Some dialogue on the Teensy forum raised the issue of
support for 24- or 32-bit output; for example see
https://forum.pjrc.com/index.php?threads/updated-8x8-and-16x16-audio.75569/post-357275
Obviously not supported by the 16-bit Audio library,
but partially supported in this library for I²S and S/PDIF.
Since the TDM support usually emits 32-bit samples, forcing use
of even-numbered ports only, there is an opportunity
to adopt the I/O objects directly by converting two
16-bit TDM port values (containing high and low words) to
and from a single F32 stream, giving 24-bit I/O.
This commit implements the required objects, plus a
minor change to AudioStream_F32 needed for the
AudioConvert_I16x2toF32 class.
Jonathan Oakley
Chip Audette