Abstract: An MDCT calculating circuit includes an x.sub.01 calculating circuit for multiplying input signals with a forward transforming window and a linear forward transforming unit for linear forward transforming an output signal of the calculating circuit. The linear forward transforming unit includes an x.sub.02 calculating circuit and an x.sub.03 calculating circuit for pre-processing the output signal of the x.sub.01 calculating circuit and an integration and summation processing circuit for executing integration and summation processing operations on an output signal of the pre-processing unit. The integration and summation processing circuit executes an integration and summation operation on an N/2 number of input signals from the pre-processing unit by grouping a k number of input signals as a processing unit and iteratively executes the integration and summation processing operations a N/(2*K) number of times for outputting a sum total of N/2 number of signals.

Abstract: An MDCT calculating circuit includes an x.sub.01 calculating circuit for multiplying input signals with a forward transforming window and a linear forward transforming unit for linear forward transforming an output signal of the calculating circuit. The linear forward transforming unit includes an x.sub.02 calculating circuit and an x.sub.03 calculating circuit for pre-processing the output signal of the x.sub.01 calculating circuit and an integration and summation processing circuit for executing integration and summation processing operations on an output signal of the pre-processing unit. The integration and summation processing circuit executes an integration and summation operation on an N/2 number of input signals from the pre-processing unit by grouping a k number of input signals as a processing unit and iteratively executes the integration and summation processing operations a N/(2*K) number of times for outputting a sum total of N/2 number of signals.

Abstract: A high efficiency encoding audio signals is disclosed. The system includes a signal energy calculating circuit for calculating allowable noise energies by utilizing characteristics of human acoustic sense and calculating allowable noise energies of a block under consideration by weighted addition of the allowable noise energies calculated for at least one past block with respect to the block under consideration, a first-order allowable noise energy calculating unit, a second-order allowable noise energy calculating unit, a calculating circuit for calculating characteristics of human acoustic sense, and a memory. Adaptive quantization is performed in the quantization circuit with the bit allocation number which is based on the calculated allowable noise energies. Signals undergoing large temporal fluctuations can be encoded efficiently, while aurally outstanding noise may be reduced to improve the sound quality by eliminating sound quality deterioration known as pre-echo.

Abstract: A data encoding method apparatus in which the volume of arithmetic-logical operations for calculating the total number of bits required for encoding for adaptive bit allocation in the variable length encoding system for expediting the processing. In the data encoding apparatus for encoding and subsequently variable length encoding the input data, spectral data obtained on orthogonal transform coding are routed to a block floating circuit 403 for normalization and re-quantized in a quantization circuit 404 depending on the bit allocation number information from a bit allocation calculating circuit 406 so as to be then variable length encoded by an encoding circuit 407 and outputted at an output terminal 408.

Abstract: An information furnishing and collection system which allows rapid furnishing of information and flexible payment of a charge and collects information regarding a reaction of a user while enhancing the security of information management is disclosed. Inputting to an information recording and reproduction apparatus and recording onto and reproduction from an information recording medium are performed under the control of a write management section. When inputting to an information inputting section or recording onto the information recording medium is to be controlled, the write management section controls the information inputting function or the information recording function using a control signal. An information signal is sent as information to the information recording medium by way of the information inputting section.

Abstract: Pre-echo in the encoding and encoding of digital audio signals is diminished by utilizing a frequency dividing circuit for dividing the input audio signals into plural bands, normalization circuits for normalizing the frequency components for each frequency band and quantization circuits for an quantizing output of the normalization circuits. The frequency dividing circuit includes a unit for detecting a position in the signal waveform in which the quantization noise not masked by the signal components, that is the pre-echo, is estimated to be generated for producing the signal suppressing information. This signal suppressing information is also quantized as is the quantized output.

Abstract: In quantizing a digital signal in respective frequency bands by quantization units and transmitting (transmitting or recording) such quantized digital signal, second quantization accuracy information indicating a difference between first quantization accuracy information serving as a reference and actual quantization accuracy information from a quantization accuracy determination unit is coded at a quantization accuracy information coding unit to transmit the coded quantization accuracy information to thereby realize efficient coding while maintaining a degree of freedom in the manner of giving quantization accuracy. Accordingly, more efficient coding can be attained while leaving the degree of freedom in the manner of giving quantization accuracy by a lesser number of bits.

Abstract: In a coding apparatus for a digital signal adapted for implementing, every variable length block, floating processing to an input digital signal by using a block floating processing circuit thereafter to orthogonally transform signal components which have undergone such processing by using orthogonal transform circuits (e.g., DCT circuits), the block floating processing circuit is constructed so as to determine the length of a variable length block and a floating coefficient of the block floating processing on the basis of the same index, e.g., a maximum absolute value in that block. Thus, a quantity subject to processing can be reduced.

