@audio/decode-amr

Decode AMR-NB and AMR-WB audio to PCM float samples with opencore-amr WASM.

Install

npm i @audio/decode-amr

Usage

import decode from '@audio/decode-amr'

// AMR-NB or AMR-WB; auto-detected from the file header
let { channelData, sampleRate } = await decode(amrBuffer)
// AMR-NB: 8000 Hz mono
// AMR-WB: 16000 Hz mono

Streaming

import { decoder } from '@audio/decode-amr'

let dec = await decoder()
let result = dec.decode(chunk)
dec.free()

decoder() is asynchronous. Its decode() and flush() methods are synchronous.

API

decode(src): Promise<AudioData>

Whole-file decode. Accepts Uint8Array or ArrayBuffer. Auto-detects AMR-NB (#!AMR\n) vs AMR-WB (#!AMR-WB\n).

decoder(): Promise<AMRDecoder>

Creates a decoder instance.

• dec.decode(data): decode a Uint8Array or ArrayBuffer chunk.
• dec.flush(): discard buffered partial data and return an empty result.
• dec.free(): release WASM memory.

Formats

• AMR-NB: 8 kHz, modes 0–7 (4.75–12.2 kbps)
• AMR-WB: 16 kHz, modes 0–8 (6.6–23.85 kbps)

Building WASM

The WASM module is prebuilt in src/amr.wasm.js. To rebuild:

npm run build

This auto-fetches opencore-amr 0.1.6 source and compiles with Emscripten.

License

ॐ · Apache-2.0 (opencore-amr)