diff --git a/trunk/src/kernel/srs_kernel_ts.cpp b/trunk/src/kernel/srs_kernel_ts.cpp
index 26ab41841..cffd67cda 100644
--- a/trunk/src/kernel/srs_kernel_ts.cpp
+++ b/trunk/src/kernel/srs_kernel_ts.cpp
@@ -298,7 +298,7 @@ srs_error_t SrsTsContext::decode(SrsBuffer* stream, ISrsTsHandler* handler)
     return err;
 }
 
-srs_error_t SrsTsContext::encode(SrsFileWriter* writer, SrsTsMessage* msg, SrsVideoCodecId vc, SrsAudioCodecId ac)
+srs_error_t SrsTsContext::encode(ISrsStreamWriter* writer, SrsTsMessage* msg, SrsVideoCodecId vc, SrsAudioCodecId ac)
 {
     srs_error_t err = srs_success;
     
@@ -380,7 +380,7 @@ void SrsTsContext::set_sync_byte(int8_t sb)
     sync_byte = sb;
 }
 
-srs_error_t SrsTsContext::encode_pat_pmt(SrsFileWriter* writer, int16_t vpid, SrsTsStream vs, int16_t apid, SrsTsStream as)
+srs_error_t SrsTsContext::encode_pat_pmt(ISrsStreamWriter* writer, int16_t vpid, SrsTsStream vs, int16_t apid, SrsTsStream as)
 {
     srs_error_t err = srs_success;
     
@@ -441,7 +441,7 @@ srs_error_t SrsTsContext::encode_pat_pmt(SrsFileWriter* writer, int16_t vpid, Sr
     return err;
 }
 
-srs_error_t SrsTsContext::encode_pes(SrsFileWriter* writer, SrsTsMessage* msg, int16_t pid, SrsTsStream sid, bool pure_audio)
+srs_error_t SrsTsContext::encode_pes(ISrsStreamWriter* writer, SrsTsMessage* msg, int16_t pid, SrsTsStream sid, bool pure_audio)
 {
     srs_error_t err = srs_success;
     
@@ -2543,7 +2543,7 @@ srs_error_t SrsTsPayloadPMT::psi_encode(SrsBuffer* stream)
     return err;
 }
 
-SrsTsContextWriter::SrsTsContextWriter(SrsFileWriter* w, SrsTsContext* c, SrsAudioCodecId ac, SrsVideoCodecId vc)
+SrsTsContextWriter::SrsTsContextWriter(ISrsStreamWriter* w, SrsTsContext* c, SrsAudioCodecId ac, SrsVideoCodecId vc)
 {
     writer = w;
     context = c;
@@ -2568,7 +2568,10 @@ srs_error_t SrsTsContextWriter::open(string p)
     // reset the context for a new ts start.
     context->reset();
     
-    if ((err = writer->open(path)) != srs_success) {
+    SrsFileWriter* fw = dynamic_cast<SrsFileWriter*>(writer);
+    srs_assert(fw);
+    
+    if ((err = fw->open(path)) != srs_success) {
         return srs_error_wrap(err, "ts: open writer");
     }
     
@@ -2607,7 +2610,10 @@ srs_error_t SrsTsContextWriter::write_video(SrsTsMessage* video)
 
 void SrsTsContextWriter::close()
 {
-    writer->close();
+    SrsFileWriter* fw = dynamic_cast<SrsFileWriter*>(writer);
+    srs_assert(fw);
+    
+    fw->close();
 }
 
 SrsVideoCodecId SrsTsContextWriter::video_codec()
@@ -3011,7 +3017,7 @@ SrsTsTransmuxer::~SrsTsTransmuxer()
     srs_freep(context);
 }
 
-srs_error_t SrsTsTransmuxer::initialize(SrsFileWriter* fw)
+srs_error_t SrsTsTransmuxer::initialize(ISrsStreamWriter* fw)
 {
     srs_error_t err = srs_success;
     
@@ -3021,10 +3027,6 @@ srs_error_t SrsTsTransmuxer::initialize(SrsFileWriter* fw)
     
     srs_assert(fw);
     
