LADSPA Center Cut

This LADSPA plugin extracts the “center channel” from a stereo audio file; of course, such a channel does not exist; the plugin extracts the common signal between right and left channels. Thus, it complements the “karaoke” effect, also known as OOPS. The plugin can also create this “karaoke” effect, but with a stereo output.

This plugin was ported from WinAmp's DSP Center Cut plugin. Kudos to the original author.

Nothing more than for any other LADSPA plugin:

• GCC;
• LADSPA-SDK.

The version number follows the original plugin version number and suffixes a local version number.

Version 1.4.0.2

The development version is available through subversion. The follow command allows you to download it:

svn co https://svn.ptaff.ca/ladspacc/trunk/

Note that the ptaff.ca certificate is self-signed; it's possible that you get a warning — you may safely ignore it.

applyplugin in.wav out.wav /path/to/ladspacc.so ladspacc 1

Extracts from in.wav the center of the stereo image and writes it to out.wav

applyplugin in.wav out.wav /path/to/ladspacc.so ladspacc 3 300

Removes from in.wav the sides and frequencies under 300Hz; writes the result in out.wav.

mplayer -ao oss -af ladspa=/path/to/ladspacc.so:ladspacc:1 audio.ogg

Uses the plugin in MPlayer to play the center channel; not all output plugins (-ao parameter) give good results.

Two parameters control the plugin:

1) The operation mode, given by an integer value between 0 and 3:

0	Removes the center channel, keeps the sides.
1	Removes the sides, keeps the center.
2	Removes the center, keeps the sides and basses (moved to the sides).
3	Removes the sides and basses, keeps the center.

2) The bass cut-off frequency for modes 1 and 3:

A value between 0 and 22050; default value is 200.

Known bugs:

• Due to the signal processing method, the resulting sound shows some distortion (echo, warbling); the algorithm is still worked on;

• Because the plugin needs an initial amount of data to start processing, latency is added and data output rate might not be the same as the input's; this probably explains the uneven quality of MPlayer output plugins.

Should you find a new bug, you must report it to ladspacc.wayne@ptaff.ca

Patrice Levesque; original code from Moitah.

Copyright © 2009 Patrice Levesque.

ladspacc is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.