synfx-dsp

synfx-dsp DSP real time audio synthesis, effect algorithms and utilities for Rust

Most of the algorithms and implementations in this library have been implemented for HexoDSP and used in HexoSynth. I factored them out, because they seem useful in other contexts too, for instance the synfx-dsp-jit crate.

I collected most of the algorithms in this crate from various GPLv3 compatible sources. They also were partially translated from multiple different C++ projects. I tried to document the source and source license diligently in the comments of this crate. I apologize if any attribution is missing and would welcome patches or reports.

Feel free to use these algorithms and utilities. Help, patches and additions are appreciated if they comply with the GPL-3.0-or-later license and don't break the test suite in HexoDSP.

Attention: HexoDSP comes with a large test suite that also covers these algorithms. And that is the one that also has to pass if these algorithms are touched. The flip side is, that these implementations are actually covered by a test suite.

Requires Nightly as of 2022-10-02 due to std::simd!

Copyright, Licenses, Attribution, Contributions

Here is a list of sources parts of this library copied or translated code from:

• [crate::quickertanh64] / [crate::quickertanh] text quickerTanh / quickerTanh64 credits to mopo synthesis library: Under GPLv3 or any later. Little IO <littleioaudio@gmail.com> Matt Tytel <matthewtytel@gmail.com>
• [crate::quicktanh64] / [crate::quicktanh] text quickTanh / quickTanh64 credits to mopo synthesis library: Under GPLv3 or any later. Little IO <littleioaudio@gmail.com> Matt Tytel <matthewtytel@gmail.com>
• [crate::tanhapproxdrive] text Taken from ValleyAudio Copyright Dale Johnson https://github.dev/ValleyAudio/ValleyRackFree/tree/v2.0 Under GPLv3 license
• [crate::AtomicFloat] text Implementation from vst-rs https://github.com/RustAudio/vst-rs/blob/master/src/util/atomic_float.rs Under MIT License Copyright (c) 2015 Marko Mijalkovic
• [crate::Biquad] text The implementation of this Biquad Filter has been adapted from SamiPerttu, Copyright (c) 2020, under the MIT License. See also: https://github.com/SamiPerttu/fundsp/blob/master/src/filter.rs

• [crate::DattorroReverb] ```text This file contains a reverb implementation that is based on Jon Dattorro's 1997 reverb algorithm. It's also largely based on the C++ implementation from ValleyAudio / ValleyRackFree

  ValleyRackFree Copyright (C) 2020, Valley Audio Soft, Dale Johnson Adapted under the GPL-3.0-or-later License.

  See also: https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Plateau/Dattorro.cpp and: https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Plateau/Dattorro.hpp

  And: https://ccrma.stanford.edu/~dattorro/music.html And: https://ccrma.stanford.edu/~dattorro/EffectDesignPart1.pdf ```

• [crate::process1polelowpass] / [crate::process1polehighpass] text one pole lp from valley rack free: https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/OnePoleFilters.cpp
• [crate::process1poletptlowpass] / [crate::process1poletpthighpass] text one pole from: http://www.willpirkle.com/Downloads/AN-4VirtualAnalogFilters.pdf (page 5)
• [crate::FixedOnePole] text Fixed one pole with setable pole and gain. Implementation taken from tubonitaub / alec-deason from https://github.com/alec-deason/virtual_modular/blob/4025f1ef343c2eb9cd74eac07b5350c1e7ec9c09/src/simd_graph.rs#L4292 under MIT License
• [crate::processhalchamberlin_svf] text Hal Chamberlin's State Variable (12dB/oct) filter https://www.earlevel.com/main/2003/03/02/the-digital-state-variable-filter/ Inspired by SynthV1 by Rui Nuno Capela, under the terms of GPLv2 or any later:
• [crate::processsimpersvf] text Simper SVF implemented from https://cytomic.com/files/dsp/SvfLinearTrapezoidalSin.pdf Big thanks go to Andrew Simper @ Cytomic for developing and publishing the paper.

