make align a bit faster.

whisperx/alignment.py

@@ -254,7 +254,7 @@ def align(
 
         trellis = get_trellis(emission, tokens, blank_id)
         # path = backtrack(trellis, emission, tokens, blank_id)
-        path = backtrack_beam(trellis, emission, tokens, blank_id)
+        path = backtrack_beam(trellis, emission, tokens, blank_id, beam_width=2)
 
         if path is None:
             print(f'Failed to align segment ("{segment["text"]}"): backtrack failed, resorting to original...')
@@ -393,24 +393,36 @@ def get_trellis(emission, tokens, blank_id=0):
 
 
 def get_wildcard_emission(frame_emission, tokens, blank_id):
-    """处理包含通配符的token emission分数
+    """处理包含通配符的token emission分数（向量化版本）
 
     Args:
         frame_emission: 当前帧的emission概率向量
         tokens: token索引列表
+        blank_id: blank token的ID
 
     Returns:
         tensor: 每个token位置的最大概率分数
     """
     assert 0 <= blank_id < len(frame_emission)
-    scores = []
-    for token in tokens:
-        if token == -1:  # 通配符
-            valid_scores = torch.cat([frame_emission[:blank_id], frame_emission[blank_id + 1:]])
-            scores.append(torch.max(valid_scores))
-        else:
-            scores.append(frame_emission[token])
-    return torch.tensor(scores)
+
+    # 将tokens转换为tensor（如果还不是的话）
+    tokens = torch.tensor(tokens) if not isinstance(tokens, torch.Tensor) else tokens
+
+    # 创建mask来标识通配符位置
+    wildcard_mask = (tokens == -1)
+
+    # 为非通配符位置获取分数
+    regular_scores = frame_emission[tokens.clamp(min=0)]  # clamp避免-1索引
+
+    # 创建掩码并计算最大值，不会修改frame_emission
+    max_valid_score = frame_emission.clone()  # 创建副本
+    max_valid_score[blank_id] = float('-inf')  # 在副本上操作
+    max_valid_score = max_valid_score.max()
+
+    # 使用where操作来组合结果
+    result = torch.where(wildcard_mask, max_valid_score, regular_scores)
+
+    return result
 
 
 @dataclass