@saschazar/wasm-avif

📦 WebAssembly AVIF decoder/encoder

A dependency-free AVIF decoder/encoder written in WebAssembly

It encodes raw RGB(A) pixels in a Uint8Array into AVIF-encoded image data and vice versa.

Installation

yarn add @saschazar/wasm-avif

or

npm install --save @saschazar/wasm-avif

Usage

It supports usage in the browser, in a Web Worker and of course Node.js.

// Node.js
import wasm_avif from '@saschazar/wasm-avif';
import defaultOptions from '@saschazar/wasm-avif/options';

// Web Worker - see: https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope/importScripts
importScripts('wasm_avif.js');

// -------- Browser/Web Worker/Node.js code below --------

// Decoding example:
// Load encoded AVIF image data in Uint8Array
const array = new Uint8Array(['some', 'encoded', 'AVIF', 'image', 'data']);
let result;

// Initialize the WebAssembly Module
const avifModule = wasm_avif({
  onRuntimeInitialized() {
    const alpha = true; // return RGBA buffer, instead of RGB
    result = avifModule.decode(array, array.length, alpha); // decode image data and return a new Uint8Array
    avifModule.free(); // clean up memory after encoding is done
  },
});

// Encoding example:
// Load raw RGB(A) pixels in Uint8Array
const array = new Uint8Array(['some', 'raw', 'RGB', 'image', 'data']);
const width = 800;
const height = 600;
let result;

// Initialize the WebAssembly Module
const avifModule = wasm_avif({
  onRuntimeInitialized() {
    const channels = 4; // 4 representing RGBA buffer in source array, 3 RGB
    const chroma = 3; // chroma subsampling: 1 for 4:4:4, 2 for 4:2:2, 3 for 4:2:0
    result = avifModule.encode(
      array,
      width,
      height,
      channels,
      defaultOptions,
      chroma
    ); // encode image data and return a new Uint8Array
    avifModule.free(); // clean up memory after encoding is done
  },
});

Example

A working example is available on RunKit.

Status

The main backbone of the project is the libavif library.

Both decoding and encoding is done via the AOM AV1 codec. Encoding is still very slow, since helpers such as multithreading and/or runtime CPU detection have to be disabled in order to successfully compile to WebAssembly.

Help needed

Concerning the encoding functionality, a few trials have been made towards using the more performant rav1e encoder, but it constantly fails during linking.

As soon as encoding is done via rav1e, decoding could be switched back to dav1d again.

Credits

This module uses the AOMediaCodec/libavif's source code and most of the code is written according to the examples provided in that repository.

License

Licensed under the MIT license.

Copyright ©️ 2020—2021 Sascha Zarhuber