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//! # How to use cpal //! //! Here are some concepts cpal exposes: //! //! - An endpoint is a target where the data of the audio channel will be played. //! - A voice is an open audio channel which you can stream audio data to. You have to choose which //! endpoint your voice targets before you create one. //! - An event loop is a collection of voices. Each voice must belong to an event loop, and all the //! voices that belong to an event loop are managed together. //! //! In order to play a sound, you first need to create an event loop: //! //! ``` //! use cpal::EventLoop; //! let event_loop = EventLoop::new(); //! ``` //! //! Then choose an endpoint. You can either use the default endpoint with the `default_endpoint()` //! function, or enumerate all the available endpoints with the `endpoints()` function. Beware that //! `default_endpoint()` returns an `Option` in case no endpoint is available on the system. //! //! ``` //! // Note: we call `unwrap()` because it is convenient, but you should avoid doing that in a real //! // code. //! let endpoint = cpal::default_endpoint().expect("no endpoint is available"); //! ``` //! //! Before we can create a voice, we must decide what the format of the audio samples is going to //! be. You can query all the supported formats with the `supported_formats()` method, which //! produces a list of `SupportedFormat` structs which can later be turned into actual `Format` //! structs. If you don't want to query the list of formats, you can also build your own `Format` //! manually, but doing so could lead to an error when building the voice if the format ends up not //! being supported. //! //! > **Note**: the `supported_formats()` method could return an error for example if the device //! > has been disconnected. //! //! ```no_run //! # let endpoint = cpal::default_endpoint().unwrap(); //! let mut supported_formats_range = endpoint.supported_formats() //! .expect("error while querying formats"); //! let format = supported_formats_range.next().expect("no supported format?!") //! .with_max_samples_rate(); //! ``` //! //! Now that we have everything, we can create a voice from that event loop: //! //! ```no_run //! # let endpoint = cpal::default_endpoint().unwrap(); //! # let format = endpoint.supported_formats().unwrap().next().unwrap().with_max_samples_rate(); //! # let event_loop = cpal::EventLoop::new(); //! let voice_id = event_loop.build_voice(&endpoint, &format).unwrap(); //! ``` //! //! The value returned by `build_voice()` is of type `VoiceId` and is an identifier that will //! allow you to control the voice. //! //! There is a last step to perform before going forward, which is to start the voice. This is done //! with the `play()` method on the event loop. //! //! ``` //! # let event_loop: cpal::EventLoop = return; //! # let voice_id: cpal::VoiceId = return; //! event_loop.play(voice_id); //! ``` //! //! Once everything is done, you must call `run()` on the `event_loop`. //! //! ```no_run //! # let event_loop = cpal::EventLoop::new(); //! event_loop.run(move |_voice_id, _buffer| { //! // write data to `buffer` here //! }); //! ``` //! //! > **Note**: Calling `run()` will block the thread forever, so it's usually best done in a //! > separate thread. //! //! While `run()` is running, the audio device of the user will from time to time call the callback //! that you passed to this function. The callback gets passed the voice ID, and a struct of type //! `UnknownTypeBuffer` that represents the buffer that must be filled with audio samples. The //! `UnknownTypeBuffer` can be one of `I16`, `U16` or `F32` depending on the format that was passed //! to `build_voice`. //! //! In this example, we simply simply fill the buffer with zeroes. //! //! ```no_run //! use cpal::UnknownTypeBuffer; //! //! # let event_loop = cpal::EventLoop::new(); //! event_loop.run(move |_voice_id, mut buffer| { //! match buffer { //! UnknownTypeBuffer::U16(mut buffer) => { //! for elem in buffer.iter_mut() { //! *elem = u16::max_value() / 2; //! } //! }, //! UnknownTypeBuffer::I16(mut buffer) => { //! for elem in buffer.iter_mut() { //! *elem = 0; //! } //! }, //! UnknownTypeBuffer::F32(mut buffer) => { //! for elem in buffer.iter_mut() { //! *elem = 0.0; //! } //! }, //! } //! }); //! ``` #![recursion_limit = "512"] #[cfg(target_os = "windows")] #[macro_use] extern crate lazy_static; // Extern crate declarations with `#[macro_use]` must unfortunately be at crate root. #[cfg(target_os = "emscripten")] #[macro_use] extern crate stdweb; pub use samples_formats::{Sample, SampleFormat}; #[cfg(all(not(windows), not(target_os = "linux"), not(target_os = "freebsd"), not(target_os = "macos"), not(target_os = "ios"), not(target_os = "emscripten")))] use null as cpal_impl; use std::error::Error; use std::fmt; use std::ops::{Deref, DerefMut}; mod null; mod samples_formats; #[cfg(any(target_os = "linux", target_os = "freebsd"))] #[path = "alsa/mod.rs"] mod cpal_impl; #[cfg(windows)] #[path = "wasapi/mod.rs"] mod cpal_impl; #[cfg(any(target_os = "macos", target_os = "ios"))] #[path = "coreaudio/mod.rs"] mod cpal_impl; #[cfg(target_os = "emscripten")] #[path = "emscripten/mod.rs"] mod cpal_impl; /// An iterator for the list of formats that are supported by the backend. /// /// See [`endpoints()`](fn.endpoints.html). pub struct EndpointsIterator(cpal_impl::EndpointsIterator); impl Iterator for EndpointsIterator { type Item = Endpoint; #[inline] fn next(&mut self) -> Option<Endpoint> { self.0.next().map(Endpoint) } #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.0.size_hint() } } /// Return an iterator to the list of formats that are supported by the system. /// /// Can be empty if the system doesn't support audio in general. #[inline] pub fn endpoints() -> EndpointsIterator { EndpointsIterator(Default::default()) } /// Deprecated. Use `endpoints()` instead. #[inline] #[deprecated] pub fn get_endpoints_list() -> EndpointsIterator { EndpointsIterator(Default::default()) } /// Return the default endpoint, or `None` if no device is available. #[inline] pub fn default_endpoint() -> Option<Endpoint> { cpal_impl::default_endpoint().map(Endpoint) } /// Deprecated. Use `default_endpoint()` instead. #[inline] #[deprecated] pub fn get_default_endpoint() -> Option<Endpoint> { default_endpoint() } /// An opaque type that identifies an endpoint that is capable of playing audio. /// /// Please note that endpoints may become invalid if they get disconnected. Therefore all the /// methods that involve an endpoint return a `Result`. #[derive(Clone, PartialEq, Eq)] pub struct Endpoint(cpal_impl::Endpoint); impl Endpoint { /// Returns an iterator that produces the list of formats that are supported by the backend. /// /// Can return an error if the endpoint is no longer valid (eg. it has been disconnected). /// The returned iterator should never be empty. #[inline] pub fn supported_formats(&self) -> Result<SupportedFormatsIterator, FormatsEnumerationError> { Ok(SupportedFormatsIterator(self.0.supported_formats()?)) } /// Deprecated. Use `supported_formats` instead. #[inline] #[deprecated] pub fn get_supported_formats_list( &self) -> Result<SupportedFormatsIterator, FormatsEnumerationError> { self.supported_formats() } /// Returns the name of the endpoint. // TODO: human-readable or system name? #[inline] pub fn name(&self) -> String { self.0.name() } /// Deprecated. Use `name()` instead. #[deprecated] #[inline] pub fn get_name(&self) -> String { self.name() } } /// Number of channels. pub type ChannelsCount = u16; /// Possible position of a channel. #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] pub enum ChannelPosition { FrontLeft, FrontRight, FrontCenter, LowFrequency, BackLeft, BackRight, FrontLeftOfCenter, FrontRightOfCenter, BackCenter, SideLeft, SideRight, TopCenter, TopFrontLeft, TopFrontCenter, TopFrontRight, TopBackLeft, TopBackCenter, TopBackRight, } /// #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] pub struct SamplesRate(pub u32); /// Describes a format. #[derive(Debug, Clone, PartialEq, Eq)] pub struct Format { pub channels: Vec<ChannelPosition>, pub samples_rate: SamplesRate, pub data_type: SampleFormat, } /// An iterator that produces a list of formats supported by the endpoint. /// /// See [`Endpoint::supported_formats()`](struct.Endpoint.html#method.supported_formats). pub struct SupportedFormatsIterator(cpal_impl::SupportedFormatsIterator); impl Iterator for SupportedFormatsIterator { type Item = SupportedFormat; #[inline] fn next(&mut self) -> Option<SupportedFormat> { self.0.next() } #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.0.size_hint() } } /// Describes a range of supported formats. #[derive(Debug, Clone, PartialEq, Eq)] pub struct SupportedFormat { pub channels: Vec<ChannelPosition>, /// Minimum value for the samples rate of the supported formats. pub min_samples_rate: SamplesRate, /// Maximum value for the samples rate of the supported formats. pub max_samples_rate: SamplesRate, /// Type of data expected by the endpoint. pub data_type: SampleFormat, } impl SupportedFormat { /// Turns this `SupportedFormat` into a `Format` corresponding to the maximum samples rate. #[inline] pub fn with_max_samples_rate(self) -> Format { Format { channels: self.channels, samples_rate: self.max_samples_rate, data_type: self.data_type, } } } impl From<Format> for SupportedFormat { #[inline] fn from(format: Format) -> SupportedFormat { SupportedFormat { channels: format.channels, min_samples_rate: format.samples_rate, max_samples_rate: format.samples_rate, data_type: format.data_type, } } } /// Collection of voices managed together. /// /// Created with the [`new`](struct.EventLoop.html#method.new) method. pub struct EventLoop(cpal_impl::EventLoop); impl EventLoop { /// Initializes a new events loop. #[inline] pub fn new() -> EventLoop { EventLoop(cpal_impl::EventLoop::new()) } /// Creates a new voice that will play on the given endpoint and with the given format. /// /// On success, returns an identifier for the voice. /// /// Can return an error if the endpoint is no longer valid, or