The purpose of the Audio File Library is to provide transparency to
the programmer of file formats and data formats.

Audio files contain a sequence of amplitudes sampled at a particular
rate, called the sampling frequency.  The method by which sounds can
be acquired or generated in this manner is referred to as pulse-code
modulation (PCM).  The representation of these amplitudes varies from
one file format to another.  Common representations for these data are
two's complement integers, unsigned integers, and floating-point
numbers.

To read from a file containing audio data, the following sequence of
function calls are typically used:

afOpenFile
afReadFrames
afCloseFile

To write to a file, a similar sequence of commands is typically
employed:

afNewFileSetup
afOpenFile
afWriteFrames
afCloseFile
