diff --git a/gb28181/source_udp.go b/gb28181/source_udp.go
index 8c4c26d..a8efb80 100644
--- a/gb28181/source_udp.go
+++ b/gb28181/source_udp.go
@@ -18,7 +18,7 @@ type UDPSource struct {
 func NewUDPSource() *UDPSource {
 	return &UDPSource{
 		rtpDeMuxer: jitterbuffer.New(),
-		rtpBuffer:  stream.NewMemoryPoolWithDirect(JitterBufferSize, true),
+		rtpBuffer:  stream.NewDirectMemoryPool(JitterBufferSize),
 	}
 }
 
diff --git a/stream/memory_pool.go b/stream/memory_pool.go
index d0845ce..e23b649 100644
--- a/stream/memory_pool.go
+++ b/stream/memory_pool.go
@@ -5,7 +5,8 @@ import (
 )
 
 // MemoryPool 从解复用阶段，拼凑成完整的AVPacket开始(写)，到GOP缓存结束(释放)，整个过程都使用池中内存
-// 类似环形缓冲区, 区别在于，写入的内存块是连续的、整块内存.
+// 类似环形缓冲区, 区别在于，内存块是连续的、整块内存.
+// AVPacket缓存使用memorypool_rb, 允许回环(内存必须完整). tranStream使用memorypool_direct, 连续一块完整的内存, 否则与合并缓存写的观念背道而驰.
 // 两种使用方式:
 //  1. 已知需要分配内存大小， 直接使用Allocate()函数分配, 并且外部自行操作内存块
 //  2. 未知分配内存大小, 先使用Mark()函数，标记内存起始偏移量, 再通过Write()函数将数据拷贝进内存块，最后调用Fetch/Reset函数完成或释放内存块
@@ -24,21 +25,22 @@ type MemoryPool interface {
 	// Fetch 获取当前内存块，必须先调用Mark函数
 	Fetch() []byte
 
-	// Reset 清空写入的数据，本次缓存的数据无效
+	// Reset 清空本次写入的数据，本次缓存的数据无效
 	Reset()
 
-	// Reserve 保留指定大小的内存空间
+	// Reserve 预留指定大小的内存空间
 	//主要是为了和实现和Write相似功能，但是不拷贝, 所以使用流程和Write一样.
 	Reserve(size int)
 
-	// FreeHead 从头部释放指定大小内存
+	// FreeHead 从头部释放一块内存
 	FreeHead()
 
-	// FreeTail 从尾部释放指定大小内存
+	// FreeTail 从尾部释放一块内存
 	FreeTail()
 
 	Data() ([]byte, []byte)
 
+	// Clear 清空所有内存块
 	Clear()
 
 	Empty() bool
@@ -48,111 +50,77 @@ type MemoryPool interface {
 	Size() int
 }
 
-func NewMemoryPool(capacity int) MemoryPool {
-	pool := &memoryPool{
-		data:       make([]byte, capacity),
-		capacity:   capacity,
-		blockQueue: NewQueue(128),
-	}
-
-	return pool
-}
-
-func NewMemoryPoolWithRecopy(capacity int) MemoryPool {
-	pool := &memoryPool{
-		data:       make([]byte, capacity),
-		capacity:   capacity,
-		blockQueue: NewQueue(128),
-		recopy:     true,
-	}
-
-	return pool
-}
-
-func NewMemoryPoolWithDirect(capacity int, recopy bool) MemoryPool {
-	pool := &memoryPool{
-		data:       make([]byte, capacity),
-		capacity:   capacity,
-		blockQueue: NewQueue(128),
-		recopy:     recopy,
-		direct:     true,
-	}
-
-	return pool
-}
-
 type memoryPool struct {
-	data []byte
-	//实际的可用容量，当尾部剩余内存不足以此次Write, 并且头部有足够的空闲内存, 则尾部剩余的内存将不可用.
-	capacity int
+	data     []byte
+	capacity int //实际的可用容量，当尾部剩余内存不足以此次Write, 并且头部有足够的空闲内存, 则尾部剩余的内存将不可用.
 	head     int
 	tail     int
 
-	//保存开始索引
-	markIndex  int
-	mark       bool
-	blockQueue *Queue
+	markIndex         int //保存开始索引
+	marked            bool
+	blockQueue        *Queue
+	discardBlockCount int
+	recopy            bool //扩容时，是否拷贝旧数据. 缓存AVPacket时, 内存已经被Data引用，所以不需要再拷贝旧数据. 用作合并写缓存时, 流还没有发送使用, 需要拷贝旧数据.
+	isFull            func(int) bool
+}
 
