Download Best Audio

Download Best Audio

This is the shared runtime behind the three site-specific skills. Resolve the absolute path to this Skill directory before running its script. Do not put a raw URL, output path, or browser profile into a shell command. Encode every user-controlled string as UTF-8 Base64 in memory, then pass only the Base64 alphabet.

py -3 "<skill-dir>\scripts\download_audio.py" --url-base64 "<UTF8_BASE64>" --expected-platform "<Bilibili|Douyin|YouTube>"

On macOS or Linux, use an available Python 3 interpreter:

python3 "<skill-dir>/scripts/download_audio.py" --url-base64 "<UTF8_BASE64>" --expected-platform "<Bilibili|Douyin|YouTube>"

For an explicit custom directory use --output-dir-base64; after per-link cookie approval use --cookies-from-browser-base64. The public positional interface remains available for direct non-shell callers.

Required behavior

• Accept exactly one published-video HTTPS URL from Douyin, Bilibili, or YouTube. The script also recognizes their normal share-link domains.
• Default to the best source audio exposed by the site and yt-dlp. Preserve the source codec; a container-only remux is acceptable, but an unexpected codec change is a failure.
• Save successful files under the current user's Downloads/Codex-Audio directory unless the user explicitly supplies another absolute output directory.
• Treat a video URL that also contains a playlist parameter as one video. Reject a playlist-only URL, multiple URLs, and an active livestream.
• Never pass raw user data through a shell. Never bypass DRM, a paywall, account entitlement, or a region restriction. Process only content the user is authorized to download and remind them that platform terms still apply when relevant.

Authentication boundary

Run once without browser cookies. If the script returns authentication_required, ask the user for permission for this URL. Only after explicit permission, Base64-encode the allowed chrome[:profile] value outside the shell and rerun with --cookies-from-browser-base64 '<UTF8_BASE64>'. Do not export cookies to a file, request a password, or persist authentication details.

Result handling

The script writes one JSON object to stdout.

• On downloaded or already_exists, tell the user the final absolute path, title, codec/container, available bitrate/sample-rate/channel details, and whether the source codec was preserved or only remuxed.
• On authentication_required, ask for cookie permission without retrying automatically.
• If any result contains recovery_path or previous_file_backup, always report that absolute recovery path so the user can preserve or inspect the old file.
• For every other failure, report the safe message and error_code. Do not expose subprocess stderr, signed media URLs, cookie data, or browser-profile paths.

Do not silently install or upgrade dependencies during a download. If the script returns dependency_missing or extractor_failed, report the installed version information and ask before changing the installation.