Abstract: A digital input signal is compressed to provide a compressed output signal in a manner which prevents pre-echo, a common defect of data compressors. The digital input signal is divided in time into frames, and into at least one block of data in each frame. The frames include a past frame preceding a present frame. Block floating is applied to the data in the block in each frame. Quantizing bits are adaptively allocated to the data in the block in the present frame in response to the block in the past frame. Finally, the resulting quantized data is added to the compressed output signal. In a first variation, a signal energy or an allowable noise level is determined for the block in each frame. A word length is determined for the block in each frame in response to the determined signal energy or allowable noise level of the block. The quantizing bits are allocated to the data in the block in the present frame in response to the word length for the block in the past frame.

Abstract: Apparatus for recording an information signal as bit-compressed digital data. The apparatus comprises a bit compressor and a recording system. The bit compressor receives the information signal as digital data. The digital data include bits, and the bits include redundant bits. The bit compressor compresses the digital data by removing only the redundant bits from the digital data to generate the bit-compressed digital data at a variable bit rate. The redundant bits are bits that result in a quantizing noise level lower than an allowed noise level at which the quantizing noise is imperceptible to a human auditory sense. The allowable noise level is determined by a masking threshold and a minimum audibility limit. The recording system receives the bit-compressed digital data from the bit compressor and records the bit-compressed data on a recording medium.

Abstract: An apparatus for compressing a digital input signal compresses a digital input signal arranged into frames of plural samples. The digital input signal is orthogonally transformed by plural orthogonal transform circuits in blocks derived by dividing the frames by a different divisor in each circuit. The resulting spectral coefficients are quantized using an adaptive number of bits. The output of one orthogonal transform circuit is selected based on the outputs of the orthogonal transform circuits. The digital input signal is divided into plural frequency ranges, and frames are formed in each range. A block length decision circuit determines division of the frames of each range signal into blocks in response to range signal dynamics. The range signals are orthogonally transformed in blocks and the spectral coefficients are quantized. The apparatus also includes a frequency analyzing circuit that derives spectral data points from the input data, and groups them in plural bands.

Abstract: A method for compressing a digital audio input signal to provide a recording signal in which the input signal is divided into frames comprising plural samples. Each frame is transformed into a block of spectral coefficients, which are divided into plural bands. For each band, block floating is applied to the spectral coefficients therein; a block floating coefficient is generated; the spectral coefficients are quantized with an adaptive number of bits to provide quantized spectral coefficients; and a word length is generated. Finally, there is added to the recording signal a block of data derived from the block of spectral coefficients and consisting of the quantized spectral coefficients, a main word length and a main block floating coefficient for each band, and a reserve word length at least for each lower frequency band. In a variation, zero bits are allocated to quantize the spectral coefficients in bands higher in frequency than a highest usable band.

Abstract: A method for performing a simplified digital spectral analysis on a block of N samples representing an information signal in the time domain, in which the block of N samples is multiplied by a forward transform window to provide a block of N processed samples. The block of processed samples is digitally preprocessed to provide a block of N/4 complex numbers, which is orthogonally transformed, using digital processing equivalent of a Fast Fourier Transform, to provide a block of N/4 transformed complex numbers. The block of transformed complex numbers is then digitally post-processed to provide a block of N/2 spectral coefficients representing the information signal in the frequency domain.

Abstract: A data compression apparatus for compressing a digital input signal to provide a compressed digital output signal. In the apparatus, a circuit derives plural spectral coefficients from the digital input signal, and groups the spectral coefficients into bands. An adaptive bit allocation circuit adaptively allocates a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each of the spectral coefficients in the band. The number of spectrum-dependent quantizing bits allocated to each band by the adaptive bit allocation circuit is determined according to the band magnitude, weighted depending on the band frequency.

Abstract: An apparatus for encoding an input digital signal divides the input digital signal to produce frequency components of increasing bandwidth as the frequency increases, performs blocking on each of the frequency components to produce blocks of decreasing time length as the frequency increases, performs a fast Fourier transformation on each block and quantizes each block using a quantization characteristic set in accordance with a comparison of the energy of each frequency component in each block with a masking spectrum. The masking spectrum includes both a masking effect on the frequency base of the input signal and masking effect on the time base of the input signal and may further include effects of the minimum audible curve of the human hearing sense characteristic. Utilization of both the temporal and frequency masking effects permits reduction in the bit rate of the encoded signal using real time processing and without deterioration in sound quality.

Abstract: The present invention relates to a digital signal encoding apparatus in which an input digital signal has its frequency range divided into a number of frequency bands so that the bandwidths are broader at higher frequencies. A first allowable noise level based on the energy levels in the respective bands, and a second allowable noise level based on the energies of the signals temporally adjacent to the signals of a frequency band under consideration, are set. Signal components of each frequency band are quantized with a number of bits corresponding to a difference between an output synthesized from the first and second noise levels and the energy level of each frequency band. In this manner, the bit rate may be lowered while deterioration in the sound quality is minimized.