coreaudio-rs-0.10.0/examples/feedback.rs

//! A basic input + output stream example, copying the mic input stream to the default output stream

extern crate coreaudio;

use std::collections::VecDeque;
use std::mem;
use std::ptr::null;
use std::sync::{Arc, Mutex};

use coreaudio::audio_unit::audio_format::LinearPcmFlags;
use coreaudio::audio_unit::render_callback::{self, data};
use coreaudio::audio_unit::{AudioUnit, Element, SampleFormat, Scope, StreamFormat};
use coreaudio::sys::*;

const SAMPLE_RATE: f64 = 44100.0;

type S = f32; const SAMPLE_FORMAT: SampleFormat = SampleFormat::F32;
// type S = i32; const SAMPLE_FORMAT: SampleFormat = SampleFormat::I32;
// type S = i16; const SAMPLE_FORMAT: SampleFormat = SampleFormat::I16;
// type S = i8; const SAMPLE_FORMAT: SampleFormat = SampleFormat::I8;

fn main() -> Result<(), coreaudio::Error> {
    let mut input_audio_unit = audio_unit_from_device(default_input_device().unwrap(), true)?;
    let mut output_audio_unit = audio_unit_from_device(default_output_device().unwrap(), false)?;

    let format_flag = match SAMPLE_FORMAT {
        SampleFormat::F32 => LinearPcmFlags::IS_FLOAT,
        SampleFormat::I32 | SampleFormat::I16 | SampleFormat::I8 => LinearPcmFlags::IS_SIGNED_INTEGER,
    };

    // Using IS_NON_INTERLEAVED everywhere because data::Interleaved is commented out / not implemented
    let in_stream_format = StreamFormat {
        sample_rate: SAMPLE_RATE,
        sample_format: SAMPLE_FORMAT,
        flags: format_flag | LinearPcmFlags::IS_PACKED | LinearPcmFlags::IS_NON_INTERLEAVED,
        // audio_unit.set_input_callback is hardcoded to 1 buffer, and when using non_interleaved
        // we are forced to 1 channel
        channels_per_frame: 1,
    };

    let out_stream_format = StreamFormat {
        sample_rate: SAMPLE_RATE,
        sample_format: SAMPLE_FORMAT,
        flags: format_flag | LinearPcmFlags::IS_PACKED | LinearPcmFlags::IS_NON_INTERLEAVED,
        // you can change this to 1
        channels_per_frame: 2,
    };

    println!("input={:#?}", &in_stream_format);
    println!("output={:#?}", &out_stream_format);
    println!("input_asbd={:#?}", &in_stream_format.to_asbd());
    println!("output_asbd={:#?}", &out_stream_format.to_asbd());

    let id = kAudioUnitProperty_StreamFormat;
    let asbd = in_stream_format.to_asbd();
    input_audio_unit.set_property(id, Scope::Output, Element::Input, Some(&asbd))?;

    let asbd = out_stream_format.to_asbd();
    output_audio_unit.set_property(id, Scope::Input, Element::Output, Some(&asbd))?;

    let buffer_left = Arc::new(Mutex::new(VecDeque::<S>::new()));
    let producer_left = buffer_left.clone();
    let consumer_left = buffer_left.clone();
    let buffer_right = Arc::new(Mutex::new(VecDeque::<S>::new()));
    let producer_right = buffer_right.clone();
    let consumer_right = buffer_right.clone();

    // seed roughly 1 second of data to create a delay in the feedback loop for easier testing
    for buffer in vec![buffer_left, buffer_right] {
        let mut buffer = buffer.lock().unwrap();
        for _ in 0..(out_stream_format.sample_rate as i32) {
            buffer.push_back(0 as S);
        }
    }

    type Args = render_callback::Args<data::NonInterleaved<S>>;

    input_audio_unit.set_input_callback(move |args| {
        let Args {
            num_frames,
            mut data,
            ..
        } = args;
        let buffer_left = producer_left.lock().unwrap();
        let buffer_right = producer_right.lock().unwrap();
        let mut buffers = vec![buffer_left, buffer_right];
        for i in 0..num_frames {
            for (ch, channel) in data.channels_mut().enumerate() {
                let value: S = channel[i];
                buffers[ch].push_back(value);
            }
        }
        Ok(())
    })?;
    input_audio_unit.start()?;

    output_audio_unit.set_render_callback(move |args: Args| {
        let Args {
            num_frames,
            mut data,
            ..
        } = args;

        let buffer_left = consumer_left.lock().unwrap();
        let buffer_right = consumer_right.lock().unwrap();
        let mut buffers = vec![buffer_left, buffer_right];
        for i in 0..num_frames {
            // Default other channels to copy value from first channel as a fallback
            let zero: S = 0 as S;
            let f: S = *buffers[0].front().unwrap_or(&zero);
            for (ch, channel) in data.channels_mut().enumerate() {
                let sample: S = buffers[ch].pop_front().unwrap_or(f);
                channel[i] = sample;
            }
        }
        Ok(())
    })?;
    output_audio_unit.start()?;

    std::thread::sleep(std::time::Duration::from_millis(100000));

    Ok(())
}

/// Copied from cpal
pub fn default_input_device() -> Option<AudioDeviceID> {
    let property_address = AudioObjectPropertyAddress {
        mSelector: kAudioHardwarePropertyDefaultInputDevice,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMaster,
    };

    let audio_device_id: AudioDeviceID = 0;
    let data_size = mem::size_of::<AudioDeviceID>();
    let status = unsafe {
        AudioObjectGetPropertyData(
            kAudioObjectSystemObject,
            &property_address as *const _,
            0,
            null(),
            &data_size as *const _ as *mut _,
            &audio_device_id as *const _ as *mut _,
        )
    };
    if status != kAudioHardwareNoError as i32 {
        return None;
    }

    Some(audio_device_id)
}

/// Copied from cpal
pub fn default_output_device() -> Option<AudioDeviceID> {
    let property_address = AudioObjectPropertyAddress {
        mSelector: kAudioHardwarePropertyDefaultOutputDevice,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMaster,
    };

    let audio_device_id: AudioDeviceID = 0;
    let data_size = mem::size_of::<AudioDeviceID>();
    let status = unsafe {
        AudioObjectGetPropertyData(
            kAudioObjectSystemObject,
            &property_address as *const _,
            0,
            null(),
            &data_size as *const _ as *mut _,
            &audio_device_id as *const _ as *mut _,
        )
    };
    if status != kAudioHardwareNoError as i32 {
        return None;
    }

    Some(audio_device_id)
}

/// Copied from cpal
fn audio_unit_from_device(
    device_id: AudioDeviceID,
    input: bool,
) -> Result<AudioUnit, coreaudio::Error> {
    let mut audio_unit = AudioUnit::new(coreaudio::audio_unit::IOType::HalOutput)?;

    if input {
        // Enable input processing.
        let enable_input = 1u32;
        audio_unit.set_property(
            kAudioOutputUnitProperty_EnableIO,
            Scope::Input,
            Element::Input,
            Some(&enable_input),
        )?;

        // Disable output processing.
        let disable_output = 0u32;
        audio_unit.set_property(
            kAudioOutputUnitProperty_EnableIO,
            Scope::Output,
            Element::Output,
            Some(&disable_output),
        )?;
    }

    audio_unit.set_property(
        kAudioOutputUnitProperty_CurrentDevice,
        Scope::Global,
        Element::Output,
        Some(&device_id),
    )?;

    Ok(audio_unit)
}