JPH03145823A - Method and apparatus for adaptive conversion encoding - Google Patents

Abstract

PURPOSE:To compress the auxiliary information quantity and to improve the coding quality while satisfying such a discrepant requirement as following the resolution and the property of an input signal by using a conversion coefficient obtained by applying linear conversion to the input signal to vary the block length N. CONSTITUTION:Normalization 2 and linear conversion 3 by an input signal are implemented as to plural block lengths to supply a relevant conversion coefficient and auxiliary information are fed to a block length selection circuit 7. When the calculation of the conversion coefficient to the block length is all finished, the block length selection circuit 7 uses N sets of conversion coefficient to each block length to select an optimum block length Nm and the conversion coefficient and auxiliary information corresponding to the optimum block length Nm are selected, the conversion coefficient is fed to a quantizer 4 and a bit distribution circuit 7 and the variance of the input signal being the auxiliary information and the optimum block length Nm are fed respectively to a multiplexing circuit 15.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to band compression technology for signals such as voice/music, and in particular to band compression technology that performs band compression after linearly converting an input signal obtained in the time domain to another domain. Regarding technology.

(Prior art) Bandwidth compression is the process of reducing the amount of information contained in signals such as voice/music in order to efficiently transmit the information contained in signals such as voice/music using lines with limited transmission capacity. Differential Pulse Code Modulation [ADPCM] (Digital
Coding of Waveforms, (Digi
talCoding of Waveforms)
, Prentice Hall Co., Ltd.
11), 1984, p. 308;
"Reference 1") and adaptive transform coding [ATC] (IEEE TRANSACTIONS ON
ASSP) Vol. 27, No. 1, 1979, pages 89-95; hereinafter referred to as "Reference 2") is known. less than,
The outline of ATC will be briefly explained according to Document 2.

FIG. 5 is a block diagram showing an example of the configuration of the ATC. In an encoder comprising linear transformation, bit allocation, and quantization, an input signal is supplied to a linear transformation circuit 3 via an input terminal 1. In general, discrete values are supplied to the input terminal 1, and a linear transformation circuit 3 performs N-point discrete linear transformation in units of input samples equal to a predetermined integer N. N is called the block length. As this N-point discrete linear transformation,
Walsh-Hadamard transform (WAT), discrete Fourier transform (DFT), discrete cosine transform (DCT), KL transform (KLT), etc. are used. The total number N of transform coefficients output from the linear transform circuit 3 are each quantized by a quantizer 4 according to a bit allocation to be described later, and then supplied to a multiplexing circuit 5. The quantizer 4 includes a number of quantizers equal to the block length N, and each transform coefficient is quantized by a dedicated quantizer. The bit allocation circuit 6 calculates the quantization bit allocation corresponding to the amplitude of the transform coefficient and supplies it to the quantizer 4. The multiplexing circuit 5 multiplexes the quantized transform coefficients supplied from the quantizer 4 and the information used for bit allocation supplied from the bit distribution circuit 6, and sends the multiplexed information to the transmission line 8.

In the decoder, which consists of bit allocation, inverse quantization, and linear inverse transformation, the multiplexed signal from the transmission line 8 is separated by a separation circuit 9, and the signal from the quantizer 4 is sent to the inverse quantizer 10, which performs bit allocation and linear inverse transformation. The signal from circuit 6 is supplied to bit allocation circuit 11. The bit allocation circuit 11 determines the bit allocation for each transform coefficient in exactly the same manner as the bit allocation circuit 6 of the encoder.

The transform coefficients dequantized by the dequantizer 10 according to the bit allocation determined by the bit allocation circuit 11 are converted again into a total number N of time domain signal samples by the linear inverse transform circuit 12, and are sent to the output terminal 14. Supplied.

There are several types of allocation methods in bit allocation circuits, but here we will use the method described in Document 2 as the sixth method.
This will be explained with reference to Figures (a) and (b).

