diff --git a/README.md b/README.md
index b0c9bcdfb..ffafac8c2 100755
--- a/README.md
+++ b/README.md
@@ -208,6 +208,7 @@ For previous versions, please read:
 
 ## V3 changes
 
+* v3.0, 2020-12-17, Fix [#1694][bug #1694], Support DVR 2GB+ MP4 file. 3.0.155
 * v3.0, 2020-12-17, Fix [#1548][bug #1548], Add edts in MP4 for Windows10. 3.0.154
 * <strong>v3.0, 2020-10-31, [3.0 release2(3.0.153)][r3.0r2] released. 122663 lines.</strong>
 * v3.0, 2020-10-31, Fix [#509][bug #509], Always malloc stack on heap. 3.0.153
@@ -1784,6 +1785,7 @@ Winlin
 [bug #1780]: https://github.com/ossrs/srs/issues/1780
 [bug #1987]: https://github.com/ossrs/srs/issues/1987
 [bug #1548]: https://github.com/ossrs/srs/issues/1548
+[bug #1694]: https://github.com/ossrs/srs/issues/1694
 [bug #yyyyyyyyyyyyy]: https://github.com/ossrs/srs/issues/yyyyyyyyyyyyy
 
 [bug #1631]: https://github.com/ossrs/srs/issues/1631
diff --git a/trunk/src/core/srs_core_version3.hpp b/trunk/src/core/srs_core_version3.hpp
index 12949ebd1..a64066df2 100644
--- a/trunk/src/core/srs_core_version3.hpp
+++ b/trunk/src/core/srs_core_version3.hpp
@@ -24,6 +24,6 @@
 #ifndef SRS_CORE_VERSION3_HPP
 #define SRS_CORE_VERSION3_HPP
 
-#define SRS_VERSION3_REVISION 154
+#define SRS_VERSION3_REVISION 155
 
 #endif
diff --git a/trunk/src/kernel/srs_kernel_buffer.hpp b/trunk/src/kernel/srs_kernel_buffer.hpp
index 821adc2b1..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.
      */
@@ -80,9 +79,12 @@ public:
     ISrsCodec();
     virtual ~ISrsCodec();
 public:
-    /**
-     * decode object from bytes in SrsBuffer.
-     */
+    // Get the number of bytes to code to.
+    virtual uint64_t nb_bytes() = 0;
+    // Encode object to bytes in SrsBuffer.
+    virtual srs_error_t encode(SrsBuffer* buf) = 0;
+public:
+    // Decode object from bytes in SrsBuffer.
     virtual srs_error_t decode(SrsBuffer* buf) = 0;
 };
 
diff --git a/trunk/src/kernel/srs_kernel_error.hpp b/trunk/src/kernel/srs_kernel_error.hpp
index 7cfece08d..de3040793 100644
--- a/trunk/src/kernel/srs_kernel_error.hpp
+++ b/trunk/src/kernel/srs_kernel_error.hpp
@@ -282,12 +282,13 @@
 #define ERROR_DASH_WRITE_FAILED             3087
 #define ERROR_TS_CONTEXT_NOT_READY          3088
 #define ERROR_MP4_ILLEGAL_MOOF              3089
-#define ERROR_OCLUSTER_DISCOVER             3090
-#define ERROR_OCLUSTER_REDIRECT             3091
-#define ERROR_INOTIFY_CREATE                3092
-#define ERROR_INOTIFY_OPENFD                3093
-#define ERROR_INOTIFY_WATCH                 3094
-#define ERROR_HTTP_URL_UNESCAPE             3095
+#define ERROR_MP4_ILLEGAL_MDAT              3090
+#define ERROR_OCLUSTER_DISCOVER             3091
+#define ERROR_OCLUSTER_REDIRECT             3092
+#define ERROR_INOTIFY_CREATE                3093
+#define ERROR_INOTIFY_OPENFD                3094
+#define ERROR_INOTIFY_WATCH                 3095
+#define ERROR_HTTP_URL_UNESCAPE             3096
 
 ///////////////////////////////////////////////////////
 // HTTP/StreamCaster protocol error.
diff --git a/trunk/src/kernel/srs_kernel_mp4.cpp b/trunk/src/kernel/srs_kernel_mp4.cpp
index 969c38568..d3d5a7731 100644
--- a/trunk/src/kernel/srs_kernel_mp4.cpp
+++ b/trunk/src/kernel/srs_kernel_mp4.cpp
@@ -190,17 +190,18 @@ int SrsMp4Box::sz_header()
     return nb_header();
 }
 
-int SrsMp4Box::update_size()
+uint64_t SrsMp4Box::update_size()
 {
     uint64_t size = nb_bytes();
 
     if (size > 0xffffffff) {
         largesize = size;
+        smallsize = SRS_MP4_USE_LARGE_SIZE;
     } else {
         smallsize = (uint32_t)size;
     }
 
