Abstract

A player piano can strike more keys, across more of the register, and in faster succession than any pianist can reach. Composers have pursued that possibility for decades, and three traditions dominate the attempt, namely Nancarrow’s tempo canons, Xenakis’ stochastic distributions, and L-system grammars. These traditions have developed in isolation, on abstractions that do not obviously combine, and none of them accounts for the instrument itself. A Disklavier does not answer instantly, because a loud note reaches the string sooner than a soft one, so music written as if the mechanism were transparent arrives at the listener distorted. This article presents Amanous, a hardware-aware composition system for the Yamaha Disklavier that unifies the three traditions through distribution-switching, in which each grammar symbol selects an entire distributional regime rather than adjusting parameters within a fixed one. A four-layer pipeline carries a symbol from grammar to actuation-ready MIDI. An L-system fixes the macro-form, each symbol is mapped to a set of distributions and a tempo-canon ratio, events are sampled and time-scaled, and a hardware abstraction layer pre-compensates the instrument’s velocity-dependent latency before any MIDI is emitted. Tempo-canon convergence points close a feedback loop that lets the music’s own temporal structure trigger the next distributional switch. I show that compositional intent survives this pipeline. Sections generated from different symbols remain statistically separable at the output. Ablating the L-system, the tempo canon, or the hardware compensation each degrades a distinct and measurable property of the result, and hardware compensation takes the mean onset error, under the modelled latency curve, from roughly 18 ms to below the instrument’s own 1 ms scanning resolution. I further find that structured and random textures are most separable near 25 notes/s and that melodic metrics lose their discriminative power over the 40–100 notes/s band, above which the remaining difference is consistent with distributional content rather than melodic order. That band marks the density range beyond which cross-domain constraints become the effective compositional lever. All reported results are computational, nothing was played or measured on an instrument, and a psychoacoustic validation protocol is proposed for future work.

Keywords

Algorithmic composition, Disklavier, distribution-switching, L-systems, tempo canons, stochastic music, hardware-aware composition

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