G.722

Directive G.722 7 kHz audio -coding within 64 kbit / s of the ITU-T describes the coding of audio signals for transmission over a digital transmission line with a 64 kbit / s, for example a B channel of the ISDN. G.722 was approved in November 1988. Meanwhile, the patents in question the proceedings have expired.

The procedure

G.722 detects the frequency range of 50 Hz to 7000 Hz with a sampling rate of 16 kHz and quantized with 14 bits. The codec thus comprises a bandwidth of approximately 7 kHz. An encoder reduces the data transfer rate to 64 kbit / s (Mode 1), 56 kbit / s (Mode 2) or 48 kbit / s ( Mode 3). The technique is based on sub-band ADPCM.

Areas of application

Currently, G.722 is particularly useful for VoIP used. Also, CAT -iq, the formula based on the DECT standard new transmission method for cordless phones, provides for this codec for wideband speech transmission between the base and handset.

G.722.2

Unlike G.722 G.722.2 uses a compression method and is thus not simply a technical extension of G.722, but technically different. The 3rd Generation Partnership Project has extended the specifications of G.722 with Directive G.722.2 Wideband coding of speech at around 16 kbit / s using Adaptive Multi-Rate Wideband ( AMR -WB ) on mobile networks of the newer generation.