npm API reference

Function signatures, processing options, reports, and errors for the sidespread npm package.

`init(input?)`

TypeScript
1function init(input?: unknown): Promise<void>;

Initializes the browser WASM module. The Node entry accepts the same call as a resolved no-op. Call and await it once before using analyze, process, or version.

`version()`

TypeScript
1function version(): string;

Returns the Rust crate and npm package version embedded in the WASM module.

`analyze(audio, sampleRate, options?)`

TypeScript
1function analyze(2  audio: Float32Array,3  sampleRate: number,4  options?: ProcessOptions5): EngineReport;

Runs missing-band and shared-bandwidth detection without changing the samples. Artifact stages are not counted as analysis findings.

`process(audio, sampleRate, options?, onProgress?)`

TypeScript
1function process(2  audio: Float32Array,3  sampleRate: number,4  options?: ProcessOptions,5  onProgress?: (event: ProcessProgress) => void6): { audio: Float32Array; report: EngineReport };

Runs the complete non-neural chain: missing-band DSP, shared bandwidth extension, harmonic debleed, high-frequency smearing repair, phase stabilization, fidelity gates, and headroom control.

The optional callback runs synchronously on the processing thread and receives events emitted at real Rust pipeline boundaries:

TypeScript
1interface ProcessProgress {2  stage:3    | 'prepare'4    | 'analyze'5    | 'missingBand'6    | 'bandwidth'7    | 'artifacts'8    | 'finalize'9    | 'complete';10  progress: number; // 0 to 111}

Use the callback inside a Web Worker for long files, then forward each event to the main thread.

Channel helpers

TypeScript
1function interleave(left: Float32Array, right: Float32Array): Float32Array;2function deinterleave(audio: Float32Array): {3  left: Float32Array;4  right: Float32Array;5};

interleave() requires equally sized channels. deinterleave() requires an even sample count.

`ProcessOptions`

All properties are optional. Unknown properties throw instead of being ignored.

Property	Default	Range or meaning
`fc`	`8000`	Historical high-frequency metric cutoff in Hz
`scanStartHz`	`5000`	Lowest dynamically inspected frequency
`rhfThreshold`	`0.3`	Absolute Side/Mid deficiency ceiling
`rhfRelativeThreshold`	`0.18`	Threshold relative to the intact Side band
`corrHigh`	`0.35`	Intact-band correlation threshold
`corrLow`	`0.40`	Transition-band correlation threshold
`transitionRhfMin`	`0.001`	Minimum transition Side/Mid energy
`dspStrength`	`2.0`	Missing-band synthesis strength, `0-3`
`dspPhaseDegrees`	`60`	Maximum phase diffusion, `0-180`
`bandwidthExtension`	`true`	Detect and extend a shared hard cutoff
`bandwidthDropDb`	`-30`	Hard-cutoff threshold, `-80` to `-12` dB
`bandwidthStrength`	`0.85`	Shared extension strength, `0-2`
`bandwidthRolloffDbPerOctave`	`3`	Synthesized high-band rolloff, `0-24`
`repairSmearing`	`true`	Enable high-frequency transient repair
`smearingStrength`	`0.35`	Smearing repair amount, `0-1`
`repairBleeding`	`true`	Enable harmonic debleed
`bleedingStrength`	`0.65`	Debleed amount, `0-1`
`stabilizePhase`	`true`	Enable Side phase stabilization
`phaseStrength`	`0.50`	Phase stabilization amount, `0-1`
`segmentMs`	`80`	Detection segment length in milliseconds
`overlap`	`0.5`	Segment overlap, `0` inclusive to `1` exclusive
`nFft`	`4096`	STFT FFT size
`hop`	`1024`	STFT hop size, no greater than `nFft`

`EngineReport`

TypeScript
1interface EngineReport {2  sampleRate: number;3  inputFrames: number;4  needsProcessing: boolean;5  processed: boolean;6  missingBand: MissingBandReport;7  bandwidth: BandwidthReport;8  artifacts: ArtifactReport;9  outputGainDb: number;10  synthesisMix: number;11  segments: SegmentReport[];12}

needsProcessing records detected deficiencies and requested artifact work. processed is stricter: it is true only when the output includes an applied stage.

Missing band

missingBand contains detectedSegments, routedSegments, multiBandSegments, lowestDefectHz, scanStartHz, and the fixed bandWidthHz of 500 Hz.

Shared bandwidth

bandwidth contains detectedCutoffHz, tailToEdgeDb, confidence, and needsExtension.

Artifact stages

Each artifact entry exposes enabled, requested strength, safety-gate retainedMix, and final appliedStrength. The entries are smearing, harmonicBleeding, and phaseIncoherence.

Errors

Calls throw for empty or odd-length audio, non-finite samples, unsupported sample rates, invalid option ranges, unknown options, invalid progress callbacks, and calls made before browser initialization.