diff --git a/flv.go b/flv.go
index c9a28c1..ab6cfa3 100644
--- a/flv.go
+++ b/flv.go
@@ -22,9 +22,9 @@ func (self *Muxer) WriteHeader(streams []av.CodecData) (err error) {
 	hasVideo := false
 	hasAudio := false
 	for _, stream := range streams {
-		if stream.IsVideo() {
+		if stream.Type().IsVideo() {
 			hasVideo = true
-		} else if stream.IsAudio() {
+		} else if stream.Type().IsAudio() {
 			hasAudio = true
 		}
 	}
diff --git a/flvio/amf0.go b/flvio/amf0.go
new file mode 100644
index 0000000..2182518
--- /dev/null
+++ b/flvio/amf0.go
@@ -0,0 +1,163 @@
+package flvio
+
+import (
+	"math"
+	"time"
+	"github.com/nareix/pio"
+)
+
+type AMFMap map[string]interface{}
+type AMFArray []interface{}
+
+func readBEFloat64(r *pio.Reader) (f64 float64, err error) {
+	var u64 uint64
+	if u64, err = r.ReadU64BE(); err != nil {
+		return
+	}
+	f64 = math.Float64frombits(u64)
+	return
+}
+
+func ReadAMF0Val(r *pio.Reader) (val interface{}, err error) {
+	const (
+		numbermarker = iota
+		booleanmarker
+		stringmarker
+		objectmarker
+		movieclipmarker
+		nullmarker
+		undefinedmarker
+		referencemarker
+		ecmaarraymarker
+		objectendmarker
+		strictarraymarker
+		datemarker
+		longstringmarker
+		unsupportedmarker
+		recordsetmarker
+		xmldocumentmarker
+		typedobjectmarker
+	)
+
+	var marker uint8
+	if marker, err = r.ReadU8(); err != nil {
+		return
+	}
+
+	switch marker {
+	case numbermarker:
+		if val, err = readBEFloat64(r); err != nil {
+			return
+		}
+
+	case booleanmarker:
+		var u8 uint8
+		if u8, err = r.ReadU8(); err != nil {
+			return
+		}
+		val = u8 != 0
+
+	case stringmarker:
+		var length uint16
+		if length, err = r.ReadU16BE(); err != nil {
+			return
+		}
+		var b []byte
+		if b, err = r.ReadBytes(int(length)); err != nil {
+			return
+		}
+		val = string(b)
+
+	case objectmarker:
+		obj := AMFMap{}
+		for {
+			var length uint16
+			if length, err = r.ReadU16BE(); err != nil {
+				return
+			}
+			if length == 0 {
+				break
+			}
+			var b []byte
+			if b, err = r.ReadBytes(int(length)); err != nil {
+				return
+			}
+			okey := string(b)
+			var oval interface{}
+			if oval, err = ReadAMF0Val(r); err != nil {
+				return
+			}
+			obj[okey] = oval
+		}
+		val = obj
+
+	case nullmarker:
+	case undefinedmarker:
+
+	case ecmaarraymarker:
+		var count uint32
+		if count, err = r.ReadU32BE(); err != nil {
+			return
+		}
+		obj := AMFMap{}
+		for ; count > 0; count-- {
+			var length uint16
+			if length, err = r.ReadU16BE(); err != nil {
+				return
+			}
+			var b []byte
+			if b, err = r.ReadBytes(int(length)); err != nil {
+				return
+			}
+			okey := string(b)
+			var oval interface{}
+			if oval, err = ReadAMF0Val(r); err != nil {
+				return
+			}
+			obj[okey] = oval
+		}
+		val = obj
+
+	case objectendmarker:
+		if _, err = r.Discard(3); err != nil {
+			return
+		}
+
+	case strictarraymarker:
+		var count uint32
+		if count, err = r.ReadU32BE(); err != nil {
+			return
+		}
+		obj := make(AMFArray, count)
+		for i := 0; i < int(count); i++ {
+			if obj[i], err = ReadAMF0Val(r); err != nil {
+				return
+			}
+		}
+		val = obj
+
+	case datemarker:
+		var ts float64
+		if ts, err = readBEFloat64(r); err != nil {
+			return
+		}
+		if _, err = r.ReadU16BE(); err != nil {
+			return
+		}
+		val = time.Unix(int64(ts/1000), (int64(ts)%1000)*1000000)
+
+	case longstringmarker:
+		var length uint32
+		if length, err = r.ReadU32BE(); err != nil {
+			return
+		}
+		var b []byte
+		if b, err = r.ReadBytes(int(length)); err != nil {
+			return
+		}
+		val = string(b)
+	}
+
+	return
+}
+
diff --git a/flvio/flvio.go b/flvio/flvio.go
index 57c7d46..15c671a 100644
--- a/flvio/flvio.go
+++ b/flvio/flvio.go
@@ -140,6 +140,7 @@ func (self Audiodata) Marshal(w *pio.Writer) (err error) {
 	if err = w.WriteU8(flags); err != nil {
 		return
 	}
+
 	if self.SoundFormat == SOUND_AAC {
 		if err = w.WriteU8(self.AACPacketType); err != nil {
 			return