[Openal-devel] Cone gain

[Sven Panne]

Hmmm, what kind of interpolation would be the physically more correct
one? If I see it correctly, the "portable" module uses linear gains
internally. What would be the correct formula for the dB-based
interpolation then? Any hints appreciated, I think I'll have to dig out
some old books in the meantime... :-]

Cheers,
   S. 

> -----Original Message-----
> From: openal-devel-admin at opensource.creative.com 
> [mailto:openal-devel-admin at opensource.creative.com] On Behalf 
> Of Peter Clare
> Sent: Mittwoch, 14. Dezember 2005 13:11
> To: Sven Panne
> Cc: openal-devel at opensource.creative.com
> Subject: [Openal-devel] Cone gain
> [...]
> A linear interpolation between inner and outer gain according 
> to angle is how things work in the DirectSound3D world.  One 
> thing to be clear on though is whether it is an interpolation 
> of volume levels expressed in dB, or interpolation between 
> two linear gains.  I've seen both in various DirectSound3D 
> drivers (!) but clearly all implementations should 
> standardise on one behaviour.
> 
> The cone gain calculations are something that should be 
> spelled out in the OpenAL spec.  The version of the spec that 
> I'm currently looking at says that the interpolation is 
> "implementation dependent".  I'd argue that this is rubbish 
> and that the precise behaviour should be stated in the spec 
> and be standard across all implementations.