From 71dbb875608570f4e955a3a5d11954de559def50 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Fri, 6 Dec 2024 03:12:48 +0400
Subject: [PATCH 01/10] Resampler low pass prototype

---
 src/conversions/sample_rate.rs |  27 ++++++++
 src/source/low_pass.rs         | 115 +++++++++++++++++++++++++++++++++
 src/source/mod.rs              |   2 +
 3 files changed, 144 insertions(+)
 create mode 100644 src/source/low_pass.rs

diff --git a/src/conversions/sample_rate.rs b/src/conversions/sample_rate.rs
index b76c23d0..bdcf2bff 100644
--- a/src/conversions/sample_rate.rs
+++ b/src/conversions/sample_rate.rs
@@ -2,6 +2,8 @@ use crate::conversions::Sample;
 
 use num_rational::Ratio;
 use std::mem;
+use std::time::Duration;
+use crate::Source;
 
 /// Iterator that converts from a certain sample rate to another.
 #[derive(Clone, Debug)]
@@ -15,6 +17,7 @@ where
     from: u32,
     /// We convert chunks of `from` samples into chunks of `to` samples.
     to: u32,
+    to_full: u32,
     /// Number of channels in the stream
     channels: cpal::ChannelCount,
     /// One sample per channel, extracted from `input`.
@@ -61,6 +64,7 @@ where
         assert!(num_channels >= 1);
         assert!(from >= 1);
         assert!(to >= 1);
+        let to_full = to;
 
         let (first_samples, next_samples) = if from == to {
             // if `from` == `to` == 1, then we just pass through
@@ -84,6 +88,7 @@ where
             input,
             from,
             to,
+            to_full,
             channels: num_channels,
             current_frame_pos_in_chunk: 0,
             next_output_frame_pos_in_chunk: 0,
@@ -120,6 +125,28 @@ where
     }
 }
 
+impl<I> Source for SampleRateConverter<I>
+where
+    I: Source,
+    I::Item: Sample,
+{
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        self.input.channels()
+    }
+
+    fn sample_rate(&self) -> u32 {
+        self.to_full
+    }
+
+    fn total_duration(&self) -> Option<Duration> {
+        self.input.total_duration()
+    }
+}
+
 impl<I> Iterator for SampleRateConverter<I>
 where
     I: Iterator,
diff --git a/src/source/low_pass.rs b/src/source/low_pass.rs
new file mode 100644
index 00000000..550e9873
--- /dev/null
+++ b/src/source/low_pass.rs
@@ -0,0 +1,115 @@
+use std::time::Duration;
+use num_rational::Ratio;
+use crate::conversions::SampleRateConverter;
+use crate::{Sample, Source};
+
+pub struct LowPass<I>
+where
+    I: Iterator,
+{
+    input: I,
+    prev: Option<I::Item>
+}
+
+impl<I> LowPass<I>
+where
+    I: Iterator,
+    I::Item: Sample,
+{
+    #[inline]
+    pub fn new(
+        mut input: I,
+    ) -> LowPass<I> {
+        LowPass {
+            input,
+            prev: None
+        }
+    }
+}
+
+impl<I> Source for LowPass<I>
+where
+    I: Source,
+    I::Item: Sample,
+{
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        self.input.channels()
+    }
+
+    fn sample_rate(&self) -> u32 {
+        self.input.sample_rate()
+    }
+
+    fn total_duration(&self) -> Option<Duration> {
+        self.input.total_duration()
+    }
+}
+
+impl<I> Iterator for LowPass<I>
+where
+    I: Iterator,
+    I::Item: Sample + Clone,
+{
+    type Item = I::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.input.next().and_then(|s| {
+            let x = self.prev.map(|p| (p.saturating_add(s)).amplify(0.5));
+            self.prev.replace(s);
+            x
+        })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::conversions::SampleRateConverter;
+    use crate::source::SineWave;
+    use crate::Source;
+    use crate::{OutputStreamBuilder};
+    use std::thread;
+    use std::time::Duration;
+    use symphonia::core::meta::StandardTagKey::Encoder;
+
+    #[test]
+    fn test_low_pass() {
+        let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
+        let mixer = stream_handle.mixer();
+        {
+            // Generate sine wave.
+            let wave = SineWave::new(740.0)
+                .amplify(0.1)
+                .take_duration(Duration::from_secs(1));
+
+            let rate_in = wave.sample_rate();
+            let channels_in = wave.channels();
+            let out_freq = 44_100;
+            let output1 = SampleRateConverter::new(
+                wave,
+                cpal::SampleRate(rate_in),
+                cpal::SampleRate(out_freq * 2),
+                channels_in,
+            );
+            
+            let lo_pass = LowPass::new(output1);
+
+            let rate_in = lo_pass.sample_rate();
+            let output2 = SampleRateConverter::new(
+                lo_pass,
+                cpal::SampleRate(rate_in),
+                cpal::SampleRate(out_freq),
+                channels_in,
+            );
+
+            mixer.add(output2);
+        }
+        WavFile
+
+        thread::sleep(Duration::from_millis(1000));
+    }
+}
diff --git a/src/source/mod.rs b/src/source/mod.rs
index e730e802..6e52a186 100644
--- a/src/source/mod.rs
+++ b/src/source/mod.rs
@@ -75,6 +75,8 @@ mod zero;
 
 #[cfg(feature = "noise")]
 mod noise;
+mod low_pass;
+
 #[cfg(feature = "noise")]
 pub use self::noise::{pink, white, PinkNoise, WhiteNoise};
 

From f8eac5703ee128af8b241867b849adccde04ff51 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Sun, 8 Dec 2024 01:41:43 +0400
Subject: [PATCH 02/10] Build fix

