Alsaequal is a real-time adjustable equalizer plugin for ALSA. It can
be adjusted using any ALSA compatible mixer, e.g. alsamixergui.

Alsaequal uses the Eq CAPS LADSPA Plugin for audio processing, actually
alsaequal is a generic LADSPA plugin interface with real-time access to
the LADSPA controls (the LADSPA plugin included with alsa doesn't allow
for real-time controls) but it was developed for and only tested with
Eq CAPS LADSPA plugin. You are welcome to try it with other plugins, it
may work. Let me know how it goes, you can reach me at
<[email protected]>.

INSTALL:
Download the latest version of the plugin and:

tar xvjf alsaequal-x.x.tar.bz2
cd alsaequal-x.x
make
sudo make install

DEPENDANCIES:
- CAPS LADSPA Package -- <http://quitte.de/dsp/caps.html>, it's
available as a package in Ubuntu, i.e. "sudo apt-get install caps"
- ALSA Development headers and alsa-lib -- you may already have it
as part of your linux distro, you can install in Ubuntu with
"sudo apt-get install libasound2-dev"


USAGE:
After installing you will have to modify your local .asoundrc alsa
configuration file, adding something like this. If you're not using
sound card 0 modify "plughw:0,0" accordingly.

ctl.equal {
	type equal;
}

pcm.plugequal {
    type equal;
	slave.pcm "plughw:0,0";
}

pcm.equal{
    type plug;
    slave.pcm plugequal;
}

You can play audio through alsaequal by addressing the plugin by name, e.g.:
mpg123 -a equal 06.Back_In_Black.mp3

You can adjust the frequency response of the equalizer by using any alsa
mixer, e.g.:  alsamixer -D equal

HELP:
If you need any help just let me know, you can reach me at:
<[email protected]>. Please keep in mind that this is
a development release and may have bugs.

More Advanced Stuff:
If you want to try out alsaequal with other plugins the configuration
(asoundrd) structure follows:

ctl.<name_equal> {
	type equal;
	controls -- filename used to store the equalizer settings,
					the default is $HOME/.alsaequal.bin
	library -- location of the LADSPA library, the default is
					"/usr/lib/ladspa/caps.so"
	module -- module name within the LADSPA library, the deafault
					is "Eq"
	channels -- number of channels, the default is 2
}

pcm.<name_pcm> {
	type equal;
	slave.pcm -- sound card to output to, will probably have to
					be a plug since alsaequal only supports
					floating point numbers, a "plug" will convert
					the data type, outputig directly to hw won't;
	controls -- filename used to store the equalizer settings,
					the default is $HOME/.alsaequal.bin
	library -- location of the LADSPA library, the default is
					"/usr/lib/ladspa/caps.so"
	module -- module name within the LADSPA library, the deafault
					is "Eq"
	channels -- number of channels, the default is 2
}

You will also probably need to pump the data through a plug to change
the format to float, which is all alsaequal supports.

pcm.<name_pcm_plug>{
    type plug;
    slave.pcm <name_pcm>;
}