[openal] problem enabling HRTF extension

[Chris Robinson]

On 06/02/2016 07:19 AM, JUNGMIN KIM wrote:
> I'm using openal-soft 1.17.2, and want to use HRTF extension, ALC_SOFT_HRTF.
>
> The problem is, it seems the audio device in my computer doesn't support
> HRTF extension.
>
> That is, with this function code in my application,
> alcGetIntegerv(device, ALC_HRTF_SOFT, 1, &hrtf_state);
> hrtf_state returns false.
>
> And here is a message from openal-info,

Hi.

It seems OpenAL Soft isn't being used, and it's instead using the 
Generic Software driver (which doesn't do HRTF). Make sure the OpenAL 
Soft DLL is in the right place, and you have the proper 32-bit or 64-bit 
one (trying to use the 32-bit DLL with a 64-bit app, or the 64-bit DLL 
with a 32-bit app, won't work).

Don't forget to check for the ALC_SOFT_HRTF extension before using it, 
too. Requesting and querying ALC_HRTF_SOFT on a device without that 
extension is going to cause errors and can leave variables in an 
undefined state (in the above example, hrtf_state could randomly end up 
being true sometimes if it wasn't initialized or if the driver does 
something silly with it when querying an unknown value).