-    return (int)size;
+    return size;
 }
 
 int SrsMp4Box::left_space(SrsBuffer* buf)
@@ -299,11 +300,11 @@ srs_error_t SrsMp4Box::discovery(SrsBuffer* buf, SrsMp4Box** ppbox)
     *ppbox = NULL;
     
     srs_error_t err = srs_success;
-    
+
     if (!buf->require(8)) {
         return srs_error_new(ERROR_MP4_BOX_REQUIRE_SPACE, "requires 8 only %d bytes", buf->left());
     }
-    
+
     // Discovery the size and type.
     uint64_t largesize = 0;
     uint32_t smallsize = (uint32_t)buf->read_4bytes();
@@ -313,15 +314,14 @@ srs_error_t SrsMp4Box::discovery(SrsBuffer* buf, SrsMp4Box** ppbox)
             return srs_error_new(ERROR_MP4_BOX_REQUIRE_SPACE, "requires 16 only %d bytes", buf->left());
         }
         largesize = (uint64_t)buf->read_8bytes();
+    }
+
+    // Reset the buffer, because we only peek it.
+    buf->skip(-8);
+    if (smallsize == SRS_MP4_USE_LARGE_SIZE) {
         buf->skip(-8);
     }
-    buf->skip(-8);
-    
-    // Only support 31bits size.
-    if (largesize > 0x7fffffff) {
-        return srs_error_new(ERROR_MP4_BOX_OVERFLOW, "overflow 31bits, largesize=%" PRId64, largesize);
-    }
-    
+
     SrsMp4Box* box = NULL;
     switch(type) {
         case SrsMp4BoxTypeFTYP: box = new SrsMp4FileTypeBox(); break;
@@ -382,9 +382,9 @@ srs_error_t SrsMp4Box::discovery(SrsBuffer* buf, SrsMp4Box** ppbox)
     return err;
 }
 
-int SrsMp4Box::nb_bytes()
+uint64_t SrsMp4Box::nb_bytes()
 {
-    int sz = nb_header();
+    uint64_t sz = nb_header();
     
     vector<SrsMp4Box*>::iterator it;
     for (it = boxes.begin(); it != boxes.end(); ++it) {
@@ -488,21 +488,16 @@ srs_error_t SrsMp4Box::encode_header(SrsBuffer* buf)
 {
     srs_error_t err = srs_success;
     
-    // Only support 31bits size.
-    if (sz() > 0x7fffffff) {
-        return srs_error_new(ERROR_MP4_BOX_OVERFLOW, "box size overflow 31bits, size=%" PRId64, sz());
-    }
-    
     int size = SrsMp4Box::nb_header();
     if (!buf->require(size)) {
         return srs_error_new(ERROR_MP4_BOX_REQUIRE_SPACE, "requires %d only %d bytes", size, buf->left());
     }
     
     buf->write_4bytes(smallsize);
+    buf->write_4bytes(type);
     if (smallsize == SRS_MP4_USE_LARGE_SIZE) {
         buf->write_8bytes(largesize);
     }
-    buf->write_4bytes(type);
     
     if (type == SrsMp4BoxTypeUUID) {
         buf->write_bytes(&usertype[0], 16);
@@ -1071,7 +1066,7 @@ SrsMp4TrunEntry::~SrsMp4TrunEntry()
 {
 }
 
-int SrsMp4TrunEntry::nb_bytes()
+uint64_t SrsMp4TrunEntry::nb_bytes()
 {
     int size = 0;
     
@@ -1291,7 +1286,7 @@ SrsMp4MediaDataBox::~SrsMp4MediaDataBox()
 {
 }
 
-int SrsMp4MediaDataBox::nb_bytes()
+uint64_t SrsMp4MediaDataBox::nb_bytes()
 {
     return SrsMp4Box::nb_header() + nb_data;
 }
@@ -1315,7 +1310,7 @@ srs_error_t SrsMp4MediaDataBox::decode(SrsBuffer* buf)
         return srs_error_wrap(err, "decode box");
     }
     
-    nb_data = (int)(sz() - nb_header());
+    nb_data = sz() - (uint64_t)nb_header();
     
     return err;
 }
@@ -3270,7 +3265,7 @@ int SrsMp4BaseDescriptor::left_space(SrsBuffer* buf)
     return srs_max(0, left);
 }
 
-int SrsMp4BaseDescriptor::nb_bytes()
+uint64_t SrsMp4BaseDescriptor::nb_bytes()
 {
     // 1 byte tag.
     int size = 1;
@@ -5964,16 +5959,15 @@ srs_error_t SrsMp4Encoder::flush()
     
