Voice Activity Detection - Polycom SoundPoint IP 300 Administrator's Manual

Administrator's Guide - SoundPoint
urable for different network environments. When packets are lost, a concealment algo-
rithm minimizes the resulting negative audio consequences.
Central
(boot
server)
Local

3.3.3 Voice Activity Detection

The purpose of voice activity detection (VAD) is to conserve network bandwidth by
detecting periods of relative "silence" in the transmit data path and replacing that
silence efficiently with special packets that indicate silence is occurring. For those
compression algorithms without an inherent VAD function, such as G.711, the phone
is compatible with the comprehensive codec-independent comfort noise transmission
algorithm specified in RFC 3389. This algorithm is derived from G.711 Appendix II,
which defines a comfort noise (CN) payload format (or bit-stream) for G.711 use in
packet-based, multimedia communication systems. The phone generates CN packets
(also known as Silence Insertion Descriptor (SID) frames) and also decodes CN pack-
ets, efficiently regenerating a facsimile of the background noise at the remote end.
Central
(boot
server)
Local
® ®
IP / SoundStation IP
Configuration file: Set the jitter buffer tuning parameters including minimum
sip.cfg and maximum size and shrink aggression.
•
Web Server Set the jitter buffer tuning parameters including minimum
(if enabled) and maximum size and shrink aggression.
Navigate to: http://<phoneIPAddress>/coreConf.htm#au
Changes are saved to local flash and backed up to <Ethernet
address>-phone.cfg on the boot server. Changes will perma-
nently override global settings unless deleted through the
Reset Local Config menu selection.
Local Phone User None.
Interface
Configuration file: Enable or disable VAD and set the detection threshold.
sip.cfg
•
Web Server None.
(if enabled)
Local Phone User None.
Interface
Copyright © 2006 Polycom, Inc.
For more information, refer to 4.6.1.8.1.2 Codec Pro-
files <profiles/> on page 109.
For more information, refer to 4.6.1.8.10 Voice Activity
Detection <VAD/> on page 118.
Features
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