Dynamic Channel Panning in Ecasound Interactive Mode

This article explains how to configure and control dynamic channel panning in real time using Ecasound’s Interactive Mode (IAM). You will learn how to apply the stereo panning effect operator, navigate chain operators within the interactive prompt, dynamically alter panning values during playback, and assign automated continuous controllers for hands-free modulation.

1. Launching Ecasound with Panning Enabled

To adjust panning dynamically, the processing chain must be initialized with the stereo panning operator (-epp). This operator takes a single parameter representing the stereo balance from 0 (hard left) to 100 (hard right), with 50 being center.

Start Ecasound in interactive mode using the -c flag along with your audio setup:

ecasound -c -i:input.wav -o:alsa -epp:50

Once loaded, Ecasound presents the interactive command prompt (ecasound ('h' for help) >).

2. Controlling Panning Manually in Real Time

In Interactive Mode, you can change the panning parameter on the fly while the engine is running.

First, start audio processing:

start

To adjust the pan value, identify and select the -epp operator. If it is the first or only operator on the chain:

cop-select 1

Modify the panning position dynamically using cop-set-param:

cop-set-param 1 0    # Hard Left
cop-set-param 1 50   # Center
cop-set-param 1 100  # Hard Right
cop-set-param 1 25   # Left-Center

Parameter 1 corresponds to the pan value. Any change takes effect immediately without audio dropouts.

3. Automating Dynamic Panning with Controllers

If you want continuous, automated panning (such as an auto-pan LFO effect), you can attach a controller directly inside Interactive Mode without restarting the session.

To attach a low-frequency oscillator (sine wave) to control panning:

ctrl-add -kos:1,0,100,0.5,0

In this command:

1 attaches the controller to parameter 1 (the pan value) of the currently selected operator.
0 is the minimum value (hard left).
100 is the maximum value (hard right).
0.5 is the frequency in Hertz (one full pan cycle every 2 seconds).
0 is the initial phase offset.

To verify or modify the controller during playback, use ctrl-list to inspect active modulators, or remove it with ctrl-remove to return to manual control.