How to Use the FFmpeg Reverb Filter

This article explains how to apply a realistic reverb effect to your audio files using FFmpeg’s native areverb filter. You will learn the basic command syntax, understand the key parameters that control the environment’s sound, and explore practical examples ranging from small room acoustics to large hall echoes.

To apply reverb in FFmpeg, you use the audio filter flag (-af) followed by the areverb filter. This filter simulates an acoustic space by adjusting parameters like room size, damping, and the mix between the original (dry) and reverberated (wet) signals.

The Basic Command Syntax

The basic structure of the command is as follows:

ffmpeg -i input.mp3 -af "areverb=parameter1=value:parameter2=value" output.mp3

Key Parameters of the areverb Filter

You can customize the reverb effect by tweaking these essential parameters:

• room_size: Sets the size of the simulated room (0 to 100). Higher values create a longer decay time, simulating a larger space. (Default: 100)
• reverberance: Controls the amount of feedback and overall wetness of the reverb (0 to 100). Higher values make the reverb more prominent. (Default: 50)
• damping: Simulates sound absorption by walls and air (0 to 100). High damping values quickly reduce high frequencies, resulting in a darker, warmer reverb. (Default: 50)
• wet_gain: Adjusts the volume of the wet (reverberated) signal in decibels (dB). (Default: -3 dB)
• dry_gain: Adjusts the volume of the original (unaffected) signal in decibels (dB). (Default: -3 dB)

Practical Examples

1. Large Cathedral / Concert Hall Reverb

For a deep, spacious, and long-lasting reverb effect, increase the room size and reverberance while lowering the damping to keep the high frequencies alive.

ffmpeg -i input.wav -af "areverb=room_size=100:reverberance=90:damping=20:wet_gain=-3:dry_gain=-3" output.wav

2. Small, Warm Room Reverb

To simulate a small, cozy room with acoustic treatment, use a low room size, low reverberance, and higher damping.

ffmpeg -i input.wav -af "areverb=room_size=30:reverberance=40:damping=70:wet_gain=-6:dry_gain=0" output.wav

3. “Wet Only” Reverb (No Dry Signal)

If you want to isolate only the reverb trail (useful for sound design and advanced audio mixing), set the dry gain to a very low level (e.g., -70 dB or lower).

ffmpeg -i input.wav -af "areverb=room_size=80:reverberance=60:wet_gain=0:dry_gain=-144" output.wav