fix: cpu usage issue

whisper_live/transcriber.py

@@ -180,7 +180,7 @@ class WhisperModel:
 
         return config
 
-    def transcribe(
+    def transcribe(                                                         # noqa: C901
         self,
         audio: Union[str, BinaryIO, np.ndarray],
         language: Optional[str] = None,
@@ -315,6 +315,9 @@ class WhisperModel:
         else:
             speech_chunks = None
 
+        if audio.shape[0] == 0:
+            return None, None
+
         features = self.feature_extractor(audio)
 
         encoder_output = None