This method minimizes the squared quantization error when dequantized in the decoder. In order to reduce the amount of auxiliary information regarding bit allocation, the transform coefficients are thinned out once, and then the interpolated values are Optimize the number of bits using The bit allocation circuit I shown in FIG.
). The conversion coefficients obtained by the linear conversion circuit 3 in FIG. 5 are supplied to the thinning circuit 42 via the input terminal 41 in FIG. 6(a). The decimation circuit 42 squares each of the N conversion coefficients, and performs 1/H decimation using an average value multiplied by an integer value M (M is a divisor of N) as a representative value. The obtained sample value of L=N/H is sent to the quantizer 43
are respectively quantized by the output terminal 44 and the inverse quantizer 45.
supplied to The quantizer 43 and inverse quantizer 45 may be omitted in some cases. In the interpolation circuit 46, after taking the base-2 logarithm, M times linear interpolation is performed in the logarithm domain. Using the interpolated signal, the bit allocation in the quantizer 4 of FIG. 5 is determined by the bit number optimization circuit 47 according to the following formula.
It will be held in

Here, R+ is the first conversion coefficient (i=1.2...
. The result is transmitted to the output terminal 48 and fed to the quantizer 4. IEE Transactions on AnisSP (IEE Transactions on ANISP) has shown that the squared quantization error can be minimized by allocating bits using equation (1).
IEEE TRANSACTIONS ON AS
SP) Vol. 25, No. 4, 1977, pages 299-309; (hereinafter referred to as "Reference 3"). The thinned signal obtained at the output terminal 44 is sent to the transmission line 8 as auxiliary information via the multiplexing circuit 5 shown in FIG. On the other hand, the bit allocation circuit 11 in FIG. 5 is configured as shown in FIG. 6(b). The signal from the separation circuit 9 of FIG. 5 is supplied to the interpolation circuit 46 via an input terminal 49. The bit allocation circuit 6 in the encoder includes a quantizer 43 and an inverse quantizer 45
, the bit allocation circuit 11 in the decoder also has a corresponding inverse quantizer 45. The interpolation circuit 46 and the bit number optimization circuit 47 perform the same interpolation and bit number optimization as the interpolation circuit 46 and the bit number optimization circuit 47 in the encoder described above.

Therefore, signals for completely equal bit allocation are obtained at the output terminal 48 in FIG. 6(a) and the output terminal 50 in FIG. 6(b), and corresponding signals are obtained on the encoder side and the decoder side. quantization/inverse quantization is performed.

In the explanation so far, the signal supplied from the bit allocation circuit 6 to the multiplexing circuit 5 as auxiliary information is the square value of the thinned-out transform coefficient obtained at the output terminal 44 in FIG. 6(a). However, the purpose of transmitting this signal to the decoder is to share approximate values of transform coefficients used for bit allocation between the encoder and the decoder. As methods for transmitting auxiliary information for this purpose, methods using PARCOR coefficients, ADPCM, vector quantization, and the like are known in addition to the square value of thinned-out transform coefficients.

In the encoder, the input signal can also be normalized in order to obtain transform coefficients whose amplitude does not depend on the power of the input signal at the output of the linear transform circuit 3 shown in FIG. In this case, as shown in FIG. 7, the input signal is normalized through the normalization circuit 2 and then supplied to the linear conversion circuit 3. In the decoder, the output of the linear inverse transform circuit 12 is subjected to processing opposite to that of the normalization circuit 2 in the inverse normalization circuit 13, and then sent to the output terminal 1.
4. The reference value used for normalization is the multiplexing circuit 5
The signal is multiplexed with the signals from the quantizer 4 and the bit allocation circuit 6, and is transmitted to the decoder via the transmission path 8.

On the decoder side, the signal is separated from the signal supplied to the dequantizer 10 and bit allocation circuit 11 by the separation circuit 9, and then transmitted to the denormalization circuit 13. FIGS. 8(a) and 8(b) show the configurations of the normalization circuit 2 and the denormalization circuit 13, respectively.

