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// Copyright © 2018-2022 The Twang Contributors.
//
// Licensed under any of:
// - Apache License, Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0)
// - Boost Software License, Version 1.0 (https://www.boost.org/LICENSE_1_0.txt)
// - MIT License (https://mit-license.org/)
// At your choosing (See accompanying files LICENSE_APACHE_2_0.txt,
// LICENSE_MIT.txt and LICENSE_BOOST_1_0.txt).
//! Library for pure Rust advanced audio synthesis.
//!
//! Most audio DSP (Digital Signal Processing) libraries have a concept of an
//! audio graph which connects sources to destinations. Twang uses a simplified
//! model: a synthesis tree (a dependency tree of sorts, a type of DAG -
//! directed acyclic graph, but limited to a single root node). Twang doesn't
//! deal with having speakers as a node on a graph, as it's only focus is
//! synthesis. A synthesis tree can do all of the things that an audio graph
//! can do, but it's simpler and much easier to learn.
//!
//! To start, first you need to construct a **synthesizer**
//! ([`Synth`](struct.Synth.html)). Then you need a type that implements the
//! `Sink` trait. `Audio` buffers have a `sink` method you can use to get a
//! `Sink`. Once you have those, you can synthesize audio with a closure that
//! has one parameter representing the **frequency counter**. You can use the
//! **frequency counter** to generate continuous pitched waveforms.
//!
//! # A3 (220 Hz) Minor Piano Example
//! This example uses the first ten piano harmonics to generate a sound that
//! sounds like an electric piano. This is an example of additive synthesis.
//!
//! ```rust,no_run
//! use fon::chan::Ch16;
//! use fon::{Audio, Frame};
//! use twang::noise::White;
//! use twang::ops::Gain;
//! use twang::osc::Sine;
//! use twang::Synth;
//!
//! /// First ten harmonic volumes of a piano sample (sounds like electric piano).
//! const HARMONICS: [f32; 10] = [
//! 0.700, 0.243, 0.229, 0.095, 0.139, 0.087, 0.288, 0.199, 0.124, 0.090,
//! ];
//! /// The three pitches in a perfectly tuned A3 minor chord
//! const PITCHES: [f32; 3] = [220.0, 220.0 * 32.0 / 27.0, 220.0 * 3.0 / 2.0];
//! /// Volume of the piano
//! const VOLUME: f32 = 1.0 / 3.0;
//!
//! // State of the synthesizer.
//! #[derive(Default)]
//! struct Processors {
//! // White noise generator.
//! white: White,
//! // 10 harmonics for 3 pitches.
//! piano: [[Sine; 10]; 3],
//! }
//!
//! fn main() {
//! // Initialize audio
//! let mut audio = Audio::<Ch16, 2>::with_silence(48_000, 48_000 * 5);
//! // Create audio processors
//! let mut proc = Processors::default();
//! // Adjust phases of harmonics.
//! for pitch in proc.piano.iter_mut() {
//! for harmonic in pitch.iter_mut() {
//! harmonic.shift(proc.white.step());
//! }
//! }
//! // Build synthesis algorithm
//! let mut synth = Synth::new(proc, |proc, mut frame: Frame<_, 2>| {
//! for (s, pitch) in proc.piano.iter_mut().zip(PITCHES.iter()) {
//! for ((i, o), v) in s.iter_mut().enumerate().zip(HARMONICS.iter()) {
//! // Get next sample from oscillator.
//! let sample = o.step(pitch * (i + 1) as f32);
//! // Pan the generated harmonic center
//! frame = frame.pan(Gain.step(sample, (v * VOLUME).into()), 0.0);
//! }
//! }
//! frame
//! });
//! // Synthesize 5 seconds of audio
//! synth.stream(audio.sink());
//! }
//! ```
extern crate alloc;
// FIXME
// pub mod file;
pub use Synth;