This is an implementation of the API described at #204. Please see that
issue for more details on the motivation.
-----
A **Host** provides access to the available audio devices on the system.
Some platforms have more than one host available, e.g.
wasapi/asio/dsound on windows, alsa/pulse/jack on linux and so on. As a
result, some audio devices are only available on certain hosts, while
others are only available on other hosts. Every platform supported by
CPAL has at least one **DefaultHost** that is guaranteed to be available
(alsa, wasapi and coreaudio). Currently, the default hosts are the only
hosts supported by CPAL, however this will change as of landing #221 (cc
@freesig). These changes should also accommodate support for other hosts
such as jack #250 (cc @derekdreery) and pulseaudio (cc @knappador) #259.
This introduces a suite of traits allowing for both compile time and
runtime dispatch of different hosts and their uniquely associated device
and event loop types.
A new private **host** module has been added containing the individual
host implementations, each in their own submodule gated to the platforms
on which they are available.
A new **platform** module has been added containing platform-specific
items, including a dynamically dispatched host type that allows for
easily switching between hosts at runtime.
The **ALL_HOSTS** slice contains a **HostId** for each host supported on
the current platform. The **available_hosts** function produces a
**HostId** for each host that is currently *available* on the platform.
The **host_from_id** function allows for initialising a host from its
associated ID, failing with a **HostUnavailable** error. The
**default_host** function returns the default host and should never
fail.
Please see the examples for a demonstration of the change in usage. For
the most part, things look the same at the surface level, however the
role of device enumeration and creating the event loop have been moved
from global functions to host methods. The enumerate.rs example has been
updated to enumerate all devices for each host, not just the default.
**TODO**
- [x] Add the new **Host** API
- [x] Update examples for the new API.
- [x] ALSA host
- [ ] WASAPI host
- [ ] CoreAudio host
- [ ] Emscripten host **Follow-up PR**
- [ ] ASIO host #221
cc @ishitatsuyuki more to review for you if you're interested, but it
might be easier after #288 lands and this gets rebased.
This allows for properly handling potential failure on macOS. We should
also consider propagating the mutex/channel poison errors through these
new types, especially considering the potential removal of the event
loop in favour of switching over to high-priority audio threads on
windows and linux.
* 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
mitchmindtree