-    if (!fw->is_open()) {
-        return srs_error_new(ERROR_KERNEL_FLV_STREAM_CLOSED, "ts: stream is not open");
-    }
-    
     writer = fw;
     
     srs_freep(tscw);
diff --git a/trunk/src/kernel/srs_kernel_ts.hpp b/trunk/src/kernel/srs_kernel_ts.hpp
index 36fd5224a..e2e1e523a 100644
--- a/trunk/src/kernel/srs_kernel_ts.hpp
+++ b/trunk/src/kernel/srs_kernel_ts.hpp
@@ -38,7 +38,7 @@
 class SrsBuffer;
 class SrsTsMessageCache;
 class SrsTsContextWriter;
-class SrsFileWriter;
+class ISrsStreamWriter;
 class SrsFileReader;
 class SrsFormat;
 class SrsSimpleStream;
@@ -403,7 +403,7 @@ public:
      * @param vc the video codec, write the PAT/PMT table when changed.
      * @param ac the audio codec, write the PAT/PMT table when changed.
      */
-    virtual srs_error_t encode(SrsFileWriter* writer, SrsTsMessage* msg, SrsVideoCodecId vc, SrsAudioCodecId ac);
+    virtual srs_error_t encode(ISrsStreamWriter* writer, SrsTsMessage* msg, SrsVideoCodecId vc, SrsAudioCodecId ac);
 // drm methods
 public:
     /**
@@ -412,8 +412,8 @@ public:
      */
     virtual void set_sync_byte(int8_t sb);
 private:
-    virtual srs_error_t encode_pat_pmt(SrsFileWriter* writer, int16_t vpid, SrsTsStream vs, int16_t apid, SrsTsStream as);
-    virtual srs_error_t encode_pes(SrsFileWriter* writer, SrsTsMessage* msg, int16_t pid, SrsTsStream sid, bool pure_audio);
+    virtual srs_error_t encode_pat_pmt(ISrsStreamWriter* writer, int16_t vpid, SrsTsStream vs, int16_t apid, SrsTsStream as);
+    virtual srs_error_t encode_pes(ISrsStreamWriter* writer, SrsTsMessage* msg, int16_t pid, SrsTsStream sid, bool pure_audio);
 };
 
 /**
@@ -1543,10 +1543,10 @@ private:
     SrsAudioCodecId acodec;
 private:
     SrsTsContext* context;
-    SrsFileWriter* writer;
+    ISrsStreamWriter* writer;
     std::string path;
 public:
-    SrsTsContextWriter(SrsFileWriter* w, SrsTsContext* c, SrsAudioCodecId ac, SrsVideoCodecId vc);
+    SrsTsContextWriter(ISrsStreamWriter* w, SrsTsContext* c, SrsAudioCodecId ac, SrsVideoCodecId vc);
     virtual ~SrsTsContextWriter();
 public:
     /**
@@ -1628,7 +1628,7 @@ private:
 class SrsTsTransmuxer
 {
 private:
-    SrsFileWriter* writer;
+    ISrsStreamWriter* writer;
 private:
     SrsFormat* format;
     SrsTsMessageCache* tsmc;
@@ -1642,7 +1642,7 @@ public:
      * initialize the underlayer file stream.
      * @param fw the writer to use for ts encoder, user must free it.
      */
-    virtual srs_error_t initialize(SrsFileWriter* fw);
+    virtual srs_error_t initialize(ISrsStreamWriter* fw);
 public:
     /**
      * write audio/video packet.
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 6a3fe9afe..a919ea232 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -243,14 +243,19 @@ srs_error_t MockSrsCodec::decode(SrsBuffer* /*buf*/)
 
 MockTsHandler::MockTsHandler()
 {
+    msg = NULL;
 }
 
 MockTsHandler::~MockTsHandler()
 {
+    srs_freep(msg);
 }
 
-srs_error_t MockTsHandler::on_ts_message(SrsTsMessage* /*msg*/)
+srs_error_t MockTsHandler::on_ts_message(SrsTsMessage* m)
 {
+    srs_freep(msg);
+    msg = m->detach();
+    
     return srs_success;
 }
 
@@ -3201,7 +3206,7 @@ VOID TEST(KernelUtilityTest, CoverTimeUtilityAll)
     }
 }
 
-VOID TEST(KernelTSTest, CoverBasicUtility)
+VOID TEST(KernelTSTest, CoverContextUtility)
 {
     if (true) {
         EXPECT_STREQ("Reserved", srs_ts_stream2string(SrsTsStreamReserved).c_str());
@@ -3238,6 +3243,9 @@ VOID TEST(KernelTSTest, CoverBasicUtility)
         SrsTsMessage* cp = m.detach();
         EXPECT_TRUE(cp != NULL);
         srs_freep(cp);
+        
+        ctx.reset();
+        EXPECT_FALSE(ctx.ready);
     }
     
     if (true) {
@@ -3294,6 +3302,44 @@ VOID TEST(KernelTSTest, CoverBasicUtility)
         EXPECT_TRUE(m.completed(0));
     }
     