---
 src/source/low_pass.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/source/low_pass.rs b/src/source/low_pass.rs
index 550e9873..0f7b2120 100644
--- a/src/source/low_pass.rs
+++ b/src/source/low_pass.rs
@@ -108,7 +108,6 @@ mod test {
 
             mixer.add(output2);
         }
-        WavFile
 
         thread::sleep(Duration::from_millis(1000));
     }

From 4a322a2fa0e474189abe5b0f6b6552d822d229e8 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Sat, 14 Dec 2024 04:09:31 +0400
Subject: [PATCH 03/10] Cleanups

---
 src/source/blt.rs      | 12 ++++++------
 src/source/low_pass.rs | 39 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/src/source/blt.rs b/src/source/blt.rs
index c7be7310..8778b0d6 100644
--- a/src/source/blt.rs
+++ b/src/source/blt.rs
@@ -5,8 +5,6 @@ use crate::Source;
 
 use super::SeekError;
 
-// Implemented following http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
-
 /// Internal function that builds a `BltFilter` object.
 pub fn low_pass<I>(input: I, freq: u32) -> BltFilter<I>
 where
@@ -22,7 +20,7 @@ where
     high_pass_with_q(input, freq, 0.5)
 }
 
-/// Same as low_pass but allows the q value (bandwidth) to be changed
+/// Same as low_pass but allows the q value (bandwidth) to be changed.
 pub fn low_pass_with_q<I>(input: I, freq: u32, q: f32) -> BltFilter<I>
 where
     I: Source<Item = f32>,
@@ -38,7 +36,7 @@ where
     }
 }
 
-/// Same as high_pass but allows the q value (bandwidth) to be changed
+/// Same as high_pass but allows the q value (bandwidth) to be changed.
 pub fn high_pass_with_q<I>(input: I, freq: u32, q: f32) -> BltFilter<I>
 where
     I: Source<Item = f32>,
@@ -55,6 +53,8 @@ where
 }
 
 /// This applies an audio filter, it can be a high or low pass filter.
+/// Implements following 
+/// https://github.com/WebAudio/Audio-EQ-Cookbook/blob/main/Audio-EQ-Cookbook.txt
 #[derive(Clone, Debug)]
 pub struct BltFilter<I> {
     input: I,
@@ -77,13 +77,13 @@ impl<I> BltFilter<I> {
         self.to_high_pass_with_q(freq, 0.5);
     }
 
-    /// Same as to_low_pass but allows the q value (bandwidth) to be changed
+    /// Same as to_low_pass but allows the q value (bandwidth) to be changed.
     pub fn to_low_pass_with_q(&mut self, freq: u32, q: f32) {
         self.formula = BltFormula::LowPass { freq, q };
         self.applier = None;
     }
 
-    /// Same as to_high_pass but allows the q value (bandwidth) to be changed
+    /// Same as to_high_pass but allows the q value (bandwidth) to be changed.
     pub fn to_high_pass_with_q(&mut self, freq: u32, q: f32) {
         self.formula = BltFormula::HighPass { freq, q };
         self.applier = None;
diff --git a/src/source/low_pass.rs b/src/source/low_pass.rs
index 0f7b2120..ea95483b 100644
--- a/src/source/low_pass.rs
+++ b/src/source/low_pass.rs
@@ -77,7 +77,7 @@ mod test {
     use symphonia::core::meta::StandardTagKey::Encoder;
 
     #[test]
-    fn test_low_pass() {
+    fn test_resample_low_pass() {
         let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
         let mixer = stream_handle.mixer();
         {
@@ -111,4 +111,41 @@ mod test {
 
         thread::sleep(Duration::from_millis(1000));
     }
+
+    #[test]
+    fn test_resample_biquad_low_pass() {
+        
+        let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
+        let mixer = stream_handle.mixer();
+        {
+            // Generate sine wave.
+            let wave = SineWave::new(740.0)
+                .amplify(0.1)
+                .take_duration(Duration::from_secs(1));
+
+            let rate_in = wave.sample_rate();
+            let channels_in = wave.channels();
+            let out_freq = 44_100;
+            let output1 = SampleRateConverter::new(
+                wave,
+                cpal::SampleRate(rate_in),
+                cpal::SampleRate(out_freq * 2),
+                channels_in,
+            );
+
+            let lo_pass = LowPass::new(output1);
+
+            let rate_in = lo_pass.sample_rate();
+            let output2 = SampleRateConverter::new(
+                lo_pass,
+                cpal::SampleRate(rate_in),
+                cpal::SampleRate(out_freq),
+                channels_in,
+            );
+
+            mixer.add(output2);
+        }
+
+        thread::sleep(Duration::from_millis(1000));
+    }
 }

From 8154e444b49cd6a0d9aec32f43bce36ec7c3fa67 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Wed, 18 Dec 2024 22:11:57 +0400
Subject: [PATCH 04/10] Cargo update

---
 Cargo.lock | 101 ++++++++++++++++++++++++-----------------------------
 1 file changed, 46 insertions(+), 55 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 636ea8cc..90a18275 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -122,9 +122,9 @@ checksum = "325918d6fe32f23b19878fe4b34794ae41fc19ddbe53b10571a4874d44ffd39b"
 
 [[package]]
 name = "cc"
-version = "1.2.2"
+version = "1.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f34d93e62b03caf570cccc334cbc6c2fceca82f39211051345108adcba3eebdc"
+checksum = "9157bbaa6b165880c27a4293a474c91cdcf265cc68cc829bf10be0964a391caf"
 dependencies = [
  "jobserver",
  "libc",
@@ -165,18 +165,18 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.21"
+version = "4.5.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb3b4b9e5a7c7514dfa52869339ee98b3156b0bfb4e8a77c4ff4babb64b1604f"
+checksum = "3135e7ec2ef7b10c6ed8950f0f792ed96ee093fa088608f1c76e569722700c84"
 dependencies = [
  "clap_builder",
 ]
 
