Provides VOX ADPCM codec related classes.
completed
decode x16???
/* File: adpcm.c
Description: Routines to convert 12 bit linear samples to the
Dialogic or Oki ADPCM coding format.
I copied the algorithms out of the book "PC Telephony - The
complete guide to designing, building and programming systems
using Dialogic and Related Hardware" by Bob Edgar. pg 272-276.
*/