rasp

An audio signal processing library in Rust.

The design, and general usage, of this library is based on the Synthesis Toolkit which is hosted by CCRMA and written in C++.

Usage

All objects intended to process samples of an audio signal implement the Processor trait. Samples are passed into the object using process() and returns an output sample.

Features

• Generic support for f32 and f64 samples
• Basic digital filters
  • RBJ filters
• Integer and linear-interpolating delays
• Peak and RMS envelope detectors
• Window function iterators

Future Work

Filters

• Analog filters, based on DSPFilters by vinniefalco
  • filter::butterworth
  • filter::chebyshev1
  • filter::chebyshev2
  • filter::elliptic
  • filter::bessel
  • filter::legendre

Delays

• delay::AllpassDelay, an all-pass interpolating delay-line (see stk::DelayA)
• Improved unit tests

Documentation

• More inline-examples
• examples/effects
  • Ping-Pong Delay
  • Compressor
  • CombFilter?
  • Chorus
  • Flanger?
  • Phaser?
  • PitchShifter using a variable delay line
  • Echo?
  • Simple reverb?

Generators

• mod generators
  • mod oscillator
  • mod envelope

Oscillators

• mod oscillators

Support of basic waveforms: Sine, Triangle, Square, and Saw. There are multiple implementations for oscillators, depending on the waveform. This list is not comprehensive.

Envelope Generators

• mod envelope
  • Adsr
  • Ahdsr
  • Ar

Utilities

• util::time, a time conversion utility?
• mod interpolate?
• FFI?

util::time, a time conversion utility

• A Ruby-inspired syntax?
  • 4.milliseconds.to_samples::<f32>::(44100f32) -> 44.1f32
  • 4.milliseconds.to_samples::<usize>::(44100f32) -> 44usize

Justification, or "Why I don't want to use time_calc"

• time_calc is designed for general time calculations, which is useful when creating a daw for example
  • So Samples in time_calc is an alias for i64, whereas time-based components in this crate rely on usize or f32
  • time_calc also includes converions that wouldn't be used in this crate (SampleHz, Ticks, Ppqn)

TL;DR: time_calc represents samples for a different use case that's uncessary for this crate

mod interpolate

Mainly for parameter smoothing functions

• Linear, lagrange, and other forms of interpolation?

Whether this is implemented or not, docs must be updated to note lack of parameter interpolation

• So discontinuities when changing parameters with an live signal are possible

FFI

If added...

• Export to C
• Header files for C++?
• Package as a JUCE module?

Argument against...

• DSP could just be done entirely in rust and abstracted as a single struct
• User can create C bindings themselves

Miscellaneous

• mod formant
• mod pluck Pluck-string model (see stk::Twang)
• FFT/IFFT and STFT/ISTFT implementations