fix utf-8 error

transcribe/pipelines/pipe_whisper.py

@@ -20,7 +20,7 @@ class WhisperPipe(BasePipe):
     def process(self, in_data: MetaItem) -> MetaItem:
         audio_data = in_data.audio
         source_language = in_data.source_language
-        segments = self.whisper.transcribe(audio_data, source_language)
+        segments = self.whisper.transcribe(audio_data, source_language) or []
         texts = "".join([s.text for s in segments])
         in_data.segments = [Segment(t0=s.t0, t1=s.t1, text=s.text) for s in segments if s.text != "�"]
         in_data.transcribe_content = texts

transcribe/whisper.py

@@ -50,4 +50,4 @@ class WhisperCPP:
             return output
         except Exception as e:
             logger.error(e)
-            return None
+            return []