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Integer-Based Wavetable Synthesis for Low-Computational Embedded Systems
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CENS-2012-02
Author(s):
Ben Wright and Somsak Sukittanon
Category:
Engineering
Abstract:
The evolution of digital music synthesis spans from tried-and-true frequency modulation to string modeling with neural networks. This project begins from a wavetable basis. The audio waveform was modeled as a superposition of formant sinusoids at various frequencies relative to the fundamental frequency. Piano sounds were reverse-engineered to derive a basis for the final formant structure, and used by to create a wavetable. The quality of reproduction hangs in a trade-off between rich notes and sampling frequency. For low- computational systems, this calls for an approach that avoids burdensome floating-point calculations. To speed up calculations while preserving resolution, floating-point math was avoided entirely--all numbers involved are integral. The method was built into the Laser Piano. Along its 12-foot length are 24 “keys,” each consisting of a laser aligned with a photoresistive sensor connected to 8-bit MCU. The synthesis is processed in the sensor array by four microcontrollers running a strictly synchronous wavetable synthesis algorithm. In the laser array is integrated a microcontroller that can toggle each laser, allowing the piano to play itself or limit playable keys.
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