Crate zenwebp 

Decoding and Encoding of WebP Images

Copyright (C) 2025 Imazen LLC

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

For commercial licensing inquiries: support@imazen.io

This crate provides both encoding and decoding of WebP images.

Features

• std (default): Enables encode_to_writer(). Everything else works without it.
• simd (default): SIMD optimizations (SSE2/SSE4.1/AVX2 on x86, SIMD128 on WASM).
• fast-yuv (default): Optimized YUV conversion via the yuv crate.
• pixel-types: Type-safe pixel formats via the rgb crate.

no_std Support

Both encoding and decoding work in no_std environments (requires alloc):

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

Only EncodeRequest::encode_to requires std (for std::io::Write).

Encoding

Use LossyConfig or LosslessConfig with EncodeRequest:

use zenwebp::{EncodeRequest, LossyConfig, PixelLayout};

let config = LossyConfig::new().with_quality(85.0).with_method(4);
let rgba_data = vec![255u8; 4 * 4 * 4];
let webp = EncodeRequest::lossy(&config, &rgba_data, PixelLayout::Rgba8, 4, 4)
    .encode()?;

Decoding

Use the convenience functions:

let webp_data: &[u8] = &[]; // your WebP data
let (pixels, width, height) = zenwebp::decode_rgba(webp_data)?;

Or WebPDecoder for two-phase decoding (inspect headers before allocating):

use zenwebp::WebPDecoder;

let webp_data: &[u8] = &[]; // your WebP data
let mut decoder = WebPDecoder::build(webp_data)?;
let info = decoder.info();
println!("{}x{}, alpha={}", info.width, info.height, info.has_alpha);

let mut output = vec![0u8; decoder.output_buffer_size().unwrap()];
decoder.read_image(&mut output)?;

Safety

This crate uses #![forbid(unsafe_code)] to prevent direct unsafe usage in source. However, when the simd feature is enabled, we rely on the archmage crate for safe SIMD intrinsics. The #[arcane] proc macro generates unsafe blocks internally (which bypass the forbid lint due to proc-macro span handling). The soundness of our SIMD code depends on archmage’s token-based safety model being correct.

Without the simd feature, this crate contains no unsafe code whatsoever.

Re-exports

pub use decoder::decode_bgr;

pub use decoder::decode_bgr_into;

pub use decoder::decode_bgra;

pub use decoder::decode_bgra_into;

pub use decoder::decode_rgb;

pub use decoder::decode_rgb_into;

pub use decoder::decode_rgba;

pub use decoder::decode_rgba_into;

pub use decoder::decode_yuv420;

pub use decoder::BitstreamFormat;

pub use decoder::DecodeConfig;

pub use decoder::DecodeError;

pub use decoder::DecodeRequest;

pub use decoder::DecodeResult;

pub use decoder::ImageInfo;

pub use decoder::Limits;

pub use decoder::LoopCount;

pub use decoder::StreamStatus;

pub use decoder::StreamingDecoder;

pub use decoder::UpsamplingMethod;

pub use decoder::WebPDecoder;

pub use decoder::YuvPlanes;

pub use encoder::ClassifierDiag;

pub use encoder::ContentType;

pub use encoder::EncodeError;

pub use encoder::EncodeProgress;

pub use encoder::EncodeRequest;

pub use encoder::EncodeResult;

pub use encoder::EncodeStats;

pub use encoder::EncoderConfig;

pub use encoder::ImageMetadata;

pub use encoder::LosslessConfig;

pub use encoder::LossyConfig;

pub use encoder::NoProgress;

pub use encoder::PixelLayout;

pub use encoder::Preset;

pub use mux::AnimFrame;

pub use mux::AnimationConfig;

pub use mux::AnimationDecoder;

pub use mux::AnimationEncoder;

pub use mux::AnimationInfo;

pub use mux::BlendMethod;

pub use mux::DemuxFrame;

pub use mux::DisposeMethod;

pub use mux::MuxError;

pub use mux::MuxFrame;

pub use mux::WebPDemuxer;

pub use mux::WebPMux;

pub use decoder::vp8;

Modules

common

Common types and utilities shared between encoder and decoder

decoder

WebP decoder implementation

encoder

WebP encoder implementation.

heuristics

Resource estimation heuristics for encoding and decoding operations. Resource estimation heuristics for encoding and decoding operations.

metadata

Standalone metadata convenience functions for already-encoded WebP data.

mux

WebP mux/demux and animation encoding. WebP mux/demux and animation encoding.

pixel

Type-safe pixel format traits for decoding and encoding. Type-safe pixel format traits for decoding and encoding.

Structs

Unstoppable

A Stop implementation that never stops (no cooperative cancellation).

Enums

StopReason

Why an operation was stopped.

Traits

Stop

Cooperative cancellation check.