# LADSPA plugins in Liquidsoap

LADSPA is a standard that allows software audio processors and effects to be plugged into a wide range of audio synthesis and recording packages.

If enabled, Liquidsoap supports LADSPA plugins. In this case, installed plugins are detected at run-time and are all available in Liquidsoap under a name of the form: `ladspa.plugin`, for instance `ladspa.karaoke`, `ladspa.flanger` etc..

The full list of those operators can be found using `liquidsoap --list-plugins`. Also, as usual, `liquidsoap -h ladspa.plugin` returns a detailed description of each LADSPA’s operators. For instance:

    ./liquidsoap -h ladspa.flanger
    *** One entry in scripting values:
    Flanger by Steve Harris <steve@plugin.org.uk>.
    Category: Source / Sound Processing
    Type: (?id:string,?delay_base:'a,?feedback:'b,
     ?lfo_frequency:'c,?max_slowdown:'d,
     source(audio='#e,video='#f,midi='#g))->
    source(audio='#e,video='#f,midi='#g)
    where 'a, 'b, 'c, 'd is either float or ()->float
    Flag: hidden
    Parameters:
    * id : string (default "")
        Force the value of the source ID.
    * delay_base : anything that is either float or ()->float (default 6.32499980927)
        Delay base (ms) (0.1 <= delay_base <= 25).
    * feedback : anything that is either float or ()->float (default 0.)
        Feedback (-1 <= feedback <= 1).
    * lfo_frequency : anything that is either float or ()->float (default 0.334370166063)
        LFO frequency (Hz) (0.05 <= lfo_frequency <= 100).
    * max_slowdown : anything that is either float or ()->float (default 2.5)
        Max slowdown (ms) (0 <= max_slowdown <= 10).
    * (unlabeled) : source(audio='#e,video='#f,midi='#g) (default None)

For advanced users, it is worth nothing that most of the parameters associated with LADSPA operators can take a function, for instance in the above: `max_slowdown : anything that is either float or ()->float` . This means that those parameters may be dynamically changed while running a liquidsoap script.