SPBGetDeviceInfo/SPBSetDeviceInfo selectors. Those
new selectors are siOSTypeInputSource 'inpt' and
siOSTypeInputAvailable 'inav'. They
work much like siInputSource and siInputSourceNames, except
that they return an
OSType rather than an integer and a list of OSTypes rather than
a list of names,
respectively.
Using the siOSTypeInputSource selector allows you to specify an
input source, such
as the external microphone, with a simple constant, kExtMicSource
('emic').
If these new selectors are not available, SPBGetDeviceInfo will return
siUnknownInfoType, so no preflighting is required. Make the call; it
will work or returns an error.