MilkDrop Visualizer

Turn audio into a MilkDrop/Butterchurn visualization MP4 and deliver it back to the requester. Triggered when a user sends an audio/video file or a link (YouTube or a direct audio URL) and asks for a visualizer / music video / "milkdrop" / trippy visuals.

Run

Everything runs from one allowlisted wrapper:

{{HOME}}/bin/milkdrop-render.sh --input <url-or-file> [options]

Options:

• --input YouTube/audio URL or a local audio/video file path (required)
• --output MP4 path (optional; defaults to ~/.openclaw/media/outbound/milkdrop-<timestamp>.mp4)
• --duration clip length in seconds (default 30)
• --start start offset in seconds (default 0)
• --width / --height canvas size
• --fps frames per second (default 30)
• --preset preset name, index, or random (default random)

Aspect shortcuts (pass the matching --width/--height):

• vertical / story / reel — --width 1080 --height 1920 (default)
• square — --width 1080 --height 1080
• landscape — --width 1920 --height 1080

On success the script prints a single-line JSON summary to stdout, e.g.

{"ok":true,"path":"{{HOME}}/.openclaw/media/outbound/milkdrop-20260612-143012.mp4","preset":"...","duration":30,"width":1080,"height":1920}

Workflow

1. Resolve the input.

   • If the user pasted a URL, pass it directly with --input <url>.
   • If the user sent an audio/video file, use the inbound media path (~/.openclaw/media/inbound/...) as --input.

2. Pick options from the request. Honor any requested length (--duration) and aspect ratio (defaults to vertical). Keep --duration modest (≤ 60s) unless the user explicitly asks for longer — rendering is real-time plus a transcode pass.

3. Run {{HOME}}/bin/milkdrop-render.sh with the chosen options.

4. Parse the JSON summary line and read path.

5. Deliver the MP4 back on the same channel the request came in on:

   openclaw message send --channel <channel> --target <chat-id> \
     --media "<path>" --force-document \
     -m "Here's your MilkDrop visualization 🌀 (preset: <preset>)"
   

   Use --force-document so the video is not re-compressed by the channel.

Notes

• Remote URLs require yt-dlp (at /usr/local/bin/yt-dlp); local files only need ffmpeg/ffprobe.
• Output files accumulate in ~/.openclaw/media/outbound/; old renders are safe to clean up.
• On failure the script exits non-zero and writes the error to stderr. Reply with a short, friendly note and the gist of the error.