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::quicker_tanh64] / [crate::quicker_tanh]

  quickerTanh / quickerTanh64 credits to mopo synthesis library:
  Under GPLv3 or any later.
  Little IO <littleioaudio@gmail.com>
  Matt Tytel <matthewtytel@gmail.com>
  

• [crate::quick_tanh64] / [crate::quick_tanh]

  quickTanh / quickTanh64 credits to mopo synthesis library:
  Under GPLv3 or any later.
  Little IO <littleioaudio@gmail.com>
  Matt Tytel <matthewtytel@gmail.com>
  

• [crate::tanh_approx_drive]

  Taken from ValleyAudio
  Copyright Dale Johnson
  https://github.dev/ValleyAudio/ValleyRackFree/tree/v2.0
  Under GPLv3 license
  

• [crate::AtomicFloat]

  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]

  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]

  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::process_1pole_lowpass] / [crate::process_1pole_highpass]

  one pole lp from valley rack free:
  https://github.com/ValleyAudio/ValleyRackFree/blob/v1.0/src/Common/DSP/OnePoleFilters.cpp
  

• [crate::process_1pole_tpt_lowpass] / [crate::process_1pole_tpt_highpass]

  one pole from:
  http://www.willpirkle.com/Downloads/AN-4VirtualAnalogFilters.pdf
  (page 5)
  

• [crate::FixedOnePole]

  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::process_hal_chamberlin_svf]

  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::process_simper_svf]

  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::process_stilson_moog]

  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]

  translated from Odin 2 Synthesizer Plugin
  Copyright (C) 2020 TheWaveWarden
  under GPLv3 or any later
  

• [crate::cubic_interpolate]

  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]

  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]

  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]

  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]

  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]

  Taken from xoroshiro128 crate under MIT License
  Implemented by Matthew Scharley (Copyright 2016)
  https://github.com/mscharley/rust-xoroshiro128
  

• [crate::u64_to_open01]

  Taken from rand::distributions
  Licensed under the Apache License, Version 2.0
  Copyright 2018 Developers of the Rand project.
  

• [crate::SplitMix64]

  Copyright 2018 Developers of the Rand project.
  
  Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
  https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
  <LICENSE-MIT or https://opensource.org/licenses/MIT>, 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::f_distort] / [crate::f_fold_distort]

  Ported from LMMS under GPLv2
  * DspEffectLibrary.h - library with template-based inline-effects
  * Copyright (c) 2006-2014 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  
  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]

  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::DCFilterX4]

  Basic 4 channel SIMD DC-filter from Understanding Digital Signal Processing by Richard Lyons.
  
  Taken from va-filter by Fredemus aka Frederik Halkjær aka RocketPhysician
  https://github.com/Fredemus/va-filter
  Under License GPL-3.0-or-later
  

• [crate::fh_va::LadderFilter] / [crate::fh_va::Svf] / [crate::fh_va::SallenKey]

  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