metaflac.wasm

Run official FLAC tools metaflac as WebAssembly, on browsers or Deno.

Installation

npm i metaflac.wasm

Examples

Reading tag

import { metaflac } from 'metaflac.wasm'

// for browsers
const blob = document.querySelector('input').files[0]
const inputFile = new Uint8Array(await blob.arrayBuffer())
// for Deno
const inputFile = await Deno.readFile('file.flac')

const { exitCode, stdout, stderr, files } = metaflac(['--show-tag=TITLE', 'file.flac'], {
  inputFiles: new Map([['file.flac', inputFile]]),
})
console.log(stdout)

Writing tag

import { metaflac } from 'metaflac.wasm'

// for browsers
const blob = document.querySelector('input').files[0]
const inputFile = new Uint8Array(await blob.arrayBuffer())
// for Deno
const inputFile = await Deno.readFile('file.flac')

const { exitCode, stdout, stderr, files } = metaflac(['--set-tag=TITLE=xxx', 'input.flac'], {
  inputFiles: new Map([['input.flac', inputFile]]),
  outputFileNames: ['input.flac'],
})
const file = files.get('input.flac')
if (file) {
  // do something with outputted file
}

Advanced

Using in Web Worker

By default, running metaflac will block the main thread which leads to be out of page response. To avoid "freezing" the UI, you can run it in a Web Worker.

Just need to change the import:

- import { metaflac } from 'metaflac.wasm'
+ import { metaflac } from 'metaflac.wasm/worker'

Preloading

It will be better that preloading the WebAssembly file, instead of fetching it when invoking.

import { preloadWASM } from 'metaflac.wasm'

preloadWASM()

preloadWASM also accept a string or an ArrayBuffer as argument. For string, it will be treated as a URL to be fetched, so you can specify custom WebAssembly location; for ArrayBuffer, it must be the WebAssembly file.

If you're using Web Worker version, you can also preload the Web Worker script:

import { preloadWorkerAndWASM } from 'metaflac.wasm/worker'

preloadWorkerAndWASM()

Notes

Using with Vite

You should exclude this package from dependency optimization:

export default defineConfig({
  optimizeDeps: {
    exclude: ['metaflac.wasm'],
  },
})

License

GPL v2

Copyright (c) 2022-present Pig Fang