Lib.rs

WebGPU compute shader JPEG decoder.

Usage:

• Create a [Gpu] context (either automatically via Gpu::open or from an existing wgpu context via Gpu::from_wgpu).
• Create a Decoder (or multiple) via Decoder::new.
• For each JPEG image you want to decode, create an ImageData object and pass it to Decoder::start_decode.
  • The Decoder will automatically resize buffers and textures when they are too small for the passed ImageData.
• Access the output Texture via DecodeOp::texture.
  • wgpu will automatically ensure that the proper barriers are in place when this Texture is used in a GPU operation.

This is an experiment to use WebGPU Compute Shaders to decode JPEG images. The main Purpose of this project is to learn how to write compute shaders.

It performs surprisingly well on my RX 6700 XT, with GPU times of around 1 ms at high GPU clocks (and 2ms spent doing preprocessing on the CPU) when decoding a 4k test image.

The approach used here is restricted to baseline JPEGs that make heavy use of restart intervals. These types of JPEGs are typically produced by hardware encoders in GPUs, phones and webcams.

Due to technical limitations, only YUV JPEGs that make use of 4:2:2 chroma subsampling are supported. In the future this restriction may be lifted.