WebP encoder/decoder in go

Is there somewhere a complete WebP encoder and decoder compatible with current weekly (or forkable)?

Is it comparable in speed to the standard png one ?

There is a package by this guy on GitHub that includes both an encoder and a decoder for WebP: https://github.com/chai2010/webp

From the readme file:

package main

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "log"

    "github.com/chai2010/webp"
)

func main() {
    var buf bytes.Buffer
    var width, height int
    var data []byte
    var err error

    // Load file data
    if data, err = ioutil.ReadFile("./testdata/1_webp_ll.webp"); err != nil {
        log.Println(err)
    }

    // GetInfo
    if width, height, _, err = webp.GetInfo(data); err != nil {
        log.Println(err)
    }
    fmt.Printf("width = %d, height = %d\n", width, height)

    // GetMetadata
    if metadata, err := webp.GetMetadata(data, "ICCP"); err != nil {
        fmt.Printf("Metadata: err = %v\n", err)
    } else {
        fmt.Printf("Metadata: %s\n", string(metadata))
    }

    // Decode webp
    m, err := webp.Decode(bytes.NewReader(data))
    if err != nil {
        log.Println(err)
    }

    // Encode lossless webp
    if err = webp.Encode(&buf, m, &webp.Options{Lossless: true}); err != nil {
        log.Println(err)
    }
    if err = ioutil.WriteFile("output.webp", buf.Bytes(), 0666); err != nil {
        log.Println(err)
    }
}