diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index ebfd3d671..19c3582b2 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -36,6 +36,7 @@ using namespace std;
 #include <srs_kernel_log.hpp>
 #include <srs_kernel_mp3.hpp>
 #include <srs_kernel_ts.hpp>
+#include <srs_kernel_mp4.hpp>
 
 #define MAX_MOCK_DATA_SIZE 1024 * 1024
 
@@ -74,6 +75,11 @@ bool MockSrsFileWriter::is_open()
     return offset >= 0;
 }
 
+void MockSrsFileWriter::seek2(int64_t offset)
+{
+    this->offset = offset;
+}
+
 int64_t MockSrsFileWriter::tellg()
 {
     return offset;
@@ -102,6 +108,19 @@ srs_error_t MockSrsFileWriter::write(void* buf, size_t count, ssize_t* pnwrite)
     return srs_success;
 }
 
+srs_error_t MockSrsFileWriter::lseek(off_t offset, int whence, off_t* seeked)
+{
+    if (seeked) {
+        *seeked = (off_t)this->offset;
+    }
+    
+    if (whence == SEEK_SET) {
+        this->offset = (int)offset;
+    }
+    
+    return srs_success;
+}
+
 void MockSrsFileWriter::mock_reset_offset()
 {
     offset = 0;
@@ -176,9 +195,15 @@ srs_error_t MockSrsFileReader::read(void* buf, size_t count, ssize_t* pnread)
     return srs_success;
 }
 
-srs_error_t MockSrsFileReader::lseek(off_t _offset, int /*whence*/, off_t* /*seeked*/)
+srs_error_t MockSrsFileReader::lseek(off_t _offset, int whence, off_t* seeked)
 {
-    offset = (int)_offset;
+    if (seeked) {
+        *seeked = (off_t)offset;
+    }
+    
+    if (whence == SEEK_SET) {
+        offset = (int)_offset;
+    }
     return srs_success;
 }
 
@@ -3492,13 +3517,6 @@ VOID TEST(KernelTSTest, CoverTransmuxer)
     MockSrsFileWriter f;
     EXPECT_TRUE(srs_success == m.initialize(&f));
     
-    if (true) {
-        uint8_t raw[] = {
-            0xaf, 0x00, 0x12, 0x10
-        };
-        EXPECT_TRUE(srs_success == m.write_audio(0, (char*)raw, sizeof(raw)));
-    }
-    
     if (true) {
         uint8_t raw[] = {
             0x17,
@@ -3509,6 +3527,13 @@ VOID TEST(KernelTSTest, CoverTransmuxer)
         EXPECT_TRUE(srs_success == m.write_video(0, (char*)raw, sizeof(raw)));
     }
     
+    if (true) {
+        uint8_t raw[] = {
+            0xaf, 0x00, 0x12, 0x10
+        };
+        EXPECT_TRUE(srs_success == m.write_audio(0, (char*)raw, sizeof(raw)));
+    }
+    
     if (true) {
         uint8_t raw[] = {
             0xaf,
@@ -3539,3 +3564,150 @@ VOID TEST(KernelTSTest, CoverTransmuxer)
     }
 }
 
