Ecasound Continuous Peak Level Monitoring Command

In Ecasound’s Interactive Mode (EIAM), the primary command used to enable continuous peak and input level monitoring is start-monitoring (shorthand mon). This article explains how the start-monitoring command works, how to configure chain operators like -ev to view real-time peak amplitudes, and the exact steps to initiate continuous level metering in a terminal session.

The Monitoring Command: start-monitoring

In Ecasound Interactive Mode, standard playback or recording is started with the start command. However, to monitor incoming audio signals and their peak levels continuously without committing audio data to disk or write-capable targets, Ecasound provides:

start-monitoring

You can also use its shorthand equivalent:

mon

When issued, the engine starts processing audio from all configured inputs. Audio flows through the chain setup, calculating dynamic statistics such as peak and RMS levels, while disabling recording to file-based outputs.

Displaying Peak Levels with the -ev Operator

While start-monitoring activates the engine, displaying peak amplitude data requires attaching a level-analysis operator to the active chain. Ecasound uses the -ev (Envelope/Peak Level) operator to track peak and average amplitude in decibels (dB) and linear percentages.

To add the peak analyzer directly inside Interactive Mode:

c-add -ev

Alternatively, you can launch Ecasound with the operator already assigned from the command line:

ecasound -c -i alsa,default -ev

Step-by-Step Workflow in Interactive Mode

Follow these steps to establish a continuous peak monitoring session inside an interactive terminal:

1. Launch Interactive Mode:

   ecasound -c

2. Add an Audio Input: Specify the audio source (e.g., an ALSA, JACK, or OSS device):

   ai-add alsa,default

3. Attach the Peak Level Analyzer: Add the peak and envelope volume analysis operator to the current chain:

   c-add -ev

4. Start Continuous Monitoring: Trigger the monitoring state:

   start-monitoring

   Or:

   mon

5. Stop Monitoring: To halt the level monitoring session at any time, run:

   stop

Key Commands Summary