An International Telecommunications Union (
ITU-T) standard for
for audio (speech)
compression and
decompression that is used in digital transmission systems, and in particular,
used for the coding of
analog signals into digital signals.
G.721 is an ITU-T standard codec that uses Adaptive
Differential
Pulse Code Modulation (ADPCM); a form of
Pulse Code Modulation
(PCM), to produce a digital signal with a lower bit rate than
standard PCM. This ITU standard for speech codecs uses ADPCM on a 32
kbit/s channel. NOTE: G.721 was first introduced in 1984. In 1990 this
standard was folded into G.726 along with G.723. (See also
ADPCM).
See G.7xx for more information on how these standards are used in telephony
networks.