The input terminal 61 in FIG. 8(a) has the input terminal 1 in FIG.
The input signal samples are provided by

After the input signal samples are temporarily stored in buffer 62,
The N samples are collectively scaled by a multiplier 63 and supplied to an output terminal 65. The output signal from the output terminal 65 is supplied to the linear conversion circuit 3 shown in FIG. The multiplier of the multiplier 63 is the reciprocal of the average value of the input sample power for one block. This value is the reciprocal of the variance for an input signal with an average of zero, and can be calculated from the variance value determined by the variance calculation circuit 64. The variance value determined by the variance calculation circuit 64 is used by the multiplier 63 to normalize the input sample, and at the same time is supplied to the multiplexing circuit 5 in FIG. 7 via the output terminal 66, and after multiplexing, It is conveyed to the decoder as auxiliary information. On the other hand, in the inverse normalization circuit of FIG. 8(b), the signal from the linear inverse transform circuit 12 of FIG. 7 is supplied to the multiplier 68 via the input terminal 67. The multiplier 68 denormalizes the output signal using the dispersion value obtained through the input terminal 69 and stores it in the buffer 70 . The dispersion value obtained at the input terminal 69 is obtained by the multiplexing circuit 5 in FIG.
The signal is transmitted from the encoder via the transmission path 8 and the separation circuit 9. Buffer 70 sequentially transmits the N decoded sample values via output terminal 71 to output terminal 14 in FIG.

(Problem to be Solved by the Invention) The number of blocks N affects the resolution of calculations performed in the linear transformation circuit 3 and the linear inverse transformation circuit 12 shown in FIGS. 5 and 7, and the larger N is, the higher the resolution is. Errors caused by encoding and decoding are reduced. Further, the auxiliary information regarding bit allocation is inversely proportional to the number of blocks included in a certain period of time, and the larger N is, the more the amount of auxiliary information is reduced. This means that more main information can be sent for a given transmission capacity, leading to improved encoding quality. On the other hand, for non-stationary signals, a large N does not necessarily give a small error. This is because although the same processing is performed on input samples within the same block, if the block is long, the characteristics of a non-stationary signal may change within the same block.

Therefore, for signals with strong non-stationarity, it is better to perform encoding that follows changes in the properties of the input signal using a small block length N. In conventional ATC, block length N
Since the resolution was fixed, it was not possible to meet the conflicting demands of resolution and ability to follow changes in the properties of the input signal.

An object of the present invention is to provide an adaptive transform encoding method and apparatus that can improve encoding quality by compressing the amount of auxiliary information while satisfying the conflicting demands of resolution and tracking changes in the properties of input signals. There is a particular thing.

(Means for Solving the Problems) The present invention performs linear transformation using the specified block length when the block length is specified, and otherwise stores input signal samples in a buffer. , independently performs linear transformation on a unit of input samples equal to the maximum number among the plurality of block lengths, independently stores the obtained transformation coefficients and auxiliary information, and simultaneously uses the transformation coefficients. determine the optimal block length, select the stored transform coefficients and auxiliary information corresponding to the optimal block length, and quantize the selected transform coefficients by bit allocation calculated using the transform coefficients. The quantization output, bit allocation information, and the selected auxiliary information are transmitted/stored together with the optimum block length.

The present invention also provides a buffer for accumulating input samples, a linear transformation circuit for independently performing linear transformation on a unit of input samples equal to the maximum number of the plurality of block lengths, and Transform coefficients and auxiliary information are each stored independently, an optimal block length is selected using the transform coefficients, and the stored transform coefficients and auxiliary information corresponding to the optimal block length are selected and output together with the optimal block length. a block length selection circuit that calculates bit allocation using the selected transform coefficient;
a quantizer that quantizes the selected transform coefficient using the bit allocation obtained by the bit allocation circuit; an output of the quantizer, an output of the bit allocation circuit, the selected auxiliary information, and the optimum block length; The device is characterized in that it includes at least a multiplexing circuit that multiplexes and transmits/stores the data.

