Simple Ambisonics on top of CPAL (and inspired by Rodio)

main.rs

extern crate cpal;
extern crate hound;

use std::f32;
use std::sync::{Arc, Mutex};
use std::sync::atomic::{AtomicBool, Ordering};
use std::thread;
use std::ops;

use cpal::{StreamData, UnknownTypeOutputBuffer};


trait Sample {
    fn as_u16(&self) -> u16;
    fn as_i16(&self) -> i16;
    fn as_f32(&self) -> f32;
    fn zero() -> Self;
}

/*
/// Blanket impl for references
impl<'a, T: Sample> Sample for &'a T {
    fn as_u16(&self) -> u16 {
        T::as_u16(self)
    }

    fn as_i16(&self) -> i16 {
        T::as_i16(self)
    }

    fn as_f32(&self) -> f32 {
        T::as_f32(self)
    }

    fn zero() -> Self {
        T::zero()
    }
}*/

impl Sample for i16 {
    fn as_u16(&self) -> u16 {
        ((u16::max_value() / 2) as i32 + *self as i32) as u16
    }

    fn as_i16(&self) -> i16 {
        *self
    }

    fn as_f32(&self) -> f32 {
        *self as f32 / i16::max_value() as f32
    }

    fn zero() -> Self {
        0
    }
}

impl Sample for f32 {
    fn as_u16(&self) -> u16 {
        ((u16::max_value() / 2) as i32 + self.as_i16() as i32) as u16
    }

    fn as_i16(&self) -> i16 {
        (*self * i16::max_value() as f32) as i16
    }

    fn as_f32(&self) -> f32 {
        *self
    }

    fn zero() -> Self {
        0.0
    }
}

trait Stream: Iterator {
    fn n_channels(&self) -> usize;

    fn broadcast(self, n: usize) -> Broadcast<Self::Item, Self>
    where
        Self: Sized,
        Self::Item: Sample,
    {
        Broadcast {
            inner: self,
            n_channels: n,
            current_sample: Self::Item::zero(),
            reps_to_go: 0,
        }
    }

    fn floatify(self) -> Floatify<Self>
    where
        Self: Sized,
    {
        Floatify {
            inner: self,
        }
    }

    fn repeat(self) -> Repeated<Self::Item>
    where
        Self: Sized,
    {
        Repeated {
            n_channels: self.n_channels(),
            buffer: self.collect(),
            index: 0,
        }
    }
}

impl<'a, S> Stream for std::iter::Cloned<std::slice::Iter<'a, S>>
where S: Sample + Clone
{
    fn n_channels(&self) -> usize {
        1
    }
}

impl<'a, S> Stream for std::vec::IntoIter<S>
where S: Sample + Clone
{
    fn n_channels(&self) -> usize {
        1
    }
}

struct Floatify<T> {
    inner: T,
}

impl<S, T> Stream for Floatify<T>
where
    T: Stream<Item=S>,
    S: Sample,
{
    fn n_channels(&self) -> usize {
        self.inner.n_channels()
    }
}

impl<S, T> Iterator for Floatify<T>
where
    T: Stream<Item=S>,
    S: Sample,
{
    type Item = f32;
    fn next(&mut self) -> Option<f32> {
        self.inner.next().map(|s| s.as_f32())
    }
}

struct Repeated<S> {
    n_channels: usize,
    buffer: Vec<S>,
    index: usize,
}

impl<S> Stream for Repeated<S>
where
    S: Clone,
{
    fn n_channels(&self) -> usize {
        self.n_channels
    }
}

impl<S> Iterator for Repeated<S>
where
    S: Clone,
{
    type Item = S;

    fn next(&mut self) -> Option<S> {
        if self.index >= self.buffer.len() {
            if self.buffer.len() == 0 {
                return None
            }
            self.index = 0;
        }

        let x = self.buffer[self.index].clone();
        self.index += 1;
        Some(x)
    }
}

#[derive(Clone)]
struct SharedBuffer<S: 'static> {
    n_channels: usize,
    buffer: Arc<Vec<S>>,
    index: usize,
}

impl<S> Stream for SharedBuffer<S>
where
    S: Clone + 'static,
{
    fn n_channels(&self) -> usize {
        self.n_channels
    }
}

impl<S> Iterator for SharedBuffer<S>
where
    S: Clone + 'static,
{
    type Item = S;

    fn next(&mut self) -> Option<S> {
        if self.index >= self.buffer.len() {
            None
        } else {
            let x = self.buffer[self.index].clone();
            self.index += 1;
            Some(x)
        }
    }
}

struct Broadcast<S, T>
{
    inner: T,
    n_channels: usize,
    current_sample: S,
    reps_to_go: usize,
}