 [[package]]
 name = "clap_builder"
-version = "4.5.21"
+version = "4.5.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b17a95aa67cc7b5ebd32aa5370189aa0d79069ef1c64ce893bd30fb24bff20ec"
+checksum = "30582fc632330df2bd26877bde0c1f4470d57c582bbc070376afcd04d8cb4838"
 dependencies = [
  "anstyle",
  "clap_lex",
@@ -185,9 +185,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.7.3"
+version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "afb84c814227b90d6895e01398aee0d8033c00e7466aca416fb6a8e0eb19d8a7"
+checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
 
 [[package]]
 name = "claxon"
@@ -262,18 +262,18 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-channel"
-version = "0.5.13"
+version = "0.5.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33480d6946193aa8033910124896ca395333cae7e2d1113d1fef6c3272217df2"
+checksum = "06ba6d68e24814cb8de6bb986db8222d3a027d15872cabc0d18817bc3c0e4471"
 dependencies = [
  "crossbeam-utils",
 ]
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.20"
+version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
 [[package]]
 name = "dasp_sample"
@@ -283,9 +283,9 @@ checksum = "0c87e182de0887fd5361989c677c4e8f5000cd9491d6d563161a8f3a5519fc7f"
 
 [[package]]
 name = "divan"
-version = "0.1.16"
+version = "0.1.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ccc40f214f0d9e897cfc72e2edfa5c225d3252f758c537f11ac0a80371c073a6"
+checksum = "e0583193020b29b03682d8d33bb53a5b0f50df6daacece12ca99b904cfdcb8c4"
 dependencies = [
  "cfg-if",
  "clap",
@@ -297,9 +297,9 @@ dependencies = [
 
 [[package]]
 name = "divan-macros"
-version = "0.1.16"
+version = "0.1.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7bdb5411188f7f878a17964798c1264b6b0a9f915bd39b20bf99193c923e1b4e"
+checksum = "8dc51d98e636f5e3b0759a39257458b22619cac7e96d932da6eeb052891bb67c"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -479,9 +479,9 @@ checksum = "62adaabb884c94955b19907d60019f4e145d091c75345379e70d1ee696f7854f"
 
 [[package]]
 name = "indexmap"
-version = "2.6.0"
+version = "2.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "707907fe3c25f5424cce2cb7e1cbcafee6bdbe735ca90ef77c29e84591e5b9da"
+checksum = "62f822373a4fe84d4bb149bf54e584a7f4abec90e072ed49cda0edea5b95471f"
 dependencies = [
  "equivalent",
  "hashbrown",
@@ -529,10 +529,11 @@ dependencies = [
 
 [[package]]
 name = "js-sys"
-version = "0.3.73"
+version = "0.3.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb15147158e79fd8b8afd0252522769c4f48725460b37338544d8379d94fc8f9"
+checksum = "6717b6b5b077764fb5966237269cb3c64edddde4b14ce42647430a78ced9e7b7"
 dependencies = [
+ "once_cell",
  "wasm-bindgen",
 ]
 
@@ -555,9 +556,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.167"
+version = "0.2.168"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09d6582e104315a817dff97f75133544b2e094ee22447d2acf4a74e189ba06fc"
+checksum = "5aaeb2981e0606ca11d79718f8bb01164f1d6ed75080182d3abf017e6d244b6d"
 
 [[package]]
 name = "libloading"
@@ -987,15 +988,15 @@ dependencies = [
 
 [[package]]
 name = "rustix"
-version = "0.38.41"
+version = "0.38.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d7f649912bc1495e167a6edee79151c84b1bad49748cb4f1f1167f459f6224f6"
+checksum = "f93dc38ecbab2eb790ff964bb77fa94faf256fd3e73285fd7ba0903b76bedb85"
 dependencies = [
  "bitflags 2.6.0",
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1009,9 +1010,9 @@ dependencies = [
 
 [[package]]
 name = "semver"
-version = "1.0.23"
+version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61697e0a1c7e512e84a621326239844a24d8207b4669b41bc18b32ea5cbf988b"
+checksum = "3cb6eb87a131f756572d7fb904f6e7b68633f09cca868c5df1c4b8d1a694bbba"
 
 [[package]]
 name = "shlex"
@@ -1197,9 +1198,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.89"
+version = "2.0.90"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "44d46482f1c1c87acd84dea20c1bf5ebff4c757009ed6bf19cfd36fb10e92c4e"
+checksum = "919d3b74a5dd0ccd15aeb8f93e7006bd9e14c295087c9896a110f490752bcf31"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1208,9 +1209,9 @@ dependencies = [
 
