Native WebP for Go

This is a native WebP encoder written entirely in Go, with no dependencies on libwebp or other external libraries. Designed for performance and efficiency, this encoder generates smaller files than the standard Go PNG encoder and is approximately 50% faster in execution.

Currently, the encoder supports only WebP lossless images (VP8L).

Decoding Support

We provide WebP decoding through a wrapper around golang.org/x/image/webp, with an additional DecodeIgnoreAlphaFlag function to handle VP8X images where the alpha flag causes decoding issues.

Benchmark

We conducted a quick benchmark to showcase file size reduction and encoding performance. Using an image from Google’s WebP Lossless and Alpha Gallery, we compared the results of our nativewebp encoder with the standard PNG encoder.

For the PNG encoder, we applied the png.BestCompression setting to achieve the most competitive compression outcomes.

		PNG encoder	nativeWebP encoder	reduction
	file size	120 kb	96 kb	20% smaller
	encoding time	42945049 ns/op	27716447 ns/op	35% faster
	file size	46 kb	36 kb	22% smaller
	encoding time	98509399 ns/op	31461759 ns/op	68% faster
	file size	236 kb	194 kb	18% smaller
	encoding time	178205535 ns/op	102454192 ns/op	43% faster
	file size	53 kb	41 kb	23% smaller
	encoding time	29088555 ns/op	14959849 ns/op	49% faster
	file size	139 kb	123 kb	12% smaller
	encoding time	63423995 ns/op	21717392 ns/op	66% faster

_{image source: https://developers.google.com/speed/webp/gallery2}

Installation

To install the nativewebp package, use the following command:

go get github.com/HugoSmits86/nativewebp

Usage

Here’s a simple example of how to encode an image:

file, err := os.Create(name)
if err != nil {
  log.Fatalf("Error creating file %s: %v", name, err)
}
defer file.Close()

err = nativewebp.Encode(file, img, nil)
if err != nil {
  log.Fatalf("Error encoding image to WebP: %v", err)
}

Here’s a simple example of how to encode an animation:

file, err := os.Create(name)
if err != nil {
  log.Fatalf("Error creating file %s: %v", name, err)
}
defer file.Close()

ani := nativewebp.Animation{
  Images: []image.Image{
    frame1,
    frame2,
  },
  Durations: []uint {
    100,
    100,
  },
  Disposals: []uint {
    0,
    0,
  },
  LoopCount: 0,
  BackgroundColor: 0xffffffff,
}

err = nativewebp.EncodeAll(file, &ani, nil)
if err != nil {
  log.Fatalf("Error encoding WebP animation: %v", err)
}