Codec

From Best Practices

Introduction

Coded is the contraction of COder DECoder. It is the algorithm used for compressing voice traffic in order to limit its bandwith consumtpion on a network. There are several type of codes: the most used one as well as their bandwidth are given in the table below for indication:

Codec family	Bandwidth	Comment
GIPS Family	13.3 Kbps and up
GSM	13 Kbps (full rate)
iLBC	15 Kbps, 20ms frame size: 13.3 Kbps, 30ms frame size
ITU G.711	64 Kbps, sample based	Also known as alaw/ulaw
ITU G.722	48/56/64 Kbps
ITU G.723.1	5.3, 6.3 Kbps
ITU G.726	16/24/32/40 Kbps
ITU G.728	16 Kbps
ITU G.729	8 Kbps, 10ms frame size
Speex	2.15 to 44.2 Kbps
LPC10	2.5 Kbps
DoD CELP	4.8 Kbps

The bandwidth indicated in the table above does not include packet header. In order to have total bandwidth, it is necessary to add the layer 2 and 3 bandwidth.