• [crate::processstilsonmoog] ```text Stilson/Moog implementation partly translated from here: https://github.com/ddiakopoulos/MoogLadders/blob/master/src/MusicDSPModel.h without any copyright as found on musicdsp.org (http://www.musicdsp.org/showone.php?id=24).

  It's also found on MusicDSP and has probably no proper license anyways. See also: https://github.com/ddiakopoulos/MoogLadders and https://github.com/rncbc/synthv1/blob/master/src/synthv1_filter.h#L103 and https://github.com/ddiakopoulos/MoogLadders/blob/master/src/MusicDSPModel.h ```

• [crate::DCBlockFilter] text translated from Odin 2 Synthesizer Plugin Copyright (C) 2020 TheWaveWarden under GPLv3 or any later

• [crate::cubic_interpolate] ```text Hermite interpolation, take from https://github.com/eric-wood/delay/blob/main/src/delay.rs#L52

  Thanks go to Eric Wood!

  For the interpolation code: MIT License, Copyright (c) 2021 Eric Wood ```

• [crate::TriSawLFO] ```text Adapted from https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/LFO.hpp

  ValleyRackFree Copyright (C) 2020, Valley Audio Soft, Dale Johnson Adapted under the GPL-3.0-or-later License. ```

• [crate::PolyBlepOscillator] text PolyBLEP by Tale (slightly modified) http://www.kvraudio.com/forum/viewtopic.php?t=375517 from http://www.martin-finke.de/blog/articles/audio-plugins-018-polyblep-oscillator/

• [crate::VPSOscillator] ```text This oscillator is based on the work "VECTOR PHASESHAPING SYNTHESIS" by: Jari Kleimola, Victor Lazzarini†, Joseph Timoney†, Vesa Välimäki *Aalto University School of Electrical Engineering Espoo, Finland; †National University of Ireland, Maynooth Ireland

  See also this PDF: http://recherche.ircam.fr/pub/dafx11/Papers/55_e.pdf ```

• [crate::Oversampling] ```text Loosely adapted from https://github.com/VCVRack/Befaco/blob/v1/src/ChowDSP.hpp Copyright (c) 2019-2020 Andrew Belt and Befaco contributors Under GPLv-3.0-or-later

  Which was originally taken from https://github.com/jatinchowdhury18/ChowDSP-VCV/blob/master/src/shared/AAFilter.hpp Copyright (c) 2020 jatinchowdhury18 ```

• [crate::next_xoroshiro128] text Taken from xoroshiro128 crate under MIT License Implemented by Matthew Scharley (Copyright 2016) https://github.com/mscharley/rust-xoroshiro128
• [crate::u64toopen01] text Taken from rand::distributions Licensed under the Apache License, Version 2.0 Copyright 2018 Developers of the Rand project.

• [crate::SplitMix64] ```text Copyright 2018 Developers of the Rand project.

  Licensed under the Apache License, Version 2.0 or the MIT license , at your option. This file may not be copied, modified, or distributed except according to those terms.

  • splitmix64 (http://xoroshiro.di.unimi.it/splitmix64.c) ```

• [crate::fdistort] / [crate::ffold_distort] ```text Ported from LMMS under GPLv2

  • DspEffectLibrary.h - library with template-based inline-effects
  • Copyright (c) 2006-2014 Tobias Doerffel

  Original source seems to be musicdsp.org, Author: Bram de Jong see also: https://www.musicdsp.org/en/latest/Effects/41-waveshaper.html ```

• [crate::PolyIIRHalfbandFilter] ```text Taken from va-filter by Fredemus aka Frederik Halkjær aka RocketPhysician https://github.com/Fredemus/va-filter Under License GPL-3.0-or-later

  originally translated from the freely available source code at https://www.musicdsp.org/en/latest/Filters/39-polyphase-filters.html ```

• [crate::fhva::LadderFilter] / [crate::fhva::Svf] / [crate::fh_va::SallenKey] text Taken from va-filter by Fredemus aka Frederik Halkjær aka RocketPhysician https://github.com/Fredemus/va-filter Under License GPL-3.0-or-later License: GPL-3.0-or-later