Phase2a of audio engine rewrite

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added `FixedSource` which mirrors `Source` but does not allow the sample rate or
+  channel count to change.
+- Added `ConstSource` which is like `FixedSource` except the sample rate and
+  channel count are fixed at compile time.
 - Added `Skippable::skipped` function to check if the inner source was skipped.
 - All sources now implement `ExactSizeIterator` when their inner source does.
 - All sources now implement `Iterator::size_hint()`.
@@ -21,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Breaking: `Microphone` now implements `FixedSource`
 - Breaking: `Done` now calls a callback instead of decrementing an `Arc<AtomicUsize>`.
 - Updated `cpal` to v0.18.
 - Clarified `Source::current_span_len()` documentation to specify it returns total span length.

Cargo.toml

@@ -250,7 +250,7 @@ required-features = ["playback", "wav"]
 
 [[example]]
 name = "microphone"
-required-features = ["playback", "recording", "wav_output"]
+required-features = ["playback", "recording"]
 
 [[example]]
 name = "mix_multiple_sources"

README.md

@@ -4,6 +4,14 @@
 [![Crates.io Downloads](https://img.shields.io/crates/d/rodio.svg)](https://crates.io/crates/rodio)
 [![Build Status](https://github.com/RustAudio/rodio/workflows/CI/badge.svg)](https://github.com/RustAudio/rodio/actions)
 
+> [!WARNING]
+> We are currently rewriting Rodio's core audio engine. The current state should
+> be working but under documented. This is expected to take at least a month.
+> For the latest unreleased work pre engine rewrite see [this
+> checkout](https://github.com/RustAudio/rodio/tree/c5f1e94290922fe4ee963ce6f85754ea6ba36243).
+> To follow our progress see the [tracking
+> issue](https://github.com/RustAudio/rodio/issues/901)
+
 Rust playback library.
 
 Playback is handled by [cpal](https://github.com/RustAudio/cpal). Format decoding is handled by [Symphonia](https://github.com/pdeljanov/Symphonia) by default, or by optional format-specific decoders:

examples/microphone.rs

@@ -1,6 +1,6 @@
 use inquire::Select;
 use rodio::microphone::{self, MicrophoneBuilder};
-use rodio::Source;
+use rodio::FixedSource;
 use std::error::Error;
 use std::thread;
 use std::time::Duration;
@@ -22,7 +22,7 @@ fn main() -> Result<(), Box<dyn Error>> {
 
     println!("Playing the recording");
     let mut output = rodio::DeviceSinkBuilder::open_default_sink()?;
-    output.mixer().add(recording);
+    output.mixer().add(recording.into_dynamic_source());
 
     thread::sleep(Duration::from_secs(5));
 

src/buffer.rs

@@ -12,9 +12,8 @@
 //!
 
 use crate::common::{ChannelCount, SampleRate};
-use crate::math::{duration_to_float, NANOS_PER_SEC};
 use crate::source::{SeekError, UniformSourceIterator};
-use crate::{Float, Sample, Source};
+use crate::{Sample, Source};
 use std::sync::Arc;
 use std::time::Duration;
 
@@ -25,37 +24,19 @@ pub struct SamplesBuffer {
     pos: usize,
     channels: ChannelCount,
     sample_rate: SampleRate,
-    duration: Duration,
 }
 
 impl SamplesBuffer {
     /// Builds a new `SamplesBuffer`.
-    ///
-    /// # Panics
-    ///
-    /// - Panics if the samples rate is zero.
-    /// - Panics if the length of the buffer is larger than approximately 16 billion elements.
-    ///   This is because the calculation of the duration would overflow.
-    ///
     pub fn new<D>(channels: ChannelCount, sample_rate: SampleRate, data: D) -> Self
     where
         D: Into<Vec<Sample>>,
     {
-        let data: Arc<[Sample]> = data.into().into();
-        let duration_ns = NANOS_PER_SEC.checked_mul(data.len() as u64).unwrap()
-            / sample_rate.get() as u64
-            / channels.get() as u64;
-        let duration = Duration::new(
-            duration_ns / NANOS_PER_SEC,
-            (duration_ns % NANOS_PER_SEC) as u32,
-        );
-
         Self {
-            data,
+            data: data.into().into(),
             pos: 0,
             channels,
             sample_rate,
-            duration,
         }
     }
 
