* Some untested placeholder code has been removed for non-Android
builds. This was adding unnecessary complexity.
* Device enumeration now includes detailed info.
* Device enumeration will now mark appropriate devices as default.
* The onContextGetDeviceInfo backend callback has been removed so that
all device info is retrieved from the enumeration process.
These changes add initial support for OSSv3. Where this is of particular
note is Linux which never updated to OSSv4. This compiles on Linux, but
I have not yet tested this at run time. Future commits will enable the
OSS backend for Linux which will be useful for getting miniaudio working
on very old versions of Linux.
In this case, device information will be retrieved through device
enumeration. This callback will eventually be removed entirely once all
backends have been updated.
This also removes the `performanceProfile` config option from
`ma_device_config`. Increase the period size if you want to be more
conservative.
Backends that have their own notion of a "latency hint" or the like will
have those options exposed via a backend-specific configuration option.
This renames the `ma_device_state` enum to `ma_device_status`, and also
renames `ma_device_get_state()` to `ma_device_get_status()`.
The reason for this change is that the new backend system uses the
notion of a "state" for backend-specific state for devices. This change
is just to avoid ambiguity between the two concepts.
For determining if a backend is enabled, just compare it to NULL:
if (ma_device_backend_wasapi != NULL) {
/* Enabled */
} else {
/* Disabled */
}
If you need to list available backends, just keep track of a list of
backends that you care about, and then check which ones are null.
This includes API changes that affect custom backends.
`ma_backend_callbacks` has been renamed to `ma_device_backend_vtable`.
The reason for this change is to to be consistent with the naming
convention used in other parts of the library. In addition, using the
term "device backend" rather than just "backend" removes ambiguity with
decoding backends.
A change has been made to the way backends manage their internal state,
and some functions in the vtable have been updated to reflect this.
Previously internal state for stock backends were located directly in
the `ma_device` structure. This works fine if stock backends are the
only backends to be concerned about, but it falls apart when you need
to consider how to manage the internal state of custom backends since
they cannot modify the `ma_device` structure. In order to simplify and
unify state management between stock and custom backends, the decision
was made to change the backend system such that backends now manage
their own internal state.
When the context is initialized with `onContextInit`, the backend must
now allocate an internal state object and output a pointer to it via
an output parameter. Typically you would do something like this:
ma_result custom_context_init(..., void** ppContextState)
{
ctx_state_t* state = malloc(...);
...
*ppContextState = state;
return MA_SUCCESS;
}
miniaudio will store a pointer to the state object internally. When you
need to access this later in other backend callbacks, you can retrieve
it straight from the context with `ma_context_get_backend_state()`:
state = (ctx_state_t*)ma_context_get_backend_state(pContext);
The same idea applies to devices and `onDeviceInit`. You can use
`ma_device_get_backend_state()` to get a pointer to the internal state
object.
When a context and device is initialized, backend-specific
configurations can be supplied. The way these configs are provided to
`onContextInit` and `onDeviceInit` has been changed. Previously, these
callbacks would take a `ma_context/device_config` object. These have
been replaced with a `const void*` which points to a backend-specific
config object which is defined by the backend. All stock backends have
their own backend-specific config object:
struct ma_context_config_wasapi
struct ma_context_config_pulseaudio
etc.
struct ma_device_config_wasapi
struct ma_device_config_pulseaudio
etc.
You can cast the config object inside the relevant callbacks:
ma_result custom_context_init(..., const void* pBackendConfig, ...)
{
ctx_config_t* pCustomConfig = (ctx_config_t*)pBackendConfig;
}
The backend itself defines whether or not a config is required. None of
the stock backends require a config. If the config is NULL, it'll use
defaults. It's recommended custom backends follow this convention.
In addition to the above, `onContextUninit` and `onDeviceUninit` have
been updated to return void instead of `ma_result`.
The last change to the backend vtable is a new callback called
`onBackendInfo`. This is used to fill the `ma_device_backend_info`
structure.
In addition to the backend vtable, some changes have been made to the
public API to make it much easier to support plugging in custom
backends.
Previously, plugging in more than one custom backend was a complete
mess. It was possible, but you had to use a stupid wrapper thing to
make it work, and you had no control over prioritization. The entire
thing was just aweful, so it's now been stripped out and replaced with
a brand new system.
When a context or device is initialized, it is done so with a config
which is standard across the entire library. A complication to this is
that backends can sometimes require their own backend-specific configs.
But since miniaudio cannot possibly know about custom backends, it
cannot put their config options inside `ma_context/device_config`. The
functions for initializing a context and device have been updated to
allow plugging in backend-specific configs.
When initializing a context, instead of passing in an array of
`ma_backend` enums, an array of `ma_device_backend_config` objects is
passed in instead. This object has two members: A pointer to a backend
vtable, and a pointer to a config object. It can be initialized
something like this:
ma_context_config_custom customContextConfig;
... initialize the custom backend config if necessary ...
ma_device_backend_config backends[] =
{
{ ma_device_backend_custom, &customContextConfig },
{ ma_device_backend_wasapi, NULL },
{ ma_device_backend_pulseaudio, NULL }
};
ma_context_init(backends, backendCount, ...);
Here `ma_device_backend_custom` is our custom backend. You can see how
the config is mapped to the backend. For stock backends (WASAPI and
PulseAudio in this example), you can pass in NULL and just set the
relevant config options straight in `ma_context_config` exactly how it
was done before:
ma_context_config contextConfig = ma_context_config_init();
contextConfig.pulseaudio.pApplicationName = "My App";
Here we are just using the standard `ma_context_config` object for
configuring the stock PulseAudio backend. This is possible for all
stock backends, but for custom backends an explicit config object will
be required. You can still use a separate explicit config object for
stock backends if you prefer that style:
ma_context_config_pulseaudio paContextConfig;
paContextConfig = ma_context_config_pulseaudio_init();
paContextConfig.pApplicationName = "My App";
ma_device_backend_config backends[] =
{
{ ma_device_backend_pulseaudio, &paContextConfig }
};
Note that if you do not use custom backends, you can still pass in NULL
for the backends in which case defaults will be used like how it's
always worked in the past.
As with contexts, devices can also have their own backend-specific
configs associated with them. These work exactly the same way, except
these configs are passed into the main `ma_device_config` object. (A
future commit may make this consistent between contexts and devices).
ma_device_backend_config deviceBackendConfigs[] =
{
{ ma_device_backend_custom, &customDeviceConfig }
};
deviceConfig.pBackendConfigs = deviceBackendConfigs;
deviceConfig.backendConfigCount = backendCount;
ma_device_init(&deviceConfig, &device);
This commit is just the start of many backend related changes. Future
commits will be cleaning up a lot of residual code from the old system,
such as removing `ma_backend`.
This is part of some future work to decouple `ma_context` and
`ma_device` from backends. If you need access to the context for some
reason, you can pass it in via the user data.
David Reid