Clear-Com VOICE2 - Manual (Page 54)

Vitec Group Communications
VoICE IP Interface User Manual
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bandwidth and the number of channels you are planning to use,
determine which codecs are better suited for your needs.
VBR/ABR CODEC
VoICE also provides leading edge variable bit rate (VBR) and
average bit rate (ABR) codecs. For more technical information
regarding the Speex codec, please visit www.speex.org.
SILENCE SUPPRESSION
Silence suppression can be enabled by selecting Fixed or Adaptive
mode from the Silence suppression drop down list. The table below
describes the configurable values for this feature:
The silence threshold calculation is done as follows:
1. An average value is calculated on the PCM samples in the buffer
(the result is between 0-65535)
2. This linear result is turned to a logarithmic scale using a "linear to
mu-law" function. (the result is between 0-255)
3. This logarithmic result is directly compared with the silence
threshold when fixed threshold is used.
SILENCE SUPPRESSION
Value Description
Signal Detection
Delay The number of milliseconds of speech
required to disable the silence suppression.
Silence Detection
Delay The number of milliseconds of silence
required to activate the silence suppression.
Silence Threshold Value between 0 and 30 representing a
threshold of the signal energy required to dis-
able the silence suppression. The higher the
value, the more aggressive the suppression.
This value is only required in Fixed mode.