MicroNet SP5004 Bedienungsanleitung PDF herunterladen (Seite 30)

3.2. Codec Selection

Codec (Coder / Decoder)

Codecs are used to convert analog signals to a digital bit stream, and another identical

codec at the far end of the communication converts digital bit stream back into an

analog signal. Codecs vary in the sound quality, the bandwidth required, the

computational requirements, etc. Codecs generally provide a compression capability

to save network bandwidth. Some codecs also support silence suppression, where

silence is not encoded or transmitted. In the VoIP world, codec's are used to encode

voice for transmission across IP networks.

Micronet VoIP gateway supports several different codecs, G.711A/µ law, G723.1,

G729, and when talking to each other, negotiate which codec they will use.

Codec Description

Bit Rate

(Kb/s)

Remark

G.723.1 G.723.1 is an ITU-T

standard codec. Its

reasonably low bit rate

(6.3Kbps or 5.3Kbps). Use

of this codec in a product

requires licensing by Sipro

Lab Telecom

5.6 / 6.3 It encodes speech or other

audio signals in frames using

linear predictive

analysis-by-synthesis coding.

G.729 Coding of speech at 8 kbit/s

using conjugate-structure

algebraic-code-excited

linear-prediction

(CS-ACELP)

8 Low delay (15 ms)

G.711 G.711 is the international

standard for encoding

telephone audio on an 64

kbps channel. It is a pulse

code modulation (PCM).

This is most

64 mu-law (US, Japan) and A-law

(Europe) companding

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MicroNet SP5004 Bedienungsanleitung Seite 30