feat(frontend): 新增多版本笔记功能，并做了向下兼容。

- 新增关于页面组件，介绍项目背景、功能和使用方法
- 重构笔记生成逻辑，支持多版本笔记
- 新增笔记版本选择、复制和导出功能
-优化笔记界面布局和交互
- 调整部分组件样式，提升用户体验

backend/app/downloaders/bilibili_downloader.py

@@ -7,6 +7,7 @@ import yt_dlp
 from app.downloaders.base import Downloader, DownloadQuality, QUALITY_MAP
 from app.models.notes_model import AudioDownloadResult
 from app.utils.path_helper import get_data_dir
+from app.utils.url_parser import extract_video_id
 
 
 class BilibiliDownloader(Downloader, ABC):
@@ -69,10 +70,19 @@ class BilibiliDownloader(Downloader, ABC):
         """
         下载视频，返回视频文件路径
         """
+
         if output_dir is None:
             output_dir = get_data_dir()
-
         os.makedirs(output_dir, exist_ok=True)
+        print("video_url",video_url)
+        video_id=extract_video_id(video_url, "bilibili")
+        video_path = os.path.join(output_dir, f"{video_id}.mp4")
+        if os.path.exists(video_path):
+            return video_path
+
+        # 检查是否已经存在
+
+
         output_path = os.path.join(output_dir, "%(id)s.%(ext)s")
 
         ydl_opts = {

backend/app/downloaders/douyin_downloader.py

@@ -249,13 +249,21 @@ class DouyinDownloader(Downloader):
         )
 
     def download_video(self, video_url: str, output_dir: Union[str, None] = None) -> str:
+
         try:
+
             if output_dir is None:
                 output_dir = get_data_dir()
             if not output_dir:
                 output_dir = self.cache_data
             os.makedirs(output_dir, exist_ok=True)
 
+            video_id = self.extract_video_id(video_url)
+            video_path = os.path.join(output_dir, f"{video_id}.mp4")
+            if os.path.exists(video_path):
+                return video_path
+
+
             output_path = os.path.join(output_dir, "%(id)s.%(ext)s")
 
             video_data = self.fetch_video_info(video_url)

backend/app/downloaders/youtube_downloader.py

@@ -7,6 +7,7 @@ import yt_dlp
 from app.downloaders.base import Downloader, DownloadQuality
 from app.models.notes_model import AudioDownloadResult
 from app.utils.path_helper import get_data_dir
+from app.utils.url_parser import extract_video_id
 
 
 class YoutubeDownloader(Downloader, ABC):
@@ -67,12 +68,15 @@ class YoutubeDownloader(Downloader, ABC):
         """
         if output_dir is None:
             output_dir = get_data_dir()
-
+        video_id = extract_video_id(video_url, "youtube")
+        video_path = os.path.join(output_dir, f"{video_id}.mp4")
+        if os.path.exists(video_path):
+            return video_path
         os.makedirs(output_dir, exist_ok=True)
         output_path = os.path.join(output_dir, "%(id)s.%(ext)s")
 
         ydl_opts = {
-            'format': 'worst[ext=mp4]/worst',
+            'format': 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]',
             'outtmpl': output_path,
             'noplaylist': True,
             'quiet': False,