Wavetables

Wavetables are a different kind of animal from every other input on this site. A wavetable WAV isn’t a recording of a note — it’s a stack of single-cycle waveforms, each exactly 2048 samples long, that the target device’s wavetable oscillator sweeps through under LFO or manual control.

Because of that, wavetables skip the whole analysis pipeline: no trimming, no envelope detection, no loop hunting, no normalization. The file is copied to the target bit-for-bit (preserving Serum’s clm metadata chunk so the target device knows how to slice it), and the exporter generates the surrounding preset with envelope and filter parameters chosen from spectral analysis of the wavetable itself.

patch-press scan-wavetables "~/wavetables/Liam Wavetables" configs/LiamWT

Format requirements

• WAV file, mono or stereo, 16-bit or 32-bit float.
• At least 2048 samples. Each 2048-sample block is one frame in the wavetable.
• If Serum’s clm chunk is present, patch-press preserves it byte-for-byte in the output. This is how the Deluge distinguishes wavetables from raw samples.

A length that isn’t an exact 2048-multiple is fine: the trailing partial window is ignored, matching how the Tracker itself floors to whole windows. Polyend’s own stock wavetables need this — they ship a few samples shy of 256 windows (e.g. 524267 = 255 windows + 2027 samples). The file is still analysed normally on its whole windows and the config is flagged REVIEW noting how many samples were dropped. Only a file shorter than a single 2048-sample window is rejected.

Stereo wavetables

Stereo is accepted, and what happens to it depends on the target — the two devices genuinely differ:

• Polyend Tracker Mini / Tracker+: both channels ship. The .pti length field counts frames per channel, so the window count is unchanged and the PCM is planar (all left, then all right) exactly like a stereo sample instrument.
• Deluge and 1010music Bento: downmixed to mono. The Deluge’s wavetable oscillator is mono-only and the firmware won’t force-load a stereo file as a wavetable at all; the Bento rejects one outright with Wavetables must be mono WAVs. The copy is no longer bit-for-bit for these files: it’s re-encoded at the source’s own bit depth, truncated to whole windows, with any clm chunk carried across.

Downmixing is a real loss for material designed as stereo — Polyend’s own stereo bank has tables whose channels correlate as low as −0.32, where mono summing cancels content rather than just narrowing it. So it’s done only where the device leaves no choice.

The archetype analysis always runs on the mono sum, on every target.

Archetype detection

scan-wavetables analyzes each file’s per-frame spectral content — brightness (centroid), flatness (noise-vs-tonal), odd/even harmonic ratio, timbral variance across the frames — and picks one of six archetypes. Each archetype maps to a canned set of Deluge parameters (envelope shape, filter cutoff, LFO2 rate/depth, starting WT position).

Archetype	When it’s picked	Vibe
drone	High spectral flatness (noisy, inharmonic frames)	Textural, FX, no clear pitch
evolving_pad	Large timbre range across frames (frames very different)	Long attack, table sweep provides the movement
pluck	Bright + odd-harmonic-dominant	Fast attack, no sustain, hollow character
lead	Bright + not odd-dominant	Fast attack, sustained, warm
bass	Dark + even-harmonic-dominant	Snappy, low-end focused
pad	Everything else (default)	Slow attack, long release

The heuristics were calibrated by ear against the Echo Sound Works Core Tables corpus.

Config shape

source:
  type: wavetable
  path: /path/to/Warm Pad 01.wav

wavetable:
  archetype: pad
  wt_position: 0.15         # starting frame (0.0 = first, 1.0 = last)
  lfo2_rate: 0.30
  lfo2_depth: 0.60
  filter_cutoff: 0.55
  attack: 0.70
  decay: 0.50
  sustain: 0.90
  release: 0.75
  filter_type: lpf

output:
  name: WarmPad01

Every 0–1 parameter is a plain fraction; the exporter maps it to the Deluge’s signed-32-bit param range.

Overriding the archetype

If the auto-detection picked something you disagree with, either:

• Re-scan with --archetype to force one archetype across the whole folder:

  patch-press scan-wavetables "~/wavetables/Basses" configs/Basses --archetype bass
  

• Or edit the YAML for that one file (archetype: and the parameter block) and re-run sample.

scan-wavetables options

Option	Default	What it does
--archetype pad\|pluck\|bass\|lead\|drone\|evolving_pad	auto	Force a single archetype for every file in the folder.

On the SD card

• Deluge: SYNTHS/<name>/, same as sample-based synths — a synth preset whose oscillator mode is set to wavetable in the XML, with the WAV alongside in the same folder.
• Polyend Tracker Mini: a self-contained .pti, the table embedded as PCM.
• 1010music Bento: a wttrack patch folder under UserPatches/Wavetable/, the table WAV next to patch.xml and named by the oscillator cell. See Bento for why the firmware’s built-in table catalogue isn’t what selects it.