@@ -91,50 +72,11 @@ impl Source for SamplesBuffer {
         self.sample_rate
     }
 
-    #[inline]
-    fn total_duration(&self) -> Option<Duration> {
-        Some(self.duration)
-    }
-
-    /// This jumps in memory till the sample for `pos`.
-    #[inline]
-    fn try_seek(&mut self, pos: Duration) -> Result<(), SeekError> {
-        // This is fast because all the samples are in memory already
-        // and due to the constant sample_rate we can jump to the right
-        // sample directly.
-
-        let curr_channel = self.pos % self.channels().get() as usize;
-        let new_pos = duration_to_float(pos)
-            * self.sample_rate().get() as Float
-            * self.channels().get() as Float;
-        // saturate pos at the end of the source
-        let new_pos = new_pos as usize;
-        let new_pos = new_pos.min(self.data.len());
-
-        // make sure the next sample is for the right channel
-        let new_pos = new_pos.next_multiple_of(self.channels().get() as usize);
-        let new_pos = new_pos - curr_channel;
-
-        self.pos = new_pos;
-        Ok(())
-    }
+    crate::common::source::buffer::source_impl! {}
 }
 
 impl Iterator for SamplesBuffer {
-    type Item = Sample;
-
-    #[inline]
-    fn next(&mut self) -> Option<Self::Item> {
-        let sample = self.data.get(self.pos)?;
-        self.pos += 1;
-        Some(*sample)
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        let remaining = self.data.len() - self.pos;
-        (remaining, Some(remaining))
-    }
+    crate::common::source::buffer::iter_impl! {}
 }
 
 impl ExactSizeIterator for SamplesBuffer {}

src/common.rs

@@ -3,6 +3,8 @@ use std::num::NonZero;
 
 use crate::math::nz;
 
+pub(crate) mod source;
+
 /// Sample rate (a frame rate or samples per second per channel).
 pub type SampleRate = NonZero<u32>;
 

src/common/source.rs

@@ -0,0 +1,44 @@
+//! Code shared between source types.
+//!
+//! Since we have three source types there is a lot of code duplication. We
+//! combat that by placing whatever can be shared here.
+//!
+//! This can be:
+//! - shared types like error enums
+//! - shared free functions
+//! - shared members / impl blocks through macro_rules
+//!
+//! # Note
+//! Effects are defined through a macro and do not need this kind of
+//! deduplication
+//!
+//! This modules structure mirrors that of what it deduplicates. For example
+//! the code shared between [fixed_source::chain] and [const_source::chain] is in
+//! common/source/chain.rs
+
+pub(crate) mod buffer;
+pub(crate) mod chain;
+
+macro_rules! add_inner_accessors {
+    ($inner:ident) => {
+        /// Get immutable access to the input to this source
+        #[inline]
+        pub fn inner(&self) -> &S {
+            &self.$inner
+        }
+
+        /// Returns a mutable reference to the inner source.
+        #[inline]
+        pub fn inner_mut(&mut self) -> &mut S {
+            &mut self.$inner
+        }
+
+        /// Returns the inner source.
+        #[inline]
+        pub fn into_inner(self) -> S {
+            self.$inner
+        }
+    };
+}
+
+pub(crate) use add_inner_accessors;

