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Pleco-Xa

Changelog

2.0

Section titled “2.0”

The 2.0 line is the release where Pleco-Xa became a complete, verifiable audio engine rather than a collection of scripts. The through-line of the development arc: prove every claim. Function after function was validated against numerical reference fixtures, and the CI suite grew to 27 test files (237 tests) that run on every push — so “correct” stopped being a marketing word and became a build-breaking test.

Fixture-verified correctness across domains

Section titled “Fixture-verified correctness across domains”

Validation during the 2.0 arc ran against reference fixtures spanning the whole analysis surface:

  • Core DSP — windows (hann/hamming/blackman), STFT magnitude and istft round-trip, fft/ifft, and the full family of frequency/time/sample conversions, all bit-exact.
  • Spectral & features — mel filterbank and melspectrogram, MFCC (full pipeline), chroma with tuning estimation, and the spectral descriptors (centroid, bandwidth, rolloff, flatness, contrast, RMS, ZCR).
  • Rhythm — onset_strength, bit-exact tempo, and beat_track with exact frame agreement.
  • Effects & decompose — trim/split, preemphasis/deemphasis, phase vocoder, time-stretch, pitch-shift, and HPSS (with margin; H+P ≈ S at margin 1).
  • Structure & sequence — DTW (bit-exact cost, exact path), recurrence matrix and recurrence↔lag, agglomerative segmentation, RQA, and the Viterbi family (viterbi_discriminative, transition matrices).
  • Missing-pieces wave — symmetric eigendecomposition (eigh), normalized graph Laplacian, k-means, PCEN (bit-exact, 9e-8), and full McFee-Ellis Laplacian segmentation built from those primitives.

Loop detection: the flagship

Section titled “Loop detection: the flagship”

The signature capability was consolidated into a single public API, loop.detect(), over four explicit strategies — fast, precise, musical, and recurrence — with:

  • A unified 0..1 confidence convention derived from real cross-correlation measurement, replacing two legacy ad-hoc scales. Confidence is never fabricated; strategies that can’t measure anything throw.
  • No silent cross-strategy fallback. Failed quality gates throw diagnostic errors that name the gate and suggest an alternative.
  • A ±10 ms golden gate in CI (loop_goldens.json), so loop regressions break the build.
  • Exposed primitives — LoopController (pure normalized loop state) and DynamicZeroCrossing (boundary snapping + micro-crossfades).

Real-time, in the browser, zero dependencies

Section titled “Real-time, in the browser, zero dependencies”

Live, in-browser capabilities:

  • RealtimeSpectrumAnalyzer and the streaming analyzers for live visualization and metering.
  • The canvas-native display tier (waveforms, spectrograms, colormaps) drawing straight to <canvas>.
  • Seamless loop playback (LoopPlayer, native sample-accurate looping) and an event-driven transport (AudioPlayer).
  • The Play layer — the Echoplex-homage creative instruments (loop playground, beat glitcher, quantum sequencer) driven by a self-correcting GibClock.

Pleco-Xa ships with zero runtime dependencies and no build step: the same code runs in the browser on a real AudioBuffer and in Node on a duck-typed shim.

Also landed

Section titled “Also landed”
  • pyin / yin pitch tracking, DTW-based sequence alignment and matching, and structural segmentation promoted onto the curated public surface.
  • Universal-runtime playback operations (half/double-speed, gap detection and closing, reversal) hoisted from the demo into the library as pure functions with an injectable buffer factory.

Versioning note. The current release line is 2.0.x (latest 2.0.3), published on npm as pleco-xa. The loop-point golden gate and the full 27-suite test run are enforced in CI on every push.