-	recopy bool
-	direct bool
+func (m *memoryPool) grow(size int) {
+	//1.5倍扩容
+	newData := make([]byte, (cap(m.data)+size)*3/2)
+	//未写入缓冲区大小
+	flushSize := m.tail - m.markIndex
+	//拷贝之前的数据
+	if m.recopy {
+		head, tail := m.Data()
+		copy(newData, head)
+		copy(newData[len(head):], tail)
+
+		m.head = 0
+		m.tail = len(head) + len(tail)
+		m.markIndex = m.tail - flushSize
+	} else {
+		//只拷贝本回合数据
+		copy(newData, m.data[m.tail-flushSize:m.tail])
+		//丢弃之前的内存块
+		m.discardBlockCount += m.blockQueue.Size()
+		m.blockQueue.Clear()
+
+		m.head = 0
+		m.tail = flushSize
+		m.markIndex = 0
+	}
+
+	m.data = newData
+	m.capacity = cap(newData)
 }
 
 // 根据head和tail计算出可用的内存地址
 func (m *memoryPool) allocate(size int) []byte {
-	if m.capacity-m.tail < size {
-		//使用从头释放的内存
-		if !m.direct && m.tail-m.markIndex+size <= m.head {
-			copy(m.data, m.data[m.markIndex:m.tail])
-			m.capacity = m.markIndex
-			m.tail = m.tail - m.markIndex
-			m.markIndex = 0
-		} else {
-			//扩容
-			writeSize := m.tail - m.markIndex
-			capacity := (cap(m.data) + writeSize + size) * 2
-			bytes := make([]byte, capacity)
-
-			if m.recopy {
-				//将扩容前的老数据复制到新的内存空间
-				head, tail := m.Data()
-				copy(bytes, head)
-				copy(bytes[len(head):], tail)
-				m.tail = len(head) + len(tail)
-				m.markIndex = m.tail - writeSize
-			} else {
-				//不对之前的内存进行复制, 已经被AVPacket引用, 自行GC
-				copy(bytes, m.data[m.markIndex:m.tail])
-				m.tail = writeSize
-				m.markIndex = 0
-			}
-
-			m.data = bytes
-			m.capacity = capacity
-			m.head = 0
-		}
+	if m.isFull(size) {
+		m.grow(size)
 	}
 
-	bytes := m.data[m.tail:]
+	bytes := m.data[m.tail : m.tail+size]
 	m.tail += size
 	return bytes
 }
 
 func (m *memoryPool) Mark() {
-	utils.Assert(!m.mark)
+	utils.Assert(!m.marked)
 
 	m.markIndex = m.tail
-	m.mark = true
+	m.marked = true
 }
 
 func (m *memoryPool) Write(data []byte) {
-	utils.Assert(m.mark)
+	utils.Assert(m.marked)
 
 	allocate := m.allocate(len(data))
 	copy(allocate, data)
 }
 
 func (m *memoryPool) Reserve(size int) {
-	utils.Assert(m.mark)
+	utils.Assert(m.marked)
 	_ = m.allocate(size)
 }
 
@@ -163,23 +131,28 @@ func (m *memoryPool) Allocate(size int) []byte {
 }
 
 func (m *memoryPool) Fetch() []byte {
-	utils.Assert(m.mark)
+	utils.Assert(m.marked)
 
-	m.mark = false
+	m.marked = false
 	size := m.tail - m.markIndex
 	m.blockQueue.Push(size)
 	return m.data[m.markIndex:m.tail]
 }
 
 func (m *memoryPool) Reset() {
-	m.mark = false
+	m.marked = false
 	m.tail = m.markIndex
 }
 
 func (m *memoryPool) FreeHead() {
-	utils.Assert(!m.mark)
+	utils.Assert(!m.marked)
 	utils.Assert(!m.blockQueue.IsEmpty())
 
+	if m.discardBlockCount > 1 {
+		m.discardBlockCount--
+		return
+	}
+
 	size := m.blockQueue.Pop().(int)
 	m.head += size
 
@@ -192,9 +165,14 @@ func (m *memoryPool) FreeHead() {
 }
 
 func (m *memoryPool) FreeTail() {
-	utils.Assert(!m.mark)
+	utils.Assert(!m.marked)
 	utils.Assert(!m.blockQueue.IsEmpty())
 
+	if m.discardBlockCount > 1 {
+		m.discardBlockCount--
+		return
+	}
+
 	size := m.blockQueue.PopBack().(int)
 	m.tail -= size
 	if m.tail == 0 && !m.blockQueue.IsEmpty() {
@@ -216,13 +194,14 @@ func (m *memoryPool) Clear() {
 	m.tail = 0
 
 	m.markIndex = 0
-	m.mark = false
+	m.marked = false
 
 	m.blockQueue.Clear()
+	m.discardBlockCount = 0
 }
 
 func (m *memoryPool) Empty() bool {
-	utils.Assert(!m.mark)
+	utils.Assert(!m.marked)
 	return m.blockQueue.Size() < 1
 }
 
diff --git a/stream/memory_pool_test.go b/stream/memory_pool_test.go
index ef2a254..eee2a6e 100644
--- a/stream/memory_pool_test.go
+++ b/stream/memory_pool_test.go
@@ -13,7 +13,7 @@ func TestMemoryPool(t *testing.T) {
 		bytes[i] = byte(i)
 	}
 
