Merge branch 'master' into feature/automatic-gain-control

CHANGELOG.md

@@ -10,7 +10,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Support for *ALAC/AIFF*
 - Add `automatic_gain_control` source for dynamic audio level adjustment.
-- New sources:
+- New test signal generator sources:
+    - `TestSignal` source generates a sine, triangle, square wave or sawtooth
+      of a given frequency and sample rate.
+    - `Chirp` source generates a sine wave with a linearly-increasing
+      frequency over a given frequency range and duration.
+    - `white` and `pink` generate white or pink noise, respectively. These
+      sources depend on the `rand` crate and are guarded with the "noise"
+      feature.
+    - Documentation for the "noise" feature has been added to `lib.rs`.
+- New Fade and Crossfade sources:
     - `fade_out` fades an input out using a linear gain fade.
     - `linear_gain_ramp` applies a linear gain change to a sound over a
       given duration. `fade_out` is implemented as a `linear_gain_ramp` and

Cargo.toml

@@ -19,6 +19,7 @@ symphonia = { version = "0.5.4", optional = true, default-features = false }
 crossbeam-channel = { version = "0.5.8", optional = true }
 
 thiserror = "1.0.49"
+rand = { version = "0.8.5", features = ["small_rng"], optional = true }
 tracing = { version = "0.1.40", optional = true }
 
 atomic_float = { version = "1.1.0", optional = true }
@@ -33,6 +34,7 @@ vorbis = ["lewton"]
 wav = ["hound"]
 mp3 = ["symphonia-mp3"]
 minimp3 = ["dep:minimp3_fixed"]
+noise = ["rand"]
 wasm-bindgen = ["cpal/wasm-bindgen"]
 cpal-shared-stdcxx = ["cpal/oboe-shared-stdcxx"]
 symphonia-aac = ["symphonia/aac"]
@@ -64,3 +66,7 @@ harness = false
 [[example]]
 name = "music_m4a"
 required-features = ["symphonia-isomp4", "symphonia-aac"]
+
+[[example]]
+name = "noise_generator"
+required-features = ["noise"]

README.md

@@ -20,6 +20,10 @@ See [the docs](https://docs.rs/rodio/latest/rodio/#alternative-decoder-backends)
 
 [The documentation](http://docs.rs/rodio) contains an introduction to the library.
 
+## Dependencies(Linux only)
+
+Rodio uses `cpal` to send audio to the OS for playback. On Linux `cpal` needs the ALSA development files. These are provided as part of the libasound2-dev package on Debian and Ubuntu distributions and alsa-lib-devel on Fedora.
+
 ## License
 [License]: #license
 

examples/noise_generator.rs

@@ -0,0 +1,41 @@
+//! Noise generator example. Use the "noise" feature to enable the noise generator sources.
+
+#[cfg(feature = "noise")]
+fn main() {
+    use rodio::source::{pink, white, Source};
+    use std::thread;
+    use std::time::Duration;
+
+    let (_stream, stream_handle) = rodio::OutputStream::try_default().unwrap();
+
+    let noise_duration = Duration::from_millis(1000);
+    let interval_duration = Duration::from_millis(1500);
+
+    stream_handle
+        .play_raw(
+            white(cpal::SampleRate(48000))
+                .amplify(0.1)
+                .take_duration(noise_duration),
+        )
+        .unwrap();
+    println!("Playing white noise");
+
+    thread::sleep(interval_duration);
+
+    stream_handle
+        .play_raw(
+            pink(cpal::SampleRate(48000))
+                .amplify(0.1)
+                .take_duration(noise_duration),
+        )
+        .unwrap();
+    println!("Playing pink noise");
+
+    thread::sleep(interval_duration);
+}
+
+#[cfg(not(feature = "noise"))]
+fn main() {
+    println!("rodio has not been compiled with noise sources, use `--features noise` to enable this feature.");
+    println!("Exiting...");
+}

