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Make the window size for configurable

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This commit is contained in:
Robbert van der Helm 2022-03-07 21:19:38 +01:00
parent 329da782b5
commit 115d03a34a
2 changed files with 79 additions and 31 deletions
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2
plugins/examples/stft/src/lib.rs
View file

@ -13,7 +13,7 @@ struct Stft {
/// An adapter that performs most of the overlap-add algorithm for us.
stft: util::StftHelper,
/// A Hann window window, passed to the overlap-add helper.
/// A Hann window function, passed to the overlap-add helper.
window_function: Vec<f32>,
/// The FFT of a simple low pass FIR filter.

106
plugins/puberty_simulator/src/lib.rs
View file

@ -20,8 +20,11 @@ use fftw::types::{c32, Flag};
use nih_plug::prelude::*;
use std::f32;
use std::pin::Pin;
use std::sync::Arc;
const WINDOW_SIZE: usize = 1024;
const MIN_WINDOW_SIZE: usize = 64;
const DEFAULT_WINDOW_SIZE: usize = 1024;
const MAX_WINDOW_SIZE: usize = 32768;
const OVERLAP_TIMES: usize = 4;
struct PubertySimulator {
@ -29,13 +32,15 @@ struct PubertySimulator {
/// An adapter that performs most of the overlap-add algorithm for us.
stft: util::StftHelper,
/// A Hann window window, passed to the overlap-add helper.
/// Contains a Hann window function of the current window length, passed to the overlap-add
/// helper. Allocated with a `MAX_WINDOW_SIZE` initial capacity.
window_function: Vec<f32>,
/// The algorithms for the FFT and IFFT operations.
plan: Plan,
/// Scratch buffers for computing our FFT. The [`StftHelper`] already contains a buffer for the
/// real values.
/// real values. This type cannot be resized, so we'll simply take a slice of it with the
/// correct length instead.
complex_fft_scratch_buffer: AlignedVec<c32>,
}
@ -50,8 +55,13 @@ unsafe impl Sync for Plan {}
#[derive(Params)]
struct PubertySimulatorParams {
/// The pitch change in octaves.
#[id = "pitch"]
pitch_octaves: FloatParam,
/// The size of the FFT window as a power of two (to prevent invalid inputs).
#[id = "wndsz"]
window_size_order: IntParam,
}
impl Default for PubertySimulator {
@ -59,14 +69,15 @@ impl Default for PubertySimulator {
Self {
params: Box::pin(PubertySimulatorParams::default()),
stft: util::StftHelper::new(2, WINDOW_SIZE),
window_function: util::window::hann(WINDOW_SIZE),
stft: util::StftHelper::new(2, MAX_WINDOW_SIZE),
window_function: Vec::with_capacity(MAX_WINDOW_SIZE),
plan: Plan {
r2c_plan: R2CPlan32::aligned(&[WINDOW_SIZE], Flag::MEASURE).unwrap(),
c2r_plan: C2RPlan32::aligned(&[WINDOW_SIZE], Flag::MEASURE).unwrap(),
// These will be initialized with proper values during the initialization
r2c_plan: R2CPlan32::aligned(&[1], Flag::MEASURE).unwrap(),
c2r_plan: C2RPlan32::aligned(&[1], Flag::MEASURE).unwrap(),
},
complex_fft_scratch_buffer: AlignedVec::new(WINDOW_SIZE / 2 + 1),
complex_fft_scratch_buffer: AlignedVec::new(MAX_WINDOW_SIZE / 2 + 1),
}
}
}
@ -89,6 +100,19 @@ impl Default for PubertySimulatorParams {
.with_smoother(SmoothingStyle::Linear(100.0))
.with_unit(" Octaves")
.with_value_to_string(formatters::f32_rounded(2)),
window_size_order: IntParam::new(
"Window Size",
(DEFAULT_WINDOW_SIZE as f32).log2() as i32,
IntRange::Linear {
min: (MIN_WINDOW_SIZE as f32).log2() as i32,
max: (MAX_WINDOW_SIZE as f32).log2() as i32,
},
)
.with_value_to_string(Arc::new(|value| format!("{}", 1 << value)))
.with_string_to_value(Arc::new(|string| {
string.parse().ok().map(|n: i32| (n as f32).log2() as i32)
})),
}
}
}
@ -123,8 +147,12 @@ impl Plugin for PubertySimulator {
) -> bool {
// Normally we'd also initialize the STFT helper for the correct channel count here, but we
// only do stereo so that's not necessary
self.stft.set_block_size(WINDOW_SIZE);
let window_size = self.window_size();
if self.window_function.len() != window_size {
self.resize_for_window(window_size);
context.set_latency_samples(self.stft.latency_samples());
}
true
}
@ -132,9 +160,21 @@ impl Plugin for PubertySimulator {
fn process(&mut self, buffer: &mut Buffer, context: &mut impl ProcessContext) -> ProcessStatus {
