cpal/README.md

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Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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# CPAL - Cross-Platform Audio Library
2014-12-11 13:22:55 +00:00
2019-10-02 11:52:27 +00:00
[![Build Status](https://travis-ci.org/RustAudio/cpal.svg?branch=master)](https://travis-ci.org/RustAudio/cpal) [![Crates.io](https://img.shields.io/crates/v/cpal.svg)](https://crates.io/crates/cpal) [![docs.rs](https://docs.rs/cpal/badge.svg)](https://docs.rs/cpal/)
2014-12-17 09:03:20 +00:00
Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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Low-level library for audio input and output in pure Rust.
2016-08-12 15:51:15 +00:00
Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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This library currently supports the following:
- Enumerate supported audio hosts.
Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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- Enumerate all available audio devices.
- Get the current default input and output devices.
- Enumerate known supported input and output stream formats for a device.
- Get the current default input and output stream formats for a device.
- Build and run input and output PCM streams on a chosen device with a given stream format.
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Currently supported hosts include:
Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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- Linux (via ALSA)
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- Windows (via WASAPI by default, see ASIO instructions below)
Update to a more general Device and Stream API. Add support for input streams (E.g. microphone). Add default format methods. (#201) * Update to a more general Device and Stream API This update prepares for adding input stream support by removing the `Endpoint` type (which only supports output streams) in favour of a more general `Device` type which may support any number of input or output streams. Previously discussed at #117. The name `Voice` has been replaced with the more ubiquitous name `Stream`. See #118 for justification. Also introduces a new `StreamData` which is now passed to the `EventLoop::run` callback rather than the `UnknownTypeBuffer`. `StreamData` allows for passing either `Input` data to be read, or `Output` data to be written. The `beep.rs` example has been updated for the API changes. None of the backends have been updated for this API change yet. Backends will be updated in the following commits. Closes #117. Closes #118. * Update ALSA backend for new `Device` and `Stream` API. * Update wasapi backend for new `Device` and `Stream` API. * Update enumerate.rs example for new `Device` and `Stream` API. * Update coreaudio backend for new `Device` and `Stream` API. * Fix lib doc tests for Device and Stream API update * Update emscripten backend for new `Device` and `Stream` API. * Update null backend for new `Device` and `Stream` API. * Merge match exprs in beep.rs example * Add Input variant along with UnknownTypeInputBuffer and InputBuffer UnknownTypeBuffer and Buffer have been renamed to UnknownTypeOutputBuffer and OutputBuffer respectively. No backends have yet been updated for this name change or the addition of the InputBuffer. * Update null backend for introduction of InputBuffer * Update emscripten backend for introduction of InputBuffer * Make InputBuffer inner field an option to call finish in drop * Update alsa backend for introduction of InputBuffer * Update wasapi backend for introduction of InputBuffer * Update coreaudio backend for introduction of InputBuffer * Update enumerate.rs example to provide more detail about devices The enumerate.rs example now also displays: - Supported input stream formats. - Default input stream format. - Default output stream format. This should also be useful for testing the progress of #201. * Add `record_wav.rs` example for demonstrating input streams Records a ~3 second WAV file to `$CARGO_MANIFEST_DIR/recorded.wav` using the default input device and default input format. Uses hound 3.0 to create and write to the WAV file. This should also be useful for testing the input stream implementations for each different cpal backend. * Implement input stream support for coreaudio backend This implements the following for the coreaudio backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream The `enumerate.rs` and `record_wav.rs` examples now work successfully on macos. * Add `SupportedFormat::cmp_default_heuristics` method This adds a comparison function which compares two `SupportedFormat`s in terms of their priority of use as a default stream format. Some backends (such as ALSA) do not provide a default stream format for their audio devices. In these cases, CPAL attempts to decide on a reasonable default format for the user. To do this we use the "greatest" of all supported stream formats when compared with this method. * Implement input stream support for ALSA backend This implements the following for the ALSA backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that ALSA itself does not give default stream formats for its devices. Thus the newly added `SupportedFormat::cmp_default_heuristics` method is used to determine the most suitable, supported stream format to use as the default. The `enumerate.rs` and `record_wav.rs` examples now work successfully on my linux machine. * Implement input stream support for wasapi backend This implements the following for the wasapi backend: - Device::supported_input_formats - Device::default_input_format - Device::default_output_format - EventLoop::build_input_stream Note that wasapi does not enumerate supported input/output stream formats for its devices. Instead, we query the `IsFormatSupported` method for supported formats ourselves. * Fix some warnings in the alsa backend * Update CHANGELOG for introduction of input streams and related items * Update README to show latest features supported by CPAL * Simplify beep example using Device::default_output_format * Remove old commented code from wasapi/stream.rs
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- macOS (via CoreAudio)
- iOS (via CoreAudio)
- Emscripten
Note that on Linux, the ALSA development files are required. These are provided
as part of the `libasound2-dev` package on Debian and Ubuntu distributions and
`alsa-lib-devel` on Fedora.
