424 lines
16 KiB
Rust
424 lines
16 KiB
Rust
// Diopser: a phase rotation plugin
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// Copyright (C) 2021-2022 Robbert van der Helm
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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#[macro_use]
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extern crate nih_plug;
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use nih_plug::{
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formatters, Buffer, BufferConfig, BusConfig, ClapPlugin, Plugin, ProcessContext, ProcessStatus,
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Vst3Plugin,
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};
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use nih_plug::{BoolParam, FloatParam, IntParam, Params, Range, SmoothingStyle};
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use nih_plug::{Enum, EnumParam};
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use std::pin::Pin;
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use std::sync::atomic::{AtomicBool, Ordering};
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use std::sync::Arc;
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#[cfg(feature = "simd")]
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use packed_simd::f32x2;
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mod filter;
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/// How many all-pass filters we can have in series at most. The filter stages parameter determines
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/// how many filters are actually active.
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const MAX_NUM_FILTERS: usize = 512;
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/// The minimum step size for smoothing the filter parmaeters.
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const MIN_AUTOMATION_STEP_SIZE: u32 = 1;
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/// The maximum step size for smoothing the filter parameters. Updating these parameters can be
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/// expensive, so updating them in larger steps can be useful.
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const MAX_AUTOMATION_STEP_SIZE: u32 = 512;
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// All features from the original Diopser have been implemented (and the spread control has been
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// improved). Other features I want to implement are:
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// - Briefly muting the output when changing the number of filters to get rid of the clicks
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// - A GUI
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//
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// TODO: Decide on whether to keep the scalar version or to just only support SIMD. Issue is that
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// packed_simd requires a nightly compiler.
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struct Diopser {
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params: Pin<Box<DiopserParams>>,
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/// Needed for computing the filter coefficients.
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sample_rate: f32,
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/// All of the all-pass filters, with vectorized coefficients so they can be calculated for
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/// multiple channels at once. [DiopserParams::num_stages] controls how many filters are
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/// actually active.
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#[cfg(feature = "simd")]
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filters: [filter::Biquad<f32x2>; MAX_NUM_FILTERS],
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#[cfg(not(feature = "simd"))]
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filters: Vec<[filter::Biquad<f32>; MAX_NUM_FILTERS]>,
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/// If this is set at the start of the processing cycle, then the filter coefficients should be
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/// updated. For the regular filter parameters we can look at the smoothers, but this is needed
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/// when changing the number of active filters.
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should_update_filters: Arc<AtomicBool>,
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/// If this is 1 and any of the filter parameters are still smoothing, thenn the filter
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/// coefficients should be recalculated on the next sample. After that, this gets reset to
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/// `unnormalize_automation_precision(self.params.automation_precision.value)`. This is to
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/// reduce the DSP load of automation parameters. It can also cause some fun sounding glitchy
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/// effects when the precision is low.
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next_filter_smoothing_in: i32,
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}
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// TODO: Some combinations of parameters can cause really loud resonance. We should limit the
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// resonance and filter stages parameter ranges in the GUI until the user unlocks.
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#[derive(Params)]
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struct DiopserParams {
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/// The number of all-pass filters applied in series.
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#[id = "stages"]
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filter_stages: IntParam,
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/// The filter's center frequqency. When this is applied, the filters are spread around this
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/// frequency.
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#[id = "cutoff"]
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filter_frequency: FloatParam,
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/// The Q parameter for the filters.
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#[id = "res"]
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filter_resonance: FloatParam,
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/// Controls a frequency spread between the filter stages in octaves. When this value is 0, the
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/// same coefficients are used for every filter. Otherwise, the earliest stage's frequency will
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/// be offset by `-filter_spread_octave_amount`, while the latest stage will be offset by
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/// `filter_spread_octave_amount`. If the filter spread style is set to linear then the negative
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/// range will cover the same frequency range as the positive range.
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#[id = "spread"]
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filter_spread_octaves: FloatParam,
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/// How the spread range should be distributed. The octaves mode will sound more musical while
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/// the linear mode can be useful for sound design purposes.
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#[id = "spstyl"]
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filter_spread_style: EnumParam<SpreadStyle>,
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/// The precision of the automation, determines the step size. This is presented to the userq as
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/// a percentage, and it's stored here as `[0, 1]` float because smaller step sizes are more
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/// precise so having this be an integer would result in odd situations.
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#[id = "autopr"]
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automation_precision: FloatParam,
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/// Very important.
