[openal] Problem putting Windows system to sleep while OpenAL is initialized but idle

[Chris Robinson]

On 07/14/2016 04:38 PM, Kirk Baker wrote:
> The above is fairly straightforward, I expect.  Is there some way for
> us to "pause" OpenAL such that it won't deny system sleep?  On
> Windows, powercfg -requests shows
> SYSTEM:
> [DRIVER] Realtek High Definition Audio (HDAUDIO \ FUNC_01 & VEN_10EC & DEV_0889 & SUBSYS_1458A022 & REV_1000 \ 4 & 36360a8e & 0 & 0201)
> An audio stream is currently in use.
>
> I am guessing that as soon as we initialize as above, an audio stream
> is started up and mixes in silence, keeping things ready for
> low-latency playback.  If we could "pause" this when our app is
> switched out, or when a system sleep event raises, or when we know
> we're not trying to play sounds then I'd expect the system to be able
> to sleep.

Hi.

This is basically the issue, yes. OpenAL Soft starts up a playback 
stream on the system when the context is created and keeps feeding it 
audio for a variety of reasons.

There are a couple ways to "pause" playback. The surest way is to use 
the ALC_SOFT_pause_device extension which provides the 
alcDevicePauseSOFT and alcDeviceResumeSOFT functions, which pause and 
resume the device respectively.

Alternatively, you can try destroying all contexts (and associated 
sources, buffers, etc). OpenAL Soft will generally try to stop playback 
when there's no contexts on the device. That's an implementation detail, 
though, and isn't guaranteed to work.