diff --git a/config.go b/config.go
index 0d3f77c..46d28f3 100644
--- a/config.go
+++ b/config.go
@@ -6,6 +6,7 @@ import (
 	"go.uber.org/zap"
 )
 
+// Config imagorvideo config.Option
 func Config(fs *flag.FlagSet, cb func() (*zap.Logger, bool)) imagor.Option {
 	var (
 		ffmpegFallbackImage = fs.String("ffmpeg-fallback-image", "",
diff --git a/ffmpeg/errors.go b/ffmpeg/errors.go
index 42c4685..0ffd823 100644
--- a/ffmpeg/errors.go
+++ b/ffmpeg/errors.go
@@ -5,6 +5,7 @@ import "C"
 
 type avError int
 
+// AV Error enum
 const (
 	ErrNoMem           = avError(-C.ENOMEM)
 	ErrEOF             = avError(C.AVERROR_EOF)
@@ -31,6 +32,7 @@ func (e avError) errorString() string {
 	}
 }
 
+// Error implements error interface
 func (e avError) Error() string {
 	return "ffmpeg: " + e.errorString()
 }
diff --git a/ffmpeg/ffmpeg.go b/ffmpeg/ffmpeg.go
index 09d5fab..2187d89 100644
--- a/ffmpeg/ffmpeg.go
+++ b/ffmpeg/ffmpeg.go
@@ -20,6 +20,7 @@ const (
 	hasAudio       = 2
 )
 
+// Metadata AV metadata
 type Metadata struct {
 	Orientation int     `json:"orientation"`
 	Duration    int     `json:"duration,omitempty"`
@@ -32,6 +33,7 @@ type Metadata struct {
 	HasAudio    bool    `json:"has_audio"`
 }
 
+// AVContext manages lifecycle of AV contexts and reader stream
 type AVContext struct {
 	opaque             unsafe.Pointer
 	reader             io.Reader
@@ -55,6 +57,7 @@ type AVContext struct {
 	closed             bool
 }
 
+// LoadAVContext load and create AVContext from reader stream
 func LoadAVContext(reader io.Reader, size int64) (*AVContext, error) {
 	av := &AVContext{
 		reader:        reader,
@@ -77,6 +80,8 @@ func LoadAVContext(reader io.Reader, size int64) (*AVContext, error) {
 	return av, createDecoder(av)
 }
 
+// ProcessFrames triggers frame processing
+// limit under max num of frames if maxFrames > 0
 func (av *AVContext) ProcessFrames(maxFrames int) (err error) {
 	if av.formatContext == nil || av.codecContext == nil {
 		return ErrDecoderNotFound
@@ -87,6 +92,7 @@ func (av *AVContext) ProcessFrames(maxFrames int) (err error) {
 	return
 }
 
+// SelectFrame triggers frame processing and select specific frame index
 func (av *AVContext) SelectFrame(n int) (err error) {
 	nn := C.int(n - 1)
 	if av.thumbContext != nil && nn > av.availableIndex {
@@ -104,6 +110,8 @@ func (av *AVContext) SelectPosition(f float64) (err error) {
 	return av.SelectDuration(av.positionToDuration(f))
 }
 
+// SelectDuration seeks to keyframe before the specified duration
+// then process frames to find precise duration
 func (av *AVContext) SelectDuration(ts time.Duration) (err error) {
 	if ts > 0 {
 		av.selectedDuration = ts
@@ -116,14 +124,18 @@ func (av *AVContext) SelectDuration(ts time.Duration) (err error) {
 	}
 }
 
+// SeekPosition seeks to keyframe before specified position percentage between 0 and 1
+// then process frames to find precise position
 func (av *AVContext) SeekPosition(f float64) error {
 	return av.SeekDuration(av.positionToDuration(f))
 }
 
+// SeekDuration seeks to keyframe before the  specified duration
 func (av *AVContext) SeekDuration(ts time.Duration) error {
 	return seekDuration(av, ts)
 }
 
