diff --git a/README.md b/README.md
index 9d71e4071..ecdc0fad3 100755
--- a/README.md
+++ b/README.md
@@ -146,6 +146,7 @@ For previous versions, please read:
 
 ## V3 changes
 
+* v3.0, 2020-02-04, Fix [#939][bug #939], response right A/V flag in FLV header. 3.0.113
 * v3.0, 2020-02-04, For [#939][bug #939], always enable fast FLV streaming.
 * <strong>v3.0, 2020-02-02, [3.0 beta0(3.0.112)][r3.0b0] released. 121709 lines.</strong>
 * v3.0, 2020-01-29, Support isolate version file. 3.0.112
diff --git a/trunk/src/app/srs_app_http_stream.cpp b/trunk/src/app/srs_app_http_stream.cpp
index e8253a94f..c7720be19 100755
--- a/trunk/src/app/srs_app_http_stream.cpp
+++ b/trunk/src/app/srs_app_http_stream.cpp
@@ -249,6 +249,7 @@ srs_error_t SrsTsStreamEncoder::dump_cache(SrsConsumer* /*consumer*/, SrsRtmpJit
 
 SrsFlvStreamEncoder::SrsFlvStreamEncoder()
 {
+    header_written = false;
     enc = new SrsFlvTransmuxer();
 }
 
@@ -265,26 +266,39 @@ srs_error_t SrsFlvStreamEncoder::initialize(SrsFileWriter* w, SrsBufferCache* /*
         return srs_error_wrap(err, "init encoder");
     }
     
-    // write flv header.
-    if ((err = enc->write_header())  != srs_success) {
-        return srs_error_wrap(err, "write header");
-    }
-    
     return err;
 }
 
 srs_error_t SrsFlvStreamEncoder::write_audio(int64_t timestamp, char* data, int size)
 {
+    srs_error_t err = srs_success;
+
+    if ((err = write_header())  != srs_success) {
+        return srs_error_wrap(err, "write header");
+    }
+
     return enc->write_audio(timestamp, data, size);
 }
 
 srs_error_t SrsFlvStreamEncoder::write_video(int64_t timestamp, char* data, int size)
 {
+    srs_error_t err = srs_success;
+
+    if ((err = write_header())  != srs_success) {
+        return srs_error_wrap(err, "write header");
+    }
+
     return enc->write_video(timestamp, data, size);
 }
 
 srs_error_t SrsFlvStreamEncoder::write_metadata(int64_t timestamp, char* data, int size)
 {
+    srs_error_t err = srs_success;
+
+    if ((err = write_header())  != srs_success) {
+        return srs_error_wrap(err, "write header");
+    }
+
     return enc->write_metadata(SrsFrameTypeScript, data, size);
 }
 
@@ -302,9 +316,52 @@ srs_error_t SrsFlvStreamEncoder::dump_cache(SrsConsumer* /*consumer*/, SrsRtmpJi
 
 srs_error_t SrsFlvStreamEncoder::write_tags(SrsSharedPtrMessage** msgs, int count)
 {
+    srs_error_t err = srs_success;
+
+    // For https://github.com/ossrs/srs/issues/939
+    if (!header_written) {
+        bool has_video = false;
+        bool has_audio = false;
+
+        for (int i = 0; i < count && (!has_video || !has_audio); i++) {
+            SrsSharedPtrMessage* msg = msgs[i];
+            if (msg->is_video()) {
+                has_video = true;
+            } else if (msg->is_audio()) {
+                has_audio = true;
+            }
+        }
+
+        // Drop data if no A+V.
+        if (!has_video && !has_audio) {
+            return err;
+        }
+
+        if ((err = write_header(has_video, has_audio))  != srs_success) {
+            return srs_error_wrap(err, "write header");
+        }
+    }
+
     return enc->write_tags(msgs, count);
 }
 
+srs_error_t SrsFlvStreamEncoder::write_header(bool has_video, bool has_audio)
+{
+    srs_error_t err = srs_success;
+
+    if (!header_written) {
+        header_written = true;
+
+        if ((err = enc->write_header(has_video, has_audio))  != srs_success) {
+            return srs_error_wrap(err, "write header");
+        }
+
+        srs_trace("FLV: write header audio=%d, video=%d", has_audio, has_video);
+    }
+
+    return err;
+}
+
 SrsAacStreamEncoder::SrsAacStreamEncoder()
 {
     enc = new SrsAacTransmuxer();
diff --git a/trunk/src/app/srs_app_http_stream.hpp b/trunk/src/app/srs_app_http_stream.hpp
index c9a6f7904..720e53e3a 100755
--- a/trunk/src/app/srs_app_http_stream.hpp
+++ b/trunk/src/app/srs_app_http_stream.hpp
@@ -82,8 +82,9 @@ public:
 // Transmux RTMP to HTTP Live Streaming.
 class SrsFlvStreamEncoder : public ISrsBufferEncoder
 {
-protected:
+private:
     SrsFlvTransmuxer* enc;
+    bool header_written;
 public:
     SrsFlvStreamEncoder();
     virtual ~SrsFlvStreamEncoder();
@@ -98,6 +99,8 @@ public:
 public:
     // Write the tags in a time.
     virtual srs_error_t write_tags(SrsSharedPtrMessage** msgs, int count);
+private:
+    virtual srs_error_t write_header(bool has_video = true, bool has_audio = true);
 };
 
 // Transmux RTMP to HTTP TS Streaming.
diff --git a/trunk/src/core/srs_core_version3.hpp b/trunk/src/core/srs_core_version3.hpp
index 05251a733..0977c5458 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 112
+#define SRS_VERSION3_REVISION 113
 
 #endif