diff --git a/functions/utils/video-processing.mjs b/functions/utils/video-processing.mjs
index 2862052..68fcd1d 100644
--- a/functions/utils/video-processing.mjs
+++ b/functions/utils/video-processing.mjs
@@ -11,7 +11,7 @@ export const timeToSeconds = (timeStr) => {
 
   const [timePart, msPart] = timeStr.split(',');
   const parts = timePart.split(':').map(Number);
-  const milliseconds = msPart ? parseInt(msPart) / 1000 : 0;
+  const milliseconds = msPart ? parseInt(msPart, 10) / 1000 : 0;
 
   if (parts.length === 2) {
     const [minutes, seconds] = parts;
diff --git a/tests/unit/utils/video-processing.test.js b/tests/unit/utils/video-processing.test.js
index a8dff95..98b7495 100644
--- a/tests/unit/utils/video-processing.test.js
+++ b/tests/unit/utils/video-processing.test.js
@@ -8,14 +8,16 @@ describe('Video Processing Utilities', () => {
       throw new Error('Invalid time string');
     }
 
-    const parts = timeStr.split(':').map(part => parseInt(part, 10));
+    const [timePart, msPart] = timeStr.split(',');
+    const parts = timePart.split(':').map(Number);
+    const milliseconds = msPart ? parseInt(msPart, 10) / 1000 : 0;
 
     if (parts.length === 2) {
       const [minutes, seconds] = parts;
-      return minutes * 60 + seconds;
+      return minutes * 60 + seconds + milliseconds;
     } else if (parts.length === 3) {
       const [hours, minutes, seconds] = parts;
-      return hours * 3600 + minutes * 60 + seconds;
+      return hours * 3600 + minutes * 60 + seconds + milliseconds;
     } else {
       throw new Error('Time string must be in HH:MM:SS or MM:SS format');
     }
@@ -87,6 +89,20 @@ describe('Video Processing Utilities', () => {
       expect(timeToSeconds('00:00:00')).toBe(0);
     });
 
+    test('should convert HH:MM:SS,mmm format with milliseconds correctly', () => {
+      expect(timeToSeconds('00:00:00,000')).toBe(0);
+      expect(timeToSeconds('01:30:45,500')).toBe(5445.5);
+      expect(timeToSeconds('00:00:01,100')).toBe(1.1);
+      expect(timeToSeconds('02:15:30,250')).toBe(8130.25);
+    });
+
+    test('should convert MM:SS,mmm format with milliseconds correctly', () => {
+      expect(timeToSeconds('00:00,000')).toBe(0);
+      expect(timeToSeconds('10:00,100')).toBe(600.1);
+      expect(timeToSeconds('01:30,500')).toBe(90.5);
+      expect(timeToSeconds('05:45,750')).toBe(345.75);
+    });
+
     test('should throw error for invalid input', () => {
       expect(() => timeToSeconds('')).toThrow('Invalid time string');
       expect(() => timeToSeconds(null)).toThrow('Invalid time string');