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#[id = "ignore"]
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very_important: BoolParam,
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}
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impl Default for Diopser {
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fn default() -> Self {
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let should_update_filters = Arc::new(AtomicBool::new(false));
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Self {
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params: Box::pin(DiopserParams::new(should_update_filters.clone())),
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sample_rate: 1.0,
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#[cfg(feature = "simd")]
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filters: [filter::Biquad::default(); MAX_NUM_FILTERS],
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#[cfg(not(feature = "simd"))]
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filters: Vec::new(),
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should_update_filters,
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next_filter_smoothing_in: 1,
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}
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}
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}
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impl DiopserParams {
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pub fn new(should_update_filters: Arc<AtomicBool>) -> Self {
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Self {
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filter_stages: IntParam::new(
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"Filter Stages",
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0,
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Range::Linear {
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min: 0,
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max: MAX_NUM_FILTERS as i32,
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},
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)
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.with_callback({
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let should_update_filters = should_update_filters.clone();
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Arc::new(move |_| should_update_filters.store(true, Ordering::Release))
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}),
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// Smoothed parameters don't need the callback as we can just look at whether the
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// smoother is still smoothing
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filter_frequency: FloatParam::new(
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"Filter Frequency",
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200.0,
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Range::Skewed {
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min: 5.0, // This must never reach 0
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max: 20_000.0,
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factor: Range::skew_factor(-2.5),
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},
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)
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// This needs quite a bit of smoothing to avoid artifacts
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.with_smoother(SmoothingStyle::Logarithmic(100.0))
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.with_unit(" Hz")
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.with_value_to_string(formatters::f32_rounded(0)),
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filter_resonance: FloatParam::new(
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"Filter Resonance",
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// The actual default neutral Q-value would be `sqrt(2) / 2`, but this value
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// produces slightly less ringing.
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0.5,
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Range::Skewed {
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min: 0.01, // This must also never reach 0
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max: 30.0,
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factor: Range::skew_factor(-2.5),
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},
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)
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.with_smoother(SmoothingStyle::Logarithmic(100.0))
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.with_value_to_string(formatters::f32_rounded(2)),
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filter_spread_octaves: FloatParam::new(
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"Filter Spread Octaves",
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0.0,
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Range::SymmetricalSkewed {
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min: -5.0,
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max: 5.0,
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factor: Range::skew_factor(-1.0),
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center: 0.0,
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},
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)
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.with_step_size(0.01)
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.with_smoother(SmoothingStyle::Linear(100.0)),
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filter_spread_style: EnumParam::new("Filter Spread Style", SpreadStyle::Octaves)
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.with_callback(Arc::new(move |_| {
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should_update_filters.store(true, Ordering::Release)
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})),
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very_important: BoolParam::new("Don't touch this", true).with_value_to_string(
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Arc::new(|value| String::from(if value { "please don't" } else { "stop it" })),
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),
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automation_precision: FloatParam::new(
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"Automation precision",
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normalize_automation_precision(128),
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Range::Linear { min: 0.0, max: 1.0 },
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)
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.with_unit("%")
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.with_value_to_string(Arc::new(|value| format!("{:.0}", value * 100.0))),
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}
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}
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}
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#[derive(Enum, Debug)]
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enum SpreadStyle {
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Octaves,
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Linear,
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}
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impl Plugin for Diopser {
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const NAME: &'static str = "Diopser";
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const VENDOR: &'static str = "Robbert van der Helm";
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const URL: &'static str = "https://github.com/robbert-vdh/nih-plug";
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const EMAIL: &'static str = "mail@robbertvanderhelm.nl";
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const VERSION: &'static str = "0.2.0";
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const DEFAULT_NUM_INPUTS: u32 = 2;
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const DEFAULT_NUM_OUTPUTS: u32 = 2;
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fn params(&self) -> Pin<&dyn Params> {
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self.params.as_ref()
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}
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fn accepts_bus_config(&self, config: &BusConfig) -> bool {
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// The scalar version can handle any channel config, while the SIMD version can only do
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// stereo
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#[cfg(feature = "simd")]
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{
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config.num_input_channels == config.num_output_channels
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&& config.num_input_channels == 2
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}
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#[cfg(not(feature = "simd"))]
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{
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config.num_input_channels == config.num_output_channels && config.num_input_channels > 0
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}
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}
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fn initialize(
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&mut self,
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_bus_config: &BusConfig,
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buffer_config: &BufferConfig,
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_context: &mut impl ProcessContext,
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) -> bool {
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#[cfg(not(feature = "simd"))]
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{
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self.filters = vec![
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[Default::default(); MAX_NUM_FILTERS];
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_bus_config.num_input_channels as usize
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];
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}
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// Initialize the filters on the first process call
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self.sample_rate = buffer_config.sample_rate;
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self.should_update_filters.store(true, Ordering::Release);
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true
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}
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fn process(
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&mut self,
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buffer: &mut Buffer,
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_context: &mut impl ProcessContext,
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) -> ProcessStatus {
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// Since this is an expensive operation, only update the filters when it's actually
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// necessary, and allow smoothing only every n samples using the automation precision
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// parameter
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let smoothing_interval =
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unnormalize_automation_precision(self.params.automation_precision.value);
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for mut channel_samples in buffer.iter_mut() {
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self.maybe_update_filters(smoothing_interval);
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// We can compute the filters for both channels at once. The SIMD version thus now only
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// supports steroo audio.
