添加语音websocket等，还没测试

keyBoard/Class/AiTalk/VM/SubtitleSync.m

@@ -0,0 +1,66 @@
+//
+//  SubtitleSync.m
+//  keyBoard
+//
+//  Created by Mac on 2026/1/15.
+//
+
+#import "SubtitleSync.h"
+
+@implementation SubtitleSync
+
+- (NSString *)visibleTextForFullText:(NSString *)fullText
+                         currentTime:(NSTimeInterval)currentTime
+                            duration:(NSTimeInterval)duration {
+
+  if (!fullText || fullText.length == 0) {
+    return @"";
+  }
+
+  NSUInteger visibleCount = [self visibleCountForFullText:fullText
+                                              currentTime:currentTime
+                                                 duration:duration];
+
+  if (visibleCount >= fullText.length) {
+    return fullText;
+  }
+
+  return [fullText substringToIndex:visibleCount];
+}
+
+- (NSUInteger)visibleCountForFullText:(NSString *)fullText
+                          currentTime:(NSTimeInterval)currentTime
+                             duration:(NSTimeInterval)duration {
+
+  if (!fullText || fullText.length == 0) {
+    return 0;
+  }
+
+  // 边界情况处理
+  if (duration <= 0) {
+    // 如果没有时长信息，直接返回全部
+    return fullText.length;
+  }
+
+  if (currentTime <= 0) {
+    return 0;
+  }
+
+  if (currentTime >= duration) {
+    return fullText.length;
+  }
+
+  // 计算进度比例
+  double progress = currentTime / duration;
+
+  // 计算可见字符数
+  // 使用略微超前的策略，确保文字不会落后于语音
+  double adjustedProgress = MIN(progress * 1.05, 1.0);
+
+  NSUInteger visibleCount =
+      (NSUInteger)round(fullText.length * adjustedProgress);
+
+  return MIN(visibleCount, fullText.length);
+}
+
+@end