diff --git a/cvat/apps/engine/media_extractors.py b/cvat/apps/engine/media_extractors.py
index 8e682950e73a..9114e1033fd6 100644
--- a/cvat/apps/engine/media_extractors.py
+++ b/cvat/apps/engine/media_extractors.py
@@ -546,7 +546,10 @@ def _get_av_container(self):
             self._source_path[0].seek(0) # required for re-reading
 
         encoding = self.get_file_encoding(self._source_path[0])
-        return av.open(self._source_path[0], metadata_encoding = encoding)
+        if encoding:
+            return av.open(self._source_path[0], metadata_encoding = encoding)
+        else:
+            return av.open(self._source_path[0])
 
     def _get_duration(self):
         with self._get_av_container() as container:
diff --git a/cvat/apps/engine/task.py b/cvat/apps/engine/task.py
index aa21cde9012c..32fd70c5a98d 100644
--- a/cvat/apps/engine/task.py
+++ b/cvat/apps/engine/task.py
@@ -970,7 +970,10 @@ def get_audio_duration(file_path):
         slogger.glob.debug("ENCODING")
         slogger.glob.debug(encoding)
         # Open the audio file
-        container = av.open(file_path, metadata_encoding=encoding)
+        if encoding:
+            container = av.open(file_path, metadata_encoding=encoding)
+        else:
+            container = av.open(file_path)
 
         # Get the first audio stream
         audio_stream = next((stream for stream in container.streams if stream.codec.type == 'audio'), None)