diff --git a/src/Common/Device.cpp b/src/Common/Device.cpp
index 71f42b39..37a0056b 100644
--- a/src/Common/Device.cpp
+++ b/src/Common/Device.cpp
@@ -78,14 +78,6 @@ void DevChannel::inputH264(const char *data, int len, uint32_t dts, uint32_t pts
     if(pts == 0){
         pts = dts;
     }
-    int prefixeSize;
-    if (memcmp("\x00\x00\x00\x01", data, 4) == 0) {
-        prefixeSize = 4;
-    } else if (memcmp("\x00\x00\x01", data, 3) == 0) {
-        prefixeSize = 3;
-    } else {
-        prefixeSize = 0;
-    }
 
     //由于rtmp/hls/mp4需要缓存时间戳相同的帧，
     //所以使用FrameNoCacheAble类型的帧反而会在转换成FrameCacheAble时多次内存拷贝
@@ -93,9 +85,8 @@ void DevChannel::inputH264(const char *data, int len, uint32_t dts, uint32_t pts
     H264Frame::Ptr frame = std::make_shared<H264Frame>();
     frame->_dts = dts;
     frame->_pts = pts;
-    frame->_buffer.assign("\x00\x00\x00\x01",4);
-    frame->_buffer.append(data + prefixeSize, len - prefixeSize);
-    frame->_prefix_size = 4;
+    frame->_buffer.assign(data, len);
+    frame->_prefix_size = prefixSize(data,len);
     inputFrame(frame);
 }
 
@@ -106,14 +97,6 @@ void DevChannel::inputH265(const char *data, int len, uint32_t dts, uint32_t pts
     if(pts == 0){
         pts = dts;
     }
-    int prefixeSize;
-    if (memcmp("\x00\x00\x00\x01", data, 4) == 0) {
-        prefixeSize = 4;
-    } else if (memcmp("\x00\x00\x01", data, 3) == 0) {
-        prefixeSize = 3;
-    } else {
-        prefixeSize = 0;
-    }
 
     //由于rtmp/hls/mp4需要缓存时间戳相同的帧，
     //所以使用FrameNoCacheAble类型的帧反而会在转换成FrameCacheAble时多次内存拷贝
@@ -121,9 +104,8 @@ void DevChannel::inputH265(const char *data, int len, uint32_t dts, uint32_t pts
     H265Frame::Ptr frame = std::make_shared<H265Frame>();
     frame->_dts = dts;
     frame->_pts = pts;
-    frame->_buffer.assign("\x00\x00\x00\x01",4);
-    frame->_buffer.append(data + prefixeSize, len - prefixeSize);
-    frame->_prefix_size = 4;
+    frame->_buffer.assign(data, len);
+    frame->_prefix_size = prefixSize(data,len);
     inputFrame(frame);
 }
 
diff --git a/src/Extension/H264.cpp b/src/Extension/H264.cpp
index 0a5314ae..0d591ea4 100644
--- a/src/Extension/H264.cpp
+++ b/src/Extension/H264.cpp
@@ -74,6 +74,21 @@ void splitH264(const char *ptr, int len, int prefix, const std::function<void(co
     }
 }
 
+int prefixSize(const char *ptr, int len){
+    if (len < 4) {
+        return 0;
+    }
+
+    if (memcmp("\x00\x00\x01", ptr, 3) == 0) {
+        return 3;
+    }
+
+    if (memcmp("\x00\x00\x00\x01", ptr, 4) == 0) {
+        return 4;
+    }
+    return 0;
+}
+
 #if 0
 //splitH264函数测试程序
 static onceToken s_token([](){
diff --git a/src/Extension/H264.h b/src/Extension/H264.h
index 974ec817..1d890af0 100644
--- a/src/Extension/H264.h
+++ b/src/Extension/H264.h
@@ -21,7 +21,7 @@ namespace mediakit{
 
 bool getAVCInfo(const string &strSps,int &iVideoWidth, int &iVideoHeight, float  &iVideoFps);
 void splitH264(const char *ptr, int len, int prefix, const std::function<void(const char *, int, int)> &cb);
-
+int prefixSize(const char *ptr, int len);
 /**
  * 264帧类
  */
diff --git a/src/Rtp/Decoder.cpp b/src/Rtp/Decoder.cpp
index 5c8a7662..e177ed8e 100644
--- a/src/Rtp/Decoder.cpp
+++ b/src/Rtp/Decoder.cpp
@@ -129,7 +129,7 @@ void DecoderImp::onDecode(int stream,int codecid,int flags,int64_t pts,int64_t d
 
             auto frame = std::make_shared<H264FrameNoCacheAble>((char *) data, bytes, dts, pts,0);
             _merger.inputFrame(frame,[this](uint32_t dts, uint32_t pts, const Buffer::Ptr &buffer) {
-                onFrame(std::make_shared<H264FrameNoCacheAble>(buffer->data(), buffer->size(), dts, pts,4));
+                onFrame(std::make_shared<H264FrameNoCacheAble>(buffer->data(), buffer->size(), dts, pts, prefixSize(buffer->data(), buffer->size())));
             });
             break;
         }
@@ -148,7 +148,7 @@ void DecoderImp::onDecode(int stream,int codecid,int flags,int64_t pts,int64_t d
             }
             auto frame = std::make_shared<H265FrameNoCacheAble>((char *) data, bytes, dts, pts, 0);
             _merger.inputFrame(frame,[this](uint32_t dts, uint32_t pts, const Buffer::Ptr &buffer) {
-                onFrame(std::make_shared<H265FrameNoCacheAble>(buffer->data(), buffer->size(), dts, pts, 4));
+                onFrame(std::make_shared<H265FrameNoCacheAble>(buffer->data(), buffer->size(), dts, pts, prefixSize(buffer->data(), buffer->size())));
             });
             break;
         }