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For optimal AEC settling-time performance, the volume of the speakers must be linearly proportional
to the level of the reference audio sent to the XVF3510. If the volume of the speakers change without
the level of the reference changing by the same linear factor, the AEC will respond as if the
environment has changed such that all echo paths have increased/decreased energy, and will
therefore incur a settling time in the AEC.
The Alternative Architecture (described in the
Alternative Architecture mode (ALT_ARCH) section)
selectively extends the AEC filters to accommodate highly reverberant environments.
The configuration parameters for the AEC are shown below:
Table 4-14 Useful Automatic Echo Canceller (AEC) commands
COMMAND
TYPE
VALUE DESCRIPTION
NOTE
S
GET_BYPASS_AEC
SET_BYPASS_AEC
uint32
[0,1]
Get/Set AEC bypass parameter. If set to one,
AEC processing is disabled.
0 = AEC bypass disabled (default)
1 = AEC bypass enabled
A
SET_ADAPTATION_CONFIG_AEC
GET_ADAPTATION_CONFIG_AEC
uint32
[0, 1, 2]
Sets AEC adaptation configuration. If AEC is set
to bypass then setting the adaptation config has
no effect.
0 = Auto adapt (default)
1 = Force adaptation ON
2 = Force adaptation OFF
B
GET_ERLE_CH0_AEC
float
Get AEC ERLE for channel 0
GET_ERLE_CH1_AEC
float
Get AEC ERLE for channel 1
RESET_FILTER_AEC
This command resets all AEC filters.
[A] When the Alternative Architecture (ALT_ARCH) mode is enabled (default), AEC bypass state will
be overwritten and so should not be used. The GET command remains functional. For more information
see the
Alternative Architecture
(ALT_ARCH)
section.
[B] If Automatic Delay Estimation is enabled, these parameters will be overwritten and so should not
be used. The GET commands remain functional. For more information see the
Automatic Delay
Estimation & Correction (ADEC)
section.
NOTE: The AEC operates on acoustic paths modelled in the AEC tail length. The Automatic Delay
Estimation and Correction module handles delays between microphone and loudspeaker introduced
by the equipment, for instance receiving the reference ahead of it actually being played out of the
loudspeakers.
4.5.3.
AUTOMATIC DELAY ESTIMATION & CORRECTION (ADEC)
The ADEC module automatically corrects for possible delay offsets between the reference and the
loudspeakers.
Echo cancellation is an adaptive filtering process which compares the reference audio to that received
from the microphones. It models the reverberant time of a room, i.e. the time it takes for acoustic
reflections to decay to insignificance. This is shown in the figure below (the red “Acoustic echo path
delay”).