impl<S, T> Stream for Broadcast<S, T>
where
    T: Stream<Item=S>,
    S: Sample + Clone,
{
    fn n_channels(&self) -> usize {
        self.n_channels
    }
}

impl<S, T> Iterator for Broadcast<S, T>
where
    T: Stream<Item=S>,
    S: Sample + Clone,
{
    type Item = S;

    fn next(&mut self) -> Option<Self::Item> {
        if self.reps_to_go == 0 {
            self.current_sample = self.inner.next()?;
            self.reps_to_go = self.n_channels;
        }

        self.reps_to_go -= 1;
        Some(self.current_sample.clone())
    }
}


struct BFormat {
    w: f32,
    x: f32,
    y: f32,
    z: f32,
}

impl BFormat {
    fn virtual_microphone(&self, dir: [f32; 3], p: f32) -> f32 {
        p * 2f32.sqrt() * self.w + (1.0 - p) * (dir[0] * self.x + dir[1] * self.y + dir[2] * self.z)
    }
}

impl Default for BFormat {
    fn default() -> Self {
        BFormat {w: 0.0, x: 0.0, y: 0.0, z: 0.0}
    }
}

impl ops::AddAssign for BFormat {
    fn add_assign(&mut self, other: Self) {
        self.w += other.w;
        self.x += other.x;
        self.y += other.y;
        self.z += other.z;
    }
}

impl<'a> ops::Mul<f32> for &'a BFormat {
    type Output = BFormat;
    fn mul(self, s: f32) -> BFormat {
        BFormat {
            w: self.w * s,
            x: self.x * s,
            y: self.y * s,
            z: self.z * s,
        }
    }
}

impl From<[f32; 3]> for BFormat {
    fn from(dir: [f32; 3]) -> Self {
        let l = (dir[0] * dir[0] + dir[1] * dir[1] + dir[1] * dir[2]).sqrt();
        BFormat {
            w: 1.0 / 2f32.sqrt(),
            x: dir[0] / l,
            y: dir[1] / l,
            z: dir[2] / l,
        }
    }
}


struct BStreamStereoDecoder {
    input: BStreamMixer,
    left_mic: [f32; 3],
    right_mic: [f32; 3],

    buffered_sample: Option<f32>,
}

impl BStreamStereoDecoder {
    fn new(input: BStreamMixer) -> Self {
        BStreamStereoDecoder {
            input,
            left_mic: [-1.0 / 2f32.sqrt(), 1.0 / 2f32.sqrt(), 0.0],
            right_mic: [1.0 / 2f32.sqrt(), 1.0 / 2f32.sqrt(), 0.0],
            buffered_sample: None,
        }
    }
}

impl Stream for BStreamStereoDecoder {
    fn n_channels(&self) -> usize {
        2
    }
}

impl Iterator for BStreamStereoDecoder {
    type Item = f32;

    fn next(&mut self) -> Option<f32> {
        match self.buffered_sample.take() {
            Some(s) => Some(s),
            None => {
                let sample = self.input.next()?;

                let left = sample.virtual_microphone(self.left_mic, 0.5);
                let right = sample.virtual_microphone(self.right_mic, 0.5);

                // emit left channel now, and right channel on next call
                self.buffered_sample = Some(right);
                Some(left)
            },
        }
    }
}

fn bstream() -> (BStreamMixer, Arc<BStreamController>) {

    let controller = Arc::new(BStreamController {
        pending_streams: Mutex::new(Vec::new()),
        has_pending: AtomicBool::new(false),
    });

    let mixer = BStreamMixer {
        input: controller.clone(),
        active_streams: Vec::with_capacity(8),
    };

    (mixer, controller)
}

struct BStreamMixer {
    input: Arc<BStreamController>,
    active_streams: Vec<SpatialStream>,
}

impl Iterator for BStreamMixer {
    type Item = BFormat;

    fn next(&mut self) -> Option<Self::Item> {
        if self.input.has_pending.load(Ordering::SeqCst) {
            let mut pending = self.input.pending_streams.lock().expect("Cannot lock pending streams");
            self.active_streams.extend(pending.drain(..));
            self.input.has_pending.store(false, Ordering::SeqCst);
        }

        let mut mix = BFormat::default();

        let mut done = Vec::new();

        for (i, stream) in self.active_streams.iter_mut().enumerate() {
            match stream.next() {
                Some(x) => mix += x,
                None => done.push(i),
            }
        }

        for i in done {
            self.active_streams.remove(i);
        }

        Some(mix)
    }
}

struct BStreamController {
    pending_streams: Mutex<Vec<SpatialStream>>,
    has_pending: AtomicBool,
}

