diff --git a/media/cache/flvcache.go b/media/cache/flvcache.go
index 15bc265..b848426 100755
--- a/media/cache/flvcache.go
+++ b/media/cache/flvcache.go
@@ -32,7 +32,7 @@ func NewFlvCache(cacheGop bool) *FlvCache {
 }
 
 // CachePack 向FlvCache中缓存包
-func (cache *FlvCache) CachePack(pack Pack) {
+func (cache *FlvCache) CachePack(pack Pack) bool {
 	tag := pack.(*flv.Tag)
 
 	cache.l.Lock()
@@ -40,25 +40,27 @@ func (cache *FlvCache) CachePack(pack Pack) {
 
 	if tag.IsMetadata() {
 		cache.metaData = tag
-		return
+		return false
 	}
 	if tag.IsH2645SequenceHeader() {
 		cache.videoSequenceHeader = tag
-		return
+		return false
 	}
 	if tag.IsAACSequenceHeader() {
 		cache.audioSequenceHeader = tag
-		return
+		return false
 	}
 
+	keyframe := tag.IsH2645KeyFrame()
 	if cache.cacheGop { // 如果启用 FlvCache
-		if tag.IsH2645KeyFrame() { // 关键帧，重置GOP
+		if keyframe { // 关键帧，重置GOP
 			cache.gop.Reset()
 			cache.gop.Push(pack)
 		} else if cache.gop.Len() > 0 { // 必须关键帧作为cache的第一个包
 			cache.gop.Push(pack)
 		}
 	}
+	return keyframe
 }
 
 // Reset 重置FlvCache缓存
diff --git a/media/cache/h264cache.go b/media/cache/h264cache.go
index 30f99d0..00c1dc0 100755
--- a/media/cache/h264cache.go
+++ b/media/cache/h264cache.go
@@ -29,11 +29,11 @@ func NewH264Cache(cacheGop bool) *H264Cache {
 }
 
 // CachePack 向H264Cache中缓存包
-func (cache *H264Cache) CachePack(pack Pack) {
+func (cache *H264Cache) CachePack(pack Pack) bool {
 	rtppack := pack.(*rtp.Packet)
 
 	if rtppack.Channel != rtp.ChannelVideo {
-		return
+		return false
 	}
 
 	// 判断是否是参数和关键帧包
@@ -44,12 +44,12 @@ func (cache *H264Cache) CachePack(pack Pack) {
 
 	if sps { // 新序列参数,重置图像参数和 GopCache
 		cache.sps = rtppack
-		return
+		return false
 	}
 
 	if pps { // 新图像参数，重置 GopCahce
 		cache.pps = rtppack
-		return
+		return false
 	}
 
 	if cache.cacheGop { // 需要缓存 GOP
@@ -60,6 +60,7 @@ func (cache *H264Cache) CachePack(pack Pack) {
 			cache.gop.Push(rtppack)
 		}
 	}
+	return islice
 }
 
 // Reset 重置H264Cache缓存
diff --git a/media/cache/hevccache.go b/media/cache/hevccache.go
index 01eee25..3335c4f 100755
--- a/media/cache/hevccache.go
+++ b/media/cache/hevccache.go
@@ -30,11 +30,11 @@ func NewHevcCache(cacheGop bool) *HevcCache {
 }
 
 // CachePack 向HevcCache中缓存包
-func (cache *HevcCache) CachePack(pack Pack) {
+func (cache *HevcCache) CachePack(pack Pack) bool {
 	rtppack := pack.(*rtp.Packet)
 
 	if rtppack.Channel != rtp.ChannelVideo {
-		return
+		return false
 	}
 
 	// 判断是否是参数和关键帧包
@@ -45,17 +45,17 @@ func (cache *HevcCache) CachePack(pack Pack) {
 
 	if vps { // 视频参数
 		cache.vps = rtppack
-		return
+		return false
 	}
 
 	if sps { // 序列头参数
 		cache.sps = rtppack
-		return
+		return false
 	}
 
 	if pps { // 图像参数
 		cache.pps = rtppack
-		return
+		return false
 	}
 
 	if cache.cacheGop { // 需要缓存 GOP
@@ -66,6 +66,7 @@ func (cache *HevcCache) CachePack(pack Pack) {
 			cache.gop.Push(rtppack)
 		}
 	}
+	return islice
 }
 
 // Reset 重置HevcCache缓存
diff --git a/media/consumption.go b/media/consumption.go
index 64e46f3..de79f93 100755
--- a/media/consumption.go
+++ b/media/consumption.go
@@ -32,6 +32,8 @@ type consumption struct {
 	closed     bool             // 消费者是否关闭
 	Flow       stats.Flow       // 流量统计
 	logger     *xlog.Logger     // 日志对象
+	discarding bool             // 媒体包丢弃中
+	maxQLen    int
 }
 
 func (c *consumption) ID() CID {
@@ -50,9 +52,20 @@ func (c *consumption) Close() error {
 }
 
