wavecraft_dsp/
traits.rs

1//! Core DSP traits for user-implemented audio processors.
2//!
3//! This module defines the primary extension points for users building plugins
4//! with Wavecraft. The `Processor` trait is the main interface for custom DSP code.
5
6/// Transport information for timing-aware DSP.
7///
8/// Provides context about playback state, tempo, and position.
9#[derive(Debug, Clone, Copy, Default)]
10pub struct Transport {
11    /// Current tempo in BPM (beats per minute).
12    pub tempo: Option<f64>,
13
14    /// Current playback position in samples.
15    pub pos_samples: i64,
16
17    /// True if the host is playing.
18    pub playing: bool,
19}
20
21/// Trait for defining processor parameters.
22///
23/// This trait provides metadata about a processor's parameters,
24/// enabling automatic UI generation and nih-plug integration.
25///
26/// Typically implemented via `#[derive(ProcessorParams)]` rather than manually.
27pub trait ProcessorParams: Default + Send + Sync + 'static {
28    /// Returns the parameter specifications for this processor.
29    fn param_specs() -> &'static [ParamSpec];
30}
31
32/// Specification for a single parameter.
33#[derive(Debug, Clone)]
34pub struct ParamSpec {
35    /// Display name of the parameter (e.g., "Frequency").
36    pub name: &'static str,
37
38    /// ID suffix for this parameter (e.g., "frequency").
39    /// Full ID will be prefixed with processor name: "my_filter_frequency"
40    pub id_suffix: &'static str,
41
42    /// Value range for this parameter.
43    pub range: ParamRange,
44
45    /// Default value.
46    pub default: f64,
47
48    /// Unit string (e.g., "dB", "Hz", "%").
49    pub unit: &'static str,
50
51    /// Optional group name for UI organization (e.g., "Input", "Processing", "Output").
52    pub group: Option<&'static str>,
53}
54
55/// Parameter value range definition.
56#[derive(Debug, Clone)]
57pub enum ParamRange {
58    /// Linear range from min to max.
59    Linear { min: f64, max: f64 },
60
61    /// Skewed range with exponential/logarithmic scaling.
62    /// Factor > 1.0 = logarithmic, factor < 1.0 = exponential.
63    Skewed { min: f64, max: f64, factor: f64 },
64
65    /// Integer stepped range (for enums, switches).
66    Stepped { min: i32, max: i32 },
67}
68
69/// Unit type has no parameters.
70impl ProcessorParams for () {
71    fn param_specs() -> &'static [ParamSpec] {
72        &[]
73    }
74}
75
76/// Trait for user-implemented DSP processors.
77///
78/// Implement this trait to define custom audio processing logic.
79/// All methods must be real-time safe (no allocations, locks, or syscalls).
80///
81/// # Example
82///
83/// ```rust,ignore
84/// use wavecraft_dsp::{Processor, ProcessorParams, Transport};
85///
86/// #[derive(ProcessorParams, Default)]
87/// struct MyGainParams {
88///     #[param(range = 0.0..=2.0, default = 1.0)]
89///     level: f32,
90/// }
91///
92/// struct MyGain {
93///     sample_rate: f32,
94/// }
95///
96/// impl Processor for MyGain {
97///     type Params = MyGainParams;
98///     
99///     fn process(&mut self, buffer: &mut [&mut [f32]], _transport: &Transport, params: &Self::Params) {
100///         for channel in buffer.iter_mut() {
101///             for sample in channel.iter_mut() {
102///                 *sample *= params.level;
103///             }
104///         }
105///     }
106/// }
107/// ```
108pub trait Processor: Send + 'static {
109    /// Associated parameter type for this processor.
110    ///
111    /// Use `()` for processors with no parameters, or define a struct
112    /// with `#[derive(ProcessorParams)]`.
113    type Params: ProcessorParams + Default + Send + Sync + 'static;
114
115    /// Process a buffer of audio samples.
116    ///
117    /// The buffer is provided as a slice of mutable slices, one per channel.
118    /// Modify samples in-place to apply your DSP effect.
119    ///
120    /// # Arguments
121    /// * `buffer` - Audio channels as `[L, R, ...]` where each channel is `[samples]`
122    /// * `transport` - Playback timing information
123    /// * `params` - Current parameter values
124    ///
125    /// # Real-Time Safety
126    /// This method is called on the audio thread. It MUST be real-time safe:
127    /// - No allocations (`Vec::push`, `String`, `Box::new`)
128    /// - No locks (`Mutex`, `RwLock`)
129    /// - No syscalls (file I/O, logging, network)
130    /// - No panics (use `debug_assert!` only)
131    fn process(&mut self, buffer: &mut [&mut [f32]], transport: &Transport, params: &Self::Params);
132
133    /// Called when the sample rate changes.
134    ///
135    /// Use this to update internal state that depends on sample rate
136    /// (e.g., filter coefficients, delay line sizes).
137    ///
138    /// # Arguments
139    /// * `sample_rate` - New sample rate in Hz (e.g., 44100.0, 48000.0)
140    ///
141    /// # Default
142    /// No-op by default. Override if your processor needs sample rate.
143    fn set_sample_rate(&mut self, _sample_rate: f32) {}
144
145    /// Reset processor state.
146    ///
147    /// Called when the host stops playback or when the user resets the plugin.
148    /// Use this to clear delay lines, reset filters, etc.
149    ///
150    /// # Default
151    /// No-op by default. Override if your processor maintains state.
152    fn reset(&mut self) {}
153}
wavecraft_dsp/traits.rs

wavecraft_dsp/
traits.rs
