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.
Top comments (1)
The key insight here is that video prompts need temporal structure, not just a richer image description. I like separating the identity block from action, camera, audio, and continuity constraints. For testing, I’d keep the character and scene blocks verbatim, then change only one motion or camera instruction per run. That makes it much clearer whether the failure came from identity drift, timing, or conflicting directions.