This paper presents a real-time piano synthesizer where both the transverse and longitudinal motion of the string is modeled by modal synthesis, resulting in a coherent and highly parallel model structure. The paper applies recent developments in piano modeling and focuses on the issues related to practical implementation (e.g., numerical stability, aliasing, and efficiency). A strong emphasis is given to modeling nonlinear string vibrations, and a new variation of earlier synthesis techniques is proposed which is particularly well suited for modal synthesis. For soundboard modeling, the possibilities of using fast Fourier transform-based fast convolution and parallel second-order filters are discussed. Additionally, the paper describes the details of the software implementation and discusses the computational complexity of each model block. The piano model runs on current computer hardware with full polyphony in real time

A filter model is proposed, allowing for the realization of a digital structure that computes a decimated version of the output signal. Each time the sampling rate is switched, pre-calculated coefficients are loaded by the processor in parallel to computing a filter state that fits the new rate. Sufficient conditions for the existence of the new state are given: holding these conditions, the sampling rate can be varied at runtime without introducing spurious transients in the output signal. The equivalence between the proposed filter model and existing polyphase networks for the efficient computation of decimated signals is discussed. If the input is null, the rate-switching structure performs a fraction of the computations that equals the decimation factor. Otherwise, the same efficiency can be achieved by linearly interpolating in between decimated input values, at the cost of introducing an error in the output signal. Particularly in the second-order case, an efficient rate-switching structure can be figured out capable of producing an error-free output also in presence of an input which is not null

No abstract

While computational acoustics techniques for musical instruments emulation reached a remarkable maturity due to continuous development in the last three decades, implementation into embedded digital instruments lags behind, with only a few notable commercial products to solely employ physicsbased algorithms for acoustic instruments tone synthesis. In this paper a parallel DSP architecture for the efficient implementation of the acoustic piano on embedded processors is reported. The resulting model is able to provide faithful reproduction of the acoustic piano physical behaviour and can also be used as an engine for novel instruments that need to provide advanced multimodal output (haptics, spatial audio) with a low-cost embedded platform.