 // 向消费者发送媒体包
-func (c *consumption) send(pack Pack) {
-	c.recvQueue.Push(pack)
-	c.Flow.AddIn(int64(pack.Size()))
+func (c *consumption) send(pack Pack, keyframe bool) {
+	if keyframe { // 是 key frame
+		n := c.recvQueue.Len()
+		if c.discarding && n < c.maxQLen {
+			c.discarding = false
+		} else if !c.discarding && n > c.maxQLen {
+			c.discarding = true
+		}
+	}
+
+	if !c.discarding {
+		c.recvQueue.Push(pack)
+		c.Flow.AddIn(int64(pack.Size()))
+	}
 }
 
 // 向消费者发送一个图像组
diff --git a/media/consumptions.go b/media/consumptions.go
index 21ca665..0e68a22 100755
--- a/media/consumptions.go
+++ b/media/consumptions.go
@@ -15,10 +15,10 @@ type consumptions struct {
 	count int32
 }
 
-func (m *consumptions) SendToAll(p Pack) {
+func (m *consumptions) SendToAll(p Pack, keyframe bool) {
 	m.Range(func(key, value interface{}) bool {
 		c := value.(*consumption)
-		c.send(p)
+		c.send(p, keyframe)
 		return true
 	})
 }
diff --git a/media/placehold.go b/media/placehold.go
index 4c392f7..303c166 100644
--- a/media/placehold.go
+++ b/media/placehold.go
@@ -17,7 +17,7 @@ import (
 type Pack = format.Packet
 
 type packCache interface {
-	CachePack(pack Pack)
+	CachePack(pack Pack) (keyframe bool) // 返回是否是关键帧
 	PushTo(q *queue.SyncQueue) int
 	Reset()
 }
@@ -27,7 +27,7 @@ var _ packCache = emptyCache{}
 type emptyCache struct {
 }
 
-func (emptyCache) CachePack(Pack)                {}
+func (emptyCache) CachePack(Pack) bool           { return false }
 func (emptyCache) PushTo(q *queue.SyncQueue) int { return 0 }
 func (emptyCache) Reset()                        {}
 
@@ -41,9 +41,9 @@ var _ flvMuxer = emptyFlvMuxer{}
 
 type emptyFlvMuxer struct{}
 
-func (emptyFlvMuxer) TypeFlags() byte                  { return 0 }
+func (emptyFlvMuxer) TypeFlags() byte                     { return 0 }
 func (emptyFlvMuxer) WriteFrame(frame *codec.Frame) error { return nil }
-func (emptyFlvMuxer) Close() error                     { return nil }
+func (emptyFlvMuxer) Close() error                        { return nil }
 
 type rtpDemuxer interface {
 	rtp.PacketWriter
@@ -54,6 +54,6 @@ var _ rtpDemuxer = emptyRtpDemuxer{}
 
 type emptyRtpDemuxer struct{}
 
-func (emptyRtpDemuxer) TypeFlags() byte               { return 0 }
+func (emptyRtpDemuxer) TypeFlags() byte                  { return 0 }
 func (emptyRtpDemuxer) WriteRtpPacket(*rtp.Packet) error { return nil }
-func (emptyRtpDemuxer) Close() error                  { return nil }
+func (emptyRtpDemuxer) Close() error                     { return nil }
diff --git a/media/stream.go b/media/stream.go
index 31e7b92..dacf82d 100755
--- a/media/stream.go
+++ b/media/stream.go
@@ -207,8 +207,8 @@ func (s *Stream) WriteRtpPacket(packet *rtp.Packet) error {
 
 	atomic.AddUint64(&s.size, uint64(packet.Size()))
 
-	s.cache.CachePack(packet)
-	s.consumptions.SendToAll(packet)
+	keyframe := s.cache.CachePack(packet)
+	s.consumptions.SendToAll(packet, keyframe)
 
 	s.rtpDemuxer.WriteRtpPacket(packet)
 	return nil
@@ -234,8 +234,8 @@ func (s *Stream) WriteFlvTag(tag *flv.Tag) error {
 		return statusErrors[status]
 	}
 
-	s.flvCache.CachePack(tag)
-	s.flvConsumptions.SendToAll(tag)
+	keyframe := s.flvCache.CachePack(tag)
+	s.flvConsumptions.SendToAll(tag, keyframe)
 	return nil
 }
 
@@ -263,6 +263,7 @@ func (s *Stream) startConsume(consumer Consumer, packetType PacketType, extra st
 		packetType: packetType,
 		extra:      extra,
 		Flow:       stats.NewFlow(),
+		maxQLen:    1000,
 	}
 
 	c.logger = s.logger.With(xlog.Fields(