diff --git a/trunk/src/app/srs_app_conn.hpp b/trunk/src/app/srs_app_conn.hpp
index 01e1e268d..7a723dfbf 100644
--- a/trunk/src/app/srs_app_conn.hpp
+++ b/trunk/src/app/srs_app_conn.hpp
@@ -102,7 +102,7 @@ public:
     virtual srs_error_t start();
     // Set socket option TCP_NODELAY.
     virtual srs_error_t set_tcp_nodelay(bool v);
-    // Set socket option SO_SNDBUF in ms.
+    // Set socket option SO_SNDBUF in srs_utime_t.
     virtual srs_error_t set_socket_buffer(srs_utime_t buffer_v);
 // interface ISrsOneCycleThreadHandler
 public:
diff --git a/trunk/src/app/srs_app_dash.cpp b/trunk/src/app/srs_app_dash.cpp
index 88eb05ae7..719c9b110 100644
--- a/trunk/src/app/srs_app_dash.cpp
+++ b/trunk/src/app/srs_app_dash.cpp
@@ -88,7 +88,7 @@ srs_error_t SrsFragmentedMp4::initialize(SrsRequest* r, bool video, SrsMpdWriter
     string file_home;
     string file_name;
     int64_t sequence_number;
-    uint64_t basetime;
+    srs_utime_t basetime;
     if ((err = mpd->get_fragment(video, file_home, file_name, sequence_number, basetime)) != srs_success) {
         return srs_error_wrap(err, "get fragment");
     }
@@ -271,14 +271,14 @@ srs_error_t SrsMpdWriter::write(SrsFormat* format)
     return err;
 }
 
-srs_error_t SrsMpdWriter::get_fragment(bool video, std::string& home, std::string& file_name, int64_t& sn, uint64_t& basetime)
+srs_error_t SrsMpdWriter::get_fragment(bool video, std::string& home, std::string& file_name, int64_t& sn, srs_utime_t& basetime)
 {
     srs_error_t err = srs_success;
     
     home = fragment_home;
     
     sn = srs_update_system_time() / fragment;
-    basetime = sn * srsu2ms(fragment);
+    basetime = sn * fragment;
     
     if (video) {
         file_name = "video-" + srs_int2str(sn) + ".m4s";
diff --git a/trunk/src/app/srs_app_dash.hpp b/trunk/src/app/srs_app_dash.hpp
index 85559802b..48dadd440 100644
--- a/trunk/src/app/srs_app_dash.hpp
+++ b/trunk/src/app/srs_app_dash.hpp
@@ -109,8 +109,8 @@ public:
     virtual srs_error_t write(SrsFormat* format);
 public:
     // Get the fragment relative home and filename.
-    // The basetime is the absolute time in ms, while the sn(sequence number) is basetime/fragment.
-    virtual srs_error_t get_fragment(bool video, std::string& home, std::string& filename, int64_t& sn, uint64_t& basetime);
+    // The basetime is the absolute time in srs_utime_t, while the sn(sequence number) is basetime/fragment.
+    virtual srs_error_t get_fragment(bool video, std::string& home, std::string& filename, int64_t& sn, srs_utime_t& basetime);
 };
 
 /**
diff --git a/trunk/src/kernel/srs_kernel_mp4.cpp b/trunk/src/kernel/srs_kernel_mp4.cpp
index c2519c8b0..7be957a80 100644
--- a/trunk/src/kernel/srs_kernel_mp4.cpp
+++ b/trunk/src/kernel/srs_kernel_mp4.cpp
@@ -6144,7 +6144,7 @@ SrsMp4M2tsSegmentEncoder::~SrsMp4M2tsSegmentEncoder()
     srs_freep(buffer);
 }
 
-srs_error_t SrsMp4M2tsSegmentEncoder::initialize(ISrsWriter* w, uint32_t sequence, uint64_t basetime, uint32_t tid)
+srs_error_t SrsMp4M2tsSegmentEncoder::initialize(ISrsWriter* w, uint32_t sequence, srs_utime_t basetime, uint32_t tid)
 {
     srs_error_t err = srs_success;
     
@@ -6252,7 +6252,7 @@ srs_error_t SrsMp4M2tsSegmentEncoder::flush(uint64_t& dts)
         traf->set_tfdt(tfdt);
         
         tfdt->version = 1;
-        tfdt->base_media_decode_time = decode_basetime;
+        tfdt->base_media_decode_time = srsu2ms(decode_basetime);
         
         SrsMp4TrackFragmentRunBox* trun = new SrsMp4TrackFragmentRunBox();
         traf->set_trun(trun);
diff --git a/trunk/src/kernel/srs_kernel_mp4.hpp b/trunk/src/kernel/srs_kernel_mp4.hpp
index 120f5ab20..6b3bed71b 100644
--- a/trunk/src/kernel/srs_kernel_mp4.hpp
+++ b/trunk/src/kernel/srs_kernel_mp4.hpp
@@ -469,6 +469,7 @@ public:
 class SrsMp4TrackFragmentDecodeTimeBox : public SrsMp4FullBox
 {
 public:
+	// It's in ms.
     uint64_t base_media_decode_time;
 public:
     SrsMp4TrackFragmentDecodeTimeBox();
@@ -2198,7 +2199,7 @@ private:
     ISrsWriter* writer;
     SrsBuffer* buffer;
     uint32_t sequence_number;
-    uint64_t decode_basetime;
+    srs_utime_t decode_basetime;
     uint32_t track_id;
 private:
     uint32_t nb_audios;
@@ -2212,7 +2213,7 @@ public:
     virtual ~SrsMp4M2tsSegmentEncoder();
 public:
     // Initialize the encoder with a writer w.
-    virtual srs_error_t initialize(ISrsWriter* w, uint32_t sequence, uint64_t basetime, uint32_t tid);
+    virtual srs_error_t initialize(ISrsWriter* w, uint32_t sequence, srs_utime_t basetime, uint32_t tid);
     // Cache a sample.
     // @param ht, The sample handler type, audio/soun or video/vide.
     // @param ft, The frame type. For video, it's SrsVideoAvcFrameType.