wpd

A safe, fast Rust and assembly WebP decoder with a C ABI.

Image	Output	image-webp (ms)	libwebp (ms)	wpd (ms)	libwebp / wpd
lossy.webp	YUV420P	—	180.40	173.56	1.04x
simplelf-lossy.webp	YUV420P	—	174.43	162.07	1.08x
anim_yuv.webp	RGBA	359.85	190.90	169.18	1.13x
lossless.webp	RGBA	231.50	195.75	111.27	1.76x
anim_rgb.webp	RGBA	206.09	104.47	62.56	1.67x
a_lossy.webp	YUVA420P	—	50.70	36.38	1.39x
anim_yuva.webp	RGBA	776.54	494.37	374.46	1.32x

Build

Dependencies:

• Rust
• nasm (on x86)

meson setup build
meson compile -C build
build/wpd [options] input.webp output.raw

The build enables assembly by default. Compile with -Denable_asm=false for memory safety guarantees at the cost of speed.

For minimal binary and library sizes:

meson setup build-minsize --buildtype=minsize
meson compile -C build-minsize

-Dnightly_size=true also needs nightly Rust and rust-src. The build then produces libwpd-sealed.a alongside libwpd.a. The sealed static lib aborts instead of unwinding on an internal panic. The build merges every object into one monolithic object for downstream consumers.

Library

meson install -C build installs the static/shared libraries, wpd.h, and wpd.pc. The library exports only the wpd_* symbols declared in the header.

C

See wpd.h for C API usage.

Rust

[dependencies]
wpd = { git = "https://github.com/halidecx/wpd" }

use wpd::{api::Decoder, image::Format, options::Options};

let mut decoder = Decoder::new();
decoder.set_format(Format::Rgba)?;
decoder.set_options(Options { scale: Some((320, 0)), ..Default::default() })?;
decoder.open(&data)?;
while let Some(frame) = decoder.next_frame()? {
    for row in frame.rows_of(0) {
        present(row);
    }
}

• rows_of() yields output-order rows, so flips don't need special stride handling
• open_stream, append, end_of_stream, and partial_frame provide streaming
• update and UpdateBuffer reuse an allocation

Test

meson test -C build
meson configure build -Dtestdata_tests=true
meson test -C build --suite testdata
./scripts/stylecheck.sh

Test data is maintained at wpd-test-data, which you can clone into the wpd/ root. ./scripts/testdata.sh runs end-to-end assembly and fallback checks.

For libwebp parity testing and benchmarking against alternative WebP decoders, build the optional third-party test binaries:

meson configure build -Dbuildtype=release -Dtrim_dsp=false
meson compile -C build
meson compile -C build libwebpdec imagewebpdec
./scripts/bench.sh

On Linux, use taskset -c 0 ./scripts/bench.sh to reproduce the CPU affinity above. The harness exports raw Hyperfine timings to build/bench/; set BENCH_DIR to select another directory. Output is discarded, but requested format conversion still runs on every decode.

The default libwebp is the pinned Meson subproject. -Dlibwebp=system or -Dlibwebpdecoder=/path/to/libwebpdecoder.a overrides it. imagewebpdec is the same harness over the pure-Rust image-webp crate, which bench.sh includes whenever it has been built.

Credits

This project would not be possible without:

• libwebp, the reference WebP implementation
• dav1d, the fastest open-source AV1 decoder
• rav1d, a Rust rewrite of dav1d