---
title: "Equalizer"
manual: "Kitodo.Presentation"
version: "dev-demo"
source: "Features/MediaPlayer/Equalizer.rst"
rendered: "2026-09-27T16:21:24+00:00"
---

# Equalizer {#equalizer}

-   [Features](#features)
-   [Configuration](#configuration)
-   [Developers](#developers)

## Features {#features}

-   Interface to change equalizer parameters and preview frequency/phase response
-   Presets (predefined via Typoscript, user-defined in Local Storage)
-   Modes:

    -   Graphic/band equalizer (via peaking filters)
    -   RIAA equalizer (combining lowcut, lowshelf and highshelf filters)

## Configuration {#eq-configuration}

The configuration options are passed to the Equalizer in the default Fluid template.

```typoscript
equalizer {
  // Whether or not the equalizer control is shown
  enabled = 1

  // Key of the preset that should be selected by default
  default = 3-band

  // Presets that are available to the user as dropdown
  presets {
    // "band-iso" defines an ISO graphic/band equalizer. Starting at 1000 Hz,
    // bands are added by stepping up and down by the specified number of octaves
    3-band {
      // Used translation key: control.sound_tools.equalizer.preset.group.graphic
      group = graphic
      mode = band-iso
      label = 3-Band
      // One decade = log2(10) octaves
      octaveStep = 3.32
    }

    // It is also possible to specify bands manually via "mode = band".
    // The following preset is (virtually) equivalent to the previous.
    3-band-manual {
      group = graphic
      mode = band
      label = 3-Band
      bands {
        0 {
          frequency = 100
          octaves = 3.32
          gain = 0
        }

        1 {
          frequency = 1000
          octaves = 3.32
          gain = 0
        }

        2 {
          frequency = 10000
          octaves = 3.32
          gain = 0
        }
      }
    }

    // In "mode = riaa", the time constants of a RIAA-style EQ can be specified.
    // Parameters that are not needed may be omitted (in particular, deepBaseRolloff).
    riaa-iec {
      group = riaa
      mode = riaa
      label = Enhanced RIAA / IEC
      params {
        trebleCut = 75
        baseBoost = 318
        baseBoostRolloff = 3180
        deepBaseRolloff = 7950
      }
    }
  }
}
```

## Developers {#developers}

### Testing {#testing}

For testing that the equalizer produces a correct frequency response, check the "Equalizer Test" page ([https://localhost:9000/equalizer.html](https://localhost:9000/equalizer.html)) hosted in [Webpack Dev Server](Developers.html#webpack_dev_server), which plays sine waves at constant amplitudes and renders the FFT.

### Class Overview {#class-overview}

-   `EqualizerPlugin`: Player plugin to set up the equalizer and connect it to an instance of `DlfMediaPlayer`.

    -   `EqualizerView`: User interface for display and manipulation of EQ parameters and presets of an `Equalizer`.
    -   `Equalizer`: Top-level class for actual equalization. Connects to an `AudioContext`, adds an FFT node that is used to test the frequency response, loads presets, and delegates to implementations of specific modes/filtersets (`BandEq` and `RiaaEq`).