Vidicode V-Tap Manual page 28

Start Channel A (else B)
This setting is only used when Audio Activated Recording is enabled.
The Start Channel is very important in the case recording is done
from a handset, because a 4-wired handset produces two audio
signals; one from its speaker and one from its microphone.
To determine the start of a call, the system can look at the audio of
the selected channel A or B only (speaker or microphone).
The goal is to set the Start Channel to the speaker signal, because
the microphone of most phones is still active when the phone is idle
and therefor produces too much audio when the handset is on-hook.
This would then result in constantly false detection of calls and audio
files are created when the room is noisy.
Most of the time, also the speaker produces some audio when the
phone is idle, but that level is much lower than the one produced by
the microphone.
To start on both channels A+B, add 512 to the Pre-Recording Time.
Audio Start/Stop Level
This value is only used when Audio Activated Recording is enabled.
The start and stop level is a border for the system to decide if a call
has started or stopped.
The value can be set from 0 till 255 and a lower value means a more
sensitive detection of audio/voice.
Stop is detected when the audio is below the level for the duration
of the Silence Timeout (see below).
The level on 0 (zero) disables the audio detector.
To set the sensitivity of the audio detector, a value can be added:
+ (1 till 127) x 256 : Debounce per 10 ms. The default is 200 ms.
For example; to set a debounce of 100 ms, add 2560 (10 x 256).
Pre-Recording Time (per 100ms)
This value is only used when Audio Activated Recording is enabled.
The system continuously stores audio samples in a rotating buffer.
When the start of a call is detected, some time in front can be taken,
so no word is missed.
The maximum is 240, which is 24 seconds when recording with a
sample rate of 8 KHz in Mono mode.
The value 512 can be added to set a special feature; then both
channels A and B are used to detect audio for start.
V-Tap Analog 2 Manual EN v4.21 Sept 2021 © 2018-2021 Vidicode 28