+VOID TEST(KernelMP4Test, CoverMP4Encoder)
+{
+    SrsMp4Encoder enc;
+    MockSrsFileWriter f;
+    SrsFormat fmt;
+    EXPECT_TRUE(srs_success == enc.initialize(&f));
+    EXPECT_TRUE(srs_success == fmt.initialize());
+    
+    if (true) {
+        uint8_t raw[] = {
+            0x17,
+            0x00, 0x00, 0x00, 0x00, 0x01, 0x64, 0x00, 0x20, 0xff, 0xe1, 0x00, 0x19, 0x67, 0x64, 0x00, 0x20,
+            0xac, 0xd9, 0x40, 0xc0, 0x29, 0xb0, 0x11, 0x00, 0x00, 0x03, 0x00, 0x01, 0x00, 0x00, 0x03, 0x00,
+            0x32, 0x0f, 0x18, 0x31, 0x96, 0x01, 0x00, 0x05, 0x68, 0xeb, 0xec, 0xb2, 0x2c
+        };
+        EXPECT_TRUE(srs_success == fmt.on_video(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeVIDE, fmt.video->frame_type, fmt.video->avc_packet_type, 0, 0, (uint8_t*)fmt.raw, fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0xaf, 0x00, 0x12, 0x10
+        };
+        EXPECT_TRUE(srs_success == fmt.on_audio(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeSOUN, 0x00, fmt.audio->aac_packet_type, 0, 0, (uint8_t*)fmt.raw, fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0xaf,
+            0x01, 0x21, 0x11, 0x45, 0x00, 0x14, 0x50, 0x01, 0x46, 0xf3, 0xf1, 0x0a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5e
+        };
+        EXPECT_TRUE(srs_success == fmt.on_audio(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeSOUN, 0x00, fmt.audio->aac_packet_type, 34, 34, (uint8_t*)fmt.raw, fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0x27,
+            0x01, 0x00, 0x00, 0x50, 0x00, 0x00, 0x00, 0x7b, 0x41, 0x9a, 0x21, 0x6c, 0x42, 0x1f, 0x00, 0x00,
+            0xf1, 0x68, 0x1a, 0x35, 0x84, 0xb3, 0xee, 0xe0, 0x61, 0xba, 0x4e, 0xa8, 0x52, 0x48, 0x50, 0x59,
+            0x75, 0x42, 0xd9, 0x96, 0x4a, 0x51, 0x38, 0x2c, 0x63, 0x5e, 0x41, 0xc9, 0x70, 0x60, 0x9d, 0x13,
+            0x53, 0xc2, 0xa8, 0xf5, 0x45, 0x86, 0xc5, 0x3e, 0x28, 0x1a, 0x69, 0x5f, 0x71, 0x1e, 0x51, 0x74,
+            0x0e, 0x31, 0x47, 0x3c, 0xd3, 0xd2, 0x10, 0x25, 0x45, 0xc5, 0xb7, 0x31, 0xec, 0x7f, 0xd8, 0x02,
+            0xae, 0xa4, 0x77, 0x6d, 0xcb, 0xc6, 0x1e, 0x2f, 0xa2, 0xd1, 0x12, 0x08, 0x34, 0x52, 0xea, 0xe8,
+            0x0b, 0x4f, 0x81, 0x21, 0x4f, 0x71, 0x3f, 0xf2, 0xad, 0x02, 0x58, 0xdf, 0x9e, 0x31, 0x86, 0x9b,
+            0x1b, 0x41, 0xbf, 0x2a, 0x09, 0x00, 0x43, 0x5c, 0xa1, 0x7e, 0x76, 0x59, 0xef, 0xa6, 0xfc, 0x82,
+            0xb2, 0x72, 0x5a
+        };
+        EXPECT_TRUE(srs_success == fmt.on_video(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeVIDE, fmt.video->frame_type, fmt.video->avc_packet_type, 40, 40, (uint8_t*)fmt.raw, fmt.nb_raw
+        ));
+    }
+    
+    EXPECT_TRUE(srs_success == enc.flush());
+}
+
+uint8_t* mock_copy_bytes(char* data, int size)
+{
+    uint8_t* cp = new uint8_t[size];
+    memcpy(cp, data, size);
+    return cp;
+}
+
+VOID TEST(KernelMP4Test, CoverMP4M2tsSegmentEncoder)
+{
+    SrsMp4M2tsSegmentEncoder enc;
+    MockSrsFileWriter f;
+    EXPECT_TRUE(srs_success == enc.initialize(&f, 0, 0, 100));
+    
+    SrsFormat fmt;
+    EXPECT_TRUE(srs_success == fmt.initialize());
+    
+    if (true) {
