From 98ff495e10c3500a302bf8c1de87092989f3f66f Mon Sep 17 00:00:00 2001
From: Mikael Finstad <finstaden@gmail.com>
Date: Wed, 15 Feb 2023 13:42:59 +0800
Subject: [PATCH] improve concat output filename extension handling

---
 src/components/ConcatDialog.jsx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/components/ConcatDialog.jsx b/src/components/ConcatDialog.jsx
index 6cb934df..92cedb87 100644
--- a/src/components/ConcatDialog.jsx
+++ b/src/components/ConcatDialog.jsx
@@ -77,7 +77,10 @@ const ConcatDialog = memo(({
       return;
     }
     const ext = getOutFileExtension({ isCustomFormatSelected, outFormat: fileFormat, filePath: firstPath });
-    setOutFileName(getSuffixedFileName(firstPath, `merged-${uniqueSuffix}${ext}`));
+    setOutFileName((existingOutputName) => {
+      if (existingOutputName == null) return getSuffixedFileName(firstPath, `merged-${uniqueSuffix}${ext}`);
+      return existingOutputName.replace(/(\.[^.]*)?$/, ext); // make sure the last (optional) .* is replaced by .ext`
+    });
   }, [fileFormat, firstPath, isCustomFormatSelected, uniqueSuffix]);
 
   const allFilesMeta = useMemo(() => {