FFmpeg superequalizer: 18-Band Audio Equalizer Guide

The FFmpeg superequalizer filter is an 18-band graphic equalizer based on a classic analog design that allows precise spectral shaping of audio streams. This guide covers the structure of the filter, the specific center frequencies for each of the 18 bands, how the gain scale functions, and practical command-line examples for common audio adjustments.

How the superequalizer Filter Works

Unlike parametric equalizers that allow you to specify arbitrary frequencies and bandwidths (Q factors), superequalizer uses 18 fixed frequency bands spaced across the audible human hearing range.

Each band is addressed using the parameters 1b through 18b.

Gain Values

  • Range: 0.0 to 20.0
  • Neutral (no change): 1.0
  • Cut (attenuation): Values between 0.0 and 1.0 (with 0.0 representing maximum cut/silence)
  • Boost (amplification): Values between 1.0 and 20.0

Any band omitted from the filter argument defaults to 1.0.

The 18 Frequency Bands

The center frequencies for the bands in superequalizer are predetermined:

  • 1b: 65 Hz (Sub-bass)
  • 2b: 92 Hz (Bass)
  • 3b: 131 Hz (Bass)
  • 4b: 185 Hz (Upper bass)
  • 5b: 262 Hz (Low midrange)
  • 6b: 370 Hz (Midrange)
  • 7b: 523 Hz (Midrange)
  • 8b: 740 Hz (Midrange)
  • 9b: 1047 Hz (Midrange)
  • 10b: 1480 Hz (Upper midrange)
  • 11b: 2093 Hz (Upper midrange)
  • 12b: 2960 Hz (Presence)
  • 13b: 4186 Hz (Presence)
  • 14b: 5920 Hz (Highs)
  • 15b: 8372 Hz (Highs)
  • 16b: 11840 Hz (Brilliance)
  • 17b: 16744 Hz (Air)
  • 18b: 20000 Hz (Ultra-high air)

Basic Syntax

The filter is applied using the -af (audio filter) flag:

ffmpeg -i input.wav -af "superequalizer=1b=1.0:2b=1.0:...:18b=1.0" -c:a pcm_s16le output.wav

Practical Examples

1. Bass Boost

To boost low-end punch while leaving higher frequencies untouched, increase the values of bands 1 through 4:

ffmpeg -i input.mp3 -af "superequalizer=1b=2.5:2b=2.0:3b=1.6:4b=1.2" output.mp3

2. High-Frequency Taming (De-Essing / Warmth)

To reduce harshness and sibilance, attenuate the bands between 4 kHz and 12 kHz:

ffmpeg -i input.wav -af "superequalizer=13b=0.7:14b=0.5:15b=0.5:16b=0.6" output.wav

3. Vocal Clarity and Midrange Lift

To improve vocal intelligibility in speech or podcasts, roll off deep sub-bass rumble, boost the core vocal presence, and add top-end clarity:

ffmpeg -i vocal.wav -af "superequalizer=1b=0.2:2b=0.5:8b=1.3:9b=1.5:10b=1.5:11b=1.4:14b=1.2" vocal_enhanced.wav

4. V-Shape (Loudness Contour)

A common preset for music that enhances both low-end weight and high-end air while scooping the midrange:

ffmpeg -i track.flac -af "superequalizer=1b=2.0:2b=1.7:3b=1.4:7b=0.8:8b=0.7:9b=0.8:14b=1.3:15b=1.6:16b=1.8" track_eq.flac

Preventing Clipping

Boosting bands significantly can push output levels beyond 0 dBFS, resulting in digital distortion. To avoid clipping, add the volume or alimiter filter directly after superequalizer:

ffmpeg -i input.wav -af "superequalizer=1b=3.0:2b=2.5,volume=0.7" output.wav