 [[package]]
 name = "terminal_size"
-version = "0.4.0"
+version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4f599bd7ca042cfdf8f4512b277c02ba102247820f9d9d4a9f521f496751a6ef"
+checksum = "5352447f921fda68cf61b4101566c0bdb5104eff6804d0678e5227580ab6a4e9"
 dependencies = [
  "rustix",
  "windows-sys 0.59.0",
@@ -1323,9 +1324,9 @@ checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.96"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "21d3b25c3ea1126a2ad5f4f9068483c2af1e64168f847abe863a526b8dbfe00b"
+checksum = "a474f6281d1d70c17ae7aa6a613c87fce69a127e2624002df63dcb39d6cf6396"
 dependencies = [
  "cfg-if",
  "once_cell",
@@ -1334,13 +1335,12 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-backend"
-version = "0.2.96"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "52857d4c32e496dc6537646b5b117081e71fd2ff06de792e3577a150627db283"
+checksum = "5f89bb38646b4f81674e8f5c3fb81b562be1fd936d84320f3264486418519c79"
 dependencies = [
  "bumpalo",
  "log",
- "once_cell",
  "proc-macro2",
  "quote",
  "syn",
@@ -1349,9 +1349,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-futures"
-version = "0.4.46"
+version = "0.4.49"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "951fe82312ed48443ac78b66fa43eded9999f738f6022e67aead7b708659e49a"
+checksum = "38176d9b44ea84e9184eff0bc34cc167ed044f816accfe5922e54d84cf48eca2"
 dependencies = [
  "cfg-if",
  "js-sys",
@@ -1362,9 +1362,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.96"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "920b0ffe069571ebbfc9ddc0b36ba305ef65577c94b06262ed793716a1afd981"
+checksum = "2cc6181fd9a7492eef6fef1f33961e3695e4579b9872a6f7c83aee556666d4fe"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -1372,9 +1372,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.96"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf59002391099644be3524e23b781fa43d2be0c5aa0719a18c0731b9d195cab6"
+checksum = "30d7a95b763d3c45903ed6c81f156801839e5ee968bb07e534c44df0fcd330c2"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1385,15 +1385,15 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.96"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e5047c5392700766601942795a436d7d2599af60dcc3cc1248c9120bfb0827b0"
+checksum = "943aab3fdaaa029a6e0271b35ea10b72b943135afe9bffca82384098ad0e06a6"
 
 [[package]]
 name = "web-sys"
-version = "0.3.73"
+version = "0.3.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "476364ff87d0ae6bfb661053a9104ab312542658c3d8f963b7ace80b6f9b26b9"
+checksum = "04dd7223427d52553d3702c004d3b2fe07c148165faa56313cb00211e31c12bc"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
@@ -1468,15 +1468,6 @@ dependencies = [
  "windows-targets 0.42.2",
 ]
 
-[[package]]
-name = "windows-sys"
-version = "0.52.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
-dependencies = [
- "windows-targets 0.52.6",
-]
-
 [[package]]
 name = "windows-sys"
 version = "0.59.0"

From b5e245d0f9a2855eeaa7a26999e4d0e94992c3fe Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Wed, 18 Dec 2024 22:13:24 +0400
Subject: [PATCH 05/10] Build fix: add rustdoc

---
 src/source/noise.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/source/noise.rs b/src/source/noise.rs
index 42ae0e61..1cb9a301 100644
--- a/src/source/noise.rs
+++ b/src/source/noise.rs
@@ -98,6 +98,7 @@ pub struct PinkNoise {
 }
 
 impl PinkNoise {
+    /// Create new pink noise source for given sample rate.
     pub fn new(sample_rate: cpal::SampleRate) -> Self {
         Self {
             white_noise: WhiteNoise::new(sample_rate),

From 55f15b9a72e6fd11ba3489cfd31a35158191d669 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Thu, 19 Dec 2024 00:24:01 +0400
Subject: [PATCH 06/10] Write test output to WAv file for offline analysis.

---
 src/source/low_pass.rs | 103 ++++++++++++++++++++++-------------------
 1 file changed, 55 insertions(+), 48 deletions(-)

diff --git a/src/source/low_pass.rs b/src/source/low_pass.rs
index ea95483b..96c44d1f 100644
--- a/src/source/low_pass.rs
+++ b/src/source/low_pass.rs
@@ -1,14 +1,13 @@
-use std::time::Duration;
-use num_rational::Ratio;
-use crate::conversions::SampleRateConverter;
 use crate::{Sample, Source};
+use hound::{SampleFormat, WavSpec};
+use std::time::Duration;
 
 pub struct LowPass<I>
 where
     I: Iterator,
 {
     input: I,
-    prev: Option<I::Item>
+    prev: Option<I::Item>,
 }
 
 impl<I> LowPass<I>
@@ -17,13 +16,8 @@ where
     I::Item: Sample,
 {
     #[inline]
-    pub fn new(
-        mut input: I,
-    ) -> LowPass<I> {
-        LowPass {
-            input,
-            prev: None
-        }
+    pub fn new(input: I) -> LowPass<I> {
+        LowPass { input, prev: None }
     }
 }
 
@@ -57,64 +51,77 @@ where
     type Item = I::Item;
 
     fn next(&mut self) -> Option<Self::Item> {
-        self.input.next().and_then(|s| {
-            let x = self.prev.map(|p| (p.saturating_add(s)).amplify(0.5));
+        self.input.next().map(|s| {
+            let x = self.prev.map_or(s, |p| (p.saturating_add(s)).amplify(0.5));
             self.prev.replace(s);
             x
         })
     }
 }
 
+pub fn output_to_wav<S: Sample>(
+    source: Box<dyn Source<Item = S>>,
+    wav_file: &str,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let format = WavSpec {
+        channels: source.channels(),
+        sample_rate: source.sample_rate(),
+        bits_per_sample: 32,
+        sample_format: SampleFormat::Float,
+    };
+    let mut writer = hound::WavWriter::create(wav_file, format)?;
+    for sample in source {
+        writer.write_sample(sample.to_f32())?;
+    }
+    writer.finalize()?;
+    Ok(())
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
     use crate::conversions::SampleRateConverter;
     use crate::source::SineWave;
+    use crate::OutputStreamBuilder;
     use crate::Source;
-    use crate::{OutputStreamBuilder};
     use std::thread;
     use std::time::Duration;
-    use symphonia::core::meta::StandardTagKey::Encoder;
 
