrum data.
It may be generated as information for identifying the data .

[Procedure Amendment 17]

[Document name to be amended] Statement

[Name of item to be corrected] 0159

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Therefore, according to the encoding apparatus of the present invention, when a spectrum having a shape similar to that of the high frequency band is present in the low frequency band, the spectrum of the low frequency band is specified to increase the high frequency.
Since it only needs to be copied to the high frequency band, there is an effect that the high frequency band spectrum can be represented more faithfully with a very small amount of data.

Continued front page    (72) Inventor Naoya Tanaka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takeshi Norimatsu             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5D045 DA20                 5J064 AA00 BA16 BC02 BC05 BC16                       BC29 BD02

Claims (24)

[Claims] 1. A coding apparatus for coding an input acoustic signal, wherein a low frequency part of frequency is encoded in spectrum data obtained by converting an input acoustic signal for a predetermined time. Encoding means, auxiliary information generating means for generating auxiliary information representing characteristics of a high frequency part of the spectrum data obtained by converting an input acoustic signal for a certain time, and the generated auxiliary information. It is characterized by further comprising: second encoding means for encoding; output means for outputting the data encoded by the first encoding means and the data encoded by the second encoding means. Encoding device. 2. The auxiliary information generating means, with respect to the spectrum data divided into a plurality of groups, a normalization coefficient with which a value obtained by quantizing the spectrum data that becomes a peak in each group in a high frequency band becomes a constant value. The encoding apparatus according to claim 1, wherein the encoding coefficient is calculated, and the calculated normalization coefficient is generated as the auxiliary information. 3. The auxiliary information generating means, with respect to the spectrum data divided into a plurality of groups, spectrum 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. 4. 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, with respect to the spectrum data divided into a plurality of groups. The encoding device according to claim 1. 5. 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 a high frequency band. The information is generated as the auxiliary information.
The encoding device according to any one of 4 to 4. 6. 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. 7. 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. 7. The encoding device according to claim 6, wherein the low-frequency band spectrum having the smallest difference from the distance on the frequency axis of is specified. 8. The auxiliary information generating means specifies a spectrum in a low frequency band part 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 part. The encoding device according to claim 6, characterized in that 9. The encoding apparatus according to claim 6, wherein the information for identifying the low band spectrum is a number for identifying the group of the identified low band spectrum. 10. The auxiliary information generating means generates, as the auxiliary information, a predetermined coefficient representing the amplification ratio of the amplitude of the high frequency band spectrum. The encoding device according to. 11. The output means further converts the data encoded by the first encoding means into an encoded audio stream defined in a predetermined format, and at the same time, in an area within the encoded audio stream. The stream output unit for storing and outputting the data encoded by the second encoding unit is provided in an area of which the use is not restricted by the encoding rule. The encoding device according to any one of claims. 12. The output means further converts the data encoded by the first encoding means into an encoded audio stream defined in a predetermined format, and encodes by the second encoding means. The encoding device according to any one of claims 1 to 10, further comprising a second stream output unit that stores the generated data in a stream different from the encoded acoustic stream and outputs the stream. 13. A decoding device for inputting and decoding encoded data encoded by the encoding device according to claim 1, wherein the decoding device encodes the input encoded data by the second encoding means. Coded data separating means for separating the encoded data, and first decoding for decoding the data encoded by the first encoding means in the input encoded data and outputting spectrum data representing a low frequency part of the frequency. Means for decoding the data encoded from the input encoded data and encoded by the second encoding means to generate the auxiliary information, and the high frequency part of the frequency based on the generated auxiliary information. Second decoding means for generating and outputting spectrum data representing the spectrum data, the spectrum data output by the first decoding means, and the spectrum data output by the second decoding means. Converting the torque data synthesizing and decoding apparatus, characterized in that it comprises an acoustic signal output means for outputting a sound signal on the time axis. 14. A decoding device for inputting and decoding coded data coded by the coding device according to claim 2, wherein the second decoding means includes the generated auxiliary information. Using the normalization coefficient of, a constant value common to each group of the high frequency part, dequantized a quantized value corresponding to a predetermined frequency spectrum data in each group, the result of the dequantized 14. The decoding apparatus according to claim 13, wherein the high band spectrum data in which the spectrum data is a peak of each group is generated. 15. A decoding device for inputting and decoding encoded data encoded by the encoding device according to claim 3, wherein the second decoding means includes the generated auxiliary information. The inverse quantization is performed on the quantized value of each of the high frequency groups by using a common normalization coefficient, and the spectrum data of the result of the inverse quantization is the peak of each group to generate the high frequency spectrum data. 14. The decoding device according to claim 13, characterized in that. 16. A decoding device for inputting and decoding the encoded data encoded by the encoding device according to claim 4, wherein the second decoding means includes the generated auxiliary information. 14. The decoding apparatus according to claim 13, wherein the high frequency band spectrum data in which the frequency position of 10 is a peak in each high frequency band group is generated. 17. A decoding device for inputting and decoding coded data coded by the coding device according to claim 5, wherein the second decoding means is a predetermined frequency position of a high frequency part. The decoding device according to any one of claims 13 to 16, wherein the spectrum data in (1) generates high frequency band spectrum data having the code in the generated auxiliary information. 18. A decoding device for inputting and decoding encoded data encoded by the encoding device according to claim 1, wherein the second decoding means is based on the auxiliary information. 18. A high-frequency spectrum data is generated by generating a predetermined noise in each group of high-frequency bands and adding it to the spectrum data.
Decoding device according to paragraph. 19. A decoding device for inputting and decoding coded data coded by the coding device according to claim 1, wherein the second decoding means is operated by the first decoding means. 18. The low frequency band spectrum data to be output is copied, and the copied spectral data is shaped based on the generated auxiliary information to generate high frequency band spectrum data. The decoding device according to any one of 1. 20. A decoding device for inputting and decoding coded data coded by the coding device according to claim 6, wherein the second decoding means further includes a high-frequency part. In the group, out of the low band spectrum data output by the first decoding means, the low band spectrum data specified by the generated auxiliary information is copied and the high band spectrum data is output. 14. Decoding device according to claim 13, characterized in that 21. A program used in an encoding device for encoding an input acoustic signal, which causes a computer to function as each unit included in the encoding device according to claim 1. program. 22. A program used in a decoding device for inputting and decoding coded data coded by the coding device according to any one of claims 1 to 12, and claiming a computer. A program that causes each unit of the decoding device according to any one of Items 13 to 20 to function. 23. A computer-readable recording medium in which the program according to claim 21 is recorded. 24. A computer-readable recording medium recording the program according to claim 22.