examples/signal_generator.rs

@@ -0,0 +1,83 @@
+//! Test signal generator example.
+
+fn main() {
+    use rodio::source::{chirp, Function, SignalGenerator, Source};
+    use std::thread;
+    use std::time::Duration;
+
+    let (_stream, stream_handle) = rodio::OutputStream::try_default().unwrap();
+
+    let test_signal_duration = Duration::from_millis(1000);
+    let interval_duration = Duration::from_millis(1500);
+
+    println!("Playing 1000 Hz tone");
+    stream_handle
+        .play_raw(
+            SignalGenerator::new(cpal::SampleRate(48000), 1000.0, Function::Sine)
+                .amplify(0.1)
+                .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+
+    println!("Playing 10,000 Hz tone");
+    stream_handle
+        .play_raw(
+            SignalGenerator::new(cpal::SampleRate(48000), 10000.0, Function::Sine)
+                .amplify(0.1)
+                .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+
+    println!("Playing 440 Hz Triangle Wave");
+    stream_handle
+        .play_raw(
+            SignalGenerator::new(cpal::SampleRate(48000), 440.0, Function::Triangle)
+                .amplify(0.1)
+                .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+
+    println!("Playing 440 Hz Sawtooth Wave");
+    stream_handle
+        .play_raw(
+            SignalGenerator::new(cpal::SampleRate(48000), 440.0, Function::Sawtooth)
+                .amplify(0.1)
+                .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+
+    println!("Playing 440 Hz Square Wave");
+    stream_handle
+        .play_raw(
+            SignalGenerator::new(cpal::SampleRate(48000), 440.0, Function::Square)
+                .amplify(0.1)
+                .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+
+    println!("Playing 20-10000 Hz Sweep");
+    stream_handle
+        .play_raw(
+            chirp(
+                cpal::SampleRate(48000),
+                20.0,
+                10000.0,
+                Duration::from_secs(1),
+            )
+            .amplify(0.1)
+            .take_duration(test_signal_duration),
+        )
+        .unwrap();
+
+    thread::sleep(interval_duration);
+}

src/lib.rs

@@ -110,6 +110,11 @@
 //! The "tracing" feature replaces the print to stderr when a stream error happens with a
 //! recording an error event with tracing.
 //!
+//! ### Feature "Noise"
+//!
+//! The "noise" feature adds support for white and pink noise sources. This feature requires the
+//! "rand" crate.
+//!
 //! ## How it works under the hood
 //!
 //! Rodio spawns a background thread that is dedicated to reading from the sources and sending
@@ -120,7 +125,7 @@
 //! hardware. Therefore there is no restriction on the number of sounds that play simultaneously or
 //! the number of sinks that can be created (except for the fact that creating too many will slow
 //! down your program).
-//!
+
 #![cfg_attr(test, deny(missing_docs))]
 pub use cpal::{
     self, traits::DeviceTrait, Device, Devices, DevicesError, InputDevices, OutputDevices,

src/source/chirp.rs

@@ -0,0 +1,76 @@
+//! Chirp/sweep source.
+
+use std::{f32::consts::TAU, time::Duration};
+
+use crate::Source;
+
+/// Convenience function to create a new `Chirp` source.
+#[inline]
+pub fn chirp(
+    sample_rate: cpal::SampleRate,
+    start_frequency: f32,
+    end_frequency: f32,
+    duration: Duration,
+) -> Chirp {
+    Chirp::new(sample_rate, start_frequency, end_frequency, duration)
+}
+
+/// Generate a sine wave with an instantaneous frequency that changes/sweeps linearly over time.
+/// At the end of the chirp, once the `end_frequency` is reached, the source is exhausted.
+#[derive(Clone, Debug)]
+pub struct Chirp {
+    start_frequency: f32,
+    end_frequency: f32,
+    sample_rate: cpal::SampleRate,
+    total_samples: u64,
+    elapsed_samples: u64,
+}
+
+impl Chirp {
+    fn new(
+        sample_rate: cpal::SampleRate,
+        start_frequency: f32,
+        end_frequency: f32,
+        duration: Duration,
+    ) -> Self {
+        Self {
+            sample_rate,
+            start_frequency,
+            end_frequency,
+            total_samples: (duration.as_secs_f64() * (sample_rate.0 as f64)) as u64,
+            elapsed_samples: 0,
+        }
+    }
+}
+
+impl Iterator for Chirp {
+    type Item = f32;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let i = self.elapsed_samples;
+        let ratio = self.elapsed_samples as f32 / self.total_samples as f32;
+        self.elapsed_samples += 1;
+        let freq = self.start_frequency * (1.0 - ratio) + self.end_frequency * ratio;
+        let t = (i as f32 / self.sample_rate() as f32) * TAU * freq;
+        Some(t.sin())
+    }
+}
+
+impl Source for Chirp {
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        1
+    }
+
+    fn sample_rate(&self) -> u32 {
+        self.sample_rate.0
+    }
+
+    fn total_duration(&self) -> Option<Duration> {
+        let secs: f64 = self.total_samples as f64 / self.sample_rate.0 as f64;
+        Some(Duration::new(1, 0).mul_f64(secs))
+    }
+}

