The <arpeggiator> element

As of 1.26.0, DecentSampler has a built-in arpeggiator. Unlike the note sequencer, which plays back a fixed, pre-authored pattern, the arpeggiator reacts live to whichever notes are currently held down: hold a chord and it generates a stream of notes from that chord, in the order and octave range you choose, for as long as you hold it.

The <arpeggiator> element is how you configure the arpeggiator. There should be exactly one <arpeggiator> element in each <DecentSampler> file, as a direct child of the root <DecentSampler> element (a sibling of <groups>, <midi>, <noteSequences>, etc.):

<DecentSampler>
  <groups>...</groups>
  <arpeggiator enabled="true"
               arpOrder="up"
               arpOctaveRange="2"
               arpOctaveMode="replayPerOctave"
               arpStepCount="16"
               arpGateLength="0.75"
               arpFollowGlobalTempo="true"
               arpSyncDivision="noteOneSixteenth"
               arpRateMultiplier="1.0"
               arpOverrideBpm="120.0"/>
</DecentSampler>

Every attribute on <arpeggiator> can also be set from a knob, button, menu, or modulator (LFO/MIDI CC) using the arpeggiator binding type — see Appendix B and the how-to guide for details.

Attributes

enabled (optional): Whether the arpeggiator is armed. When armed, it takes over every note played anywhere on the keyboard — the raw notes are not also passed through to the sample playback engine. Valid values are true and false. Default: false.
arpOrder (optional): The order in which held notes (and their octave-expanded copies) are played. See Order Modes below for the full list and worked examples. Default: up.
arpOctaveRange (optional): How many octaves the held notes are spread across, counting the octave you’re actually holding. 1 means no octave duplication at all — just the notes you’re holding. Whole number from 1 to 8. Default: 1.
arpOctaveMode (optional): How the octave-expanded copies are woven into the pattern. replayPerOctave repeats the held-note pattern once per octave (the octave you’re holding, then the whole pattern again an octave up, and so on) — this is how most hardware/software arpeggiators behave. interleaveByPitch instead merges every note across every octave into one pitch-sorted list before applying the order. Default: replayPerOctave.
arpStepCount (optional): A hard ceiling on how many notes make up one cycle of the pattern, from 1 to 16. If the held chord × octave range would produce more notes than this, the pattern is truncated to the first arpStepCount notes (built according to arpOctaveMode) — it is never padded. Default: 16.
arpGateLength (optional): How long each note rings out, as a fraction of one step’s duration. 0.5 means each note is cut roughly halfway through the step, leaving a gap before the next one; 1.0 means the note rings for the full step and (depending on the sample’s own release/loop behavior) may audibly overlap with the next note. Floating point number, 0 or greater. Default: 0.75.
arpFollowGlobalTempo (optional): Whether the arpeggiator’s rate tracks the host/DAW’s tempo. When true, the rate is computed from the current tempo and arpSyncDivision. When false, the rate is computed from arpOverrideBpm and arpSyncDivision instead, ignoring whatever the host reports. Valid values are true and false. Default: true.
arpSyncDivision (optional): The musical note value of one step, e.g. noteOneSixteenth for a 16th-note arpeggio. Valid values: noteOneSixtyFourthTriplet, noteOneSixtyFourth, noteOneThirtySecondTriplet, noteOneSixtyFourthDotted, noteOneThirtySecond, noteOneSixteenthTriplet, noteOneThirtySecondDotted, noteOneSixteenth, noteOneEighthTriplet, noteOneSixteenthDotted, noteOneEighth, noteOneFourthTriplet, noteOneEighthDotted, noteOneFourth, noteOneHalfTriplet, noteOneFourthDotted, noteOneHalf, noteOneTriplet, noteOneHalfDotted, noteWhole, noteWholeDotted. Default: noteOneSixteenth.
arpRateMultiplier (optional): A continuous multiplier applied on top of arpSyncDivision’s rate — higher values play faster. This is the attribute you’d bind a knob or an LFO to if you want a live, sweepable rate control rather than snapping between discrete note values. Floating point number, 0.01 to 100. Default: 1.0.
arpOverrideBpm (optional): The tempo used to compute the rate when arpFollowGlobalTempo="false". Floating point number, 1 to 1000. Default: 120.0.

Order Modes

Given the chord C4-E4-G4 (MIDI notes 60, 64, 67) with arpOctaveRange="2" and arpOctaveMode="replayPerOctave", the expanded note pool is 60, 64, 67, 72, 76, 79 (the chord, then the same chord an octave up). Here’s what each arpOrder value produces:

`arpOrder`	One full cycle
`up`	60, 64, 67, 72, 76, 79 → loops back to 60
`down`	79, 76, 72, 67, 64, 60 → loops back to 79 (the exact reverse of `up`)
`up_down`	60, 64, 67, 72, 76, 79, 76, 72, 67, 64 → loops back to 60 (top/bottom note plays once per cycle)
`up_down_inclusive`	60, 64, 67, 72, 76, 79, 79, 76, 72, 67, 64, 60 → loops back to 60 (top/bottom note repeats at each turnaround)
`down_up`	79, 76, 72, 67, 64, 60, 64, 67, 72, 76 → loops back to 79
`down_up_inclusive`	79, 76, 72, 67, 64, 60, 60, 64, 67, 72, 76, 79 → loops back to 79
`as_played`	Whatever order you actually pressed the notes in, replayed per octave. If you pressed G, then C, then E, this plays 67, 60, 64, 79, 72, 76. (If you happened to press them low-to-high, this is identical to `up`.)
`random`	A note is picked at random from the pool on every step. The same note can repeat back-to-back.
`random_no_repeat`	Same as `random`, but the same note never plays twice in a row.

Example

This example arms the arpeggiator at 16th notes, tracking the host tempo, spread across 2 octaves:

<DecentSampler>
  <groups>
    <group>
      <sample path="Samples/Piano-C4.wav" rootNote="60" loNote="0" hiNote="127"/>
    </group>
  </groups>
  <arpeggiator enabled="true"
               arpOrder="up_down_inclusive"
               arpOctaveRange="2"
               arpOctaveMode="replayPerOctave"
               arpGateLength="0.6"
               arpFollowGlobalTempo="true"
               arpSyncDivision="noteOneSixteenth"/>
</DecentSampler>

For a full discussion of how to bind knobs and modulators to the arpeggiator, see the tutorial on how to use the arpeggiator.