How to Use FFmpeg Superequalizer for 18-Band EQ

This article provides a practical guide on how to use the superequalizer audio filter in FFmpeg to achieve highly precise 18-band graphic equalization. You will learn the specific frequency bands mapped by this filter, the syntax required to adjust them, and concrete command-line examples to boost or cut specific frequencies in your audio files.

Understanding the Superequalizer Filter

The superequalizer filter in FFmpeg is a high-fidelity, 18-band graphic equalizer implemented using Fast Fourier Transform (FFT). Unlike the standard equalizer filter which only targets one frequency band at a time, superequalizer allows you to manipulate 18 fixed frequency bands simultaneously.

The 18 bands are pre-configured to the following center frequencies (in Hz):

1. 65 Hz (Sub-bass)
2. 92 Hz (Sub-bass)
3. 131 Hz (Bass)
4. 185 Hz (Bass)
5. 263 Hz (Low-mids)
6. 372 Hz (Low-mids)
7. 526 Hz (Midrange)
8. 745 Hz (Midrange)
9. 1050 Hz (Midrange)
10. 1490 Hz (Upper-mids)
11. 2100 Hz (Upper-mids)
12. 2970 Hz (Presence)
13. 4200 Hz (Presence)
14. 5950 Hz (Presence / Brilliance)
15. 8400 Hz (Brilliance)
16. 11900 Hz (Brilliance)
17. 16800 Hz (Brilliance / Air)
18. 23800 Hz (Air / Ultrasonic)

Filter Syntax and Parameters

The filter accepts 18 parameters, named b1 through b18, corresponding to each of the 18 bands.

• Value Type: Floating-point number.
• Default Value: 1.0 (no change to the original volume of the band).
• Behavior: The input values represent gain multipliers rather than decibels (dB).
  • 1.0 = 0 dB (neutral)
  • 2.0 = Approx. +6 dB boost
  • 0.5 = Approx. -6 dB cut
  • 0.0 = Complete attenuation (mute) of the band

You can define the bands using named parameters or positional parameters.

Named Parameter Syntax

superequalizer=b1=g1:b2=g2:b3=g3...

Positional Parameter Syntax

superequalizer=g1:g2:g3:g4:g5:g6:g7:g8:g9:g10:g11:g12:g13:g14:g15:g16:g17:g18

Practical Command-Line Examples

Example 1: Bass Boost

To boost the lower frequencies (65 Hz to 185 Hz) while leaving the middle and high frequencies untouched, multiply the first four bands by 2.0 and keep the rest at 1.0:

ffmpeg -i input.mp3 -af "superequalizer=b1=2:b2=2:b3=1.8:b4=1.5" output.mp3

Using positional shorthand, the same command looks like this:

ffmpeg -i input.mp3 -af "superequalizer=2:2:1.8:1.5:1:1:1:1:1:1:1:1:1:1:1:1:1:1" output.mp3

Example 2: Vocal Presence and Clarity Boost

To make vocals stand out, you can gently boost the midrange and presence frequencies (approx. 1050 Hz to 4200 Hz) while slightly rolling off the extreme sub-bass:

ffmpeg -i input.wav -af "superequalizer=b1=0.8:b2=0.8:b9=1.2:b10=1.4:b11=1.5:b12=1.5:b13=1.3" output.wav

Example 3: Treble Boost / High-End Air

To add sparkle and air to a mix, boost the high-frequency bands (from 8400 Hz up to 23800 Hz):

ffmpeg -i input.ogg -af "superequalizer=b15=1.3:b16=1.5:b17=1.8:b18=1.8" output.ogg

Example 4: De-essing / Harshness Reduction

If an audio track sounds too harsh or sibilant, you can cut the presence and lower brilliance frequencies (typically around 4200 Hz to 8400 Hz):

ffmpeg -i input.mp3 -af "superequalizer=b13=0.7:b14=0.6:b15=0.6" output.mp3