SoundFont

SoundFont is a term used for a file-based sample library and its playback technology, used to synthesize musical instrument sounds in computer-based music production. The core idea is to store multi-sampled recordings of instruments and mapping data that allow a software sampler to render those sounds across the MIDI keyboard with varying dynamics and articulations.

The most widely used variant is the SoundFont 2 (SF2) format, originally developed by E-mu Systems in the 1990s. An SF2 file contains audio samples and a set of presets that describe how those samples are triggered. Each instrument maps samples to specific key ranges and velocity layers, with tuning, envelopes, and optional modulators such as vibrato or filters. When a MIDI note is played, the sampler selects appropriate samples, interpolates between velocity layers, and applies the instrument’s ADSR envelope and modulation settings.

SoundFonts have been a common standard in PC-based music software, accessible through a variety of software samplers and DAWs. Open-source and commercial players such as Fluidsynth, Viena, and Polyphone support SF2 files, contributing to their long-standing compatibility. While newer sample formats exist, SF2 remains popular due to its portability and extensive legacy libraries.

Construction and licensing of SoundFonts vary: they can be public domain, released under Creative Commons, or distributed with commercial licenses. The perceived quality of a SoundFont depends on sampling accuracy, loop points, the number of velocity layers, tuning precision, and the sophistication of envelopes and modulation within the presets.

See also: sample-based synthesis, SFZ format, MIDI, software synthesizers.