     #[test]
     fn test_resample_low_pass() {
-        let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
-        let mixer = stream_handle.mixer();
-        {
-            // Generate sine wave.
-            let wave = SineWave::new(740.0)
-                .amplify(0.1)
-                .take_duration(Duration::from_secs(1));
-
-            let rate_in = wave.sample_rate();
-            let channels_in = wave.channels();
-            let out_freq = 44_100;
-            let output1 = SampleRateConverter::new(
-                wave,
-                cpal::SampleRate(rate_in),
-                cpal::SampleRate(out_freq * 2),
-                channels_in,
-            );
-            
-            let lo_pass = LowPass::new(output1);
-
-            let rate_in = lo_pass.sample_rate();
-            let output2 = SampleRateConverter::new(
-                lo_pass,
-                cpal::SampleRate(rate_in),
-                cpal::SampleRate(out_freq),
-                channels_in,
-            );
-
-            mixer.add(output2);
-        }
-
-        thread::sleep(Duration::from_millis(1000));
+        // Generate sine wave.
+        let wave = SineWave::new(740.0)
+            .amplify(0.1)
+            .take_duration(Duration::from_secs(1));
+
+        let rate_in = wave.sample_rate();
+        let channels_in = wave.channels();
+        let out_freq = 44_100 / 3;
+        let output1 = SampleRateConverter::new(
+            wave,
+            cpal::SampleRate(rate_in),
+            cpal::SampleRate(out_freq * 2), 
+            channels_in,
+        );
+
+        // output_to_wav(Box::new(output1), "resample-orig.wav")
+        //     .expect("write wav file");
+
+        let lo_pass = LowPass::new(output1);
+        
+        let rate_in = lo_pass.sample_rate();
+        let output2 = SampleRateConverter::new(
+            lo_pass,
+            cpal::SampleRate(rate_in),
+            cpal::SampleRate(out_freq),
+            channels_in,
+        );
+        output_to_wav(Box::new(output2), "resample-primitive-low-pass.wav")
+            .expect("write wav file");
     }
 
     #[test]
     fn test_resample_biquad_low_pass() {
-        
         let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
         let mixer = stream_handle.mixer();
         {

From 58d650fee9e2a1b40cef98a51fcde3610b8edbb1 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Thu, 19 Dec 2024 22:49:06 +0400
Subject: [PATCH 07/10] Low pass filter as resampler postprocessing prototype

---
 src/conversions/sample_rate.rs | 167 ++++++++++++++++++++++++++++++++-
 src/source/blt.rs              |   8 +-
 src/source/low_pass.rs         | 158 -------------------------------
 src/source/mod.rs              |   3 +-
 src/source/simple_low_pass.rs  |  63 +++++++++++++
 src/source/sine.rs             |  15 ++-
 6 files changed, 247 insertions(+), 167 deletions(-)
 delete mode 100644 src/source/low_pass.rs
 create mode 100644 src/source/simple_low_pass.rs

diff --git a/src/conversions/sample_rate.rs b/src/conversions/sample_rate.rs
index bdcf2bff..98eaa8d9 100644
--- a/src/conversions/sample_rate.rs
+++ b/src/conversions/sample_rate.rs
@@ -1,11 +1,11 @@
 use crate::conversions::Sample;
 
+use crate::Source;
 use num_rational::Ratio;
 use std::mem;
 use std::time::Duration;
-use crate::Source;
 
-/// Iterator that converts from a certain sample rate to another.
+/// Iterator that converts from one sample rate to another.
 #[derive(Clone, Debug)]
 pub struct SampleRateConverter<I>
 where
@@ -279,9 +279,14 @@ where
 #[cfg(test)]
 mod test {
     use super::SampleRateConverter;
+    use crate::{Sample, Source};
     use core::time::Duration;
     use cpal::{ChannelCount, SampleRate};
+    use dasp_sample::FromSample;
+    use hound::{SampleFormat, WavSpec};
     use quickcheck::{quickcheck, TestResult};
+    use std::io::BufReader;
+    use std::path;
 
