A real time Equalizer for sound out.


Equalizer basics

A equalizer is a tool that transform the sound in a defined way. The ways that the sound can be transformed is by changing the strenght (volume) of the sound in independent frequency bands.

One important aspect of a equalizer is how many bands there are, and how the frequency space is divided up in to a set of bands, ie which boarder values to use. Another important aspect is how many dB (decibel) it can turn up/down the sound.

Requrements for this Equalizer

  • It should operate on sound out in real time.
  • It should have >= 10 frequency bands.

  • It should allow +/- 24 dB or more.
  • Via a GUI and a CLI users shall be able to
    • change the volume of each frequency band
    • turn on/off the equalizer
    • save and load profiles (A profile contain the volume of each band.)
    • do operations on all bands such as multiplicy all band volumes with a value. This can perhaps be implemented as a slider.

Use Cases

  • Johns Subwoofer is too loud compared with the Speakers. So he would like to lower the Basses. But he can't do so with some players that doesn't have an Equalizer.


This specification covers feature specifications for Ubuntu and Launchpad. It is not meant as a more general specification format. - I dont understand what to put here






Why +/- 24 dB or more?

While people with normal hearing would probaly work out fine with +/- 12 dB, people with hearing loss that differ a lot betwen low and high frequencies will find +/- 12 dB too limiting. About 10% of the population suffer from hearing loss. This should be the description of why this spec is being defined.

Scope and Use Cases


Implementation Plan



Should this tie in with PulseAudio (http://blueprints.launchpad.net/ubuntu/+spec/cleanup-audio-jumble)? - -- funkyHat 2007-01-20 18:02:42

Outstanding Issues


BoF agenda and discussion

Added idea


EqualizerForSoundOut (last edited 2008-11-21 13:46:54 by chocwise)