// Compensate for the window function, the overlap, and the extra gain introduced by the
// IDFT operation
const GAIN_COMPENSATION: f32 = 2.0 / OVERLAP_TIMES as f32 / WINDOW_SIZE as f32;
let window_size = self.window_size();
let sample_rate = context.transport().sample_rate;
let gain_compensation: f32 = 2.0 / OVERLAP_TIMES as f32 / window_size as f32;
// If the window size has changed since the last process call, reset the buffers and chance
// our latency. All of these buffers already have enough capacity
if self.window_function.len() != window_size {
self.resize_for_window(window_size);
context.set_latency_samples(self.stft.latency_samples());
}
// Since this type cannot be resized, we'll simply slice the full buffer instead
let complex_fft_scratch_buffer =
&mut self.complex_fft_scratch_buffer.as_slice_mut()[..window_size / 2 + 1];
let mut smoothed_pitch_value = 0.0;
self.stft.process_overlap_add(
@ -150,7 +190,7 @@ impl Plugin for PubertySimulator {
.params
.pitch_octaves
.smoothed
.next_step((WINDOW_SIZE / OVERLAP_TIMES) as u32);
.next_step((window_size / OVERLAP_TIMES) as u32);
}
// Negated because pitching down should cause us to take values from higher frequency bins
let frequency_multiplier = 2.0f32.powf(-smoothed_pitch_value);
@ -158,41 +198,36 @@ impl Plugin for PubertySimulator {
// Forward FFT, the helper has already applied window function
self.plan
.r2c_plan
.r2c(
real_fft_scratch_buffer,
&mut self.complex_fft_scratch_buffer,
)
.r2c(real_fft_scratch_buffer, complex_fft_scratch_buffer)
.unwrap();
// This simply interpolates between the complex sinusoids from the frequency bins
// for this bin's frequency scaled by the octave pitch multiplies. The iteration
// order dependson the pitch shifting direction since we're doing it in place.
let num_bins = self.complex_fft_scratch_buffer.len();
let num_bins = complex_fft_scratch_buffer.len();
let mut process_bin = |bin_idx| {
let frequency = bin_idx as f32 / WINDOW_SIZE as f32 * sample_rate;
let frequency = bin_idx as f32 / window_size as f32 * sample_rate;
let target_frequency = frequency * frequency_multiplier;
// Simple linear interpolation
let target_bin = target_frequency / sample_rate * WINDOW_SIZE as f32;
let target_bin = target_frequency / sample_rate * window_size as f32;
let target_bin_low = target_bin.floor() as usize;
let target_bin_high = target_bin.ceil() as usize;
let target_low_t = target_bin % 1.0;
let target_high_t = 1.0 - target_low_t;
let target_low = self
.complex_fft_scratch_buffer
let target_low = complex_fft_scratch_buffer
.get(target_bin_low)
.copied()
.unwrap_or_default();
let target_high = self
.complex_fft_scratch_buffer
let target_high = complex_fft_scratch_buffer
.get(target_bin_high)
.copied()
.unwrap_or_default();
self.complex_fft_scratch_buffer[bin_idx] = (target_low * target_low_t
complex_fft_scratch_buffer[bin_idx] = (target_low * target_low_t
+ target_high * target_high_t)
* 3.0 // Random extra gain, not sure
* GAIN_COMPENSATION;
* gain_compensation;
};
if frequency_multiplier >= 1.0 {
@ -209,10 +244,7 @@ impl Plugin for PubertySimulator {
// which gets written back to the host at a one block delay.
self.plan
.c2r_plan
.c2r(
&mut self.complex_fft_scratch_buffer,
real_fft_scratch_buffer,
)
.c2r(complex_fft_scratch_buffer, real_fft_scratch_buffer)
.unwrap();
},
);
@ -221,6 +253,22 @@ impl Plugin for PubertySimulator {
}
}
impl PubertySimulator {
fn window_size(&self) -> usize {
1 << self.params.window_size_order.value as usize
}
/// `window_size` should not exceed `MAX_WINDOW_SIZE` or this will allocate.
fn resize_for_window(&mut self, window_size: usize) {
self.stft.set_block_size(window_size);
self.window_function.resize(window_size, 0.0);
util::window::hann_in_place(&mut self.window_function);
self.plan.r2c_plan = R2CPlan32::aligned(&[window_size], Flag::MEASURE).unwrap();
self.plan.c2r_plan = C2RPlan32::aligned(&[window_size], Flag::MEASURE).unwrap();
}
}
impl ClapPlugin for PubertySimulator {
const CLAP_ID: &'static str = "nl.robbertvanderhelm.puberty-simulator";
const CLAP_DESCRIPTION: &'static str = "Simulates a pitched down cracking voice";