The Free On-line Dictionary of Computing (19 January 2023):

Adaptive Digital Pulse Code Modulation
ADPCM

    (ADPCM) A compression technique which
   records only the difference between samples and adjusts the
   coding scale dynamically to accomodate large and small
   differences.  ADPCM is simple to implement, but introduces
   much noise.

   [Used where?  Does the Sony minidisk use ADPCM or ATRAC?]

   (1998-12-10)