Add support AAC audio for HTTP-FLV

pkg/httpflv/amf0.go

@@ -0,0 +1,165 @@
+package httpflv
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+)
+
+const (
+	TypeNumber byte = iota
+	TypeBoolean
+	TypeString
+	TypeObject
+	TypeEcmaArray = 8
+	TypeObjectEnd = 9
+)
+
+var Err = errors.New("amf0 read error")
+
+// AMF0 spec: http://download.macromedia.com/pub/labs/amf/amf0_spec_121207.pdf
+type AMF0 struct {
+	buf []byte
+	pos int
+}
+
+func NewReader(b []byte) *AMF0 {
+	return &AMF0{buf: b}
+}
+
+func (a *AMF0) ReadMetaData() map[string]interface{} {
+	if b, _ := a.ReadByte(); b != TypeString {
+		return nil
+	}
+	if s, _ := a.ReadString(); s != "onMetaData" {
+		return nil
+	}
+
+	b, _ := a.ReadByte()
+	switch b {
+	case TypeObject:
+		v, _ := a.ReadObject()
+		return v
+	case TypeEcmaArray:
+		v, _ := a.ReadEcmaArray()
+		return v
+	}
+
+	return nil
+}
+
+func (a *AMF0) ReadMap() (map[interface{}]interface{}, error) {
+	dict := make(map[interface{}]interface{})
+
+	for a.pos < len(a.buf) {
+		k, err := a.ReadItem()
+		if err != nil {
+			return nil, err
+		}
+		v, err := a.ReadItem()
+		if err != nil {
+			return nil, err
+		}
+		dict[k] = v
+	}
+
+	return dict, nil
+}
+
+func (a *AMF0) ReadItem() (interface{}, error) {
+	dataType, err := a.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	switch dataType {
+	case TypeNumber:
+		return a.ReadNumber()
+
+	case TypeBoolean:
+		v, err := a.ReadByte()
+		return v != 0, err
+
+	case TypeString:
+		return a.ReadString()
+
+	case TypeObject:
+		return a.ReadObject()
+
+	case TypeObjectEnd:
+		return nil, nil
+	}
+
+	return nil, Err
+}
+
+func (a *AMF0) ReadByte() (byte, error) {
+	if a.pos >= len(a.buf) {
+		return 0, Err
+	}
+
+	v := a.buf[a.pos]
+	a.pos++
+	return v, nil
+}
+
+func (a *AMF0) ReadNumber() (float64, error) {
+	if a.pos+8 >= len(a.buf) {
+		return 0, Err
+	}
+
+	v := binary.BigEndian.Uint64(a.buf[a.pos : a.pos+8])
+	a.pos += 8
+	return math.Float64frombits(v), nil
+}
+
+func (a *AMF0) ReadString() (string, error) {
+	if a.pos+2 >= len(a.buf) {
+		return "", Err
+	}
+
+	size := int(binary.BigEndian.Uint16(a.buf[a.pos:]))
+	a.pos += 2
+
+	if a.pos+size >= len(a.buf) {
+		return "", Err
+	}
+
+	s := string(a.buf[a.pos : a.pos+size])
+	a.pos += size
+
+	return s, nil
+}
+
+func (a *AMF0) ReadObject() (map[string]interface{}, error) {
+	obj := make(map[string]interface{})
+
+	for {
+		k, err := a.ReadString()
+		if err != nil {
+			return nil, err
+		}
+
+		v, err := a.ReadItem()
+		if err != nil {
+			return nil, err
+		}
+
+		if k == "" {
+			break
+		}
+
+		obj[k] = v
+	}
+
+	return obj, nil
+}
+
+func (a *AMF0) ReadEcmaArray() (map[string]interface{}, error) {
+	if a.pos+4 >= len(a.buf) {
+		return nil, Err
+	}
+	a.pos += 4 // skip size
+
+	return a.ReadObject()
+}