Tremolo Effect Chain Operator in Ecasound

This article explains how to apply a tremolo modulation effect using Ecasound, a versatile command-line multitrack audio processing utility. It identifies the dedicated native chain operator for tremolo modulation, details its syntax and control parameters, and provides actionable command-line examples to demonstrate how to process audio files directly from the terminal.

The chain operator used to apply a native tremolo modulation effect in Ecasound is -etm.

Syntax and Parameters

The operator takes two mandatory parameters separated by a comma:

-etm:tremolo-speed,depth

• tremolo-speed: Specifies the rate of the volume oscillation, measured in beats per minute (BPM).
• depth: Specifies the modulation depth as a percentage ranging from 0 to 100. A value of 0 results in no modulation (the original signal remains unchanged), while 100 produces maximum amplitude attenuation at the troughs of the modulation cycle.

Practical Example

To apply a tremolo effect to an audio file named input.wav with a modulation rate of 120 BPM and a depth of 75%, and save the result to output.wav, run the following command:

ecasound -i input.wav -o output.wav -etm:120,75

The -etm operator alters the signal amplitude dynamically over time by multiplying the incoming signal with a low-frequency oscillator (LFO), creating the rhythmic pulsing sensation characteristic of classic analog tremolo circuits.