@jsquash/avif

@jsquash/avif

An easy experience for encoding and decoding AVIF images in the browser. Powered by WebAssembly ⚡️.

Uses the libavif library.

A jSquash package. Codecs and supporting code derived from the Squoosh app.

Installation

npm install --save @jsquash/avif
# Or your favourite package manager alternative

Usage

Note: You will need to either manually include the wasm files from the codec directory or use a bundler like WebPack or Rollup to include them in your app/server.

decode(data: ArrayBuffer): Promise

Decodes AVIF binary ArrayBuffer to raw RGB image data.

data

Type: ArrayBuffer

options (optional)

Type: object

• bitDepth: 8 | 10 | 12 | 16 (default: 8). Specifies the desired bit depth of the decoded image data.
  • If bitDepth is 8 (or not provided), the function returns a standard ImageData object.
  • If bitDepth is 10, 12, or 16, the function returns an ImageData-like object. The data property will be a Uint16Array.

Example

import { decode } from '@jsquash/avif';

const formEl = document.querySelector('form');
const formData = new FormData(formEl);
// Assuming user selected an input avif file
const imageData = await decode(await formData.get('image').arrayBuffer());

encode(data: ImageData, options?: EncodeOptions): Promise

Encodes raw RGB image data to AVIF format and resolves to an ArrayBuffer of binary data.

data

Type: ImageData

options

Type: Partial<EncodeOptions>

The AVIF encoder options for the output image. See default values.

[!NOTE] To encode images with a bit depth greater than 8, the data property of the image object must be a Uint16Array. The pixel values will need to be in the appropriate range for the bit depth.

Example

import { encode } from '@jsquash/avif';

async function loadImage(src) {
  const img = document.createElement('img');
  img.src = src;
  await new Promise(resolve => img.onload = resolve);
  const canvas = document.createElement('canvas');
  [canvas.width, canvas.height] = [img.width, img.height];
  const ctx = canvas.getContext('2d');
  ctx.drawImage(img, 0, 0);
  return ctx.getImageData(0, 0, img.width, img.height);
}

const rawImageData = await loadImage('/example.png');
const avifBuffer = await encode(rawImageData);

Lossless Example

import { encode } from '@jsquash/avif';

const rawImageData = await loadImage('/example.png');
// Lossless encoding can be achieved by setting the `lossless` option to `true`
const avifBuffer = await encode(rawImageData, { lossless: true });

Manual WASM initialisation (not recommended)

In most situations there is no need to manually initialise the provided WebAssembly modules. The generated glue code takes care of this and supports most web bundlers.

One situation where this arises is when using the modules in Cloudflare Workers (See the README for more info).

The encode and decode modules both export an init function that can be used to manually load the wasm module.

import decode, { init as initAvifDecode } from '@jsquash/avif/decode';

initAvifDecode(WASM_MODULE); // The `WASM_MODULE` variable will need to be sourced by yourself and passed as an ArrayBuffer.
const image = await fetch('./image.avif').then(res => res.arrayBuffer()).then(decode);

You can also pass custom options to the init function to customise the behaviour of the module. See the Emscripten documentation for more information.

import decode, { init as initAvifDecode } from '@jsquash/avif/decode';

initAvifDecode(null, {
  // Customise the path to load the wasm file
  locateFile: (path, prefix) => `https://example.com/${prefix}/${path}`,
});
const image = await fetch('./image.avif').then(res => res.arrayBuffer()).then(decode);

Known Issues

See jSquash Project README