This extension indicates support for the AL_FORMAT_BFORMAT2D_8,
AL_FORMAT_BFORMAT2D_16, AL_FORMAT_BFORMAT_FLOAT2D_32,
AL_FORMAT_BFORMAT3D_8, AL_FORMAT_BFORMAT3D_16 and
AL_FORMAT_BFORMAT_FLOAT3D_32 buffer formats.
These provide 2D (WXY) and 3D (WXYZ) 8bit int, 16bit int and ALfloat
support for Ambisonic three- or four-channel B-Format (using W X Y Z
channel ordering, encoded as the first three or four channels of
Furse-Malham higher order Ambisonics). Use of these formats indicate
that sources are Ambisonic sources. Such sources can be oriented via
alSourcefv() using the AL_ORIENTATION tag, which takes the same
parameters as the alListenerfv(AL_ORIENTATION,...). Such sources DO
support AL_SOURCE_RELATIVE and the soundfield will rotate to reflect
the listener's orientation if this is off (the default). Other
behaviour is as for stereo or multichannel assets.
Note that Ambisonics orients X, Y and Z axes in a different way to
OpenAL. For clarity, we ignore the Ambisonic coordinate system in
the API and stick to the OpenAL one, making sure that the Front of
the Ambisonic soundfield (actually Ambisonic +X) matches the Front
of the OpenAL coordinate system (-Z by default) etc. For instance,
if the orientation of the source is set so that the "at" vector is
to the left, then the front of the B-Format soundfield will be
presented to the left.