feat: 简单实现字幕功能

lib/utils/subtitle.dart

@@ -0,0 +1,32 @@
+class SubTitleUtils {
+  // 格式整理
+  static String convertToWebVTT(List jsonData) {
+    String webVTTContent = 'WEBVTT FILE\n\n';
+
+    for (int i = 0; i < jsonData.length; i++) {
+      final item = jsonData[i];
+      double from = item['from'] as double;
+      double to = item['to'] as double;
+      int sid = (item['sid'] ?? 0) as int;
+      String content = item['content'] as String;
+
+      webVTTContent += '$sid\n';
+      webVTTContent += '${formatTime(from)} --> ${formatTime(to)}\n';
+      webVTTContent += '$content\n\n';
+    }
+
+    return webVTTContent;
+  }
+
+  static String formatTime(num seconds) {
+    final String h = (seconds / 3600).floor().toString().padLeft(2, '0');
+    final String m = (seconds % 3600 / 60).floor().toString().padLeft(2, '0');
+    final String s = (seconds % 60).floor().toString().padLeft(2, '0');
+    final String ms =
+        (seconds * 1000 % 1000).floor().toString().padLeft(3, '0');
+    if (h == '00') {
+      return "$m:$s.$ms";
+    }
+    return "$h:$m:$s.$ms";
+  }
+}