$ show surge-synthesizer/OB-Xf
OB-Xf is an actively maintained, GPL-3.0 virtual analog synthesizer implemented as a JUCE-based audio plugin and standalone application. It emulates the Oberheim OB-X architecture with a polyphonic voice engine, anti-aliased oscillators using BLEP/BLAMP tables, dual filters, ADSR envelopes, LFOs, unison, portamento, and a modulation matrix. The project builds VST3, AU, LV2, CLAP, and standalone targets across Windows, macOS, Linux, and iOS. It also ships a large factory preset library in FXP format, a themeable XML-driven GUI, MIDI learn, MPE support, MTS-ESP microtuning, and Python bindings for offline rendering and patch exploration. The dominant character is a production-grade software instrument, even though it contains a substantial preset asset collection and research-flavored DSP tests.
The LLM identified 5 files worth highlighting for reuse:
Precomputed BLEP/BLAMP tables for anti-aliased saw, pulse, and triangle oscillator edges. Self-contained header data with oversampling factor 64, directly reusable in any virtual analog synth engine; demonstrates advanced DSP lookup-table design and numerical craftsmanship.
C++ ADSR envelope with bounded timing, smooth parameter handling, and golden-value test coverage. Isolated header implementation that can be extracted into any synthesizer or audio effect with minimal modification.
Configurable 2/4-pole filter used in the voice path, validated by golden regression tests and performance benchmarks. Self-contained DSP module with careful numerical implementation suitable for reuse in other audio software.
Parameter normalization, scaling, and mutation algorithms for patch generation and randomization. This is a generic toolkit for synth parameter systems that can be extracted and adapted to other instrument or plugin projects.
Resolution-independent image cache that scales bitmaps once and reuses them across zoom levels, supporting both SVG and bitmap sources. A reusable JUCE GUI component that solves a common high-DPI rendering problem in audio plugin interfaces.