     // Write mdat box.
     if (true) {
-        // Update the mdat box header.
-        if ((err = wsio->lseek(mdat_offset, SEEK_SET, NULL)) != srs_success) {
-            return srs_error_wrap(err, "seek to mdat");
-        }
-        
         // Write mdat box with size of data,
         // its payload already writen by samples,
         // and we will update its header(size) when flush.
         SrsMp4MediaDataBox* mdat = new SrsMp4MediaDataBox();
         SrsAutoFree(SrsMp4MediaDataBox, mdat);
+
+        // Update the size of mdat first, for over 2GB file.
+        mdat->nb_data = mdat_bytes;
+        mdat->update_size();
         
         int nb_data = mdat->sz_header();
         uint8_t* data = new uint8_t[nb_data];
@@ -5981,12 +5975,25 @@ srs_error_t SrsMp4Encoder::flush()
         
         SrsBuffer* buffer = new SrsBuffer((char*)data, nb_data);
         SrsAutoFree(SrsBuffer, buffer);
-        
-        // TODO: FIXME: Support 64bits size.
-        mdat->nb_data = (int)mdat_bytes;
+
         if ((err = mdat->encode(buffer)) != srs_success) {
             return srs_error_wrap(err, "encode mdat");
         }
+
+        // We might adjust the offset of mdat, for large size, 2GB+ as such.
+        if (nb_data > 8) {
+            // For large size, the header of mdat MUST be 16.
+            if (nb_data != 16) {
+                return srs_error_new(ERROR_MP4_ILLEGAL_MDAT, "Invalid mdat header size %d", nb_data);
+            }
+            // Use large size, to the start of reserved free box.
+            mdat_offset -= 8;
+        }
+
+        // Seek to the start of mdat.
+        if ((err = wsio->lseek(mdat_offset, SEEK_SET, NULL)) != srs_success) {
+            return srs_error_wrap(err, "seek to mdat");
+        }
         
         // TODO: FIXME: Ensure all bytes are writen.
         if ((err = wsio->write(data, nb_data, NULL)) != srs_success) {
@@ -6448,7 +6455,7 @@ srs_error_t SrsMp4M2tsSegmentEncoder::flush(uint64_t& dts)
         // @remark Remember the data_offset of turn is size(moof)+header(mdat), not including styp or sidx.
         int moof_bytes = moof->nb_bytes();
         trun->data_offset = (int32_t)(moof_bytes + mdat->sz_header());
-        mdat->nb_data = (int)mdat_bytes;
+        mdat->nb_data = mdat_bytes;
 
         // Update the size of sidx.
         SrsMp4SegmentIndexEntry* entry = &sidx->entries[0];
diff --git a/trunk/src/kernel/srs_kernel_mp4.hpp b/trunk/src/kernel/srs_kernel_mp4.hpp
index 655f452ae..4e856df23 100644
--- a/trunk/src/kernel/srs_kernel_mp4.hpp
+++ b/trunk/src/kernel/srs_kernel_mp4.hpp
@@ -205,7 +205,7 @@ public:
     // @remark For mdat box, we must codec its header, use this instead of sz().
     virtual int sz_header();
     // Update the size of box.
-    virtual int update_size();
+    virtual uint64_t update_size();
     // Get the left space of box, for decoder.
     virtual int left_space(SrsBuffer* buf);
     // Box type helper.
@@ -227,7 +227,7 @@ public:
     static srs_error_t discovery(SrsBuffer* buf, SrsMp4Box** ppbox);
 // Interface ISrsCodec
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
 protected:
@@ -495,7 +495,7 @@ public:
     SrsMp4TrunEntry(SrsMp4FullBox* o);
     virtual ~SrsMp4TrunEntry();
     
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
 
@@ -581,8 +581,7 @@ class SrsMp4MediaDataBox : public SrsMp4Box
 {
 public:
     // The contained media data, which we never directly read/write it.
-    // TODO: FIXME: Support 64bits size.
-    int nb_data;
+    uint64_t nb_data;
 public:
     SrsMp4MediaDataBox();
     virtual ~SrsMp4MediaDataBox();
@@ -590,7 +589,7 @@ public:
 public:
     // The total size of bytes, including the sz_header() and nb_data,
     // which used to write the smallsize or largesize of mp4.
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     // To encode the mdat box, the buf should only contains the sz_header(),
     // because the mdata only encode the header.
     virtual srs_error_t encode(SrsBuffer* buf);
@@ -1369,7 +1368,7 @@ public:
     virtual int left_space(SrsBuffer* buf);
 // Interface ISrsCodec
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
 protected:
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 9c791afd2..4ca8b0c61 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;
 }
diff --git a/trunk/src/utest/srs_utest_kernel.hpp b/trunk/src/utest/srs_utest_kernel.hpp
index 90efb4ee9..f32d1f063 100644
--- a/trunk/src/utest/srs_utest_kernel.hpp
+++ b/trunk/src/utest/srs_utest_kernel.hpp
@@ -130,7 +130,7 @@ public:
     MockSrsCodec();
     virtual ~MockSrsCodec();
 public:
-    virtual int nb_bytes();
+    virtual uint64_t nb_bytes();
     virtual srs_error_t encode(SrsBuffer* buf);
     virtual srs_error_t decode(SrsBuffer* buf);
 };