[openal] Runtime devices management
chris.kcat at gmail.com
Fri Sep 9 12:48:56 EDT 2016
On 09/09/2016 05:38 AM, alberto box wrote:
> Moreover, the device change is not recognized even re-initializing openal
> at runtime.
Currently, OpenAL Soft does not implement any preferred-device tracking.
When a device is opened, the returned ALCdevice is tied to that output
or input device.
Part of the problem is that the OpenAL API has no method to deal with
such behavior. The best it could do is secretly move playback or capture
to a different device and continue to report the old device's name, but
that could cause unintended consequences. The alternative is to simply
not report the name of the device being used, so if it moves it won't
need to change anything... but then the app can't tell the user what
device is actually being used.
> 2. Is there a way to be notified when a device status changes at runtime?
You can check to see if a device has been disconnected using the
Essentially, you periodically check the device's connection status:
alcGetIntegerv(device, ALC_CONNECTED, 1, &connected);
/* We've been lost! */
When the device has been disconnected, it will not play or record any
more samples, and it will never reconnect on its own, even if the device
is reconnected. You'll need to close the device handle and open a new
one if you want to keep playing/recording (there has been talk about
allowing alcResetDeviceSOFT to try to restore playback/capture from a
previously-disconnected device, although this behavior is not currently
> 3. Is there a way to make openal initialization (following the first one)
> aware of new devices status?
This is ultimately down to the system. At least when using OpenAL Soft
directly, every enumeration request is passed on to the underlying API
(mmdevapi, dsound) to get a fresh list of device names each time. If the
underlying API doesn't update its internal list of available devices,
OpenAL Soft won't know about any changes either.
If you're using the router (the OpenAL32.dll provided by Creative's
installer, with soft_oal.dll to provide the OpenAL Soft devices), then
that may be caching the device list so it never asks OpenAL Soft to
recheck the devices. You'll have to use the OpenAL Soft DLL directly to
work around that, if that's what's happening.
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