Processing of acoustic waveforms
First Claim
1. A method of processing an acoustic waveform, the method comprising:
- sampling the waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples;
analyzing each frame of samples to extract a set of variable frequency components having individual amplitudes;
matching said variable components from one frame to a next frame such that a component in one frame is matched with a component in a successive frame that has a similar value regarless of shifts in frequency and spectral energy; and
interpolating the matched values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation.
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Abstract
A sinusoidal model for acoustic waveforms is applied to develop a new analysis/synthesis technique which characterizes a waveform by the amplitudes, frequencies, and phases of component sine waves. These parameters are estimated from a short-time Fourier transform. Rapid changes in the highly-resolved spectral components are tracked using the concept of "birth" and "death" of the underlying sine waves. The component values are interpolated from one frame to the next to yield a respresentation that is applied to a sine wave generator. The resulting synthetic waveform preserves the general waveform shape and is perceptually indistinguishable from the original. Furthermore, in the presence of noise the perceptual characteristics of the waveform as well as the noise are maintained. The method and devices are particularly useful in speech coding, time-scale modification, frequency scale modification and pitch modification.
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Citations
64 Claims
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1. A method of processing an acoustic waveform, the method comprising:
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sampling the waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing each frame of samples to extract a set of variable frequency components having individual amplitudes; matching said variable components from one frame to a next frame such that a component in one frame is matched with a component in a successive frame that has a similar value regarless of shifts in frequency and spectral energy; and interpolating the matched values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A device for processing an acoustic waveform, the device comprising:
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sampling means for sampling the waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples to extract a set of variable frequency components having individual amplitudes; matching means for matching said variable components from one frame to a next frame such that a component in one frame is matched with a component in a successive frame that has a similar value regardless of shifts in frequency and spectral energy; and interpolating means for interpolating the matched values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A coded speech transmission system comprising:
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sampling means for sampling a speech waveform to obtain a series of discrete samples and for constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples by Fourier analysis to extract a set of variable frequency components having individual amplitude values; coding means for coding the component values; decoding means for decoding the coded values after transmission and for reconstituting the variable components; matching means for matching the reconstituted, variable components from one frame to a next frame such that a component is one frame is matched with a component in a successive frame that has a similar value regardless of shifts in frequency and spectral energy; and interpolation means for interpolating the values of the frequency components from the one frame to the next frame to obtain a representation of the waveform whereby synthetic speech can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation. - View Dependent Claims (52, 53, 54, 55, 56, 57)
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58. A device for altering the time-scale of an audible waveform, the device comprising:
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sampling means for sampling the waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples to extract a set of variable frequency components having individual amplitudes; matching means for matching said variable components from one frame to a next frame such that a component in one frame is matched with a component in a successive frame that has a similar value regardless of shifts in frequency and spectral energy; interpolating means for interpolating the amplitude and frequency values of the components from the one frame to the next frame to obtain a representation of the waveform whereby a synthetic waveform can be constructed by generating a set of sine waves corresponding to the interpolated representation; interpolation rate adjusting means for altering the rate of interpolation; and synthesizing means for constructing a time-scaled synthetic waveform by generating a series of constituent sine waves corresponding in frequency and amplitude to the extracted components, the sine waves being generated at said alterable interpolation rate. - View Dependent Claims (59, 60, 61, 62, 63, 64)
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Specification