(Operation) The adaptive transform encoding method and apparatus of the present invention makes the block length N variable using transform coefficients obtained by linearly transforming an input signal, thereby adapting to changes in resolution and properties of the input signal. It is possible to improve the encoding quality by compressing the amount of auxiliary information while satisfying the conflicting demands of tracking.

(Example) Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, if a block length is specified, encoding is performed using the specified block length, otherwise, linear transformation is performed on the input signal, and the obtained transformation coefficients are used to perform encoding. The optimal block length is determined and encoding is performed using the optimal block length. For this purpose, a block length selection circuit 7 and a block length designation signal input terminal 17 are provided. Next, the operation of the embodiment shown in FIG. 1 will be explained.

When no input signal is supplied to the block length designation signal input terminal 17, the input signal supplied to the input terminal 1 is normalized by the variance value of the input signal in the normalization circuit 2 using one block length candidate N1. be done.

The normalized signal is converted to N in the linear conversion circuit 3.

After being subjected to point discrete linear transformation, it is supplied to the block length selection circuit 7. Next, normalization and linear transformation are performed on the samples equal to the second block length N2 in the same manner as in the case of N1, and the results are supplied to the block length selection circuit 7. In the same manner as in the cases of N1 and N2 explained above, normalization and linear transformation using input signals are performed for the cases of multiple block lengths N3, N4, ...Nn, and the corresponding transform coefficients and auxiliary information are converted into blocks. The signal is supplied to the length selection circuit 7.

However, normally N1 × N2 × N3 × N4...<Nn
Then, 2 N += N H+t (1≦inn,). Block length N1, N2, N3, N4,...
When calculation of all transform coefficients for Nn is completed, the block length selection circuit 7 selects the optimum block length Nln using N transform coefficients for each block length.

The transform coefficients and auxiliary information corresponding to the optimal block length Nm are selected, and the transform coefficients are sent to the quantizer 4 and the bit allocation circuit 7.
The dispersion value of the input signal and the optimum block length Nm, which are auxiliary information, are respectively supplied to the multiplexing circuit 15. The optimal block length NlTl may be transmitted to the multiplexing circuit 15 after being quantized.

The bit allocation circuit 6 performs bit allocation using the transformation coefficients supplied from the block length selection circuit 7, and the quantizer 4 uses the obtained bit allocation information to select the transformation circuit supplied from the block length selection circuit 7. Performs quantization. The quantized transform coefficients and the bit allocation information are sent to the multiplexing circuit 1.
At step 5, the signal is multiplexed with the optimal block length NIn and the dispersion value of the input signal, and sent to the transmission path 8.

When an input signal is supplied to the block length designation signal input terminal 17, the block length selection circuit 7 forcibly sets the supplied block length N to the optimum block length Nln. Therefore, subsequent quantization is performed based on the supplied block length N. Next, the configuration of the block length selection circuit 7 will be explained in detail.

The deterioration of the decoded signal when a large block length is employed is significant when the input signal amplitude increases and decreases rapidly. In such a case, the variation in the amplitude of the N conversion coefficients becomes wider due to the conversion coefficient component that causes the sudden fluctuation in the amplitude. The number of bits required to obtain a constant encoding quality increases. Therefore, when encoding with a constant number of bits, it is necessary to check the variations in the amplitudes of N transform coefficients and select the block length with the smallest variation. Maximum encoding quality can be obtained by using

FIG. 2 shows an example of the configuration of the block length selection circuit 7. Although various criteria can be considered for the above-mentioned variation, the variance of the conversion coefficient is used here.

Input signals 21, 22, and 23 in FIG. 2 are block length designation signals supplied to the input terminal 17, and linear conversion circuit 3
The transform coefficients supplied from the normalization circuit 2 correspond to the dispersion values of the input signal supplied from the normalization circuit 2, respectively.