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#[cfg(feature = "simd")]
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{
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let mut samples =
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f32x2::new(*unsafe { channel_samples.get_unchecked_mut(0) }, *unsafe {
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channel_samples.get_unchecked_mut(1)
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});
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for filter in self
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.filters
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.iter_mut()
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.take(self.params.filter_stages.value as usize)
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{
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samples = filter.process(samples);
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}
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*unsafe { channel_samples.get_unchecked_mut(0) } = samples.extract(0);
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*unsafe { channel_samples.get_unchecked_mut(1) } = samples.extract(1);
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}
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#[cfg(not(feature = "simd"))]
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// We get better cache locality by iterating over the filters and then over the channels
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for filter_idx in 0..self.params.filter_stages.value as usize {
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for (channel_idx, filters) in self.filters.iter_mut().enumerate() {
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// We can also use `channel_samples.iter_mut()`, but the compiler isn't able to
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// optmize that iterator away and it would add a ton of overhead over indexing
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// the buffer directly
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let sample = unsafe { channel_samples.get_unchecked_mut(channel_idx) };
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*sample = filters[filter_idx].process(*sample);
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}
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}
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}
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ProcessStatus::Normal
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}
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}
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impl Diopser {
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/// Check if the filters need to be updated beased on [Self::should_update_filters] and the
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/// smoothing interval, and update them as needed.
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fn maybe_update_filters(&mut self, smoothing_interval: u32) {
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// In addition to updating the filters, we should also clear the filter's state when
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// changing a setting we can't neatly interpolate between.
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let reset_filters = self
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.should_update_filters
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.compare_exchange(true, false, Ordering::Acquire, Ordering::Relaxed)
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.is_ok();
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let should_update_filters = reset_filters
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|| ((self.params.filter_frequency.smoothed.is_smoothing()
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|| self.params.filter_resonance.smoothed.is_smoothing()
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|| self.params.filter_spread_octaves.smoothed.is_smoothing())
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&& self.next_filter_smoothing_in <= 1);
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if should_update_filters {
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self.update_filters(smoothing_interval, reset_filters);
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self.next_filter_smoothing_in = smoothing_interval as i32;
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} else {
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self.next_filter_smoothing_in -= 1;
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}
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}
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/// Recompute the filter coefficients based on the smoothed paraetersm. We can skip forwardq in
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/// larger steps to reduce the DSP load.
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fn update_filters(&mut self, smoothing_interval: u32, reset_filters: bool) {
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if self.filters.is_empty() {
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return;
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}
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let frequency = self
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.params
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.filter_frequency
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.smoothed
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.next_step(smoothing_interval);
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let resonance = self
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.params
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.filter_resonance
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.smoothed
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.next_step(smoothing_interval);
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let spread_octaves = self
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.params
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.filter_spread_octaves
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.smoothed
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.next_step(smoothing_interval);
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let spread_style = self.params.filter_spread_style.value();
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const MIN_FREQUENCY: f32 = 5.0;
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let max_frequency = self.sample_rate / 2.05;
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for filter_idx in 0..self.params.filter_stages.value as usize {
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// The index of the filter normalized to range [-1, 1]
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let filter_proportion =
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(filter_idx as f32 / self.params.filter_stages.value as f32) * 2.0 - 1.0;
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// The spread parameter adds an offset to the frequency depending on the number of the
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// filter
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let filter_frequency = match spread_style {
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SpreadStyle::Octaves => frequency * 2.0f32.powf(spread_octaves * filter_proportion),
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SpreadStyle::Linear => frequency * 2.0f32.powf(spread_octaves) * filter_proportion,
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}
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.clamp(MIN_FREQUENCY, max_frequency);
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let coefficients =
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filter::BiquadCoefficients::allpass(self.sample_rate, filter_frequency, resonance);
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#[cfg(feature = "simd")]
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{
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self.filters[filter_idx].coefficients = coefficients;
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if reset_filters {
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self.filters[filter_idx].reset();
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}
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}
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#[cfg(not(feature = "simd"))]
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for channel in self.filters.iter_mut() {
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channel[filter_idx].coefficients = coefficients;
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if reset_filters {
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channel[filter_idx].reset();
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}
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}
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}
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}
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}
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fn normalize_automation_precision(step_size: u32) -> f32 {
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(MAX_AUTOMATION_STEP_SIZE - step_size) as f32
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/ (MAX_AUTOMATION_STEP_SIZE - MIN_AUTOMATION_STEP_SIZE) as f32
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}
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fn unnormalize_automation_precision(normalized: f32) -> u32 {
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MAX_AUTOMATION_STEP_SIZE
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- (normalized * (MAX_AUTOMATION_STEP_SIZE - MIN_AUTOMATION_STEP_SIZE) as f32).round() as u32
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}
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impl ClapPlugin for Diopser {
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const CLAP_ID: &'static str = "nl.robbertvanderhelm.diopser";
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}
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impl Vst3Plugin for Diopser {
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const VST3_CLASS_ID: [u8; 16] = *b"DiopserPlugRvdH.";
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const VST3_CATEGORIES: &'static str = "Fx|Filter";
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}
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nih_export_clap!(Diopser);
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nih_export_vst3!(Diopser);
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