rubatoflexible

Rubatoflexible is a term used in music technology to describe a framework for implementing flexible rubato in performance data. It refers to methods and representations that allow tempo to vary in nuanced, performer-driven ways within and across musical phrases, beyond traditional global tempo changes.

The concept emerged in the 2020s among researchers and practitioners exploring expressive timing in digital systems. The name combines rubato, the historical practice of expressive tempo fluctuation, with flexible, signaling a computational approach that accommodates non-uniform tempo changes.

Technical characteristics: A central element is a tempo map or tempo curve that encodes tempo as a function of time or beat position. This enables per-phrase or per-voice tempo variation while maintaining a coherent metrical structure. Data can be stored in MIDI time events, JSON schemas, or DAW project data. Metrics such as tempo variance, beat-alignment error, and rhythmic stability are used to quantify its effect.

Applications: In performance playback, rubatoflexible allows real-time tempo shaping by track or instrument. In composition and algorithmic music, it guides models to produce natural-sounding rubato. In education and analysis, it provides a framework to study perceptual impacts of expressive timing.

Implementation and standards: There is no single governing standard, and implementations vary by platform. Some plugins expose a tempo map editor or expressive timing controls; others provide APIs to apply tempo curves to MIDI or audio playback. Interoperability often relies on MIDI clock, time-stretching, and beat-grid alignment.

See also rubato, tempo map, expressive timing.