Further, the output signals 30, 31, and 32 are the optimum block length Nm supplied to the multiplexing circuit 15, the transformation coefficient supplied to the quantizer 4 and the bit allocation circuit 6, and the input signal supplied to the multiplexing circuit 15. correspond to the variance values of . Transform coefficients and input signal variance values corresponding to each block length are independently stored in storage devices 25 and 26. After these input signals are stored in the storage devices 25 and 26, they are sent to the selector 2.
At 8.29, values corresponding to the optimum block length Nm, which are the outputs of the selector 27, are selected and output as output signals 31 and 32, respectively. On the other hand, input signal 2
2 is also supplied to the storage device 25 and the distribution calculation circuit 24 at the same time, and the distribution calculation circuit 24 calculates the transformation coefficient yj (Nl) (j=1 The variance δ(N1) for the amplitude of ...Nl) is calculated. However, 1・1 is the absolute value operator, 1y (
tL) l is the average value of I yj (Nl) l for j. N1 giving m1n(δ(Nl)) is Nl, l
is selected and supplied to the selector 27. However, m1
n(·) represents a minimum value operator. The selector 27 is also supplied with a block length selection signal as the input signal 21.

The selector 27 selects the block length selection signal when the block length selection signal is supplied, and selects the optimal block length NIr+ supplied from the variance calculation circuit 24 in other cases, and outputs it as the output signal 31. As already mentioned, the selectors 28 and 29 are controlled by the output signal 31. With the above operation, the optimal block length Nm using the variance of the transform coefficient as the selection criterion is obtained as the output signal 30, and the variance value of the transform coefficient and input signal sample corresponding to N and n are obtained as the output signals 31 and 32, respectively. It will be done.

FIG. 3 shows another example of the structure of the block length selection circuit 7. As the criterion for the variation, the minimum value of the difference between the maximum amplitude and the minimum amplitude of the conversion coefficient is used here.

Since FIG. 3 can be obtained by replacing the variance calculation circuit 24 in FIG. 2 with the maximum-minimum calculation circuit 33, only the maximum-minimum calculation circuit 33 will be described here. The maximum/minimum calculation circuit 33 calculates the minimum difference between the maximum amplitude and the minimum amplitude of the conversion coefficient yj (Nl) (j=1...N,) for each block length candidate value N1 (1≦i<n). The value min[max(I
yj(Nl) l )-min(I yj(tL) l
)] is calculated. However, min[・], maX(・
), 1.1 represent the minimum value operator, maximum value operator, and absolute value operator, respectively. .

min[max(I ydN+) l )−min(I
yj(Nl) l )] is selected as Nrn and supplied to the selector 27. Similar results can be obtained by using the respective norms instead of the maximum and minimum amplitudes of the conversion coefficients as the standard for the variation. next,
Referring to FIG. 4, the actual procedure for selecting the optimum block length will be explained, taking as an example the case where the optimum block length is determined from n types of block lengths. Here, in order to simplify the explanation, it is assumed that n=3 (the optimum block length is selected from three different block lengths) as shown in FIG.

Let time 1=0 be the time when the encoder starts operating. At time NIT (T is the sampling period), N1 input signal samples are accumulated in the buffer in the normalization circuit of FIG. This situation is shown in (A) of FIG. 4(a). In the same figure, the input signal sample indicated as N and (1), that is, the hatched portion indicated as I, is subjected to linear transformation with a block length of N, and the transformation coefficients are stored in a storage device. At time N2T, samples equal to the second block length N2 (N1 < N2) are accumulated in the buffer. This situation is shown in Figure 4 (a) and (B).
Shown below. At this time, the input signal sample indicated as N,(2) in the same figure, that is, the hatched part indicated as ■, is subjected to linear transformation with block length N, and then N2(1) Linear transformation with block length N2 is performed on the displayed input signal samples, that is, the hatched part marked I and the hatched part marked ■, and the respective transformation coefficients are stored in a storage device. to be memorized. At time (N1+N2)T, sample files equal to N+N2 are accumulated in the buffer.

