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x42-fil4.1 |
README.md
fil4.lv2 - Parametric Equalizer
fil4.lv2 is a 4 band parametric equalizer with additional low+high shelf filters, Low and High-pass, as well as an optional, custom GUI displaying the transfer function and realtime signal spectrum or spectrogram.
It is available as LV2 plugin and standalone JACK-application.
Usage
The parameters can be set by moving the nodes in the graph or directly via control knobs:
- Shift + click: reset to default
- Right-click on knob: toggle current value with default, 2nd click restore.
- Right-click on button: temporarily toggle, until release
The Ctrl key allows for fine-grained control when dragging or using the mouse-wheel on a knob.
Mouse-wheel granularity:
- Gain: 1dB (fine: 0.2dB)
- Frequency: 1/6 octave (fine: 1/24 octave)
- Bandwidth: 1/3 octave (fine: 15 steps for a ratio 1:2)
All switches and controls are internally smoothed, so they can be used 'live' without any clicks or zipper noises. This should make this plugin a good candidate for use in systems that allow automation of plugin control ports, such as Ardour, or for stage use.
Install
Binaries for Intel-platform (GNU/Linux, OSX and Windows) are available for releases. Most GNU/Linux distributions include this fil4 as part of the x42-plugins collection.
Compiling fil4 requires the LV2 SDK, jack-headers, gnu-make, a c++-compiler, libpango, libcairo and openGL (sometimes called: glu, glx, mesa).
git clone https://github.com/x42/fil4.lv2.git
cd fil4.lv2
make submodules
make
sudo make install PREFIX=/usr
Note to packagers: the Makefile honors PREFIX
and DESTDIR
variables as well
as CXXFLAGS
, LDFLAGS
and OPTIMIZATIONS
(additions to CXXFLAGS
), also
see the first 10 lines of the Makefile.
You really want to package the superset of x42-plugins.
Screenshots
Details
Fil4 is based on fil-plugins LADSPA by Fons Adriaensen.
Fil4 consists of four 2nd order resonant filters using a Regalia-Mitra style lattice filter, which has the nice property of being stable even while parameters are being changed.
The high/low-shelf filters are standard 2nd order biquad/IIR filters.
High and Low pass are 2nd order resonant filters (-12dB/octave).
- Quality 0.0: -6dB at cutoff-freq (no feedback)
- Quality 0.7: -3dB at cutoff-freq
- Quality 1.0: 0dB at cutoff (resonant)
All filters are zero latency with correct equivalent analog gain at Nyquist (signal phase-shift at Nyquist frequency is zero).
Why another EQ?
Because I was unhappy with all existing ones: they are either not portable (OSX, Windows, BSD, GNU/Linux,..), or simply unprofessional textbook biquad filters (phase-shifts, not decramped, comb-filter effect when values are changed), or lack important attention to the detail (control knob granularity), or are not available as LV2, or a combination of those issues.