+        uint8_t raw[] = {
+            0x17,
+            0x00, 0x00, 0x00, 0x00, 0x01, 0x64, 0x00, 0x20, 0xff, 0xe1, 0x00, 0x19, 0x67, 0x64, 0x00, 0x20,
+            0xac, 0xd9, 0x40, 0xc0, 0x29, 0xb0, 0x11, 0x00, 0x00, 0x03, 0x00, 0x01, 0x00, 0x00, 0x03, 0x00,
+            0x32, 0x0f, 0x18, 0x31, 0x96, 0x01, 0x00, 0x05, 0x68, 0xeb, 0xec, 0xb2, 0x2c
+        };
+        EXPECT_TRUE(srs_success == fmt.on_video(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeVIDE, fmt.video->frame_type, 0, 0, mock_copy_bytes(fmt.raw, fmt.nb_raw), fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0xaf, 0x00, 0x12, 0x10
+        };
+        EXPECT_TRUE(srs_success == fmt.on_audio(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeSOUN, 0x00, 0, 0, mock_copy_bytes(fmt.raw, fmt.nb_raw), fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0xaf,
+            0x01, 0x21, 0x11, 0x45, 0x00, 0x14, 0x50, 0x01, 0x46, 0xf3, 0xf1, 0x0a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5e
+        };
+        EXPECT_TRUE(srs_success == fmt.on_audio(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeSOUN, 0x00, 34, 34, mock_copy_bytes(fmt.raw, fmt.nb_raw), fmt.nb_raw
+        ));
+    }
+    
+    if (true) {
+        uint8_t raw[] = {
+            0x27,
+            0x01, 0x00, 0x00, 0x50, 0x00, 0x00, 0x00, 0x7b, 0x41, 0x9a, 0x21, 0x6c, 0x42, 0x1f, 0x00, 0x00,
+            0xf1, 0x68, 0x1a, 0x35, 0x84, 0xb3, 0xee, 0xe0, 0x61, 0xba, 0x4e, 0xa8, 0x52, 0x48, 0x50, 0x59,
+            0x75, 0x42, 0xd9, 0x96, 0x4a, 0x51, 0x38, 0x2c, 0x63, 0x5e, 0x41, 0xc9, 0x70, 0x60, 0x9d, 0x13,
+            0x53, 0xc2, 0xa8, 0xf5, 0x45, 0x86, 0xc5, 0x3e, 0x28, 0x1a, 0x69, 0x5f, 0x71, 0x1e, 0x51, 0x74,
+            0x0e, 0x31, 0x47, 0x3c, 0xd3, 0xd2, 0x10, 0x25, 0x45, 0xc5, 0xb7, 0x31, 0xec, 0x7f, 0xd8, 0x02,
+            0xae, 0xa4, 0x77, 0x6d, 0xcb, 0xc6, 0x1e, 0x2f, 0xa2, 0xd1, 0x12, 0x08, 0x34, 0x52, 0xea, 0xe8,
+            0x0b, 0x4f, 0x81, 0x21, 0x4f, 0x71, 0x3f, 0xf2, 0xad, 0x02, 0x58, 0xdf, 0x9e, 0x31, 0x86, 0x9b,
+            0x1b, 0x41, 0xbf, 0x2a, 0x09, 0x00, 0x43, 0x5c, 0xa1, 0x7e, 0x76, 0x59, 0xef, 0xa6, 0xfc, 0x82,
+            0xb2, 0x72, 0x5a
+        };
+        EXPECT_TRUE(srs_success == fmt.on_video(0, (char*)raw, sizeof(raw)));
+        EXPECT_TRUE(srs_success == enc.write_sample(
+            SrsMp4HandlerTypeVIDE, fmt.video->frame_type, 40, 40, mock_copy_bytes(fmt.raw, fmt.nb_raw), fmt.nb_raw
+        ));
+    }
+    
+    uint64_t dts = 0;
+    EXPECT_TRUE(srs_success == enc.flush(dts));
+}
+
diff --git a/trunk/src/utest/srs_utest_kernel.hpp b/trunk/src/utest/srs_utest_kernel.hpp
index 787920ae3..0ea27d27b 100644
--- a/trunk/src/utest/srs_utest_kernel.hpp
+++ b/trunk/src/utest/srs_utest_kernel.hpp
@@ -61,9 +61,11 @@ public:
     virtual void close();
 public:
     virtual bool is_open();
+    virtual void seek2(int64_t offset);
     virtual int64_t tellg();
 public:
     virtual srs_error_t write(void* buf, size_t count, ssize_t* pnwrite);
+    virtual srs_error_t lseek(off_t offset, int whence, off_t* seeked);
 // for mock
 public:
     void mock_reset_offset();