README
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avif
Go encoder/decoder for AV1 Image File Format (AVIF) with support for animated AVIF images.
Based on libavif with dav1d (decode) and aom (encode) 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.
Build tags
nodynamic- do not use dynamic/shared library (use only WASM)wasm2go- transpile the WASM to pure Go with wasm2go instead of running it with wazero
Documentation
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Overview ¶
Package avif implements an AVIF image decoder based on libavif compiled to WASM.
Index ¶
- Constants
- Variables
- func Decode(r io.Reader, opts ...Options) (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
- func EncodeAll(w io.Writer, anim *AVIF, o ...Options) error
- type AVIF
- type Exif
- 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 .
var ErrNoExif = errors.New("avif: no exif data")
ErrNoExif is returned by DecodeExif when the AVIF has no Exif item.
Functions ¶
func Decode ¶
Decode reads a AVIF image from r; pass Options{AutoRotate: true} to apply the orientation.
func DecodeConfig ¶
DecodeConfig returns the color model and dimensions of a AVIF image without decoding the entire image.
func Dynamic ¶ added in v0.2.1
func Dynamic() error
Dynamic returns error (if there was any) during opening dynamic/shared library.
Types ¶
type AVIF ¶ added in v0.1.5
type AVIF struct {
// Decoded images, NRGBA or NRGBA64.
Image []image.Image
// Delay times, one per frame, in seconds.
Delay []float64
// LoopCount is the number of times the animation repeats (0 = infinite).
LoopCount int
}
AVIF represents the possibly multiple images stored in a AVIF file.
type Exif ¶ added in v0.5.3
type Exif struct {
// Basic image info
Orientation int // EXIF orientation (1-8). 1 = normal, values 2-8 indicate rotation/flip.
Width int // Image width in pixels.
Height int // Image height in pixels.
// Camera info
Make string // Camera manufacturer (e.g., "Canon").
Model string // Camera model (e.g., "Canon EOS 5D Mark III").
Software string // Software used to process/create the image.
// Date/Time (format: "YYYY:MM:DD HH:MM:SS")
DateTime string // File modification date/time.
DateTimeOriginal string // Original capture date/time (when photo was taken).
// Exposure settings
ExposureTime float64 // Shutter speed in seconds (e.g., 0.004 = 1/250s).
FNumber float64 // Aperture f-number (e.g., 5.6 = f/5.6).
ISOSpeed int // ISO speed rating (e.g., 800).
FocalLength float64 // Lens focal length in millimeters.
Flash int // Flash mode/status (0 = no flash, non-zero = flash fired).
// GPS location
GPSLatitude float64 // Latitude in decimal degrees (positive = North, negative = South).
GPSLongitude float64 // Longitude in decimal degrees (positive = East, negative = West).
GPSAltitude float64 // Altitude in meters above sea level.
// Copyright/Author
Copyright string // Copyright notice.
Artist string // Creator/photographer name.
}
Exif holds the EXIF metadata decoded from an AVIF image.
type Options ¶ added in v0.2.5
type Options struct {
// Quality in the range [0,100]. 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
// Lossless enables lossless compression. Lossless ignores quality and forces 4:4:4 chroma.
Lossless bool
// AutoRotate applies the irot/imir orientation to the decoded image (Decode/DecodeAll only).
AutoRotate bool
}
Options are the encoding parameters.
Source Files