diff --git a/trunk/src/kernel/srs_kernel_buffer.hpp b/trunk/src/kernel/srs_kernel_buffer.hpp
index 0b0d776a5..061ea8338 100644
--- a/trunk/src/kernel/srs_kernel_buffer.hpp
+++ b/trunk/src/kernel/srs_kernel_buffer.hpp
@@ -41,8 +41,7 @@ public:
     /**
      * get the number of bytes to code to.
      */
-    // TODO: FIXME: change to uint64_t.
-    virtual int nb_bytes() = 0;
+    virtual uint64_t nb_bytes() = 0;
     /**
      * encode object to bytes in SrsBuffer.
      */
diff --git a/trunk/src/kernel/srs_kernel_rtc_rtcp.cpp b/trunk/src/kernel/srs_kernel_rtc_rtcp.cpp
index feebb14fe..4e0f98eee 100644
--- a/trunk/src/kernel/srs_kernel_rtc_rtcp.cpp
+++ b/trunk/src/kernel/srs_kernel_rtc_rtcp.cpp
@@ -115,7 +115,7 @@ srs_error_t SrsRtcpCommon::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpCommon::nb_bytes()
+uint64_t SrsRtcpCommon::nb_bytes()
 {
     return sizeof(SrsRtcpHeader) + 4 + payload_len_;
 }
@@ -255,7 +255,7 @@ srs_error_t SrsRtcpApp::decode(SrsBuffer *buffer)
     return srs_success;
 }
 
-int SrsRtcpApp::nb_bytes()
+uint64_t SrsRtcpApp::nb_bytes()
 {
     return sizeof(SrsRtcpHeader) + sizeof(ssrc_) + sizeof(name_) + payload_len_;
 }
@@ -422,7 +422,7 @@ block  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     return err;
 }
 
-int SrsRtcpSR::nb_bytes()
+uint64_t SrsRtcpSR::nb_bytes()
 {
     return (header_.length + 1) * 4;
 }
@@ -644,7 +644,7 @@ block  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     return err;
 }
 
-int SrsRtcpRR::nb_bytes()
+uint64_t SrsRtcpRR::nb_bytes()
 {
     return (header_.length + 1) * 4;
 }
@@ -863,7 +863,7 @@ srs_error_t SrsRtcpTWCC::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpTWCC::nb_bytes()
+uint64_t SrsRtcpTWCC::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1271,7 +1271,7 @@ srs_error_t SrsRtcpNack::decode(SrsBuffer *buffer)
 
     return err;
 }
-int SrsRtcpNack::nb_bytes()
+uint64_t SrsRtcpNack::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1403,7 +1403,7 @@ srs_error_t SrsRtcpPsfbCommon::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpPsfbCommon::nb_bytes()
+uint64_t SrsRtcpPsfbCommon::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1455,7 +1455,7 @@ srs_error_t SrsRtcpPli::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpPli::nb_bytes()
+uint64_t SrsRtcpPli::nb_bytes()
 {
     return 12;
 }
@@ -1548,7 +1548,7 @@ srs_error_t SrsRtcpSli::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpSli::nb_bytes()
+uint64_t SrsRtcpSli::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1619,7 +1619,7 @@ srs_error_t SrsRtcpRpsi::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpRpsi::nb_bytes()
+uint64_t SrsRtcpRpsi::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1672,7 +1672,7 @@ srs_error_t SrsRtcpXr::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpXr::nb_bytes()
+uint64_t SrsRtcpXr::nb_bytes()
 {
     return kRtcpPacketSize;
 }
@@ -1775,7 +1775,7 @@ srs_error_t SrsRtcpCompound::decode(SrsBuffer *buffer)
     return err;
 }
 
-int SrsRtcpCompound::nb_bytes()
+uint64_t SrsRtcpCompound::nb_bytes()
 {
     return kRtcpPacketSize;
 }
diff --git a/trunk/src/kernel/srs_kernel_rtc_rtcp.hpp b/trunk/src/kernel/srs_kernel_rtc_rtcp.hpp
index 588acb89a..56c30912a 100644
--- a/trunk/src/kernel/srs_kernel_rtc_rtcp.hpp
+++ b/trunk/src/kernel/srs_kernel_rtc_rtcp.hpp
@@ -103,7 +103,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);
 };
 
@@ -129,7 +129,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);
 };
 
@@ -181,7 +181,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);
 };
 
@@ -215,7 +215,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);
 
 };
@@ -322,7 +322,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);   
 private:
     srs_error_t do_encode(SrsBuffer *buffer);
@@ -351,7 +351,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);      
 };
 
@@ -369,7 +369,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);   
 };
 
@@ -382,7 +382,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);  
 };
 
@@ -399,7 +399,7 @@ public:
  // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);   
 }; 
 
@@ -418,7 +418,7 @@ public:
  // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);   
 };
 
@@ -431,7 +431,7 @@ public:
    // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);   
 };
 
@@ -457,7 +457,7 @@ public:
 // interface ISrsCodec
 public:
     virtual srs_error_t decode(SrsBuffer *buffer);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer *buffer);
 };
 
diff --git a/trunk/src/kernel/srs_kernel_rtc_rtp.cpp b/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
index aaecd8d0c..d07f18097 100644
--- a/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
+++ b/trunk/src/kernel/srs_kernel_rtc_rtp.cpp
@@ -136,7 +136,7 @@ srs_error_t SrsRtpExtensionTwcc::decode(SrsBuffer* buf)
     return err;
 }
 
