Update tokenizer.py

faster_whisper/tokenizer.py

@@ -6,6 +6,10 @@
 import tokenizers
 
 
+class TokenizationError(Exception):
+    pass
+
+
 class Tokenizer:
     """Simple wrapper around a tokenizers.Tokenizer."""
 
@@ -87,23 +91,44 @@ def encode(self, text: str) -> List[int]:
         return self.tokenizer.encode(text, add_special_tokens=False).ids
 
     def decode(self, tokens: List[int]) -> str:
-        text_tokens = [token for token in tokens if token < self.eot]
-        return self.tokenizer.decode(text_tokens)
+        try:
+            text_tokens = [token for token in tokens if token < self.eot]
+            if not text_tokens:
+                return ""
+            if any(not isinstance(t, int) or t < 0 for t in text_tokens):
+                raise ValueError("Invalid token values detected")
+            return self.tokenizer.decode(text_tokens)
+        except Exception as e:
+            raise TokenizationError(f"Failed to decode tokens: {e}") from e
 
     def decode_with_timestamps(self, tokens: List[int]) -> str:
-        outputs = [[]]
-
-        for token in tokens:
-            if token >= self.timestamp_begin:
-                timestamp = f"<|{(token - self.timestamp_begin) * 0.02:.2f}|>"
-                outputs.append(timestamp)
-                outputs.append([])
-            else:
-                outputs[-1].append(token)
-
-        return "".join(
-            [s if isinstance(s, str) else self.tokenizer.decode(s) for s in outputs]
-        )
+        try:
+            if not tokens:
+                raise ValueError("Empty token sequence")
+            if any(not isinstance(t, int) or t < 0 for t in tokens):
+                raise ValueError("Invalid token values detected")
+
+            outputs = [[]]
+            for token in tokens:
+                if token >= self.timestamp_begin:
+                    timestamp = f"<|{(token - self.timestamp_begin) * 0.02:.2f}|>"
+                    outputs.append(timestamp)
+                    outputs.append([])
+                else:
+                    outputs[-1].append(token)
+
+            decoded = [
+                s if isinstance(s, str) else self.tokenizer.decode(s) for s in outputs
+            ]
+
+            if not any(decoded) and not any(isinstance(s, str) for s in outputs):
+                return ""
+
+            return "".join(decoded)
+        except Exception as e:
+            raise TokenizationError(
+                f"Failed to decode tokens with timestamps: {e}"
+            ) from e
 
     @cached_property
     def non_speech_tokens(self) -> Tuple[int]:
@@ -205,10 +230,7 @@ def split_tokens_on_spaces(
         return words, word_tokens
 
 
-_TASKS = (
-    "transcribe",
-    "translate",
-)
+_TASKS = ("transcribe", "translate")
 
 _LANGUAGE_CODES = (
     "af",