src/source/mod.rs

@@ -11,6 +11,7 @@ pub use self::amplify::Amplify;
 pub use self::blt::BltFilter;
 pub use self::buffered::Buffered;
 pub use self::channel_volume::ChannelVolume;
+pub use self::chirp::{chirp, Chirp};
 pub use self::crossfade::Crossfade;
 pub use self::delay::Delay;
 pub use self::done::Done;
@@ -27,6 +28,7 @@ pub use self::periodic::PeriodicAccess;
 pub use self::position::TrackPosition;
 pub use self::repeat::Repeat;
 pub use self::samples_converter::SamplesConverter;
+pub use self::signal_generator::{Function, SignalGenerator};
 pub use self::sine::SineWave;
 pub use self::skip::SkipDuration;
 pub use self::skippable::Skippable;
@@ -42,6 +44,7 @@ mod amplify;
 mod blt;
 mod buffered;
 mod channel_volume;
+mod chirp;
 mod crossfade;
 mod delay;
 mod done;
@@ -58,6 +61,7 @@ mod periodic;
 mod position;
 mod repeat;
 mod samples_converter;
+mod signal_generator;
 mod sine;
 mod skip;
 mod skippable;
@@ -68,6 +72,11 @@ mod take;
 mod uniform;
 mod zero;
 
+#[cfg(feature = "noise")]
+mod noise;
+#[cfg(feature = "noise")]
+pub use self::noise::{pink, white, PinkNoise, WhiteNoise};
+
 /// A source of samples.
 ///
 /// # A quick lesson about sounds

src/source/noise.rs

@@ -0,0 +1,158 @@
+//! Noise sources.
+//!
+//!
+
+use crate::Source;
+
+use super::SeekError;
+
+use rand::{rngs::SmallRng, RngCore, SeedableRng};
+
+/// Convenience function to create a new `WhiteNoise` noise source.
+#[inline]
+pub fn white(sample_rate: cpal::SampleRate) -> WhiteNoise {
+    WhiteNoise::new(sample_rate)
+}
+
+/// Convenience function to create a new `PinkNoise` noise source.
+#[inline]
+pub fn pink(sample_rate: cpal::SampleRate) -> PinkNoise {
+    PinkNoise::new(sample_rate)
+}
+
+/// Generates an infinite stream of random samples in [-1.0, 1.0]. This source generates random
+/// samples as provided by the `rand::rngs::SmallRng` randomness source.
+#[derive(Clone, Debug)]
+pub struct WhiteNoise {
+    sample_rate: cpal::SampleRate,
+    rng: SmallRng,
+}
+
+impl WhiteNoise {
+    /// Create a new white noise generator, seeding the RNG with `seed`.
+    pub fn new_with_seed(sample_rate: cpal::SampleRate, seed: u64) -> Self {
+        Self {
+            sample_rate,
+            rng: SmallRng::seed_from_u64(seed),
+        }
+    }
+
+    /// Create a new white noise generator, seeding the RNG with system entropy.
+    pub fn new(sample_rate: cpal::SampleRate) -> Self {
+        Self {
+            sample_rate,
+            rng: SmallRng::from_entropy(),
+        }
+    }
+}
+
+impl Iterator for WhiteNoise {
+    type Item = f32;
+
+    #[inline]
+    fn next(&mut self) -> Option<Self::Item> {
+        let rand = self.rng.next_u32() as f32 / u32::MAX as f32;
+        let scaled = rand * 2.0 - 1.0;
+        Some(scaled)
+    }
+}
+
+impl Source for WhiteNoise {
+    #[inline]
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    #[inline]
+    fn channels(&self) -> u16 {
+        1
+    }
+
+    #[inline]
+    fn sample_rate(&self) -> u32 {
+        self.sample_rate.0
+    }
+
+    #[inline]
+    fn total_duration(&self) -> Option<std::time::Duration> {
+        None
+    }
+
+    #[inline]
+    fn try_seek(&mut self, _: std::time::Duration) -> Result<(), SeekError> {
+        // Does nothing, should do nothing
+        Ok(())
+    }
+}
+
+/// Generates an infinite stream of pink noise samples in [-1.0, 1.0].
+///
+/// The output of the source is the result of taking the output of the `WhiteNoise` source and
+/// filtering it according to a weighted-sum of seven FIR filters after [Paul Kellett's
+/// method][pk_method] from *musicdsp.org*.
+///
+/// [pk_method]: https://www.musicdsp.org/en/latest/Filters/76-pink-noise-filter.html
+pub struct PinkNoise {
+    white_noise: WhiteNoise,
+    b: [f32; 7],
+}
+
+impl PinkNoise {
+    pub fn new(sample_rate: cpal::SampleRate) -> Self {
+        Self {
+            white_noise: WhiteNoise::new(sample_rate),
+            b: [0.0f32, 0.0f32, 0.0f32, 0.0f32, 0.0f32, 0.0f32, 0.0f32],
+        }
+    }
+}
+
+impl Iterator for PinkNoise {
+    type Item = f32;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let white = self.white_noise.next().unwrap();
+        self.b[0] = 0.99886 * self.b[0] + white * 0.0555179;
+        self.b[1] = 0.99332 * self.b[1] + white * 0.0750759;
+        self.b[2] = 0.969 * self.b[2] + white * 0.153852;
+        self.b[3] = 0.8665 * self.b[3] + white * 0.3104856;
+        self.b[4] = 0.550 * self.b[4] + white * 0.5329522;
+        self.b[5] = -0.7616 * self.b[5] - white * 0.016898;
+
+        let pink = self.b[0]
+            + self.b[1]
+            + self.b[2]
+            + self.b[3]
+            + self.b[4]
+            + self.b[5]
+            + self.b[6]
+            + white * 0.5362;
+
+        self.b[6] = white * 0.115926;
+
+        Some(pink)
+    }
+}
+
+impl Source for PinkNoise {
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    fn channels(&self) -> u16 {
+        1
+    }
+
+    fn sample_rate(&self) -> u32 {
+        self.white_noise.sample_rate()
+    }
+
+    fn total_duration(&self) -> Option<std::time::Duration> {
+        None
+    }
+
+    #[inline]
+    fn try_seek(&mut self, _: std::time::Duration) -> Result<(), SeekError> {
+        // Does nothing, should do nothing
+        Ok(())
+    }
+}