-int SrsRtpExtensionTwcc::nb_bytes()
+uint64_t SrsRtpExtensionTwcc::nb_bytes()
 {
     return 3;
 }
@@ -260,7 +260,7 @@ srs_error_t SrsRtpExtensions::decode_0xbede(SrsBuffer* buf)
     return err;
 }
 
-int SrsRtpExtensions::nb_bytes()
+uint64_t SrsRtpExtensions::nb_bytes()
 {
     int size =  4 + (twcc_.has_twcc_ext() ? twcc_.nb_bytes() : 0);
     // add padding
@@ -488,7 +488,7 @@ srs_error_t SrsRtpHeader::set_twcc_sequence_number(uint8_t id, uint16_t sn)
     return extensions_.set_twcc_sequence_number(id, sn);
 }
 
-int SrsRtpHeader::nb_bytes()
+uint64_t SrsRtpHeader::nb_bytes()
 {
     return kRtpHeaderFixedSize + cc * 4 + (extensions_.exists() ? extensions_.nb_bytes() : 0);
 }
@@ -634,7 +634,7 @@ void SrsRtpPacket2::set_extension_types(const SrsRtpExtensionTypes* v)
     return header.set_extensions(v);
 }
 
-int SrsRtpPacket2::nb_bytes()
+uint64_t SrsRtpPacket2::nb_bytes()
 {
     if (!cached_payload_size) {
         int nn_payload = (payload? payload->nb_bytes():0);
@@ -714,7 +714,7 @@ SrsRtpRawPayload::~SrsRtpRawPayload()
 {
 }
 
-int SrsRtpRawPayload::nb_bytes()
+uint64_t SrsRtpRawPayload::nb_bytes()
 {
     return nn_payload;
 }
@@ -833,7 +833,7 @@ srs_error_t SrsRtpRawNALUs::read_samples(vector<SrsSample*>& samples, int packet
     return srs_success;
 }
 
-int SrsRtpRawNALUs::nb_bytes()
+uint64_t SrsRtpRawNALUs::nb_bytes()
 {
     int size = 0;
 
@@ -944,7 +944,7 @@ SrsSample* SrsRtpSTAPPayload::get_pps()
     return NULL;
 }
 
-int SrsRtpSTAPPayload::nb_bytes()
+uint64_t SrsRtpSTAPPayload::nb_bytes()
 {
     int size = 1;
 
@@ -1048,7 +1048,7 @@ SrsRtpFUAPayload::~SrsRtpFUAPayload()
     }
 }
 
-int SrsRtpFUAPayload::nb_bytes()
+uint64_t SrsRtpFUAPayload::nb_bytes()
 {
     int size = 2;
 
@@ -1158,7 +1158,7 @@ SrsRtpFUAPayload2::~SrsRtpFUAPayload2()
 {
 }
 
-int SrsRtpFUAPayload2::nb_bytes()
+uint64_t SrsRtpFUAPayload2::nb_bytes()
 {
     return 2 + size;
 }
diff --git a/trunk/src/kernel/srs_kernel_rtc_rtp.hpp b/trunk/src/kernel/srs_kernel_rtc_rtp.hpp
index 8ba2fcc7f..76a39fbc5 100644
--- a/trunk/src/kernel/srs_kernel_rtc_rtp.hpp
+++ b/trunk/src/kernel/srs_kernel_rtc_rtp.hpp
@@ -135,7 +135,7 @@ public:
     // ISrsCodec
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual srs_error_t encode(SrsBuffer* buf);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
 };
 
 class SrsRtpExtensions : public ISrsCodec
@@ -160,7 +160,7 @@ private:
     srs_error_t decode_0xbede(SrsBuffer* buf);
 public:
     virtual srs_error_t encode(SrsBuffer* buf);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
 };
 
 class SrsRtpHeader : public ISrsCodec
@@ -185,7 +185,7 @@ private:
     srs_error_t parse_extensions(SrsBuffer* buf);
 public:
     virtual srs_error_t encode(SrsBuffer* buf);
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
 public:
     void set_marker(bool v);
     bool get_marker() const;
@@ -262,7 +262,7 @@ public:
     void set_extension_types(const SrsRtpExtensionTypes* v);
 // interface ISrsEncoder
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
 };
@@ -280,7 +280,7 @@ public:
     virtual ~SrsRtpRawPayload();
 // interface ISrsRtpPayloader
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual ISrsRtpPayloader* copy();
@@ -305,7 +305,7 @@ public:
     srs_error_t read_samples(std::vector<SrsSample*>& samples, int packet_size);
 // interface ISrsRtpPayloader
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual ISrsRtpPayloader* copy();
@@ -328,7 +328,7 @@ public:
     SrsSample* get_pps();
 // interface ISrsRtpPayloader
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual ISrsRtpPayloader* copy();
@@ -353,7 +353,7 @@ public:
     virtual ~SrsRtpFUAPayload();
 // interface ISrsRtpPayloader
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual ISrsRtpPayloader* copy();
@@ -378,7 +378,7 @@ public:
     virtual ~SrsRtpFUAPayload2();
 // interface ISrsRtpPayloader
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
     virtual ISrsRtpPayloader* copy();
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 13caea980..9c69f5b70 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -361,7 +361,7 @@ MockSrsCodec::~MockSrsCodec()
 {
 }
 
-int MockSrsCodec::nb_bytes()
+uint64_t MockSrsCodec::nb_bytes()
 {
     return 0;
 }