-	pool := NewMemoryPool(5)
+	pool := NewDirectMemoryPool(5)
 	last := uintptr(0)
 	for i := 0; i < 10; i++ {
 		pool.Mark()
diff --git a/stream/memorypool_direct.go b/stream/memorypool_direct.go
new file mode 100644
index 0000000..bf1edcc
--- /dev/null
+++ b/stream/memorypool_direct.go
@@ -0,0 +1,23 @@
+package stream
+
+type directMemoryPool struct {
+	*memoryPool
+}
+
+func (m *directMemoryPool) isFull(size int) bool {
+	//尾部没有大小合适的内存空间
+	return m.capacity-m.tail < size
+}
+
+func NewDirectMemoryPool(capacity int) MemoryPool {
+	pool := &directMemoryPool{}
+	pool.memoryPool = &memoryPool{
+		data:       make([]byte, capacity),
+		capacity:   capacity,
+		blockQueue: NewQueue(capacity),
+		recopy:     true,
+		isFull:     pool.isFull,
+	}
+
+	return pool
+}
diff --git a/stream/memorypool_rb.go b/stream/memorypool_rb.go
new file mode 100644
index 0000000..f5dc158
--- /dev/null
+++ b/stream/memorypool_rb.go
@@ -0,0 +1,32 @@
+package stream
+
+type rbMemoryPool struct {
+	*memoryPool
+}
+
+func (m *rbMemoryPool) isFull(size int) bool {
+	//已经回环
+	over := m.tail < m.head
+	if over && m.head-m.tail >= size {
+		//头部有大小合适的内存空间
+	} else if !over && m.capacity-m.tail >= size {
+		//尾部有大小合适的内存空间
+	} else {
+		return true
+	}
+
+	return false
+}
+
+func NewRbMemoryPool(capacity int) MemoryPool {
+	pool := &rbMemoryPool{}
+	pool.memoryPool = &memoryPool{
+		data:       make([]byte, capacity),
+		capacity:   capacity,
+		blockQueue: NewQueue(capacity),
+		recopy:     false,
+		isFull:     pool.isFull,
+	}
+
+	return pool
+}
diff --git a/stream/source.go b/stream/source.go
index 635fae1..7adee40 100644
--- a/stream/source.go
+++ b/stream/source.go
@@ -225,15 +225,15 @@ func (s *SourceImpl) FindOrCreatePacketBuffer(index int, mediaType utils.AVMedia
 
 	if s.pktBuffers[index] == nil {
 		if utils.AVMediaTypeAudio == mediaType {
-			s.pktBuffers[index] = NewMemoryPool(48000 * 64)
+			s.pktBuffers[index] = NewRbMemoryPool(48000 * 64)
 		} else if AppConfig.GOPCache {
 			//开启GOP缓存
 			//以每秒钟4M码率大小创建视频内存池
-			s.pktBuffers[index] = NewMemoryPool(4096 * 1024)
+			s.pktBuffers[index] = NewRbMemoryPool(4096 * 1024)
 		} else {
 			//未开启GOP缓存
 			//以每秒钟4M的1/8码率大小创建视频内存池
-			s.pktBuffers[index] = NewMemoryPool(4096 * 1024 / 8)
+			s.pktBuffers[index] = NewRbMemoryPool(4096 * 1024 / 8)
 		}
 	}
 
diff --git a/stream/trans_stream.go b/stream/trans_stream.go
index a5ba311..74bf368 100644
--- a/stream/trans_stream.go
+++ b/stream/trans_stream.go
@@ -208,10 +208,10 @@ func (c *CacheTransStream) Init() {
 	c.TransStreamImpl.Init()
 
 	c.StreamBuffers = make([]MemoryPool, 2)
-	c.StreamBuffers[0] = NewMemoryPoolWithDirect(1024*4000, true)
+	c.StreamBuffers[0] = NewDirectMemoryPool(1024 * 4000)
 
 	if c.ExistVideo && AppConfig.MergeWriteLatency > 0 {
-		c.StreamBuffers[1] = NewMemoryPoolWithDirect(1024*4000, true)
+		c.StreamBuffers[1] = NewDirectMemoryPool(1024 * 4000)
 	}
 
 	c.SegmentOffset = 0