The Problem Nobody Talks About
Everyone's posting AI-generated videos — characters speaking with lip-sync, manga panels coming alive, virtual idols dancing. The pitch: "just describe what you want."
I tried. For months. Here's what I got:
- Character's face morphed by frame 2
- "Slowly looks up" became "violent head shake"
- Voice-over sounded like Google Translate
- Same prompt, 3 runs, 3 completely different results
- No idea what to include or how long the prompt should be
Tutorials were either too vague ("be detailed") or too technical (parameter tuning from line 1).
The real issue: video prompts are structurally different from text/image prompts. You need to simultaneously control visuals, motion, audio, camera, and consistency constraints — in the right order, at the right length.
What I Found
A Skill in the Model Studio official repo called happyhorse-prompt-studio. It doesn't teach you theory — it asks you questions and assembles the prompt for you.
4-phase flow:
1. Inspiration Menu
Shows you 4 "flavors" of what HappyHorse can do:
| Flavor | What it does |
|---|---|
| A · Voiced Manga Drama | Characters talk to each other, with voice + lip-sync |
| B · Character Voice PV | Single character self-introduction, 8-10 sec |
| C · Manga Panel Motion | Static manga panel starts breathing |
| D · Virtual Idol MV | Idol performance with choreography |
2. Discovery
Asks you conversationally: character appearance, scene, emotion, dialogue, voice type, art style, camera.
3. Prompt Assembly
Assembles using the HappyHorse Formula:
Scene + Subject + Motion + Audio + Quality
Key techniques:
@「Image n」syntax locks character identity across shots- Dialogue ≤15 characters (split shots if longer)
- Japanese prompts work best (HappyHorse is JP-optimized)
- Always end with
キャラの顔・髪・衣装が変わらない(face/hair/outfit stays unchanged)
4. Quality Check
Auto-reviews: completeness, compliance, cost estimate, optimization tips.
Before vs. After
| Dimension | Writing myself | With Prompt Studio |
|---|---|---|
| Attempts needed | 10-20 before one usable | 2-3 to satisfaction |
| Time per prompt | 1-2 hours (research + trial) | 5-10 minutes |
| Character consistency | Collapsed by frame 2 | R2V syntax locks it |
| Common pitfalls | Learned by failing | Built-in troubleshooting |
Honest Limitations
- No guarantee of perfection on first try (AI video has inherent randomness)
- Can't replace your creativity (character design is still yours)
- Max ~30 seconds per generation
- Requires API key (free tier available)
- Japanese prompts get best results; CN/EN work but JP is optimized
Setup
npx skills add modelstudioai/skills --skill happyhorse-prompt-studio -g
Then tell your AI assistant: "I want to make a video with HappyHorse"
Execute the assembled prompt:
bl video generate --image ./char.png --prompt "[assembled prompt]" --download output.mp4
Links
Open-source Skill. Free tier available. Results subject to model randomness.
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