zenwebp

High-performance WebP encoding and decoding in pure Rust.

Forked from image-webp with significant improvements:

• ~2x faster decoding (from ~3x slower than libwebp to ~1.4x slower)
• Lossy encoding (the original only supported lossless)
• Full no_std support with alloc (both encoder and decoder)
• WASM SIMD128 support for WebAssembly targets

Current Status

• Decoder: Supports all WebP format features including both lossless and lossy compression, alpha channel, and animation. Both the "simple" and "extended" formats are handled, and it exposes methods to extract ICC, EXIF, and XMP chunks. Decoding speed is approximately 70% of libwebp.

• Encoder: Supports both lossy and lossless encoding. The lossy encoder includes RD-optimized mode selection, trellis quantization, and SIMD acceleration. Encoding speed is approximately 40% of libwebp with comparable quality.

Features

• Pure Rust implementation (no C dependencies)
• #![forbid(unsafe_code)] - completely safe Rust
• SIMD acceleration via archmage (x86: SSE2/SSE4.1/AVX2, WASM: SIMD128)
• no_std + alloc - full encoding/decoding without std
• Lossy encoding with full mode search (I16, I4, UV modes)
• Lossless encoding
• Animation support (decode)
• Alpha channel support
• ICC, EXIF, XMP metadata extraction

Quick Start

Decoding

use zenwebp::WebPDecoder;

// From a slice (no_std compatible)
let webp_data: &[u8] = &read_webp_file();
let mut decoder = WebPDecoder::new(webp_data)?;
let (width, height) = decoder.dimensions();

// Allocate output buffer (RGBA)
let mut output = vec![0u8; decoder.output_buffer_size()?];
decoder.read_image(&mut output)?;

Encoding

use zenwebp::{WebPEncoder, EncoderParams, ColorType};

// Lossy encoding (quality 0-100)
let mut output = Vec::new();
let mut encoder = WebPEncoder::new(&mut output);
encoder.set_params(EncoderParams::lossy(75));
encoder.encode(&rgb_data, width, height, ColorType::Rgb8)?;

// Lossless encoding
let mut output = Vec::new();
let mut encoder = WebPEncoder::new(&mut output);
encoder.set_params(EncoderParams::lossless());
encoder.encode(&rgb_data, width, height, ColorType::Rgb8)?;

no_std Usage

[dependencies]
zenwebp = { version = "0.1", default-features = false }

Both encoder and decoder work with no_std + alloc. The decoder takes &[u8] slices, and the encoder writes to Vec<u8>. Only encode_to_writer() requires the std feature.

Performance

Benchmarks on 768x512 Kodak image at Q75:

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

AI-Generated Code Notice

Developed with Claude (Anthropic). Not all code manually reviewed. Review critical paths before production use.