[ie/jiosaavn] Fix format extensions (#9609)

Authored by: bashonly

yt_dlp/extractor/jiosaavn.py

@@ -24,7 +24,7 @@ class JioSaavnSongIE(JioSaavnBaseIE):
         'md5': '3b84396d15ed9e083c3106f1fa589c04',
         'info_dict': {
             'id': 'OQsEfQFVUXk',
-            'ext': 'mp4',
+            'ext': 'm4a',
             'title': 'Leja Re',
             'album': 'Leja Re',
             'thumbnail': 'https://c.saavncdn.com/258/Leja-Re-Hindi-2018-20181124024539-500x500.jpg',
@@ -61,9 +61,10 @@ class JioSaavnSongIE(JioSaavnBaseIE):
             if not media_data.get('auth_url'):
                 self.report_warning(f'Unable to extract format info for {bitrate}')
                 continue
+            ext = media_data.get('type')
             formats.append({
                 'url': media_data['auth_url'],
-                'ext': media_data.get('type'),
+                'ext': 'm4a' if ext == 'mp4' else ext,
                 'format_id': bitrate,
                 'abr': int(bitrate),
                 'vcodec': 'none',