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## ASIO on Windows
[ASIO](https://en.wikipedia.org/wiki/Audio_Stream_Input/Output) is an audio
driver protocol by Steinberg. While it is available on multiple operating
systems, it is most commonly used on Windows to work around limitations of
WASAPI including access to large numbers of channels and lower-latency audio
processing.
CPAL allows for using the ASIO SDK as the audio host on Windows instead of
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WASAPI. To do so, follow these steps:
1. **Download the ASIO SDK** `.zip` from [this
link](https://www.steinberg.net/en/company/developers.html). The version as
of writing this is 2.3.1.
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2. Extract the files and place the directory somewhere you are happy for it to stay
(e.g. `~/.asio`).
3. Assign the full path of the directory (that contains the `readme`, `changes`,
`ASIO SDK 2.3` pdf, etc) to the `CPAL_ASIO_DIR` environment variable. This is
necessary for the `asio-sys` build script to build and bind to the SDK.
4. `bindgen`, the library used to generate bindings to the C++ SDK, requires
clang. **Download and install LLVM** from
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[here](http://releases.llvm.org/download.html) under the "Pre-Built Binaries"
section. The version as of writing this is 7.0.0.
5. Add the LLVM `bin` directory to a `LIBCLANG_PATH` environment variable. If
you installed LLVM to the default directory, this should work in the command
prompt:
```
setx LIBCLANG_PATH "C:\Program Files\LLVM\bin"
```
6. If you don't have any ASIO devices or drivers available, you can [**download
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and install ASIO4ALL**](http://www.asio4all.org/). Be sure to enable the
"offline" feature during installation despite what the installer says about
it being useless.
7. **Loading VCVARS**. `rust-bindgen` uses the C++ tool-chain when generating
bindings to the ASIO SDK. As a result, it is necessary to load some
environment variables in the command prompt that we use to build our project.
On 64-bit machines run:
```
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" amd64
```
On 32-bit machines run:
```
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x86
```
Note that, depending on your version of Visual Studio, this script might be
in a slightly different location.
8. Select the ASIO host at the start of our program with the following code:
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```rust
let host;
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#[cfg(target_os = "windows")]
{
host = cpal::host_from_id(cpal::HostId::Asio).expect("failed to initialise ASIO host");
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}
```
If you run into compilations errors produced by `asio-sys` or `bindgen`, make
sure that `CPAL_ASIO_DIR` is set correctly and try `cargo clean`.
9. Make sure to enable the `asio` feature when building CPAL:
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```
cargo build --features "asio"
```
or if you are using CPAL as a dependency in a downstream project, enable the
feature like this:
```toml
cpal = { version = "*", features = ["asio"] }
```
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In the future we would like to work on automating this process to make it
easier, but we are not familiar enough with the ASIO license to do so yet.
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*Updated as of ASIO version 2.3.3.*