Video Generation

Video Generation System — Render descriptions into real MP4 video

Overview

This skill renders an actual video by calling the Seedance API (BytePlus ModelArk) through an async submit → poll → download flow. It is the motion companion to the Image Generation System. It is subject-agnostic: it builds the prompt from whatever the user types and has no built-in character, persona, or stored identity. Whatever the user describes is what gets animated.

Video is expensive — a single clip can cost ~$1–$3.50. The cost-confirmation gate (Step 5) is mandatory and non-negotiable.

Protocol

1. Extract motion intent from user input. Read the typed description and pull out: subject, scene/setting, camera movement (static / slow push-in / orbit / handheld / dolly / crane), pacing (calm drift vs energetic), and mood. The prompt is built from their words only — never from a stored character profile, an "appearance" file, or any baked-in identity.

2. (Optional) Consult the Library System. IF the Library System feature is installed AND the user references a saved entry (e.g. "use my noir style"), read that user-authored entry and fold it into the prompt. This is the only persisted source the skill reads, and it is 100% user-owned content — never a shipped persona.

3. (Optional) Image-to-video. IF the user wants to animate a local still (e.g. one produced by the Image Generation System), pass it to the helper as -FirstFrame (opening frame), -LastFrame (closing frame), or -ReferenceImages (style/subject anchors). The helper base64's local files automatically — no hosting needed. URLs are also accepted.

4. Resolve the output path.

   • Default folder: media-generation/video-generation/ inside the user's memory root (created at install; its path is recorded in master-memory.md).
   • Honor an explicit to [path] override.
   • Sanitize the filename (strip < > : " / \ | ? *, lowercase, hyphenate whitespace) and append a -YYYYMMDD-HHmmss.mp4 timestamp suffix.

5. MANDATORY cost-confirmation gate. Run the helper with -WhatIfCost (no API call) to get the estimate for the chosen resolution/duration. Present it clearly, emphasizing video is pricey, and get an explicit go-ahead. NEVER auto-fire a paid render.

6. Invoke the render helper (async submit → poll → download) and report the result.

   • PowerShell:

     & Invoke-VideoGen.ps1 -Prompt "<final prompt>" -OutFile "<resolved path>" -Resolution "<480p|720p|1080p>" -Duration <seconds> -AspectRatio "16:9" [-FirstFrame "<path|url>"]
     

   • Bash:

     invoke-video-gen.sh --prompt "<final prompt>" --outfile "<resolved path>" --resolution "<res>" --duration <seconds> [--first-frame "<path|url>"]
     

   • Report back the saved_path, the cost estimate, elapsed time, and task_id.

Resolution & Duration Reference

Cost ≈ rate × duration. Default to a short duration unless the user asks otherwise. Verify current pricing at BytePlus ModelArk — these are indicative only.

Mandatory Rules

1. Build prompts only from user input (plus optional user-owned Library entries). The feature is subject-agnostic — no baked-in character, persona, or appearance.
2. Always confirm the cost via -WhatIfCost before a paid render (Step 5). No silent paid calls. Video is expensive — never skip this.
3. Always save into media-generation/video-generation/ unless the user overrides with a path.
4. Never commit .env, never print the API key, never include the key in any output.
5. Surface sanitized errors (the scripts strip ark-/sk- patterns). Never auto-retry a failed render — API errors (moderation, quota, malformed) need human diagnosis.
6. The helper is canonical — never inline the HTTP submit/poll/download logic in conversation; always call the script.