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Add a basic version of Crisp

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This commit is contained in:
Robbert van der Helm 2022-03-08 21:10:36 +01:00
parent 4cca7af930
commit 46901bf5c9
2 changed files with 14 additions and 10 deletions
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22
plugins/crisp/src/lib.rs
View file

@ -15,6 +15,7 @@
// along with this program. If not, see <https://www.gnu.org/licenses/>.
use nih_plug::prelude::*;
use pcg::Pcg32iState;
use std::pin::Pin;
mod pcg;
@ -23,7 +24,7 @@ mod pcg;
const NUM_CHANNELS: usize = 2;
/// These seeds being fixed makes bouncing deterministic.
const INITIAL_PRNG_SEEDS: [u32; 2] = [69, 420];
const INITIAL_PRNG_SEED: Pcg32iState = Pcg32iState::new(69, 420);
/// This plugin essentially layers the sound with another copy of the signal AM'ed with white (or
/// filtered) noise. That other copy of the sound may have a low pass filter applied to it since
@ -31,9 +32,9 @@ const INITIAL_PRNG_SEEDS: [u32; 2] = [69, 420];
struct Crisp {
params: Pin<Box<CrispParams>>,
/// The OS RNG is only used for the initial seeds, after that we'll implement PCG ourselves so
/// we can easily SIMD-ify this in the future.
prng_seeds: [u32; NUM_CHANNELS],
/// A PRNG for generating noise, after that we'll implement PCG ourselves so we can easily
/// SIMD-ify this in the future.
prng: Pcg32iState,
}
// TODO: Filters
@ -51,7 +52,7 @@ impl Default for Crisp {
Self {
params: Box::pin(CrispParams::default()),
prng_seeds: INITIAL_PRNG_SEEDS,
prng: INITIAL_PRNG_SEED,
}
}
}
@ -91,7 +92,7 @@ impl Plugin for Crisp {
fn reset(&mut self) {
// By using the same seeds each time bouncing can be made deterministic
self.prng_seeds = INITIAL_PRNG_SEEDS;
self.prng = INITIAL_PRNG_SEED;
}
fn process(
@ -103,9 +104,12 @@ impl Plugin for Crisp {
let amount = self.params.amount.smoothed.next();
// TODO: SIMD-ize this to process both channels at once
for (channel_idx, sample) in channel_samples.into_iter().enumerate() {
// TODO: Calculate some uniformly (or Gaussian?) distributed white noise in the
// range of `[-1, 1]`, add that scaled by `amount` to `sample`.
// TODO: This does not sound quite right
for sample in channel_samples.into_iter() {
let noise = self.prng.next_f32() * 2.0 - 1.0;
let am = *sample * noise;
*sample += am * amount;
}
}

2
plugins/crisp/src/pcg.rs
View file

@ -65,7 +65,7 @@ impl Pcg32iState {
.wrapping_mul(PCG_DEFAULT_MULTIPLIER_32)
.wrapping_add(self.inc);
let word = ((old_state >> ((old_state >> 28) + 4)) ^ old_state) * 277803737;
let word = ((old_state >> ((old_state >> 28) + 4)) ^ old_state).wrapping_mul(277803737);
(word >> 22) ^ word
}