cannot correctly resolve `bilibili.com` video URLs contained in a festival / bilibili.com 的包含在 festival 中的视频链接不能被正确解析

[szdytom]

Checklist

• [x] I'm reporting a broken site support
• [x] I've verified that I'm running youtube-dl version 2021.12.17
• [x] I've checked that all provided URLs are alive and playable in a browser
• [x] I've checked that all URLs and arguments with special characters are properly quoted or escaped
• [x] I've searched the bugtracker for similar issues including closed ones

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['https://www.bilibili.com/video/BV1dZ4y1Y7bt', '-v']
[debug] Encodings: locale cp936, fs mbcs, out cp936, pref cp936
[debug] youtube-dl version 2021.12.17
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.19041
[debug] exe versions: none
[debug] Proxy map: {}
[BiliBili] 1dZ4y1Y7bt: Downloading webpage
[BiliBili] 1dZ4y1Y7bt: Downloading video info page
ERROR: Unable to extract title; please report this issue on https://yt-dl.org/bug . Make sure you are using
 the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and
 include its complete output.
Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\Youtube
DL.py", line 815, in wrapper
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\Youtube
DL.py", line 836, in __extract_info
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\extract
or\common.py", line 534, in extract
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\extract
or\bilibili.py", line 213, in _real_extract
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\extract
or\common.py", line 1021, in _html_search_regex
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpupik7c6w\build\youtube_dl\extract
or\common.py", line 1012, in _search_regex
youtube_dl.utils.RegexNotFoundError: Unable to extract title; please report this issue on https://yt-dl.org
/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-
dl with the --verbose flag and include its complete output.

Description

cannot correctly resolve bilibili.com video URLs which is contained in a festival. for example,

https://www.bilibili.com/festival/lty10th?bvid=BV1dZ4y1Y7bt

while a normal video(not contained in a festival) URL should look like

https://www.bilibili.com/video/BVxxxxxxxx

but using https://www.bilibili.com/video/BV1dZ4y1Y7bt still does not work for it auto redirects back to the festival URL.

bilibili.com 的包含在 festival 中的视频链接不能被正确解析。

[dirkf]

1. The _VALID_URL can be updated to match URLs like https://www.bilibili.com/festival/lty10th?bvid=BV1dZ4y1Y7bt. Is this the only such format (ie .../festival/slug?bvid=...) or should other top-level path components and/or more path components be matched?

2. The error occurs because the title extraction fails. In the problem page there is this <title>洛天依十周年官方演唱会</title>. If that should be the fallback title, that's fine, but I'm not familiar with the content. Then

   $ python3.9 -m youtube_dl -v -F 'https://www.bilibili.com/festival/lty10th?bvid=BV1dZ4y1Y7bt'
   [debug] System config: ['--prefer-ffmpeg']
   [debug] User config: []
   [debug] Custom config: []
   [debug] Command-line args: ['-v', '-F', 'https://www.bilibili.com/festival/lty10th?bvid=BV1dZ4y1Y7bt']
   [debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
   [debug] youtube-dl version 2021.12.17
   [debug] Git HEAD: a5464aca1
   [debug] Python version 3.9.16 (CPython) - Linux-4.4.0-210-generic-i686-with-glibc2.23
   [debug] exe versions: avconv 4.3, avprobe 4.3, ffmpeg 4.3, ffprobe 4.3
   [debug] Proxy map: {}
   [BiliBili] 1dZ4y1Y7bt: Downloading webpage
   [BiliBili] 1dZ4y1Y7bt: Downloading video info page
   WARNING: unable to extract description; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
   WARNING: unable to extract og:image; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
   [info] Available formats for 1dZ4y1Y7bt:
   format code  extension  resolution note
   0            flv        unknown    3.53GiB
   $

[li6in9muyou]

1. URL format like .../festival/<slug>?bvid=<bvid>) is used on rare occasions.
2. What's in the