Automatic Volume Control (AVC) Configuration

Automatic Volume Control - example

This article will explain the principle on how to setup and configure Automatic Gain Control (AGC) in Exigo.

Step 1: Add AVC Source Device To The System

To add an AVC Source Device to the system:

1. In Components view, open Devices.
2. In Kits and Accessories locate AVC Source Device.
3. Drag and drop AVC Source Device to System in the device tree.

Add AVC Source Device to the system

Step 2: Add the AVC Source Device To The Zone

To add the AVC Source Device to the zone:

1. Locate the desired AVC Source Device in the device tree.
2. Drag and drop the AVC Source Device to the Zone.

Add AVC Source Device to the zone

Step 3: Adjust the settings for the AVC Source Device(s)

To adjust the settings for the AVC device(s) in a zone:

1. Go to the designated Zone (top level).
2. Do the necessary settings.

AVC settings

Parameter Details

AVC Enabled: Enable/Disable the Automatic Volume Control (AVC).

Adjust Mode: Positive or Negative mode.

Positive: Gain adjustment is from zero at AVC threshold and adjusted positive. Audio Receiver should have a low base gain.

Negative: Gain adjustment is from zero at AVC max level and adjusted with negative gain downwards. Audio Receiver should have a high base gain.

Lower Threshold: Mic signal level where AVC start to work. Below this level no adjustment is done, and AVC Receiver should work on default base gain.

Default value at -45 dB is empirically measured using default mic sensitivity 5, and target ambient audio SPL level at 65 dBA.

Example: Threshold = -40 dB

When AVC Device measurement < -40 dB: No AVC adjustment

When AVC Device measurement > -40 dB: AVB adjust gain on Players 1 dB per dB above threshold

Upper Threshold: Mic signal level where AVC stops to work. Abowe this level no adjustment is done.

The difference between upper and lower threshold also defines the working range for AVC gain adjustments.

In negative AVC mode this also defines the ambient level where configured base output gain is reached (offset adjustment is zero).

Advanced Settings

Attack Rate (dB/sec): This determines how quickly the AVC adjusts gain on raising ambient audio level.

Decay Rate (dB/sec): This determines how quickly the AVC adjusts gain on falling ambient audio level.

Hysteresis (dB): Hysteresis around previous set ambient audio level before doing adjustments.

Far-End Lockout Time (sec): When playing audio in AVC Zone (far-end-signal) all AVC adjustments is locked. When far-end-signal ends, adjustments commences after this lockout-time. Lower values allows more adjustments in pauses of signal played.

AVC Devices

Source Selection Strategy: The AVC Receiver will receive ambient audio levels or Gain adjust values from a number of AVC Sources. This configures the selection strategy for final gain adjusts on AVC Receiver.

The different settings are: Highest, Average, Average Mid. Average and Average Mid require at least four AVC devices.

IP reliant configuration

AVC is reliant on the IP of each device to be able to work. This requires that the IP of each device is configured in EMT. This is done by:

A) GET from controller:

When performing a GET from the controller, the IP of all endpoints is written to the database and automatically entered in the AVC configuration

B) Manually enter IP:

Also possible to manually enter the IP of each device in the AVC configuration

Availability

A technical preview is available in Exigo 1.3.3.1.
Official release is available from Exigo 1.4 and newer.