icodec

icodec

Image encoders & decoders built with WebAssembly.

Module	Encoder	Decoder
jpeg	MozJPEG
png	OxiPNG + imagequant	image-png
qoi	qoi
webp	libwebp
heic	libheif + x265	libheif + libde265
avif	libavif + aom
jxl	libjxl
wp2	libwebp2

[!WARNING] Since libheif does not support specify thread count for x265 encoder, The encode of the heic module only work on webworker, and has performance issue.

icodec is aimed at the web platform and has some limitations:

• Decode output & Encode input only support RGBA format.
• No animated image support, you should use video instead.

Usage

Requirement: The target environment must support WebAssembly SIMD.

pnpm add icodec

Use in browser:

// All codec modules (see the table above) are named export.
import { avif, jxl } from "icodec";

const response = await fetch("https://raw.githubusercontent.com/Kaciras/icodec/master/test/snapshot/image.avif")

// This should be called once before you invoke `decode()`
await avif.loadDecoder();

// Decode AVIF to ImageData.
const image = avif.decode(await response.arrayBuffer());

// This should be called once before you invoke `encode()`
await jxl.loadEncoder();

// Encode the image to JPEG XL.
const encoded = jxl.encode(image, /*{ options }*/);

To use icodec in Node, just change the import specifier to icodec/node, and loadEncoder/loadDecoder will use readFileSync instead of fetch.

import { avif, jxl } from "icodec/node";

If your bundler requires special handing of WebAssembly, you can pass the URL of WASM files to load* function. WASM files are exported in the format icodec/<codec>-<enc|dec>.wasm.

icodec is tree-shakable, with a bundler the unused code and wasm file can be eliminated from loading.

import { avif, jxl } from "icodec";

// Example for Vite
import AVIFEncWASM from "icodec/avif-enc.wasm?url";
import JxlDecWASM from "icodec/jxl-dec.wasm?url";

await avif.loadDecoder(AVIFEncWASM);
await jxl.loadEncoder(JxlDecWASM);

Type of each codec module:

/**
 * Provides a uniform type for codec modules that support encoding.
 *
 * @example
 * import { wp2, ICodecModule } from "icodec";
 *
 * const encoder: ICodecModule<wp2.Options> = wp2;
 */
interface ICodecModule<T = any> {
  /**
   * The default options of `encode` function.
   */
  defaultOptions: Required<T>;

  /**
   * The MIME type string of the format.
   */
  mimeType: string;

  /**
   * File extension (without the dot) of this format.
   */
  extension: string;

  /**
   * Load the decoder WASM file, must be called once before decode.
   *
   * @param source If pass a string, it's the URL of WASM file to fetch,
   *               else it will be treated as the WASM bytes.
   * @return the underlying WASM module, which is not part of
   *               the public API and can be changed at any time.
   */
  loadDecoder(source?: WasmSource): Promise<any>;

  /**
   * Convert the image to raw RGBA data.
   */
  decode(input: Uint8Array): ImageData;

  /**
   * Load the encoder WASM file, must be called once before encode.
   *
   * @param source If pass a string, it's the URL of WASM file to fetch,
   *               else it will be treated as the WASM bytes.
   * @return the underlying WASM module, which is not part of
   *               the public API and can be changed at any time.
   */
  loadEncoder(source?: WasmSource): Promise<any>;

  /**
   * Encode an image with RGBA pixels data.
   */
  encode(image: ImageDataLike, options?: T): Uint8Array;
}

The png module exports extra members:

/**
 * Reduces the colors used in the image at a slight loss, using a combination
 * of vector quantization algorithms.
 *
 * Can be used before other compression algorithm to boost compression ratio.
 */
declare function reduceColors(image: ImageDataLike, options?: QuantizeOptions): Uint8Array;

Performance

Decode & Encode test/snapshot/image.* files, time.SD is Standard Deviation of the time.

This benchmark ignores extra code size introduced by icodec, which in practice needs to be taken into account.

Decode on Edge browser.

No.	Name	codec	time	time.SD
0	icodec	avif	3.22 ms	8.24 us
1	2d	avif	1.50 ms	3.13 us
2	WebGL	avif	3.08 ms	26.33 us
3	icodec	heic	3.06 ms	16.84 us
4	icodec	jpeg	727.85 us	1.65 us
5	2d	jpeg	601.21 us	3.51 us
6	WebGL	jpeg	1,876.96 us	8.85 us
7	icodec	jxl	3.57 ms	17.73 us
8	icodec	png	419.48 us	2,901.49 ns
9	2d	png	573.07 us	801.34 ns
10	WebGL	png	1,835.78 us	16,278.04 ns
11	icodec	qoi	444.00 us	1.08 us
12	icodec	webp	792.57 us	1.58 us
13	2d	webp	805.07 us	4.04 us
14	WebGL	webp	2,156.43 us	36.42 us
15	icodec	wp2	2.59 ms	12.10 us

Decode on Node, vs Sharp.

No.	Name	codec	time	time.SD
0	icodec	avif	2.95 ms	6.46 us
1	Sharp	avif	2.54 ms	7.16 us
2	icodec	jpeg	471.99 us	2.99 us
3	Sharp	jpeg	842.17 us	1.50 us
4	icodec	jxl	3.03 ms	7.62 us
5	icodec	png	186.18 us	1.94 us
6	Sharp	png	645.95 us	1.78 us
7	icodec	qoi	200.62 us	1.41 us
8	icodec	webp	557.32 us	2.92 us
9	Sharp	webp	1,708.96 us	12.14 us
10	icodec	wp2	2.27 ms	1.99 us

Encode on Node, vs Sharp. Note that icodec and Sharp do not use the same code, so the output images are not exactly equal.

No.	Name	codec	time	time.SD
0	icodec	avif	2.97 ms	9.51 us
1	Sharp	avif	2.61 ms	8.28 us
2	icodec	jpeg	479.30 us	2.10 us
3	Sharp	jpeg	894.27 us	2.11 us
4	icodec	jxl	3.18 ms	114.32 us
5	icodec	png	189.39 us	1.36 us
6	Sharp	png	689.49 us	2.36 us
7	icodec	qoi	204.42 us	1.26 us
8	icodec	webp	555.51 us	1.59 us
9	Sharp	webp	1,773.42 us	10.45 us
10	icodec	wp2	2.34 ms	50.14 us

Contribute

To build WASM modules, you will need to install:

• Cmake >= 3.24
• Rust & wasm-pack
• Emscripten
• Perl
• Git
• A proper C/C++ compiler toolchain, depending on your operating system

Run the build script:

node scripts/build.js

TODOs:

• Could it be possible to remove HEIC & VVIC encoder dependency on pthread, or limit the number of threads?
• Cannot specify vvenc & vvdec paths for libheif build.

Rnn tests:

pnpm exec tsc
node --test test/test-*.js

Start web demo:

node scripts/start-demo.js