Adjust 18-Band Gains in FFmpeg Superequalizer

This article provides a practical guide on how to adjust individual band gains using the 18-band superequalizer audio filter in FFmpeg. You will learn the exact command-line syntax, understand how the gain values work, and see the frequency mapping for each of the 18 bands so you can precisely shape your audio's frequency response.

Understanding the Superequalizer Syntax

The superequalizer filter allows you to adjust 18 specific frequency bands. The gain for each band is defined as a floating-point multiplier, where:

  • 1.0 is the default value (unity gain, meaning no change).
  • Values between 0.0 and 1.0 attenuate (lower) the volume of that frequency band.
  • Values above 1.0 boost the volume of that frequency band (up to a maximum of 20.0).

The basic syntax for the filter is:

-af "superequalizer=b1=gain1:b2=gain2:...:b18=gain18"

You do not need to specify all 18 bands in your command. Any band you omit will automatically remain at its default value of 1.0.

Frequency Band Mapping

Each parameter from b1 to b18 corresponds to a specific center frequency:

  • b1: 65 Hz (Sub-bass)
  • b2: 92 Hz
  • b3: 131 Hz
  • b4: 185 Hz
  • b5: 263 Hz (Bass / Low-mids)
  • b6: 372 Hz
  • b7: 526 Hz
  • b8: 744 Hz
  • b9: 1052 Hz (Midrange)
  • b10: 1488 Hz
  • b11: 2104 Hz
  • b12: 2976 Hz (Upper-mids)
  • b13: 4209 Hz
  • b14: 5953 Hz
  • b15: 8419 Hz (Presence / Treble)
  • b16: 11907 Hz
  • b17: 16839 Hz
  • b18: 23814 Hz (Brilliance / Air)

Practical Examples

Example 1: Boosting the Bass

To boost the lowest bass frequencies (65 Hz and 92 Hz) by 50% while leaving the rest of the audio untouched, set b1 and b2 to 1.5:

ffmpeg -i input.mp3 -af "superequalizer=b1=1.5:b2=1.5" output.mp3

Example 2: Cutting High-Frequency Hiss

To reduce high-frequency noise or hiss, you can attenuate the top bands (from 8.4 kHz up to 23.8 kHz) by setting them to 0.3:

ffmpeg -i input.wav -af "superequalizer=b15=0.3:b16=0.3:b17=0.3:b18=0.3" output.wav

Example 3: Creating a Custom Preset (Classic "V" Shape)

To boost both the bass and treble while slightly dipping the midrange, you can chain multiple band adjustments together:

ffmpeg -i input.ogg -af "superequalizer=b1=1.5:b2=1.4:b3=1.3:b8=0.8:b9=0.7:b10=0.8:b16=1.3:b17=1.4:b18=1.5" output.ogg