webp-rust

Pure Rust WebP decoder and partial encoder.

Status

Still image decode: VP8 lossy, VP8L lossless
Still image encode: lossy VP8 and lossless VP8L from RGBA
Alpha: ALPH for lossy still images and lossy animation frames
Animation: compositing to RGBA frame sequence
Library output: RGBA only
BMP output: example only

Library API

Top-level still-image decode:

let image = webp_rust::decode(&data)?;
println!("{}x{}", image.width, image.height);

Top-level still-image encode:

let webp = webp_rust::encode(
    &image,
    2,
    100,
    webp_rust::WebpEncoding::Lossless,
    None,
)?;
let lossy = webp_rust::encode_lossy(&image, 0, 90, None)?;
let lossless = webp_rust::encode_lossless(&image, 2, None)?;

To embed raw EXIF metadata, pass the chunk payload directly:

let webp = webp_rust::encode_lossless(&image, 2, Some(exif_bytes))?;

Native file input:

#[cfg(not(target_family = "wasm"))]
let image = webp_rust::decode_file("input.webp")?;

Animated WebP is not accepted by decode / decode_file. For animation, use the decoder module directly:

let animation = webp_rust::decoder::decode_animation_webp(&data)?;
println!("{}", animation.frames.len());

Advanced encoder tuning stays in the encoder module:

let lossy_options = webp_rust::LossyEncodingOptions {
    quality: 90,
    optimization_level: 0,
};
let lossy = webp_rust::encoder::encode_lossy_image_to_webp_with_options_and_exif(
    &image,
    &lossy_options,
    Some(exif_bytes),
)?;

let lossless_options = webp_rust::LosslessEncodingOptions {
    optimization_level: 6,
};
let lossless = webp_rust::encoder::encode_lossless_image_to_webp_with_options_and_exif(
    &image,
    &lossless_options,
    Some(exif_bytes),
)?;

Current encoder scope is still-image only. The lossy path currently targets opaque RGBA input and emits a minimal intra-only VP8 bitstream. Animated encode is not implemented.

Examples

webp2bmp converts still WebP to a BMP file and animated WebP to a BMP sequence.

Still image:

cargo run --example webp2bmp -- _testdata/sample.webp target/sample.bmp

Animation:

cargo run --example webp2bmp -- _testdata/sample_animation.webp target/sample_animation

This writes:

target/sample_animation_0000.bmp
target/sample_animation_0001.bmp
...

bmp2webp converts an uncompressed 24bpp or 32bpp BMP file to a still WebP.

Lossless:

cargo run --example bmp2webp -- --opt-level 6 input.bmp output.webp

Lossy:

cargo run --example bmp2webp -- --lossy --quality 90 input.bmp output.webp

This default lossy path uses -z 0 for fast encode speed.

Lossless effort also accepts -z 0..9. -z 6 is the balanced preset. z7 is the current heavy preset, and z8..9 currently reuse that path until a better high-effort strategy lands.

Heavier lossy search:

cargo run --example bmp2webp -- --lossy --quality 90 -z 9 input.bmp output.webp

Tests

cargo test --tests

License