src/source/signal_generator.rs

@@ -0,0 +1,185 @@
+//! Generator sources for various periodic test waveforms.
+//!
+//! This module provides several periodic, deterministic waveforms for testing other sources and
+//! for simple additive sound synthesis. Every source is monoaural and in the codomain [-1.0f32,
+//! 1.0f32].
+//!
+//! # Example
+//!
+//! ```
+//! use rodio::source::{SignalGenerator,Function};
+//!
+//! let tone = SignalGenerator::new(cpal::SampleRate(48000), 440.0, Function::Sine);
+//! ```
+use std::f32::consts::TAU;
+use std::time::Duration;
+
+use super::SeekError;
+use crate::Source;
+
+/// Waveform functions.
+#[derive(Clone, Debug)]
+pub enum Function {
+    /// A sinusoidal waveform.
+    Sine,
+    /// A triangle waveform.
+    Triangle,
+    /// A square wave, rising edge at t=0.
+    Square,
+    /// A rising sawtooth wave.
+    Sawtooth,
+}
+
+impl Function {
+    /// Create a single sample for the given waveform
+    #[inline]
+    fn render(&self, i: u64, period: f32) -> f32 {
+        let cycle_pos: f32 = i as f32 / period;
+
+        match self {
+            Self::Sine => (TAU * cycle_pos).sin(),
+            Self::Triangle => 4.0f32 * (cycle_pos - (cycle_pos + 0.5f32).floor()).abs() - 1f32,
+            Self::Square => {
+                if cycle_pos % 1.0f32 < 0.5f32 {
+                    1.0f32
+                } else {
+                    -1.0f32
+                }
+            }
+            Self::Sawtooth => 2.0f32 * (cycle_pos - (cycle_pos + 0.5f32).floor()),
+        }
+    }
+}
+
+/// An infinite source that produces one of a selection of test waveforms.
+#[derive(Clone, Debug)]
+pub struct SignalGenerator {
+    sample_rate: cpal::SampleRate,
+    period: f32,
+    function: Function,
+    i: u64,
+}
+
+impl SignalGenerator {
+    /// Create a new `TestWaveform` object that generates an endless waveform
+    /// `f`.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if `frequency` is equal to zero.
+    #[inline]
+    pub fn new(sample_rate: cpal::SampleRate, frequency: f32, f: Function) -> SignalGenerator {
+        assert!(frequency != 0.0, "frequency must be greater than zero");
+        let period = sample_rate.0 as f32 / frequency;
+        SignalGenerator {
+            sample_rate,
+            period,
+            function: f,
+            i: 0,
+        }
+    }
+}
+
+impl Iterator for SignalGenerator {
+    type Item = f32;
+
+    #[inline]
+    fn next(&mut self) -> Option<f32> {
+        let val = Some(self.function.render(self.i, self.period));
+        self.i += 1;
+        val
+    }
+}
+
+impl Source for SignalGenerator {
+    #[inline]
+    fn current_frame_len(&self) -> Option<usize> {
+        None
+    }
+
+    #[inline]
+    fn channels(&self) -> u16 {
+        1
+    }
+
+    #[inline]
+    fn sample_rate(&self) -> u32 {
+        self.sample_rate.0
+    }
+
+    #[inline]
+    fn total_duration(&self) -> Option<Duration> {
+        None
+    }
+
+    #[inline]
+    fn try_seek(&mut self, duration: Duration) -> Result<(), SeekError> {
+        self.i = (self.sample_rate.0 as f32 * duration.as_secs_f32()) as u64;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::source::{Function, SignalGenerator};
+    use approx::assert_abs_diff_eq;
+
+    #[test]
+    fn square() {
+        let mut wf = SignalGenerator::new(cpal::SampleRate(2000), 500.0f32, Function::Square);
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+    }
+
+    #[test]
+    fn triangle() {
+        let mut wf = SignalGenerator::new(cpal::SampleRate(8000), 1000.0f32, Function::Triangle);
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(-0.5f32));
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(-0.5f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(-0.5f32));
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(1.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(-0.5f32));
+    }
+
+    #[test]
+    fn saw() {
+        let mut wf = SignalGenerator::new(cpal::SampleRate(200), 50.0f32, Function::Sawtooth);
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+        assert_eq!(wf.next(), Some(-0.5f32));
+        assert_eq!(wf.next(), Some(0.0f32));
+        assert_eq!(wf.next(), Some(0.5f32));
+        assert_eq!(wf.next(), Some(-1.0f32));
+    }
+
+    #[test]
+    fn sine() {
+        let mut wf = SignalGenerator::new(cpal::SampleRate(1000), 100f32, Function::Sine);
+
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.0f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.58778525f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.95105652f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.95105652f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.58778525f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), 0.0f32);
+        assert_abs_diff_eq!(wf.next().unwrap(), -0.58778554f32);
+    }
+}

