[openal] Querying speaker configuration

Peter Mulholland peter.mulholland at vpltd.com
Sat Oct 4 09:54:55 EDT 2014


On 04/10/2014 14:51, Chris Robinson wrote:
>
> Mainly because it's problematic. Though I can understand the utility in knowing whether you're
> playing out stereo or 5.1 when it's just being used as a pass-through, you get into issues when it
> could start reporting unexpected configurations. Like if an app were made and tested against stereo,
> quad, 5.1, and 7.1 systems, what is it going to do if a user's system suddenly has it return 6.1?
> And in the future, new formats can be added like 8-channel cube, 3D7.1 (which is sort-of-compatible
> with 5.1), B-Format, or a completely user-specified custom setup, which such an app would have no
> way to properly acknowledge or deal with.
>

Surely if you were using a single source to play a 5.1 or 7.1 premixed source, it is up to OpenAL to 
convert it if appropriate for the output format?

> It would quickly get to a point where all OpenAL could do is lie about what it is and remix the
> input to fit the output, putting you back where you are now.

Isn't it doing that already?
>
> It's unfortunate that SDL's audio API doesn't work that great for surround sound, because OpenAL
> really isn't designed to be a thin audio API wrapper. Not only does it have its own channel
> remixing, but it adds latency for real-time streams because the buffer queue is another buffering
> layer on top of the card (the system may even have its own latency-adding buffer in addition to that).

I guess PortAudio is more appropriate for this. However in my case, I have used OpenAL because our 
sound code (which is emulating DirectSound, MMDevice and to some extent Xaudio2) may require mixing 
depending on the game running upon it.

-- 
Regards,

Peter Mulholland
Software Developer & System Administrator
Virtual Programming Ltd

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