avif

README

avif

Go encoder/decoder for AV1 Image File Format (AVIF) with support for animated AVIF images (decode only).

Based on libavif and aom compiled to WASM and used with wazero runtime (CGo-free).

The library will first try to use a dynamic/shared library (if installed) via purego and will fall back to WASM.

Documentation

Overview

Package avif implements an AVIF image decoder based on libavif compiled to WASM.

Index

• Constants
• Variables
• func Decode(r io.Reader) (image.Image, error)
• func DecodeConfig(r io.Reader) (image.Config, error)
• func Dynamic() error
• func Encode(w io.Writer, m image.Image, o ...Options) error
• type AVIF
  • func DecodeAll(r io.Reader) (*AVIF, error)
• type Options

Constants

const DefaultQuality = 60

DefaultQuality is the default quality encoding parameter.

const DefaultSpeed = 10

DefaultSpeed is the default speed encoding parameter.

Variables

var (
	ErrMemRead  = errors.New("avif: mem read failed")
	ErrMemWrite = errors.New("avif: mem write failed")
	ErrDecode   = errors.New("avif: decode failed")
	ErrEncode   = errors.New("avif: encode failed")
)

Errors .

Functions

func Decode

func Decode(r io.Reader) (image.Image, error)

Decode reads a AVIF image from r and returns it as an image.Image.

func DecodeConfig

func DecodeConfig(r io.Reader) (image.Config, error)

DecodeConfig returns the color model and dimensions of a AVIF image without decoding the entire image.

func Dynamic

func Dynamic() error

Dynamic returns error (if there was any) during opening dynamic/shared library.

func Encode

func Encode(w io.Writer, m image.Image, o ...Options) error

Encode writes the image m to w with the given options.

Types

type AVIF

type AVIF struct {
	// Decoded images, NRGBA or NRGBA64.
	Image []image.Image
	// Delay times, one per frame, in seconds.
	Delay []float64
}

AVIF represents the possibly multiple images stored in a AVIF file.

func DecodeAll

func DecodeAll(r io.Reader) (*AVIF, error)

DecodeAll reads a AVIF image from r and returns the sequential frames and timing information.

type Options

type Options struct {
	// Quality in the range [0,100]. Quality of 100 implies lossless. Default is 60.
	Quality int
	// Quality in the range [0,100].
	QualityAlpha int
	// Speed in the range [0,10]. Slower should make for a better quality image in less bytes.
	Speed int
	// Chroma subsampling, 444|422|420.
	ChromaSubsampling image.YCbCrSubsampleRatio
}

Options are the encoding parameters.