摘要:
A waveform data structure includes a plurality of types of frames having different data sizes. Each of the plurality of types of frames includes an auxiliary information area and a data area. The auxiliary information area includes an area for storing common effective-bit length data for a section of waveform samples, and an area for storing an identifier for identifying one of the plurality of types of frames. The data area is an area for storing extracted waveform samples which are extracted from the waveform samples based on the common effective-bit length. The number of the extracted waveform samples is determined based on the common effective-bit length.
摘要:
For respective sampling data of waveform data of sounds to be coded, a prediction residual value is calculated as sampling residual data, and an effective bit length is calculated from this residual waveform data. Then, for the effective bit length data, a maximum effective bit length among processing targets is generated as common effective actual data, and coded data in which this common effective actual data and information indicating the common effective bit length are arranged in a predetermined configuration format are generated. The information included in the coded data is analyzed and each of the plurality of the common effective bit information is extracted. Then, waveform data of the sounds are decoded by performing inverse linear prediction processing from an analysis result on the residual waveform data decompressed by performing bit extension which adds a portion other than the common effective bit length.
摘要:
Compressed waveform data structure is proposed which is suited for segmentation of a plurality of samples of compressed waveform data into a plurality of frames and subsequent storage of each of the frames. The number of bits per sample of the compressed waveform data is variable between the frames, but uniform, i.e. the same among all of the samples, within each of the frames. Each of the frames has a same data storage size. Each of the frames includes, in a predetermined layout, an auxiliary information area for storing auxiliary information that includes compression-related information to be used for decompressing the compressed waveform data, and a data area for storing a plurality of samples of the compressed waveform data of the frame with each of the samples comprising a same number of bits.
摘要:
In a method for characterizing a signal representing an audio content a measure is determined for a tonality of the signal, whereupon a statement is made about the audio content of the signal on the basis of the measure for the tonality of the signal. The measure for the tonality is derived from a quotient whose numerator is the mean of the summed values of spectral components of the signal exponentiated with a first power and whose denominator is the mean of the summed values of spectral components exponentiated with a second power, the first and second powers differing from each other. The measure for the tonality of the signal for the content analysis is robust in relation to a signal distortion, due e.g. to MP3 coding, and has a high correlation with the content of the analysed signal.
摘要:
An sound encoder accepts a sound signal and then produces a plurality of codes which represent the sound signal on a frame-by-frame basis. The sound encoder determines the order in which the plurality of codes is to be multiplexed into a multiplexed code based on one of the plurality of codes on a frame-by-frame basis, multiplexes the plurality of codes one by one into a multiplexed code in the determined order, and acquires an error correction code for the multiplexed code. The sound encoder then outputs the multiplexed code including the acquired error correction code added to the end thereof as a sound code.
摘要:
An improved method for shifting the pitches of a tone is disclosed. It comprises: (a) subjecting a digitized original waveform to a whitening process using an all-zero filter (AZF) to obtain a whitened waveform; (b) resampling the whitened waveform at a desired scaling ratio to obtain a scaled and whitened waveform; (c) subjecting the scaled and whitened waveform to a coloring process using an all-pole filter (APF) to obtain a synthesized waveform. In a preferred embodiment, the all-zero filter performs the transformation function of: ##EQU1## and the all-pole filter performs the transformation function of: ##EQU2## wherein the a.sub.i 's and b.sub.i 's are linear predictive coefficients. The whitened waveforms can be compressed and stored as wavetables, which can be subsequently retrieved and decompressed before resampling.
摘要:
According to a first invention, provided is an electronic musical instrument, which decodes and reads waveforms that are compressed by the DPCM method or the ADPCM method, that stores a prediction filter coefficient that is consonant with each waveform and reproduces musical tones by using the prediction filter coefficient. In the first invention, a waveform that is stored in the electronic musical instrument is stored together with a prediction filter coefficient that is used when the waveform was prepared, and the optimal prediction filter coefficient is employed for each waveform to reproduce a waveform. According to a second invention, provided is an electronic musical instrument, which decodes waveforms that are compressed by the DPCM method or the ADPCM method and repeatedly reads the decoded data, that can repetitiously read waveform data at the loop top without requiring a device for setting a decoding device. In the second embodiment, a waveform that is to be repeatedly read is coded by a prediction filter, for which a prediction filter coefficient is set so that the result of decoding at the repeated reading head portion matches each time.
摘要:
A method for processing a digital signal produced by digitizing an analog signal such as a musical instrument sound signal, and an apparatus for producing sound source data. When the input signal contains a periodically repetitive waveform portion, the fundamental frequency and its high harmonic components of the input signal is extracted by a comb filter prior to signal processing which takes advantage of the periodicity of the input signal. The fundamental frequency or pitch is detected by performing Fourier transform to produce frequency components, phase matching these frequency components and performing inverse Fourier transform. When extracting a repetitive waveform portion or so-called looping domain, such looping domain having the highest similarity in waveform in the vicinity of both ends of the domain is selected. When the bit compression of digital signal data is performed by selecting a filter with blocks each consisting of plural samples as units, a pseudo signal is affixed to the input signal, before the start point of the input signal, which pseudo signal will cause a filter of the lowest order to be selected. The looping domain is set so as to be a whole number multiple of the block which serves as the unit for bit compression, and the parameters of the looping start block are formed on the basis of data of the start and the end blocks. By applying a part or the whole of the signal processing method to a sound source data forming apparatus, sound source data may be formed which is reduced in the looping noise and error caused by data compression and which is of superior sound quality.
摘要:
A pseudo-random or transient synthesized signal is provided by analysis of a plurality of related signals by vector quantization of linear predictive coding coefficients (cluster representatives) of time blocks of the signals and providing cumulative probability matrices for the transition from one cluster representative for one block to a cluster representative of the next successive block of each of the signals. Synthesis of the pseudo-random signal is provided by randomly selecting according to a cumulative transition probability, the cluster representative of a next successive block given the selected cluster representative of the previous block, the coefficient of each block time being applied to a noise-excited recursive filter to generate the pseudo-random synthesized signal. Synthesis includes probabalistic models using Markov transitions, to produce transient sounds such as sonar, hatch closings, and hull groans.
摘要:
Various technologies for generating a synthesized singing voice waveform. In one implementation, the computer program may receive a request from a user to create a synthesized singing voice using the lyrics of a song and a digital file containing its melody as inputs. The computer program may then dissect the lyrics' text and its melody file into its corresponding sub-phonemic units and musical score respectively. The musical score may be further dissected into a sequence of musical notes and duration times for each musical note. The computer program may then determine a fundamental frequency (F0), or pitch, of each musical note.