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Higher-order integrated wavetable and sampling synthesis

 
: Franck, A.; Välimäki, V.

Journal of the Audio Engineering Society 61 (2013), No.9, pp.624-636
ISSN: 0004-7554
ISSN: 1549-4950
English
Journal Article
Fraunhofer IDMT ()

Abstract
Wavetable and sampling synthesis are popular methods enabling the efficient creation of musical sounds. Using sample rate conversion techniques, arbitrary musical pitches can be generated from one wavetable or from a small set of wavetables: downsampling is used for raising the pitch and upsampling for lowering it. A challenge when changing the pitch of a sampled waveform is to avoid disturbing aliasing artifacts. Besides bandlimited resampling algorithms, the use of an integrated wavetable and a differentiation of the output signal has been proposed previously by Geiger. This paper extends Geiger's method by integrating the waveform multiple times before storing it, to improve alias-reduction. During playback, a sample rate conversion method is first applied and the output signal is then differentiated as many times as the wavetable has been integrated. The influence of the different components of the algorithm, namely the resampling algorithm and the differentiation f ilter, on the synthesis quality is investigated. It is shown that, unlike Geiger's method, higher orders of integration/differentiation necessitate the use of an effective interpolation filter. It is shown that the higher-order integrated wavetable/sampling synthesis technique reduces aliasing more than the first-order technique with a minor increase in computational cost.

: http://publica.fraunhofer.de/documents/N-300652.html