@prefix blop: . @prefix dct: . @prefix doap: . @prefix lv2: . @prefix morph: . @prefix opts: . @prefix units: . @prefix urid: . blop:tracker a lv2:Plugin ; lv2:project blop: ; lv2:symbol "tracker" ; lv2:microVersion 0 ; lv2:minorVersion 0 ; lv2:extensionData opts:interface ; lv2:optionalFeature lv2:hardRTCapable , urid:map ; lv2:port [ a lv2:CVPort , lv2:InputPort ; lv2:index 0 ; lv2:name "Gate" ; lv2:portProperty lv2:toggled ; lv2:symbol "gate" ] , [ a lv2:ControlPort , lv2:InputPort , morph:MorphPort ; lv2:default 100 ; lv2:index 1 ; lv2:maximum 0.5 ; lv2:minimum 0.00001 ; lv2:name "High Attack Rate" ; lv2:portProperty , lv2:sampleRate ; lv2:symbol "hattack" ; morph:supportsType lv2:CVPort ; units:unit units:hz ] , [ a lv2:ControlPort , lv2:InputPort , morph:MorphPort ; lv2:default 100 ; lv2:index 2 ; lv2:maximum 0.5 ; lv2:minimum 0.00001 ; lv2:name "High Decay Rate" ; lv2:portProperty , lv2:sampleRate ; lv2:symbol "hdecay" ; morph:supportsType lv2:CVPort ; units:unit units:hz ] , [ a lv2:ControlPort , lv2:InputPort , morph:MorphPort ; lv2:default 100 ; lv2:index 3 ; lv2:maximum 0.5 ; lv2:minimum 0.00001 ; lv2:name "Low Attack Rate" ; lv2:portProperty , lv2:sampleRate ; lv2:symbol "lattack" ; morph:supportsType lv2:CVPort ; units:unit units:hz ] , [ a lv2:ControlPort , lv2:InputPort , morph:MorphPort ; lv2:default 100 ; lv2:index 4 ; lv2:maximum 0.5 ; lv2:minimum 0.00001 ; lv2:name "Low Decay Rate" ; lv2:portProperty , lv2:sampleRate ; lv2:symbol "ldecay" ; morph:supportsType lv2:CVPort ; units:unit units:hz ] , [ a lv2:AudioPort , lv2:InputPort ; lv2:index 5 ; lv2:name "Input" ; lv2:symbol "in" ] , [ a lv2:AudioPort , lv2:OutputPort ; lv2:index 6 ; lv2:name "Output" ; lv2:symbol "out" ] ; dct:replaces , ; doap:name "Tracker" ; lv2:documentation """

This tracks an incoming signal and outputs the result.

The rate controls tell the plugin how quickly to respond to a change in input. Low values will mean a slower response - a setting of 0 will hold the last value, and a very high value will track the input exactly.

Attack rate is how quickly an upward change is tracked, and Decay for downward changes. There are two pairs of these - the one used depends on the level of the Gate.

Example uses:

  • An envelope tracker- use the ‘Gate Low’ track rates with the Gate held low, and run the output through a full-wave rectifier (an ABS() operator) to get an estimate of the level of a signal.
  • Sample and Hold- run a narrow pulse wave into the gate, set the ‘Gate High’ rates to maximum, and the ‘Gate Low’ rates set to 0.
  • Track and Hold- run a variable pulse wave into the gate, set the ‘Gate High’ rates to 0, and the ‘Gate Low’ rates set high. Varying the pulsewidth will vary the time the input is tracked, and when it is held.
""" .