     quickcheck! {
         /// Check that resampling an empty input produces no output.
@@ -424,4 +429,162 @@ mod test {
         assert_eq!(output, [0, 5, 10, 15]);
         assert!((size_estimation as f32 / output.len() as f32).abs() < 2.0);
     }
+
+    pub fn output_to_wav<S: Sample, P: AsRef<path::Path>>(
+        source: Box<dyn Source<Item = S>>,
+        wav_file: &P,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        let format = WavSpec {
+            channels: source.channels(),
+            sample_rate: source.sample_rate(),
+            bits_per_sample: 32,
+            sample_format: SampleFormat::Float,
+        };
+        let mut writer = hound::WavWriter::create(wav_file, format)?;
+        for sample in source {
+            writer.write_sample(sample.to_f32())?;
+        }
+        writer.finalize()?;
+        Ok(())
+    }
+
+    use crate::source::{SimpleLowPass, SineWave};
+    use crate::Sink;
+
+    #[test]
+    fn resampler_tweaks() {
+        // let new_source = || Box::new(SineWave::new_with_sample_rate(frequency, rate_in)
+        //     .amplify(0.1)
+        //     .take_duration(Duration::from_secs(1)));
+        // assert!(rate_in as f32 > frequency * 2.0);
+        let new_source = move || {
+            let sink = Sink::new();
+            let file = std::fs::File::open("tmp-584/rodio-crackling-issue/crackling.mp3")
+                .expect("open mp3 file");
+            crate::Decoder::new(BufReader::new(file)).expect("can decode mp3")
+        };
+        // resampler_tweaks_generate(740.0, 44_123, 14_707);
+        resampler_tweaks_generate("584mp3", &new_source, 44_100); // Bug #584
+    }
+
+    fn resampler_tweaks_generate<S: Sample + 'static, Src: Source<Item = S> + 'static>(
+        source_tag: &str,
+        new_source: &dyn Fn() -> Src,
+        rate_out: u32,
+    ) where
+        S: cpal::FromSample<f32>,
+        f32: cpal::FromSample<S>,
+    {
+        let format_file_name = |variant: &str| {
+            let rate_in = new_source().sample_rate();
+            format!("resample_{variant}_{source_tag}_in{rate_in}_out{rate_out}.wav")
+        };
+
+        output_to_wav(
+            resample_reference(Box::new(new_source()), rate_out),
+            &format_file_name("reference"),
+        )
+        .expect("write wav file");
+
+        output_to_wav(
+            resample_with_simple_low_pass_direct(Box::new(new_source()), rate_out),
+            &format_file_name("simple_low_pass_direct"),
+        )
+        .expect("write wav file");
+
+        output_to_wav(
+            resample_with_simple_low_pass_upsample(Box::new(new_source()), rate_out),
+            &format_file_name("simple_low_pass_upsampled"),
+        )
+        .expect("write wav file");
+
+        output_to_wav(
+            resample_with_biquad_low_pass(Box::new(new_source()), rate_out),
+            &format_file_name("biquad_low_pass"),
+        )
+        .expect("write wav file");
+    }
+
+    fn resample_reference<S: Sample + 'static>(
+        source: Box<dyn Source<Item = S>>,
+        rate_out: u32,
+    ) -> Box<dyn Source<Item = S>> {
+        // Make an output recording to compare various tweaks from the tests below.
+        let channels_in = source.channels();
+        let rate_in = source.sample_rate();
+        let output1 = SampleRateConverter::new(
+            source,
+            SampleRate(rate_in),
+            SampleRate(rate_out),
+            channels_in,
+        );
+
+        Box::new(output1)
+    }
+
+    fn resample_with_simple_low_pass_direct<S: Sample + 'static>(
+        source: Box<dyn Source<Item = S>>,
+        rate_out: u32,
+    ) -> Box<dyn Source<Item = S>> {
+        let channels_in = source.channels();
+        let rate_in = source.sample_rate();
+        let output1 = SampleRateConverter::new(
+            source,
+            SampleRate(rate_in),
+            SampleRate(rate_out),
+            channels_in,
+        );
+
+        Box::new(output1)
+    }
+
+    fn resample_with_simple_low_pass_upsample<S: Sample + 'static>(
+        source: Box<dyn Source<Item = S>>,
+        rate_out: u32,
+    ) -> Box<dyn Source<Item = S>> {
+        let channels_in = source.channels();
+        let rate_in = source.sample_rate();
+        let output1 = SampleRateConverter::new(
+            source,
+            SampleRate(rate_in),
+            SampleRate(rate_out * 2),
+            channels_in,
+        );
+
+        let lo_pass = SimpleLowPass::new(output1);
+        let rate_in = lo_pass.sample_rate();
+        let output2 = SampleRateConverter::new(
+            lo_pass,
+            SampleRate(rate_in),
+            SampleRate(rate_out),
+            channels_in,
+        );
+
+        Box::new(output2)
+    }
+
+    fn resample_with_biquad_low_pass<S: Sample + 'static>(
+        source: Box<dyn Source<Item = S>>,
+        rate_out: u32,
+    ) -> Box<dyn Source<Item = S>>
+    where
+        f32: FromSample<S>,
+        S: FromSample<f32>,
+    {
+        let channels_in = source.channels();
+        let rate_in = source.sample_rate();
+        let output1 = SampleRateConverter::new(
+            source,
+            SampleRate(rate_in),
+            SampleRate(rate_out),
+            channels_in,
+        );
+
+        let lo_pass = output1
+            .convert_samples::<f32>()
+            .low_pass(rate_in / 2)
+            .convert_samples::<S>();
+
+        Box::new(lo_pass)
+    }
 }
diff --git a/src/source/blt.rs b/src/source/blt.rs
index 8778b0d6..e6fc245c 100644
--- a/src/source/blt.rs
+++ b/src/source/blt.rs
@@ -8,7 +8,7 @@ use super::SeekError;
 /// Internal function that builds a `BltFilter` object.
 pub fn low_pass<I>(input: I, freq: u32) -> BltFilter<I>
 where
-    I: Source<Item = f32>,
+    I: Iterator<Item = f32>,
 {
     low_pass_with_q(input, freq, 0.5)
 }
@@ -23,7 +23,7 @@ where
 /// Same as low_pass but allows the q value (bandwidth) to be changed.
 pub fn low_pass_with_q<I>(input: I, freq: u32, q: f32) -> BltFilter<I>
 where
-    I: Source<Item = f32>,
+    I: Iterator<Item = f32>,
 {
     BltFilter {
         input,
@@ -53,7 +53,7 @@ where
 }
 
 /// This applies an audio filter, it can be a high or low pass filter.
-/// Implements following 
+/// Implements following
 /// https://github.com/WebAudio/Audio-EQ-Cookbook/blob/main/Audio-EQ-Cookbook.txt
 #[derive(Clone, Debug)]
 pub struct BltFilter<I> {
@@ -112,7 +112,7 @@ impl<I> Iterator for BltFilter<I>
 where
     I: Source<Item = f32>,
 {
-    type Item = f32;
+    type Item = I::Item;
 
