bilibili-mp3

name	bilibili-mp3
description	Download Bilibili video audio as MP3 with cover art and metadata (supports multiple URLs)
allowed-tools	["Bash(yt-dlp *)","Bash(mid3v2 *)","Bash(mkdir *)","Bash(cp *)","Bash(ls *)"]
argument-hint	<url1> [url2] ...
disable-model-invocation	true
arguments	["urls"]

Bilibili to MP3

Download Bilibili video audio as MP3 files with embedded cover art, title, and artist metadata. Supports one or more URLs in a single invocation. Saves to ~/音乐/.

Inputs

• $urls: One or more Bilibili video URLs, space-separated (e.g. https://www.bilibili.com/video/BV11x411g7DG or b23.tv short links)

Goal

For each URL, produce an MP3 file at ~/音乐/{artist}-{title}.mp3 with:

• Embedded cover art (FRONT_COVER)
• Title in ID3 TIT2
• Artist in ID3 TPE1
• Album in ID3 TALB (same as title)

Steps

For each URL in $urls, execute steps 1–6. Then run step 7 once at the end.

1. Fetch video metadata

Use yt-dlp -j "$url" to get full video info as JSON. Extract:

• title
• uploader (Bilibili account name)
• thumbnail / pic (cover URL)
• description (may contain artist credits)

2. Identify artist and confirm with user

Read the description to reason about who the artist is. Common patterns in Bilibili music videos:

• ■Music：name or Music: name
• ■Vocal：name or vocals listed in description
• 作曲 / 作詞 / 編曲 / 歌 fields
• The uploader may or may not be the artist

Present the extracted title and artist to the user for confirmation using AskUserQuestion. Offer the detected artist as the first option, the uploader as a second option, and allow freeform input.

If no artist can be reasonably inferred from the description, ask the user directly.

3. Download audio as MP3 with thumbnail

cd /tmp && yt-dlp \
  -x --audio-format mp3 --audio-quality 0 \
  --embed-thumbnail \
  --embed-metadata \
  --convert-thumbnails jpg \
  --write-thumbnail \
  -o "bilibili_%(id)s.%(ext)s" \
  "$url"

This produces /tmp/bilibili_{id}.mp3 and /tmp/bilibili_{id}.jpg.

Success criteria: Both files exist and the MP3 has non-zero size.

4. Set artist metadata

mid3v2 --artist "$artist" --album "$title" /tmp/bilibili_{id}.mp3

5. Copy to music directory

Before copying, check if the target file already exists:

mkdir -p ~/音乐

If ~/音乐/"$artist-$title.mp3" already exists, ask the user whether to overwrite or skip. Do not overwrite without explicit confirmation.

cp /tmp/bilibili_{id}.mp3 ~/音乐/"$artist-$title.mp3"

6. Verify

mid3v2 ~/音乐/"$artist-$title.mp3"

Confirm that TIT2 (title), TPE1 (artist), TALB (album), and APIC (cover) are all present and correct.

Success criteria: The file at ~/音乐/{artist}-{title}.mp3 has all four metadata fields set correctly.

7. Cleanup

Remove all temporary /tmp/bilibili_* files created during this run.