This situation is shown in FIG. 4(a)(C). At this time, the input signal sample indicated as N 1 (3) in the same figure,
That is, the hatched portion indicated by ■ is subjected to linear transformation using a block length N, and the transformation coefficients are stored in a storage device. Furthermore, at time N3T, the third block length N 3 (N , < N 2 <
Samples equal to N 3) are accumulated. This situation is shown in FIG. 4(a)(D).

At this time, the input signal sample indicated as N, (4) in the same figure, that is, the hatched part indicated as ■, is subjected to linear transformation using block length N1, and is also indicated as N2 (2). input signal samples, i.e.
Linear transformation with block length N2 is performed on the hatched part shown as , and the hatched part shown as ■, and the input signal sample shown as N5(1), that is, Linear transformation using block length N3 is performed on the hatched portions indicated by (1), (2), and (2), and the respective transformation coefficients are stored in a storage device. Hereinafter, N 1 (1) stored in the storage device,
Using the conversion coefficients corresponding to N 1 (2), N 1 (3), N 1 (4), the conversion coefficients corresponding to N2 (1) and N2 (2), and the conversion coefficient corresponding to N5 (1), hand,
Variance δ of transform coefficients for block lengths N4, N2, N3
The optimal block length Nm is determined by calculating (N1), δ(N2), and δ(N3) and detecting the minimum value thereof.

The above processing procedure is summarized in FIG. 4(b). N
Taking the case of 5=2N2=4Nt as an example, the maximum block length N3 is 11I [, ■, ■, the four minimum block lengths N1
It can be expressed as Linear transformation using the block length N1 for the input data of the blocks (1), (2), (2), and (2) is performed in the blocks (2), (2), (2), and Io, respectively.

Linear transformation using the block length N2 for the input data of the blocks I1II and 2+2 is performed in the blocks 2 and 2, respectively. Furthermore, I+n+II[+I
Linear transformation using block length N3 for the input data of the block of V is performed in the block of work. Therefore, for block Io, which has the largest amount of processing, linear transformation using block length N1 for ■, linear transformation using block length N2 for III+N, linear transformation using block length N2 for III+N, linear transformation using block length N2 for
Linear transformation using block length N3 for +IV, and variances of transformation coefficients δ(N,), δ(N2), δ(N3)
The optimum block length Nm must be determined by calculating the minimum value of Nm. That is, it is assumed that the time required for all these processes is shorter than N and T.

As is clear from FIG. 4(b), the buffer in the normalization circuit 2 must have a capacity of at least N3T, and is reset every N3T. Transform coefficients corresponding to the selected optimal block length are taken out from the storage device in N3 samples at a time, quantized by the quantizer 4, and then sent to the transmission line 8 in FIG. Therefore, as shown in FIG. 4(c), the data sent to the transmission path 8 has consecutive blocks of the same length in units of N3.

The description of the embodiments so far has been based on the assumption that the normalization circuit 2 exists, but as already described with reference to FIGS. 5 and 7 in the description of the conventional ATC, the input signal is The process of normalizing by variance can also be omitted. However, unlike the conventional example, the buffer cannot be omitted.

Note that in FIG. 2, when the input signal shown in FIG. 7 is not normalized, the input signal 23 and the output signal 32 do not exist, and accordingly, the storage device 26 and the selector 2
9 becomes unnecessary.