src/common/source/buffer.rs

@@ -0,0 +1,66 @@
+macro_rules! source_impl {
+    () => {
+        /// # Panics
+        /// If the length of the buffer is larger than approximately 16 billion elements.
+        /// This is because the calculation of the duration would overflow.
+        #[inline]
+        fn total_duration(&self) -> Option<Duration> {
+            use crate::math::NANOS_PER_SEC;
+
+            let duration_ns = NANOS_PER_SEC
+                .checked_mul(self.data.len() as u64)
+                .expect("slices longer then 16 billion elements are not supported")
+                / self.sample_rate().get() as u64
+                / self.channels().get() as u64;
+            let duration = Duration::new(
+                duration_ns / NANOS_PER_SEC,
+                (duration_ns % NANOS_PER_SEC) as u32,
+            );
+
+            Some(duration)
+        }
+
+        /// This jumps in memory to the sample corresponding to `pos`.
+        #[inline]
+        fn try_seek(&mut self, pos: Duration) -> Result<(), SeekError> {
+            // This is fast because all the samples are in memory already
+            // and due to the constant sample_rate we can jump to the right
+            // sample directly.
+
+            let curr_channel = self.pos % self.channels().get() as usize;
+            let new_pos = crate::math::duration_to_float(pos)
+                * self.sample_rate().get() as crate::Float
+                * self.channels().get() as crate::Float;
+            // saturate pos at the end of the source
+            let new_pos = new_pos as usize;
+            let new_pos = new_pos.min(self.data.len());
+
+            // make sure the next sample is for the right channel
+            let new_pos = new_pos.next_multiple_of(self.channels().get() as usize);
+            let new_pos = new_pos - curr_channel;
+
+            self.pos = new_pos;
+            Ok(())
+        }
+    };
+}
+
+macro_rules! iter_impl {
+    () => {
+        type Item = Sample;
+        #[inline]
+        fn next(&mut self) -> Option<Self::Item> {
+            let sample = self.data.get(self.pos)?;
+            self.pos += 1;
+            Some(*sample)
+        }
+        #[inline]
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            let remaining = self.data.len() - self.pos;
+            (remaining, Some(remaining))
+        }
+    };
+}
+
+pub(crate) use iter_impl;
+pub(crate) use source_impl;

src/common/source/chain.rs

@@ -0,0 +1,94 @@
+use crate::source::SeekError;
+
+#[derive(Debug, thiserror::Error)]
+pub enum ChainSeekError {
+    #[error("Could not get duration of first source ({ty}")]
+    NoTotalDurationForFirst { ty: &'static str },
+    #[error("Could not seek in first source")]
+    FailedToSeekInFirst {
+        ty: &'static str,
+        #[source]
+        error: SeekError,
+    },
+    #[error("Could not seek in second source")]
+    FailedToSeekInSecond {
+        ty: &'static str,
+        #[source]
+        error: SeekError,
+    },
+}
+
+macro_rules! source_impl {
+    () => {
+        fn channels(&self) -> crate::ChannelCount {
+            self.first.channels()
+        }
+
+        fn sample_rate(&self) -> crate::SampleRate {
+            self.first.sample_rate()
+        }
+
+        fn total_duration(&self) -> Option<std::time::Duration> {
+            self.first
+                .total_duration()
+                .and_then(|d| self.second.total_duration().map(|d2| d2 + d))
+        }
+
+        fn try_seek(&mut self, pos: std::time::Duration) -> Result<(), crate::source::SeekError> {
+            use crate::source::SeekError;
+            use std::any::type_name_of_val;
+            use std::sync::Arc;
+
+            let Some(first) = self.first.total_duration() else {
+                return Err(ChainSeekError::NoTotalDurationForFirst {
+                    ty: type_name_of_val(&self.first),
+                })
+                .map_err(Arc::new)
+                .map_err(|e| SeekError::Other(e));
+            };
+
+            if pos < first {
+                self.first
+                    .try_seek(pos)
+                    .map_err(|error| ChainSeekError::FailedToSeekInFirst {
+                        ty: type_name_of_val(&self.first),
+                        error,
+                    })
+                    .map_err(Arc::new)
+                    .map_err(|e| SeekError::Other(e))
+            } else {
+                self.second
+                    .try_seek(pos)
+                    .map_err(|error| ChainSeekError::FailedToSeekInSecond {
+                        ty: type_name_of_val(&self.second),
+                        error,
+                    })
+                    .map_err(Arc::new)
+                    .map_err(|e| SeekError::Other(e))
+            }
+        }
+    };
+}
+
+macro_rules! iter_impl {
+    () => {
+        type Item = Sample;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            if self.playing_inner {
+                match self.first.next() {
+                    Some(sample) => Some(sample),
+                    None => {
+                        self.playing_inner = false;
+                        self.second.next()
+                    }
+                }
+            } else {
+                self.second.next()
+            }
+        }
+    };
+}
+
+pub(crate) use iter_impl;
+pub(crate) use source_impl;