Fix MT model loading: Revert to nllb-200-distilled-600M and add fallback

- Reverted translation model to facebook/nllb-200-distilled-600M (facebook/nllb-200-distilled-200M does not exist)
- Added fallback mechanism in _initialize_mt_model to handle model loading failures
- Modified translate_text to return source text if the translation model is not loaded
- Added initialization of mt_model and mt_tokenizer as None in __init__

app.py

@@ -55,6 +55,8 @@ class TalklasTranslator:
         self.source_lang = source_lang
         self.target_lang = target_lang
         self.sample_rate = 16000
+        self.mt_model = None  # Initialize as None
+        self.mt_tokenizer = None  # Initialize as None
         self._initialize_stt_model()
         self._initialize_mt_model()
         self._initialize_tts_model()
@@ -72,16 +74,19 @@ class TalklasTranslator:
 
     def _initialize_mt_model(self):
         try:
-            print("Trying to load facebook/nllb-200-distilled-200M...")
-            self.mt_model = AutoModelForSeq2SeqLM.from_pretrained("facebook/nllb-200-distilled-200M")
+            print("Trying to load facebook/nllb-200-distilled-600M...")
+            self.mt_model = AutoModelForSeq2SeqLM.from_pretrained("facebook/nllb-200-distilled-600M")
             self.mt_tokenizer = AutoTokenizer.from_pretrained(
-                "facebook/nllb-200-distilled-200M",
+                "facebook/nllb-200-distilled-600M",
                 clean_up_tokenization_spaces=True
             )
             self.mt_model.to(self.device)
             print("Loaded NLLB translation model successfully")
         except Exception as e:
-            raise RuntimeError(f"MT model initialization failed: {e}")
+            print(f"Failed to load facebook/nllb-200-distilled-600M: {e}")
+            print("Translation model not loaded, translation will return source text as a fallback")
+            self.mt_model = None
+            self.mt_tokenizer = None
 
     def _initialize_tts_model(self):
         try:
@@ -124,6 +129,9 @@ class TalklasTranslator:
         return transcription
 
     def translate_text(self, text: str) -> str:
+        if self.mt_model is None or self.mt_tokenizer is None:
+            print("Translation model not loaded, returning source text as fallback")
+            return text
         source_code = self.NLLB_LANGUAGE_CODES[self.source_lang]
         target_code = self.NLLB_LANGUAGE_CODES[self.target_lang]
         self.mt_tokenizer.src_lang = source_code