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🖼️ rav1e AVIF encoder

An AVIF encoder using rav1e written in WebAssembly.

💁 This is an experimental repository. My other WebAssembly-related projects are collected in the saschazar21/webassembly repository.

Prerequisites

To build the WebAssembly package, the following prerequisites are needed (either as a native install, or using the included Dockerfile):

Native

  • A Rust setup, preferably using rustup
  • wasm-pack for compiling and creating a WebAssembly package

Docker

Everything listed above is already included in the Dockerfile. To build a Docker image using the Dockerfile, run the following command:

$ docker build -t <yourname>:rust .

To compile the WebAssembly package, mount the repository in the Docker container:

$ docker run --rm -it --name rust -v `pwd`:/app <yourname>:rust bash

This will create a new Docker container, mount the current working directory at the /app path and start a bash session.

Build

To build this project as a WebAssembly package, execute the following command:

$ wasm-pack build

Hint: append --target nodejs, if you want to compile it for the Node.js environment, instead of the browser. More information is available in the wasm-pack docs.

Usage

The package exposes only one function – encode() for encoding raw RGB(A) pixel data in a Uint8Array to AVIF:

// Node.js example

// import encode function from './pkg'
const { encode } = require('./pkg');

// default options
const options = {
  width: 640,         // mandatory property
  height: 480,        // mandatory property
  quality: 75,        // 0 (worst) - 100 (best)
  alpha_quality: 25,  // 0 (worst) - 100 (best)
  speed: 6,           // 0 (slowest) - 10 (fastest)
  premultiplied_alpha: false,
  color_space: 0,     // 0 (YCbCr), 1 (RGB)
  chroma: 0,          // 0 (4:4:4) - only 4:4:4 works atm...
};

const raw_pixels = new Uint8Array([...]);

const encoded = encode(raw_pixels, options);

Issues

  1. Speed: the encoding process is single-threaded and dead slooow (I mean, really, really slow) - encoding a single 3072*2048 pixel image using the default options above takes ~4 min!

  2. Chroma Subsampling: Other Chroma subsamplings than 4:4:4 currently return a corrupted image. Haven't found any clue yet.

License

Licensed under the MIT license.

Copyright ©️ 2021 Sascha Zarhuber