+    if (true) {
+        SrsTsMessage m;
+        
+        EXPECT_TRUE(m.completed(1));
+        EXPECT_TRUE(!m.completed(0));
+        
+        m.PES_packet_length = 8;
+        SrsBuffer b((char*)"\x00\x01\x02\x03", 4);
+        
+        int nb_bytes = 0;
+        EXPECT_TRUE(srs_success == m.dump(&b, &nb_bytes));
+        EXPECT_EQ(4, nb_bytes);
+        
+        b.skip(-4);
+        EXPECT_TRUE(srs_success == m.dump(&b, &nb_bytes));
+        EXPECT_EQ(4, nb_bytes);
+        
+        EXPECT_TRUE(m.completed(0));
+    }
+    
+    if (true) {
+        MockTsHandler* h = new MockTsHandler();
+        srs_freep(h);
+        
+        SrsTsContext ctx;
+        EXPECT_TRUE(!ctx.is_pure_audio());
+        
+        ctx.set(100, SrsTsPidApplyPAT);
+        ctx.set(101, SrsTsPidApplyPMT);
+        ctx.set(102, SrsTsPidApplyVideo);
+        ctx.set(102, SrsTsPidApplyVideo);
+        
+        ctx.on_pmt_parsed();
+        EXPECT_TRUE(!ctx.is_pure_audio());
+        
+        EXPECT_EQ(100, ctx.get(100)->pid);
+    }
+    
     if (true) {
         MockTsHandler* h = new MockTsHandler();
         srs_freep(h);
@@ -3309,6 +3355,48 @@ VOID TEST(KernelTSTest, CoverBasicUtility)
         EXPECT_TRUE(ctx.is_pure_audio());
         
         EXPECT_EQ(100, ctx.get(100)->pid);
+        EXPECT_TRUE(NULL == ctx.get(200));
+    }
+    
+    if (true) {
+        SrsTsContext ctx;
+        EXPECT_EQ(0x47, ctx.sync_byte);
+        
+        ctx.set_sync_byte(0x01);
+        EXPECT_EQ(0x01, ctx.sync_byte);
+    }
+}
+
+VOID TEST(KernelTSTest, CoverContextCodec)
+{
+    SrsTsContext ctx;
+    MockTsHandler h;
+    
+    if (true) {
+        SrsBuffer b;
+        EXPECT_TRUE(srs_success == ctx.decode(&b, &h));
+        EXPECT_TRUE(NULL == h.msg);
+    }
+    
+    if (true) {
+        SrsBuffer b((char*)"\x00", 1);
+        
+        srs_error_t err = ctx.decode(&b, &h);
+        EXPECT_TRUE(srs_success != err);
+        srs_freep(err);
+    }
+    
+    if (true) {
+        MockSrsFileWriter f;
+        SrsTsMessage m;
+        
+        srs_error_t err = ctx.encode(&f, &m, SrsVideoCodecIdDisabled, SrsAudioCodecIdDisabled);
+        EXPECT_TRUE(srs_success != err);
+        srs_freep(err);
+        
+        err = ctx.encode(&f, &m, SrsVideoCodecIdHEVC, SrsAudioCodecIdOpus);
+        EXPECT_TRUE(srs_success != err);
+        srs_freep(err);
     }
 }
 
diff --git a/trunk/src/utest/srs_utest_kernel.hpp b/trunk/src/utest/srs_utest_kernel.hpp
index 7b2adcab2..787920ae3 100644
--- a/trunk/src/utest/srs_utest_kernel.hpp
+++ b/trunk/src/utest/srs_utest_kernel.hpp
@@ -110,11 +110,13 @@ public:
 
 class MockTsHandler : public ISrsTsHandler
 {
+public:
+    SrsTsMessage* msg;
 public:
     MockTsHandler();
     virtual ~MockTsHandler();
 public:
-    virtual srs_error_t on_ts_message(SrsTsMessage* msg);
+    virtual srs_error_t on_ts_message(SrsTsMessage* m);
 };
 
 #endif