Analysis and Synthesis of Tones by Spectral Interpolation
A technique is presented for the analysis and digital resynthesis of instrumental sounds. The technique is based on a model that uses interpolation of amplitude spectra to reproduce short-time spectral variations. The main focus of this work is the analysis algorithm. Starting from a digital recording the authors were able to compute automatically the parameters of this model. The parameters themselves, harmonic amplitudes at selected times, are small in number and intuitively interpretable. The model leads to a synthesis technique more efficient than classical additive synthesis. Moreover it allows dynamic spectral variations to be controlled with only a few high-level parameters in real time. Two analysis/synthesis methods are studied based on spectral interpolation. The first uses only spectral interpolation. This method made it possible to compress recordings of orchestral instruments to an average of 400 bytes per second without perceptible loss of realism, and to resynthesize these sounds with about 10 arithmetic operations per sample. The second method is a hybrid in which a sampled attack is spliced onto a sustain synthesized via spectral interpolation. The spectral interpolation model has been applied successfully to different instruments belonging to the brass and woodwind family. The authors plan to extend the study to many more instruments.
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