@audio/decode-wavpack

@audio/decode-wavpack

Decode WavPack (.wv) to PCM float samples

npm install @audio/decode-wavpack

import decode, { decoder } from '@audio/decode-wavpack'

libwavpack (the reference WavPack 5 implementation, David Bryant) compiled to a single-file WASM ES module — no side files, loads from any CDN, Node, workers and AudioWorklets. Handles everything the format defines: lossless and hybrid/lossy, 8/16/24/32-bit integer and 32-bit float, mono through multichannel, and DSD-as-PCM (OPEN_DSD_AS_PCM, decimated to 24-bit PCM by the library). Streaming decode drives libwavpack's own block reader through a memory-backed WavpackStreamReader64, so multichannel block groups and adaptive decorrelation state are handled exactly as the reference library handles them — this package only tracks byte-level block boundaries.

let { channelData, sampleRate } = await decode(wvBytes)

let dec = await decoder()
let head = dec.decode(chunk1)   // synchronous; partial blocks carry over
let tail = dec.flush()          // drops an incomplete trailing block, if any
dec.free()

AudioData is { channelData: Float32Array[], sampleRate: number }, samples in [-1, 1]. Integer PCM is scaled by 2^(bits-1) (asymmetric, matching WAV convention: max positive sample maps to <1, max negative to exactly -1); float PCM is a direct bit reinterpretation (WavPack stores float samples pre-normalized when opened with OPEN_NORMALIZE, which this package always sets). Channels come out in the order libwavpack reports them, which for standard Microsoft-ordered sources (anything ffmpeg or the WavPack CLI produces) is WAV order: FL, FR, FC, LFE, BL, BR, ...

decode() drains every sample libwavpack can produce from the blocks fed so far, every call — there's no encoder lookahead or block-spanning delay to hold back, so flush() only ever discards an incomplete trailing block (a stream cut off mid-block) and returns nothing new.

Hybrid/lossy WavPack (-b<n>) decodes at whatever quality it was encoded at; the .wvc correction file (lossless-hybrid two-file mode) is not read — only the standalone .wv bitstream. A garbage or non-WavPack input throws instead of returning empty/wrong data.

Use when: you need a from-scratch, spec-accurate WavPack decoder in the browser or Node — audio tools reading .wv files, WavPack-in-container demuxers, or any pipeline that already speaks @audio's {channelData, sampleRate} shape.

Part of @audio/decode — the decode family umbrella.

ॐ · BSD-3-Clause, inherited from the bundled libwavpack.