src/source/sine.rs

@@ -1,6 +1,6 @@
-use std::f32::consts::PI;
 use std::time::Duration;
 
+use crate::source::{Function, SignalGenerator};
 use crate::Source;
 
 use super::SeekError;
@@ -10,17 +10,18 @@ use super::SeekError;
 /// Always has a rate of 48kHz and one channel.
 #[derive(Clone, Debug)]
 pub struct SineWave {
-    freq: f32,
-    num_sample: usize,
+    test_sine: SignalGenerator,
 }
 
 impl SineWave {
+    const SAMPLE_RATE: u32 = 48000;
+
     /// The frequency of the sine.
     #[inline]
     pub fn new(freq: f32) -> SineWave {
+        let sr = cpal::SampleRate(Self::SAMPLE_RATE);
         SineWave {
-            freq,
-            num_sample: 0,
+            test_sine: SignalGenerator::new(sr, freq, Function::Sine),
         }
     }
 }
@@ -30,10 +31,7 @@ impl Iterator for SineWave {
 
     #[inline]
     fn next(&mut self) -> Option<f32> {
-        self.num_sample = self.num_sample.wrapping_add(1);
-
-        let value = 2.0 * PI * self.freq * self.num_sample as f32 / 48000.0;
-        Some(value.sin())
+        self.test_sine.next()
     }
 }
 
@@ -50,7 +48,7 @@ impl Source for SineWave {
 
     #[inline]
     fn sample_rate(&self) -> u32 {
-        48000
+        Self::SAMPLE_RATE
     }
 
     #[inline]
@@ -58,12 +56,11 @@ impl Source for SineWave {
         None
     }
 
+    /// `try_seek()` does nothing on the sine generator. If you need to
+    /// generate a sine tone with a precise phase or sample offset, consider
+    /// using `skip::skip_samples()`.
     #[inline]
     fn try_seek(&mut self, _: Duration) -> Result<(), SeekError> {
-        // This is a constant sound, normal seeking would not have any effect.
-        // While changing the phase of the sine wave could change how it sounds in
-        // combination with another sound (beating) such precision is not the intend
-        // of seeking
         Ok(())
     }
 }