impl BStreamController {
    fn attach<T: 'static + Stream<Item = f32> + Send>(&self, stream: T, direction: [f32; 3]) -> Arc<SpatialStreamController> {
        let controller = Arc::new(SpatialStreamController{
            direction: Mutex::new(direction),
            update: AtomicBool::new(false),
        });

        let sstream = SpatialStream {
            inner: Box::new(stream),
            bfactors: direction.into(),
            controller: controller.clone(),
        };

        self.pending_streams.lock().expect("Cannot lock pending streams").push(sstream);
        self.has_pending.store(true, Ordering::SeqCst);

        controller
    }
}

struct SpatialStream {
    inner: Box<Stream<Item = f32> + Send>,
    bfactors: BFormat,

    controller: Arc<SpatialStreamController>,
}

impl Iterator for SpatialStream {
    type Item = BFormat;

    fn next(&mut self) -> Option<Self::Item> {
        if self.controller.update.load(Ordering::SeqCst) {
            self.bfactors = (*self.controller.direction.lock().unwrap()).into();
            self.controller.update.store(false, Ordering::SeqCst);
        }

        let x = self.inner.next()?;
        Some(&self.bfactors * x)
    }
}

struct SpatialStreamController {
    direction: Mutex<[f32; 3]>,
    update: AtomicBool,
}

impl SpatialStreamController {
    fn set_direction(&self, d: [f32; 3]) {
        *self.direction.lock().unwrap() = d;
        self.update.store(true, Ordering::SeqCst);
    }
}


fn stream_player<T>(device: &cpal::Device, format: &cpal::Format, mut stream: T) -> thread::JoinHandle<()>
where
    T: Stream + Send + 'static,
    T::Item: Sample,
{
    let event_loop = cpal::EventLoop::new();
    let stream_id = event_loop.build_output_stream(&device, &format).unwrap();
    event_loop.play_stream(stream_id);

    thread::spawn(move || {
        event_loop.run(move |_stream_id, stream_data| {
            match stream_data {
                StreamData::Output { buffer: UnknownTypeOutputBuffer::U16(mut buffer) } => {
                    for elem in buffer.iter_mut() {
                        *elem = stream.next().unwrap().as_u16();
                    }
                },
                StreamData::Output { buffer: UnknownTypeOutputBuffer::I16(mut buffer) } => {
                    for elem in buffer.iter_mut() {
                        *elem = stream.next().unwrap().as_i16();
                    }
                },
                StreamData::Output { buffer: UnknownTypeOutputBuffer::F32(mut buffer) } => {
                    for elem in buffer.iter_mut() {
                        *elem = stream.next().unwrap().as_f32();
                    }
                },
                _ => (),
            }
        });
    })
}


fn main() {
    println!("Hello, world!");

    let mut reader = hound::WavReader::open(r"U:\Ling\Audio wav files\short\A.wav").unwrap();

    println!("{:?}", reader.spec());
    let sound: Vec<_> = reader
        .samples::<i16>()
        .map(|s| s.unwrap())
        .collect();

    let sound = Arc::new(sound);

    let sound = SharedBuffer {
        n_channels: 1,
        buffer: sound,
        index: 0,
    };

    println!("Audio Devices:");
    for device in cpal::devices() {
        println!("  -> {}", device.name());
    }

    let device = cpal::default_output_device().expect("no output device available");
    println!("Default Device:\n  {}", device.name());

    let supported_formats_range = device.supported_output_formats()
        .expect("error while querying formats");

    println!("Supported formats:");
    for format in supported_formats_range {
        println!("{:?}", format);
    }

    let format = device.supported_output_formats().unwrap().next()
        .expect("no supported format?!")
        .with_max_sample_rate();

    let (mixer, controller) = bstream();
    let decoder = BStreamStereoDecoder::new(mixer);

    let player = stream_player(&device, &format, decoder);

    /*for a in 0..=16 {
        let a = a as f32 / 16.0 * 2.0 * f32::consts::PI;
        controller.attach(sound.clone().into_iter().floatify(), [a.sin(), a.cos(), 0.0]);
        thread::sleep_ms(1000);
    }*/

    //let player = stream_player(&device, &format, sound.into_iter().broadcast(2));

    //let sc = controller.attach(sound.clone().into_iter().floatify().repeat(), [0.0, 1.0, 0.0]);

    //controller.attach(sound.clone().floatify(), [-1.0, 0.0, 0.0]);
    //thread::sleep_ms(500);

    let sc = controller.attach(sound.floatify().repeat(), [0.0, 1.0, 0.0]);

    for a in 0..1000 {
        let a = a as f32 / 100.0;
        sc.set_direction([a.sin(), a.cos(), 0.0]);
        thread::sleep_ms(10);
    }

    //thread::sleep_ms(5000);
    //player.join();
}