[openal] Preparing for 1.18
christian.hoene at symonics.com
Sun May 28 13:24:16 EDT 2017
in respect to regular layouts, I thought about a solution for OpenAL. OpenAL likes to have a regular layout and has restrictions on the maximal size of this layout. It does not work well with all Sofa files.
Instead of using the original layout of a Sofa file, especially if it is not suitable for OpenAL, one could resample/interpolate the HRTF using a layout that works well with OpenAL.
Libmysofa (see https://www.hdfgroup.org/2017/04/hdf5-under-the-sofa-hdf5-on-embedded-and-mobile-devices/) has an interpolation unit. Thus, it would be straight forward to change makehrtf to support irregular HRTFs by simply resampling the HRTF for a given, fixed layout.
The only thing which needs to be changed in the OpenAL core is the mirroring of HRTFs. Mirroring HRTFs can be imprecise, see: http://www.aes.org/e-lib/online/browse.cfm?elib=18590
With best regards,
> Chris Robinson <chris.kcat at gmail.com> hat am 28. Mai 2017 um 18:09 geschrieben:
> On 05/28/2017 07:32 AM, Christian Hoene wrote:
> > Hi Chris,
> > sadly enough, support for SOFA files has not yet been added:
> > https://github.com/kcat/openal-soft/pull/80
> > Any changes that this extension (or a similar) to support powerful HRTFs will be considered at some times?
> Supporting SOFA files is something I'm going to look into after 1.18 is
> released. In regards to that PR in particular, it seems quite a bit more
> complex than should be necessary given this loading function by
> It should only need a relatively minor change to makehrtf.c to use an
> alternate loading function to prepare the HrirDataT structure from a
> SOFA file.
> I've done tests to successfully load a .sofa file in an independent app,
> but there's some things to work out before being able to make mhr files
> out of them (such as checking for and dealing with irregular layouts,
> where a ring of measurements are not equally spaced; and it would
> greatly benefit from stereo/dual-ear measurements). And considering how
> long it's been since the last release and not knowing how long it would
> take to work the issues out, it's on hold until after the release.
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