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The desired output level of voice content is defined by an upper and lower threshold. If a voice signal
is outside of the upper and lower threshold then the gain will adapt accordingly. If the voice signal is
within the upper and lower threshold then the gain will remain constant.
The rate at which the gain increases or decreases per audio frame can also be configured. The gain
increment value must be greater than 1, whilst the gain decrement value must be below 1. When the
gain is adapting, the current gain value is multiplied by either the increment or decrement value to
calculate the gain value to be applied on the next audio frame.
The Loss Control process improves the subjective audio quality by attenuating any residual echo of
the reference far-end audio. It is designed to be used on the communications channel. In cases where
there is both far-end echo and near-end audio then the attenuation is reduced, allowing listeners to
interrupt each other. The Loss Control relies on the Automatic Echo Canceller in order to classify and
attenuate residual far-end echo.
The following table details the configuration parameters for the AGC.
Table 4-19 Automatic Gain Control (AGC) parameters
COMMAND
SET_ADAPT_CH0_AGC
SET_ADAPT_CH1_AGC
GET_ADAPT_CH0_AGC
GET_ADAPT_CH1_AGC
SET_LC_ENABLED_CH0_AGC
SET_LC_ENABLED_CH1_AGC
GET_LC_ENABLED_CH0_AGC
GET_LC_ENABLED_CH1_AGC
SET_GAIN_CH0_AGC
SET_GAIN_CH1_AGC
GET_GAIN_CH0_AGC
GET_GAIN_CH1_AGC
SET_MAX_GAIN_CH0_AGC
SET_MAX_GAIN_CH1_AGC
GET_MAX_GAIN_CH0_AGC
GET_MAX_GAIN_CH1_AGC
SET_UPPER_THRESHOLD_CH0_AGC
SET_UPPER_THRESHOLD_CH1_AGC
GET_UPPER_THRESHOLD_CH0_AGC
GET_UPPER_THRESHOLD_CH1_AGC
SET_LOWER_THRESHOLD_CH0_AGC
SET_LOWER_THRESHOLD_CH1_AGC
GET_LOWER_THRESHOLD_CH0_AGC
GET_LOWER_THRESHOLD_CH1_AGC
XM-014232-PC
TYPE
VALUE
DESCRIPTION
Set to enable gain adaptation in the AGC for
channel 0 or 1.
uint32
[0,1]
0 - adaptation disabled for the channel
1 - adaptation enabled for the channel
Set Loss Control to be enabled in the AGC for
channel 0 or 1.
uint32
[0,1]
0 - Loss Control disabled for the channel
1 - Loss Control enabled for the channel
Set the linear gain parameter to be applied in the
AGC for channel 0 or 1. Values are linear.
Q16.16
[0..32767]
Default: 500
Set the maximum gain threshold in the AGC for
channel 0 or 1. Values are linear.
Q16.16
[0..32767]
Default: 1000
Set the upper threshold for desired voice level.
Q1.31
[0..1]
Values are in range 0 to 1 (full-scale) and must be
greater than the lower threshold of the channel.
Set the lower threshold for desired voice level.
Q1.31
[0..1]
Values are in range 0 to 1 (full-scale) and must be
lower than the upper threshold of the channel.
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