     #[inline]
     fn next(&mut self) -> Option<f32> {
diff --git a/src/source/low_pass.rs b/src/source/low_pass.rs
deleted file mode 100644
index 96c44d1f..00000000
--- a/src/source/low_pass.rs
+++ /dev/null
@@ -1,158 +0,0 @@
-use crate::{Sample, Source};
-use hound::{SampleFormat, WavSpec};
-use std::time::Duration;
-
-pub struct LowPass<I>
-where
-    I: Iterator,
-{
-    input: I,
-    prev: Option<I::Item>,
-}
-
-impl<I> LowPass<I>
-where
-    I: Iterator,
-    I::Item: Sample,
-{
-    #[inline]
-    pub fn new(input: I) -> LowPass<I> {
-        LowPass { input, prev: None }
-    }
-}
-
-impl<I> Source for LowPass<I>
-where
-    I: Source,
-    I::Item: Sample,
-{
-    fn current_frame_len(&self) -> Option<usize> {
-        None
-    }
-
-    fn channels(&self) -> u16 {
-        self.input.channels()
-    }
-
-    fn sample_rate(&self) -> u32 {
-        self.input.sample_rate()
-    }
-
-    fn total_duration(&self) -> Option<Duration> {
-        self.input.total_duration()
-    }
-}
-
-impl<I> Iterator for LowPass<I>
-where
-    I: Iterator,
-    I::Item: Sample + Clone,
-{
-    type Item = I::Item;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.input.next().map(|s| {
-            let x = self.prev.map_or(s, |p| (p.saturating_add(s)).amplify(0.5));
-            self.prev.replace(s);
-            x
-        })
-    }
-}
-
-pub fn output_to_wav<S: Sample>(
-    source: Box<dyn Source<Item = S>>,
-    wav_file: &str,
-) -> Result<(), Box<dyn std::error::Error>> {
-    let format = WavSpec {
-        channels: source.channels(),
-        sample_rate: source.sample_rate(),
-        bits_per_sample: 32,
-        sample_format: SampleFormat::Float,
-    };
-    let mut writer = hound::WavWriter::create(wav_file, format)?;
-    for sample in source {
-        writer.write_sample(sample.to_f32())?;
-    }
-    writer.finalize()?;
-    Ok(())
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use crate::conversions::SampleRateConverter;
-    use crate::source::SineWave;
-    use crate::OutputStreamBuilder;
-    use crate::Source;
-    use std::thread;
-    use std::time::Duration;
-
-    #[test]
-    fn test_resample_low_pass() {
-        // Generate sine wave.
-        let wave = SineWave::new(740.0)
-            .amplify(0.1)
-            .take_duration(Duration::from_secs(1));
-
-        let rate_in = wave.sample_rate();
-        let channels_in = wave.channels();
-        let out_freq = 44_100 / 3;
-        let output1 = SampleRateConverter::new(
-            wave,
-            cpal::SampleRate(rate_in),
-            cpal::SampleRate(out_freq * 2), 
-            channels_in,
-        );
-
-        // output_to_wav(Box::new(output1), "resample-orig.wav")
-        //     .expect("write wav file");
-
-        let lo_pass = LowPass::new(output1);
-        
-        let rate_in = lo_pass.sample_rate();
-        let output2 = SampleRateConverter::new(
-            lo_pass,
-            cpal::SampleRate(rate_in),
-            cpal::SampleRate(out_freq),
-            channels_in,
-        );
-        output_to_wav(Box::new(output2), "resample-primitive-low-pass.wav")
-            .expect("write wav file");
-    }
-
-    #[test]
-    fn test_resample_biquad_low_pass() {
-        let stream_handle = OutputStreamBuilder::open_default_stream().unwrap();
-        let mixer = stream_handle.mixer();
-        {
-            // Generate sine wave.
-            let wave = SineWave::new(740.0)
-                .amplify(0.1)
-                .take_duration(Duration::from_secs(1));
-
-            let rate_in = wave.sample_rate();
-            let channels_in = wave.channels();
-            let out_freq = 44_100;
-            let output1 = SampleRateConverter::new(
-                wave,
-                cpal::SampleRate(rate_in),
-                cpal::SampleRate(out_freq * 2),
-                channels_in,
-            );
-
-            let lo_pass = LowPass::new(output1);
-
-            let rate_in = lo_pass.sample_rate();
-            let output2 = SampleRateConverter::new(
-                lo_pass,
-                cpal::SampleRate(rate_in),
-                cpal::SampleRate(out_freq),
-                channels_in,
-            );
-
-            mixer.add(output2);
-        }
-
-        thread::sleep(Duration::from_millis(1000));
-    }
-}
diff --git a/src/source/mod.rs b/src/source/mod.rs
index 31a7231c..b919f334 100644
--- a/src/source/mod.rs
+++ b/src/source/mod.rs
@@ -31,6 +31,7 @@ pub use self::repeat::Repeat;
 pub use self::samples_converter::SamplesConverter;
 pub use self::sawtooth::SawtoothWave;
 pub use self::signal_generator::{Function, SignalGenerator};
+pub use self::simple_low_pass::SimpleLowPass;
 pub use self::sine::SineWave;
 pub use self::skip::SkipDuration;
 pub use self::skippable::Skippable;
@@ -81,7 +82,7 @@ mod zero;
 
 #[cfg(feature = "noise")]
 mod noise;
-mod low_pass;
+mod simple_low_pass;
 
