diff --git a/README.md b/README.md
index 56658c3dcf..bec6c8de60 100755
--- a/README.md
+++ b/README.md
@@ -153,6 +153,7 @@ For previous versions, please read:
 
 ## V4 changes
 
+* v4.0, 2020-02-25, For [#1615][bug #1615], support default app(live) for vmix SRT. 4.0.9
 * v4.0, 2020-02-21, For [#1598][bug #1598], support SLB health checking by TCP. 4.0.8
 * v4.0, 2020-02-19, For [#1579][bug #1579], support rolling update of k8s. 4.0.7
 * v4.0, 2020-02-18, For [#1579][bug #1579], support start/final wait for gracefully quit. 4.0.6
@@ -1685,6 +1686,7 @@ Winlin
 [bug #1601]: https://github.com/ossrs/srs/issues/1601
 [bug #1579]: https://github.com/ossrs/srs/issues/1579
 [bug #1598]: https://github.com/ossrs/srs/issues/1598
+[bug #1615]: https://github.com/ossrs/srs/issues/1615
 [bug #xxxxxxxxxxxxx]: https://github.com/ossrs/srs/issues/xxxxxxxxxxxxx
 
 [exo #828]: https://github.com/google/ExoPlayer/pull/828
diff --git a/trunk/conf/full.conf b/trunk/conf/full.conf
index 3352538b6a..928925e00a 100644
--- a/trunk/conf/full.conf
+++ b/trunk/conf/full.conf
@@ -290,6 +290,9 @@ srt_server {
     connect_timeout 4000;
     peerlatency 300;
     recvlatency 300;
+    # Default app for vmix, see https://github.com/ossrs/srs/pull/1615
+    # default: live
+    default_app live;
 }
 
 #############################################################################################
diff --git a/trunk/src/app/srs_app_config.cpp b/trunk/src/app/srs_app_config.cpp
index 89f3da8b55..0eaabb4c9b 100644
--- a/trunk/src/app/srs_app_config.cpp
+++ b/trunk/src/app/srs_app_config.cpp
@@ -3529,7 +3529,8 @@ srs_error_t SrsConfig::check_normal_config()
             if (n != "enabled" && n != "listen" && n != "maxbw"
                 && n != "mss" && n != "latency" && n != "recvlatency"
                 && n != "peerlatency" && n != "tlpkdrop" && n != "connect_timeout"
-                && n != "sendbuf" && n != "recvbuf" && n != "payloadsize") {
+                && n != "sendbuf" && n != "recvbuf" && n != "payloadsize"
+                && n != "default_app") {
                 return srs_error_new(ERROR_SYSTEM_CONFIG_INVALID, "illegal srt_stream.%s", n.c_str());
             }
         }
@@ -6893,6 +6894,20 @@ int SrsConfig::get_srto_payloadsize() {
     return atoi(conf->arg0().c_str());
 }
 
+string SrsConfig::get_default_app_name() {
+    static string DEFAULT = "live";
+    SrsConfDirective* conf = root->get("srt_server");
+    if (!conf) {
+        return DEFAULT;
+    }
+
+    conf = conf->get("default_app");
+    if (!conf || conf->arg0().empty()) {
+        return DEFAULT;
+    }
+    return conf->arg0();
+}
+
 bool SrsConfig::get_http_stream_enabled()
 {
     SrsConfDirective* conf = root->get("http_server");
diff --git a/trunk/src/app/srs_app_config.hpp b/trunk/src/app/srs_app_config.hpp
index 17bcd49639..dde708f8e1 100644
--- a/trunk/src/app/srs_app_config.hpp
+++ b/trunk/src/app/srs_app_config.hpp
@@ -623,6 +623,8 @@ class SrsConfig
     virtual int get_srto_recvbuf();
     // SRTO_PAYLOADSIZE
     virtual int get_srto_payloadsize();
+    // Get the default app.
+    virtual std::string get_default_app_name();
 
 // http_hooks section
 private:
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index f5d2ad53cb..da3e2b8043 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -24,6 +24,6 @@
 #ifndef SRS_CORE_VERSION4_HPP
 #define SRS_CORE_VERSION4_HPP
 
-#define SRS_VERSION4_REVISION 8
+#define SRS_VERSION4_REVISION 9
 
 #endif
diff --git a/trunk/src/srt/srt_conn.cpp b/trunk/src/srt/srt_conn.cpp
index 4ea90bda15..e2f18af276 100644
--- a/trunk/src/srt/srt_conn.cpp
+++ b/trunk/src/srt/srt_conn.cpp
@@ -3,6 +3,8 @@
 #include "stringex.hpp"
 #include <vector>
 
+#include <srs_app_config.hpp>
+
 bool is_streamid_valid(const std::string& streamid) {
     if (streamid.empty()) {
         return false;
@@ -71,7 +73,7 @@ bool get_streamid_info(const std::string& streamid, int& mode, std::string& url_
     if (pos != 0) {
         pos = streamid.find("/");
         if (pos == streamid.npos) {
-            url_subpath = "live/" + streamid;
+            url_subpath = _srs_config->get_default_app_name() + "/" + streamid;
             return true;
         }
         url_subpath = streamid;