Adaptive Differential Pulse Code Modulation
A form of pulse
code modulation (PCM) that produces a digital signal with a lower bit rate
than standard PCM thus taking up less space.
ADPCM produces a lower bit
rate by recording only the difference between samples and adjusting the
coding scale dynamically to accommodate large and small differences. Some
applications use ADPCM to digitise a voice signal so data and voice can be
transmitted at the same time over digital equipment normally used only for
one or the other.