if the format is not supported /// by the endpoint. #[inline] pub fn build_voice(&self, endpoint: &Endpoint, format: &Format) -> Result<VoiceId, CreationError> { self.0.build_voice(&endpoint.0, format).map(VoiceId) } /// Destroys an existing voice. /// /// # Panic /// /// If the voice doesn't exist, this function can either panic or be a no-op. /// #[inline] pub fn destroy_voice(&self, voice_id: VoiceId) { self.0.destroy_voice(voice_id.0) } /// Takes control of the current thread and processes the sounds. /// /// > **Note**: Since it takes control of the thread, this method is best called on a separate /// > thread. /// /// Whenever a voice needs to be fed some data, the closure passed as parameter is called. /// You can call the other methods of `EventLoop` without getting a deadlock. #[inline] pub fn run<F>(&self, mut callback: F) -> ! where F: FnMut(VoiceId, UnknownTypeBuffer) + Send { self.0.run(move |id, buf| callback(VoiceId(id), buf)) } /// Instructs the audio device that it should start playing. /// /// Has no effect is the voice was already playing. /// /// Only call this after you have submitted some data, otherwise you may hear /// some glitches. /// /// # Panic /// /// If the voice doesn't exist, this function can either panic or be a no-op. /// #[inline] pub fn play(&self, voice: VoiceId) { self.0.play(voice.0) } /// Instructs the audio device that it should stop playing. /// /// Has no effect is the voice was already paused. /// /// If you call `play` afterwards, the playback will resume where it was. /// /// # Panic /// /// If the voice doesn't exist, this function can either panic or be a no-op. /// #[inline] pub fn pause(&self, voice: VoiceId) { self.0.pause(voice.0) } } /// Identifier of a voice in an events loop. #[derive(Debug, Clone, PartialEq, Eq, Hash)] pub struct VoiceId(cpal_impl::VoiceId); /// This is the struct that is provided to you by cpal when you want to write samples to a buffer. /// /// Since the type of data is only known at runtime, you have to fill the right buffer. pub enum UnknownTypeBuffer<'a> { /// Samples whose format is `u16`. U16(Buffer<'a, u16>), /// Samples whose format is `i16`. I16(Buffer<'a, i16>), /// Samples whose format is `f32`. F32(Buffer<'a, f32>), } impl<'a> UnknownTypeBuffer<'a> { /// Returns the length of the buffer in number of samples. #[inline] pub fn len(&self) -> usize { match self { &UnknownTypeBuffer::U16(ref buf) => buf.target.as_ref().unwrap().len(), &UnknownTypeBuffer::I16(ref buf) => buf.target.as_ref().unwrap().len(), &UnknownTypeBuffer::F32(ref buf) => buf.target.as_ref().unwrap().len(), } } } /// Error that can happen when enumerating the list of supported formats. #[derive(Debug)] pub enum FormatsEnumerationError { /// The device no longer exists. This can happen if the device is disconnected while the /// program is running. DeviceNotAvailable, } impl fmt::Display for FormatsEnumerationError { #[inline] fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> { write!(fmt, "{}", self.description()) } } impl Error for FormatsEnumerationError { #[inline] fn description(&self) -> &str { match self { &FormatsEnumerationError::DeviceNotAvailable => { "The requested device is no longer available (for example, it has been unplugged)." }, } } } /// Error that can happen when creating a `Voice`. #[derive(Debug)] pub enum CreationError { /// The device no longer exists. This can happen if the device is disconnected while the /// program is running. DeviceNotAvailable, /// The required format is not supported. FormatNotSupported, } impl fmt::Display for CreationError { #[inline] fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> { write!(fmt, "{}", self.description()) } } impl Error for CreationError { #[inline] fn description(&self) -> &str { match self { &CreationError::DeviceNotAvailable => { "The requested device is no longer available (for example, it has been unplugged)." }, &CreationError::FormatNotSupported => { "The requested samples format is not supported by the device." }, } } } /// Represents a buffer that must be filled with audio data. /// /// You should destroy this object as soon as possible. Data is only sent to the audio device when /// this object is destroyed. /// /// This struct implements the `Deref` and `DerefMut` traits to `[T]`. Therefore writing to this /// buffer is done in the same way as writing to a `Vec` or any other kind of Rust array. // TODO: explain audio stuff in general #[must_use] pub struct Buffer<'a, T: 'a> where T: Sample { // Always contains something, taken by `Drop` // TODO: change that target: Option<cpal_impl::Buffer<'a, T>>, } impl<'a, T> Deref for Buffer<'a, T> where T: Sample { type Target = [T]; #[inline] fn deref(&self) -> &[T] { panic!("It is forbidden to read from the audio buffer"); } } impl<'a, T> DerefMut for Buffer<'a, T> where T: Sample { #[inline] fn deref_mut(&mut self) -> &mut [T] { self.target.as_mut().unwrap().buffer() } } impl<'a, T> Drop for Buffer<'a, T> where T: Sample { #[inline] fn drop(&mut self) { self.target.take().unwrap().finish(); } }