SFZ

SFZ is an open, plain-text format for defining sample-based instruments used by audio samplers. A file with the .sfz extension describes how one or more audio samples should be played, including how they map to keyboard keys and velocity, looping behavior, and playback parameters such as volume and pitch. There is no single reference implementation; an SFZ file is interpreted by a software sampler that supports the SFZ specification, with variations across engines.

An SFZ document is organized into sections such as global, group, and region blocks. Each region associates a sample file (via the sample directive) with a specific key range (set by lokey and hikey) and velocity range (lovel and hivel). Regions can specify per-sample playback attributes, including tuning, volume, and loop points. Global provides default values for regions, and group blocks let users share parameters across multiple regions. SFZ regions can be layered and crossfaded to build multi-sampled instruments.

SFZ supports looping and a range of opcode-based parameters for controlling volume, pan, pitch, and, depending on the engine, envelopes or filters. Many engines extend the basic syntax with additional opcodes or features, but core functionality centers on mapping samples to key and velocity ranges and applying per-region playback settings. The format’s text-based nature makes it easy to edit instruments with a plain editor, and it is widely used for customizing and distributing sample libraries.

Software and usage: SFZ is supported by several samplers and players, including LinuxSampler and the Sforzando player by Plogue, as well as various DAWs that host SFZ instruments via plugins. Because it is an open, extensible standard, users can create and modify instruments without relying on proprietary formats while maintaining broad compatibility across compatible engines.