Using SmallRng for white noise generation

This resolves a PR code review note and should make the source run
much faster.

Cargo.toml

@@ -18,7 +18,7 @@ minimp3_fixed = { version = "0.5.4", optional = true}
 symphonia = { version = "0.5.4", optional = true, default-features = false }
 crossbeam-channel = { version = "0.5.8", optional = true }
 thiserror = "1.0.49"
-rand = "0.8.5"
+rand = {version = "0.8.5", features = ["small_rng"]}
 
 [features]
 default = ["flac", "vorbis", "wav", "mp3"]

src/source/noise.rs

@@ -2,6 +2,9 @@ use crate::Source;
 
 use super::SeekError;
 
+use rand::rngs::SmallRng;
+use rand::{RngCore, SeedableRng};
+
 /// Create a new white noise source.
 #[inline]
 pub fn white(sample_rate: cpal::SampleRate) -> WhiteNoise {
@@ -18,12 +21,16 @@ pub fn pink(sample_rate: cpal::SampleRate) -> PinkNoise {
 #[derive(Clone, Debug)]
 pub struct WhiteNoise {
  sample_rate: cpal::SampleRate,
+ rng: SmallRng,
 }
 
 impl WhiteNoise {
  /// Create a new white noise generator.
  pub fn new(sample_rate: cpal::SampleRate) -> Self {
- Self { sample_rate }
+ Self {
+ sample_rate,
+ rng: SmallRng::from_entropy(),
+ }
  }
 }
 
@@ -32,7 +39,7 @@ impl Iterator for WhiteNoise {
 
  #[inline]
  fn next(&mut self) -> Option<Self::Item> {
- let randf = rand::random::<f32>();
+ let randf = self.rng.next_u32() as f32 / u32::MAX as f32;
  let scaled = randf * 2.0 - 1.0;
  Some(scaled)
  }