diff --git a/pktque/normalizer.go b/pktque/normalizer.go
new file mode 100644
index 0000000..4b7113b
--- /dev/null
+++ b/pktque/normalizer.go
@@ -0,0 +1,76 @@
+package pktque
+
+import (
+	"github.com/nareix/av"
+	"time"
+)
+
+type Normalizer struct {
+	que []*Queue
+	timecr *TimeCorrector
+	streams []av.CodecData
+	timediff time.Duration
+}
+
+func (self *Normalizer) Push(pkt av.Packet) {
+	self.timecr.Correct(&pkt)
+	i := int(pkt.Idx)
+	self.que[i].Push(pkt)
+}
+
+func (self *Normalizer) removeBeforeTime(tm time.Duration) {
+	for _, que := range self.que {
+		for que.Count() > 0 {
+			if que.Head().Time < tm {
+				que.Pop()
+			}
+		}
+	}
+}
+
+func (self *Normalizer) Pop() (pkt av.Packet, dur time.Duration, ok bool) {
+	mintm := time.Duration(0)
+	minidx := -1
+	for i, que := range self.que {
+		if que.Count() > 0 {
+			if minidx == -1 || que.Head().Time < mintm {
+				minidx = i
+			}
+		}
+	}
+	if minidx == -1 {
+		return
+	}
+
+	que := self.que[minidx]
+	if que.Count() >= 2 {
+		maxgap, defdur := CorrectTimeParams(self.streams[pkt.Idx])
+		ok = true
+		starttime := que.HeadIdx(0).Time
+		endtime := que.HeadIdx(1).Time
+		dur = endtime - starttime
+		pkt = que.Pop()
+		pkt.Time -= self.timediff
+		if dur > maxgap {
+			dur = defdur
+			endtime -= defdur
+			self.timediff += endtime - starttime
+			self.removeBeforeTime(endtime)
+		}
+		return
+	}
+
+	return
+}
+
+func NewNormalizer(streams []av.CodecData) *Normalizer {
+	self := &Normalizer{}
+	self.que = make([]*Queue, len(streams))
+	for i := range self.que {
+		self.que[i] = &Queue{}
+	}
+	self.timecr = NewTimeCorrector(streams)
+	self.streams = streams
+	return self
+}
+
diff --git a/pktque/queue.go b/pktque/queue.go
new file mode 100644
index 0000000..076cac5
--- /dev/null
+++ b/pktque/queue.go
@@ -0,0 +1,65 @@
+package pktque
+
+import (
+	"github.com/nareix/av"
+)
+
+//        time
+// 0 ----- 5 -----  10
+// 
+// V-A-V-V-A-V-V-A-V-V
+// |                 |
+// head           tail
+// pop            push
+
+type Queue struct {
+	buf []av.Packet
+	head int
+	tail int
+	n int
+}
+
+func (self *Queue) Push(pkt av.Packet) {
+	if self.n == len(self.buf) {
+		self.buf = append(self.buf, pkt)
+		self.n++
+	} else {
+		self.buf[self.tail] = pkt
+		self.tail = (self.tail+1)%len(self.buf)
+		self.n++
+	}
+}
+
+func (self *Queue) Pop() (pkt av.Packet) {
+	if self.n == 0 {
+		return
+	}
+	pkt = self.buf[self.head]
+	self.head = (self.head+1)%len(self.buf)
+	self.n--
+	return
+}
+
+func (self *Queue) Head() (pkt av.Packet) {
+	return self.buf[self.head]
+}
+
+func (self *Queue) Tail() (pkt av.Packet) {
+	return self.buf[self.tail]
+}
+
+func (self *Queue) HeadIdx(diff int) (pkt av.Packet) {
+	i := (self.head+diff)%len(self.buf)
+	return self.buf[i]
+}
+
+func (self *Queue) TailIdx(diff int) (pkt av.Packet) {
+	i := (self.tail-diff+len(self.buf))%len(self.buf)
+	return self.buf[i]
+}
+
+func (self *Queue) Count() int {
+	return self.n
+}
+
+
diff --git a/pktque/timecorrect.go b/pktque/timecorrect.go
new file mode 100644
index 0000000..4ad6224
--- /dev/null
+++ b/pktque/timecorrect.go
@@ -0,0 +1,75 @@
+package pktque
+
+import (
+	"github.com/nareix/av"
+	"time"
+)
+
+type TimeCorrector struct {
+	streams []av.CodecData
+	intimes []time.Duration
+	indurs []time.Duration
+	intime time.Duration
+	outtime time.Duration
+}
+
+func NewTimeCorrector(streams []av.CodecData) *TimeCorrector {
+	self := &TimeCorrector{}
+	self.intimes = make([]time.Duration, len(streams))
+	self.indurs = make([]time.Duration, len(streams))
+	self.streams = streams
+	return self
+}
+
+func (self *TimeCorrector) updateIntimes() {
+	for i := range self.intimes {
+		self.intimes[i] = self.intime
+	}
+}
+
+func (self *TimeCorrector) Correct(pkt *av.Packet) {
+	i := int(pkt.Idx)
+
+	if pkt.Time < self.intime {
+		self.intime = pkt.Time
+		self.updateIntimes()
+	} else {
+		diff := pkt.Time - self.intimes[i]
+		maxgap, defdur := CorrectTimeParams(self.streams[i])
+
+		if diff > maxgap {
+			var outdiff time.Duration
+			dur := self.indurs[i]
+			if dur == time.Duration(0) {
+				dur = defdur
+			}
+			adjust := self.intimes[i]+dur
+			if adjust > self.intime {
+				outdiff = adjust - self.intime
+			}
+			self.outtime += outdiff
+			self.intime = pkt.Time
+			self.updateIntimes()
+		} else {
+			self.indurs[i] = pkt.Time-self.intimes[i]
+			self.intimes[i] = pkt.Time
+			self.outtime += pkt.Time-self.intime
+			self.intime = pkt.Time
+		}
+	}
+
+	pkt.Time = self.outtime
+	return
+}
+
+func CorrectTimeParams(stream av.CodecData) (maxgap time.Duration, dur time.Duration) {
+	if stream.Type().IsAudio() {
+		maxgap = time.Millisecond*500
+		dur = time.Millisecond*20
+	} else {
+		maxgap = time.Millisecond*500
+		dur = time.Millisecond*20
+	}
+	return
+}
+