(Effects of the Invention) As described in detail above, according to the present invention, the characteristics of the input signal are determined based on the transform coefficients obtained by performing linear transform with different block lengths, and the optimal block length is selected. In order to transmit information by quantizing transform coefficients corresponding to A method and apparatus for transform encoding can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, an example of the state of a buffer that stores force samples and a procedure for selecting an optimal block length, FIG. 5 is a block diagram showing a conventional example, and FIG. Figures (a) and (b) are diagrams showing details of the bit allocation circuit and bit allocation circuit (■) in Figure 5, Figure 7 is a diagram showing another conventional example, and Figures 8 (a) and (b). 7 is a diagram showing details of the normalization circuit and the denormalization circuit in FIG. 7. FIG. In the figure, 1.17 is an input terminal, 2 is a normalization circuit, and 3
is a linear conversion circuit, 4 is a quantizer, 6 is a bit allocation circuit,
7 represents a block length selection circuit, 8 represents a transmission path, and 15 represents a multiplexing circuit.

Claims (6)

[Claims] (1) When adaptively converting an input signal to compress and transmit/storage the information content of a signal such as voice/music, if a block length is specified, the specified block length is used. Otherwise, the input signal samples are stored in a buffer and the linear transformation is performed independently in units of input samples equal to the maximum number of the plurality of block lengths. , store the obtained transform coefficients and auxiliary information independently, simultaneously determine an optimal block length using the transform coefficients, select the stored transform coefficients and auxiliary information corresponding to the optimal block length, and select the stored transform coefficients and auxiliary information corresponding to the optimal block length. quantization is performed on the converted transform coefficients by bit allocation calculated using the transform coefficients, and the quantized output, bit allocation information, and the selected auxiliary information are transmitted/stored together with the optimal block length. Features adaptive transform coding method. (2) The adaptive transform encoding method according to claim 1, wherein the determination of the optimal block length using the transform coefficients is performed using the variance of the transform coefficients. (3) The adaptive transform encoding method according to claim 1, wherein the determination of the optimal block length using the transform coefficients is performed using the maximum amplitude value and the minimum amplitude value of the transform coefficients. (4) A buffer that accumulates input samples, a linear conversion circuit that independently performs linear conversion using input samples equal to the maximum number of block lengths as a unit, and the obtained conversion coefficients. and auxiliary information independently, selects an optimal block length using transform coefficients, selects the stored transform coefficients and auxiliary information corresponding to the optimal block length, and outputs the selected transform coefficients and auxiliary information together with the optimal block length. a long selection circuit; a bit allocation circuit that calculates bit allocation using the selected transform coefficient; and a quantizer that quantizes the selected transform coefficient using the bit allocation obtained by the bit allocation circuit. and a multiplexing circuit that multiplexes and transmits/stores the output of the quantizer, the output of the bit allocation circuit, the selected auxiliary information, and the optimal block length. (5) The block length selection circuit includes a first block length selection circuit that stores transform coefficients.
a second storage device that stores auxiliary information; and a second storage device that stores auxiliary information.
a variance calculation circuit that receives the transformation coefficient, calculates its variance, and outputs a signal corresponding to a block length that provides the minimum variance; and receives an output of the variance calculation circuit and a block length designation signal supplied from the outside; a first selector that selects and outputs one of the input signals using the block length designation signal; and a first selector that receives the output of the first storage device and selects and outputs one of the input signals using the output of the first selector. 5. The adaptation according to claim 4, further comprising a third selector that receives the output of the second storage device and selects and outputs one of the outputs of the first selector. Transform coding device. (6) The block length selection circuit includes a first block length selection circuit that stores transform coefficients.
a second storage device that stores auxiliary information; and a second storage device that stores auxiliary information.
a maximum-minimum calculation circuit that receives the transformation coefficient, detects the maximum value and minimum value of its amplitude, and outputs a signal corresponding to a block length that gives the minimum value of the difference between the maximum value and the minimum value; a first selector that receives the output of the calculation circuit and a block length designation signal supplied from the outside, and selects and outputs one of the input signals using the block length designation signal;
a second selector that receives the output of the storage device and selects and outputs one of the outputs of the first selector;
5. The adaptive transform encoding apparatus according to claim 4, further comprising a third selector that receives the output of the storage device and selects and outputs one of the outputs of the first selector.