 #[cfg(feature = "noise")]
 pub use self::noise::{pink, white, PinkNoise, WhiteNoise};
diff --git a/src/source/simple_low_pass.rs b/src/source/simple_low_pass.rs
new file mode 100644
index 00000000..bef22ab0
--- /dev/null
+++ b/src/source/simple_low_pass.rs
@@ -0,0 +1,63 @@
+use crate::{Sample, Source};
+use std::time::Duration;
+
+/// Simplest low pass filter with approximately sample_rate/2 cutoff.
+/// See also tunable low pass filter implementations [crate::source::blt::low_pass]
+/// and [crate::source::blt::low_pass_with_q].
+pub struct SimpleLowPass<I>
+where
+    I: Iterator,
+{
+    input: I,
+    prev: Option<I::Item>,
+}
+
+impl<I> SimpleLowPass<I>
+where
+    I: Iterator,
+    I::Item: Sample,
+{
+    /// Create new simple low pass filter.
+    #[inline]
+    pub fn new(input: I) -> SimpleLowPass<I> {
+        SimpleLowPass { input, prev: None }
+    }
+}
+
+impl<I> Source for SimpleLowPass<I>
+where
+    I: Source,
+    I::Item: Sample,
+{
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        self.input.channels()
+    }
+
+    fn sample_rate(&self) -> u32 {
+        self.input.sample_rate()
+    }
+
+    fn total_duration(&self) -> Option<Duration> {
+        self.input.total_duration()
+    }
+}
+
+impl<I> Iterator for SimpleLowPass<I>
+where
+    I: Iterator,
+    I::Item: Sample + Clone,
+{
+    type Item = I::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.input.next().map(|s| {
+            let x = self.prev.unwrap_or(s).saturating_add(s).amplify(0.5);
+            self.prev.replace(s);
+            x
+        })
+    }
+}
diff --git a/src/source/sine.rs b/src/source/sine.rs
index f8b054c7..7412335e 100644
--- a/src/source/sine.rs
+++ b/src/source/sine.rs
@@ -1,7 +1,6 @@
-use std::time::Duration;
-
 use crate::source::{Function, SignalGenerator};
 use crate::Source;
+use std::time::Duration;
 
 use super::SeekError;
 
@@ -27,6 +26,18 @@ impl SineWave {
             test_sine: SignalGenerator::new(sr, freq, Function::Sine),
         }
     }
+
+    /// Create a new generator with given frequency and sample rate.
+    pub fn new_with_sample_rate(freq: f32, sample_rate: u32) -> SineWave {
+        assert!(
+            sample_rate > (freq * 2.0) as u32,
+            "frequency is too high for the sample rate"
+        );
+        let sr = cpal::SampleRate(sample_rate);
+        SineWave {
+            test_sine: SignalGenerator::new(sr, freq, Function::Sine),
+        }
+    }
 }
 
 impl Iterator for SineWave {

From 604b96a8da3b4f73d982d3091901c2b32191185b Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Thu, 19 Dec 2024 22:59:43 +0400
Subject: [PATCH 08/10] Cleanup

---
 src/conversions/sample_rate.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/conversions/sample_rate.rs b/src/conversions/sample_rate.rs
index 98eaa8d9..b1ed107d 100644
--- a/src/conversions/sample_rate.rs
+++ b/src/conversions/sample_rate.rs
@@ -448,17 +448,14 @@ mod test {
         Ok(())
     }
 
-    use crate::source::{SimpleLowPass, SineWave};
-    use crate::Sink;
+    use crate::source::SimpleLowPass;
 
     #[test]
     fn resampler_tweaks() {
-        // let new_source = || Box::new(SineWave::new_with_sample_rate(frequency, rate_in)
+        // let new_source = || Box::new(crate::source::SineWave::new_with_sample_rate(2345.0, 43210)
         //     .amplify(0.1)
         //     .take_duration(Duration::from_secs(1)));
-        // assert!(rate_in as f32 > frequency * 2.0);
         let new_source = move || {
-            let sink = Sink::new();
             let file = std::fs::File::open("tmp-584/rodio-crackling-issue/crackling.mp3")
                 .expect("open mp3 file");
             crate::Decoder::new(BufReader::new(file)).expect("can decode mp3")

From e13d3c4429a4802f3c2594c806a56d7e13240c62 Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Thu, 19 Dec 2024 23:21:01 +0400
Subject: [PATCH 09/10] Use existing file for tests

So the test is runnable out of box.
---
 src/conversions/sample_rate.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/conversions/sample_rate.rs b/src/conversions/sample_rate.rs
index b1ed107d..41d33ec1 100644
--- a/src/conversions/sample_rate.rs
+++ b/src/conversions/sample_rate.rs
@@ -456,7 +456,7 @@ mod test {
         //     .amplify(0.1)
         //     .take_duration(Duration::from_secs(1)));
         let new_source = move || {
-            let file = std::fs::File::open("tmp-584/rodio-crackling-issue/crackling.mp3")
+            let file = std::fs::File::open("assets/music.mp3")
                 .expect("open mp3 file");
             crate::Decoder::new(BufReader::new(file)).expect("can decode mp3")
         };

From 9bbdaefc6a62dd144d9a60a2327d4b4c601733de Mon Sep 17 00:00:00 2001
From: Petr Gladkikh <petrglad@gmail.com>
Date: Fri, 20 Dec 2024 21:08:20 +0400
Subject: [PATCH 10/10] cargo fmt

---
 src/conversions/sample_rate.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/conversions/sample_rate.rs b/src/conversions/sample_rate.rs
index 41d33ec1..436bc3ff 100644
--- a/src/conversions/sample_rate.rs
+++ b/src/conversions/sample_rate.rs
@@ -456,8 +456,7 @@ mod test {
         //     .amplify(0.1)
         //     .take_duration(Duration::from_secs(1)));
         let new_source = move || {
-            let file = std::fs::File::open("assets/music.mp3")
-                .expect("open mp3 file");
+            let file = std::fs::File::open("assets/music.mp3").expect("open mp3 file");
             crate::Decoder::new(BufReader::new(file)).expect("can decode mp3")
         };
         // resampler_tweaks_generate(740.0, 44_123, 14_707);