# AI Video Generation Constraints

Technical limitations and best practices for AI-generated video content.

## Scene Structure

### One Action Per Scene

**Rule**: Each scene = ONE clear action or moment

AI video generators cannot handle:
- Compound actions ("walks in AND sits down AND starts talking")
- Quick-cut montages within a single clip
- Complex choreography

**Good**: "Woman walks along rooftop edge, city skyline behind"
**Bad**: "Woman walks to edge, sits down, picks up drink, looks at sunset"

### Scene = Frame = Clip

The pipeline works like this:
1. Script defines scenes
2. Grid generates ONE frame per scene
3. Each frame becomes ONE video clip
4. Clips are assembled into final video

**Implication**: Write each scene as if describing a single photograph that will come to life.

---

## Visual Direction

### Shot Types

Always specify one of:
- `wide` — Establishing, shows environment
- `medium` — Standard, shows person waist-up
- `close-up` — Face/detail, emotional connection
- `extreme-close-up` — Specific detail (rarely used)

### Camera Movement

Simple movements only:
- `static` — No movement (most reliable)
- `slow-push` — Gentle zoom in (adds intimacy)
- `slow-pull` — Gentle zoom out (reveals context)
- `orbit` — Slight circular movement (dynamic but risky)

**Avoid**: Fast movements, complex paths, whip pans, drone shots

### Brackets for Visual Cues

When writing prompts, use brackets for specific visual directions:
- `[close-up of phone screen]`
- `[wind catches her dress]`
- `[golden hour lighting]`
- `[eye contact with camera]`

---

## Word Count Guidelines

| Duration | Word Count | Notes |
|----------|------------|-------|
| 15 seconds | ~35-40 words | Minimal, punchy |
| 30 seconds | ~70-80 words | Standard |
| 45 seconds | ~110-120 words | Detailed |
| 60 seconds | ~140-160 words | Comprehensive |

**For visual-only content**: These counts apply to scene descriptions, not dialogue (since there is none).

---

## Character Consistency

### The Challenge

AI generators struggle to maintain consistent character appearance across multiple frames/clips. Without explicit, repeated, specific descriptors, the model will drift toward a generic "attractive person" that looks different in every frame.

### Rules

1. **Repeat the full physical description in EVERY scene** — not just the first one. Every frame prompt must include: age, face shape, specific facial features, hair texture/length/color, body type, and signature accessories.
2. **Use specific descriptors from reference photos** — "mid-30s woman with defined angular cheekbones, blue-green eyes, wavy shoulder-length platinum blonde hair" NOT "beautiful blonde woman".
3. **Never generalize or idealize** — describe the real person's actual age, face, and build. Do not make them look younger or more generic.
4. **Anchor to the characteristic shot** — when generating grids or frames, always reference the characteristic shot as the face/appearance anchor.
5. **Signature accessory as continuity thread** — identify one accessory visible in reference photos (necklace, bracelet, ring) and include it in every scene description.

### For Grid/Frame Generation Prompts

Start the NanoBanana prompt with a dedicated consistency paragraph:
```
CRITICAL: The woman must look IDENTICAL in all frames — same face, same age,
same features as the reference photos. [List specific features].
Do not make her look younger or more idealized than the references.
```

Then repeat the key identifiers in each individual frame description.

---

## What Works Well

### Reliable Elements

- Static shots with simple movement (walking, turning)
- Natural environments (beaches, cityscapes, interiors)
- Single-person scenes
- Consistent lighting (golden hour, studio lighting)
- Subtle expressions (smile, look at camera)

### Risky Elements

- Multiple people in frame
- Complex interactions between characters
- Specific hand gestures or positions
- Text/logos that need to be readable
- Rapid movement or action sequences

---

## Conversational Elements

Research shows conversational style improves retention by ~30%.

**For voiceover content**:
- Use contractions ("don't" not "do not")
- Rhetorical questions ("Know what I mean?")
- Direct address ("You've probably felt this")

**For visual-only content**:
Music sync replaces conversational rhythm:
- Beat drops = emphasis
- Rhythm changes = transitions
- Silence = dramatic pause

---

## Duration Constraints

### Video Generator Limits

Different providers have different constraints:
- **Kling**: 5 or 10 seconds per clip
- **Veo3**: 4, 6, or 8 seconds per clip

**Plan accordingly**: Match scene durations to generator capabilities.

### Minimum/Maximum

- Minimum scene: 3 seconds (shorter feels rushed)
- Maximum scene: 10 seconds (longer loses attention)
- Sweet spot: 4-6 seconds per scene

---

## Common Mistakes

1. **Compound actions**: Break into multiple scenes
2. **Complex camera**: Stick to static or slow movements
3. **Vague descriptions**: "Character looks upset" → "shoulders slump, eyes downcast"
4. **Missing environment**: "Trees pass by" → "Interior of car, trees visible through window"
5. **Inconsistent character**: Different descriptions = different-looking person
6. **Too many people**: One person per scene is safest
7. **Fast movement**: Slow, graceful movement renders better