+// Export frame to RGB or RGBA buffer
 func (av *AVContext) Export(bands int) (buf []byte, err error) {
 	if err = av.ProcessFrames(-1); err != nil {
 		return
@@ -137,10 +149,12 @@ func (av *AVContext) Export(bands int) (buf []byte, err error) {
 	return exportBuffer(av, bands)
 }
 
+// Close AVContext objects
 func (av *AVContext) Close() {
 	closeAVContext(av)
 }
 
+// Metadata AV metadata
 func (av *AVContext) Metadata() *Metadata {
 	var fps float64
 	if av.stream != nil {
diff --git a/ffmpeg/logging.go b/ffmpeg/logging.go
index c8453cd..2ac0528 100644
--- a/ffmpeg/logging.go
+++ b/ffmpeg/logging.go
@@ -8,7 +8,7 @@ import "sync"
 // AVLogLevel defines the ffmpeg threshold for dumping information to stderr.
 type AVLogLevel int
 
-// Possible values for AVLogLevel.
+// AVLogLevel enum
 const (
 	AVLogQuiet AVLogLevel = (iota - 1) * 8
 	AVLogPanic
@@ -35,6 +35,7 @@ func SetFFmpegLogLevel(logLevel AVLogLevel) {
 
 type LoggingHandlerFunction func(messageLevel AVLogLevel, message string)
 
+// SetLogging set AV logging handler
 func SetLogging(handler LoggingHandlerFunction) {
 	onceLogging.Do(func() {
 		C.goavLogSetup()
diff --git a/option.go b/option.go
index 3eee880..50835b2 100644
--- a/option.go
+++ b/option.go
@@ -2,14 +2,17 @@ package imagorvideo
 
 import "go.uber.org/zap"
 
+// Option imagorvideo option
 type Option func(p *Processor)
 
+// WithDebug with debug option
 func WithDebug(debug bool) Option {
 	return func(p *Processor) {
 		p.Debug = debug
 	}
 }
 
+// WithLogger with logger option
 func WithLogger(logger *zap.Logger) Option {
 	return func(p *Processor) {
 		if logger != nil {
@@ -18,6 +21,7 @@ func WithLogger(logger *zap.Logger) Option {
 	}
 }
 
+// WithFallbackImage with fallback imagor option on error
 func WithFallbackImage(image string) Option {
 	return func(p *Processor) {
 		p.FallbackImage = image
diff --git a/processor.go b/processor.go
index 2b9c5e7..4741dbe 100644
--- a/processor.go
+++ b/processor.go
@@ -13,12 +13,14 @@ import (
 	"time"
 )
 
+// Processor for imagorvideo that implements imagor.Processor interface
 type Processor struct {
 	Logger        *zap.Logger
 	Debug         bool
 	FallbackImage string
 }
 
+// NewProcessor creates Processor
 func NewProcessor(options ...Option) *Processor {
 	p := &Processor{
 		Logger: zap.NewNop(),
@@ -29,6 +31,7 @@ func NewProcessor(options ...Option) *Processor {
 	return p
 }
 
+// Startup implements imagor.Processor interface
 func (p *Processor) Startup(_ context.Context) error {
 	ffmpeg.SetLogging(func(level ffmpeg.AVLogLevel, message string) {
 		message = strings.TrimSuffix(message, "\n")
@@ -49,10 +52,12 @@ func (p *Processor) Startup(_ context.Context) error {
 	return nil
 }
 
+// Shutdown implements imagor.Processor interface
 func (p *Processor) Shutdown(_ context.Context) error {
 	return nil
 }
 
+// Process implements imagor.Processor interface
 func (p *Processor) Process(ctx context.Context, in *imagor.Blob, params imagorpath.Params, load imagor.LoadFunc) (out *imagor.Blob, err error) {
 	defer func() {
 		if err == nil || out != nil {
@@ -179,6 +184,7 @@ func (p *Processor) Process(ctx context.Context, in *imagor.Blob, params imagorp
 	return
 }
 
+// Metadata imagorvideo metadata
 type Metadata struct {
 	Format      string `json:"format"`
 	ContentType string `json:"content_type"`