diff --git a/api.go b/api.go
index 218dd0d..d7f9f73 100644
--- a/api.go
+++ b/api.go
@@ -21,15 +21,20 @@ type MergeTsDir_Resp struct {
 var gMergeIsRunning bool
 var gMergeIsRunningLocker sync.Mutex
 
-func MergeTsDir(InputTsDir string, OutputMp4Name string) (resp MergeTsDir_Resp) {
-	{
-		gMergeIsRunningLocker.Lock()
-		defer gMergeIsRunningLocker.Unlock()
+func beginMerge() bool {
+	gMergeIsRunningLocker.Lock()
+	defer gMergeIsRunningLocker.Unlock()
 
-		if gMergeIsRunning != false {
-			return resp
-		}
-		gMergeIsRunning = true
+	if gMergeIsRunning != false {
+		return false
+	}
+	gMergeIsRunning = true
+	return true
+}
+
+func MergeTsDir(InputTsDir string, OutputMp4Name string) (resp MergeTsDir_Resp) {
+	if !beginMerge() {
+		return resp
 	}
 
 	defer func() {
diff --git a/m3u8d-qt/mainwindow.ui b/m3u8d-qt/mainwindow.ui
index 31044ee..346f6fa 100644
--- a/m3u8d-qt/mainwindow.ui
+++ b/m3u8d-qt/mainwindow.ui
@@ -18,7 +18,7 @@
     <item>
      <widget class="QStackedWidget" name="stackedWidget">
       <property name="currentIndex">
-       <number>1</number>
+       <number>0</number>
       </property>
       <widget class="QWidget" name="page">
        <layout class="QVBoxLayout" name="verticalLayout_2">