Medias Mediatrix 1204, Reference Manual

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Echo Cancellation Reference Manual (SIP Version)
Mediatrix 1204 211
The following settings are available:
See “Enabling Individual Codecs” on page 202 for more details.
Echo Cancellation
Echo cancellation eliminates the echo effect caused by signal reflections. An echo is a signal that has been
reflected or otherwise returned with enough magnitude and delay to be perceived. The echo cancellation is
usually an active process in which echo signals are measured and cancelled or eliminated by combining an
inverted signal with the echo signal.
You cannot disable echo cancellation on the Mediatrix 1204.
Furthermore, the Mediatrix 1204 has an additional correlator feature that automatically fine-tunes the echo
cancellation activity.
Comfort Noise
Comfort Noise (CN) defines how the Mediatrix 1204 processes silence periods information it receives.
During silence periods, the Mediatrix 1204 may receive CN packets containing information about background
noise. When enabling Comfort Noise Generation (CNG), those packets are used to generate local comfort
noise.
X
To enable Comfort Noise:
1. In the voiceIfMIB , locate the voiceIfTable group.
2. Define the type of comfort noise in the voiceIfG711ComfortNoiseGenerationEnable variable.
The following settings are available:
3. Restart the Mediatrix 1204 so that the changes may take effect.
Table 135: G.729 VAD Settings
Setting Description
disable G.729 uses annex A only. The Mediatrix 1204 does not send G.729 Annex B
comfort noise frames.
enable G.729 annex A is used with annex B. The Mediatrix 1204 sends G.729 Annex
B comfort noise frames during silence periods.
Standards Supported • RFC 3389: Real-time Transport Protocol (RTP) Payload for
Comfort Noise (CN)
Note:
Comfort noise only applies to the G.711 and G.726 codecs. G.723 and G.729 CNG is not
configurable because it is part of the codec.
Table 136: Comfort Noise Settings
Setting Description
disable CNG disabled.
whiteNoise CNG enabled – white noise.
customNoise CNG enabled – custom noise. More elaborated background noise that
sounds better than white comfort noise.