135 lines
6.0 KiB
Markdown
135 lines
6.0 KiB
Markdown
# LTX Video Prompting — Quick Reference
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Condensed from the 544-line deep research at `/home/n8n/workspace/general/LTX_prompt_instructions.md`.
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## Prompt Order (Official LTX 2.3)
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LTX Studio's pipelines weight tokens by position. Two orderings work well:
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**Order one (shot-size-first):** framing → subject → action → style → motion
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Use when the shot size is the most important decision. "Wide shot, low angle, a detective in a long coat walks toward a warehouse door, harsh sodium lighting, slow push-in."
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**Order two (subject-first):** subject → action → framing → style → motion
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Use when the character or object is more critical. "A woman in a red coat walks through a Tokyo street at night, medium tracking shot, neon reflections in puddles, handheld follow."
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**Failure mode:** piling every adjective into one long noun phrase. Cut to the 2-3 that matter most.
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**For I2V specifically:** Focus the prompt on motion and action — the visual starting point is already defined by the input image. Avoid describing static elements already visible in the image. Describe the transition from stillness to motion.
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Source: ltx.io/blog/ltx-2-3-prompt-guide, ltx.io/blog/how-to-write-a-prompt (official, June 2026)
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## Shot Sizes
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| Shot | What It Shows |
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|------|---------------|
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| Extreme Wide | Vast environment, subject tiny |
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| Wide / Establishing | Full body + surroundings |
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| Medium Wide | Knees up |
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| Medium Shot | Waist up |
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| Medium Close-up | Chest up |
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| Close-up | Face and neck |
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| Extreme Close-up | Single feature |
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## Camera Angles
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| Angle | Effect |
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|-------|--------|
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| Eye Level | Neutral, familiar |
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| Low Angle | Power, dominance |
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| High Angle | Vulnerability |
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| Bird's Eye | Detached, god-like |
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| Dutch Angle | Unease, tension |
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| Over-the-Shoulder | Dialogue |
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| POV | First-person immersion |
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## Camera Movements
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| Movement | Prompt Phrase |
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|----------|---------------|
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| Static | "Static camera," "tripod-locked" |
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| Dolly-in | "Slow dolly-in," "camera pushes forward" |
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| Dolly-out | "Camera pulls back slowly" |
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| Pan | "Slow pan left/right" |
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| Tilt | "Tilts up to reveal" |
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| Tracking | "Tracks alongside," "follows behind" |
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| Orbit | "Camera orbits slowly around" |
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| Handheld | "Subtle handheld, micro-shakes only" |
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## Lighting
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| Type | Prompt Phrase |
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|------|---------------|
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| Window light | "Soft north-window light, gentle falloff" |
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| Golden hour | "Golden hour rim light, long shadows" |
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| Overcast | "Overcast, diffuse light, low contrast" |
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| Tungsten | "Practical lamp as key, warm tungsten" |
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| Neon | "Neon glow, cyan and magenta reflections" |
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| Backlight | "Backlit rim light, subject silhouetted" |
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| High contrast | "High-contrast studio lighting, deep shadows" |
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## Lens Cues
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- "35mm lens, f/2.8, shallow depth of field" — people/products
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- "85mm portrait lens, bokeh, crisp eyes" — talking heads
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- "16mm wide, deep focus" — rooms/landscapes
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- "50mm standard" — natural perspective
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## Motion Verbs
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Walking, pouring, turning, lifting, revealing, drifting, sprinting, reaching, pausing, stepping, rising, falling, swaying, flickering, rotating, gliding, accelerating, decelerating, spinning, floating, sliding, bouncing, nodding, shaking, gesturing, breathing, blinking, smiling, frowning, gasping, laughing, crying, whispering, shouting
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## Emotion — Show, Don't Tell
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❌ "A sad woman sits at a table"
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✅ "A woman sits at a table, her shoulders slumped forward, eyes downcast, fingers tracing the rim of an empty coffee cup"
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## Negative Prompt
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```
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no extra limbs, no face warp, no object duplication
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no text artifacts, no floating logos, no watermark
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no extreme motion blur, no rolling shutter wobble
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no flicker, no frame-to-frame texture shift
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no Dutch angle, no rapid handheld, keep horizon level
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```
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For I2V: add `static, frozen, no motion, Ken Burns zoom`
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## Transition LoRA (zhuanchang)
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- **Use ONLY on transition/morph scenes** — character morph, style change, scene switch, day→night
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- **NEVER on standard I2V** — the LoRA forces transformation behavior even without the trigger word. Confirmed 2026-07-21: caused subject duplication and wrong-scene hallucination on standard I2V scenes.
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- **Place at END of prompt**
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- **CFG: 4.0** (not 1.0 — Transition LoRA needs higher CFG)
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- **Strength: 1.0**
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- **Node: LoraLoaderModelOnly** (standard ComfyUI node, NOT LTX2LoraLoaderAdvanced)
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## guide_strength (RESOLVED 2026-07-22)
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**Use 1.0 for all standard I2V with ID LoRA dropped.** The old "1.0 = NEVER" rule was from v4 where ID LoRA was also at 1.0 — the duplication was stacked LoRA interference, not guide_strength alone. With ID LoRA dropped, 1.0 is clean and provides proper start-frame anchoring.
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| Value | When | Why |
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|-------|------|-----|
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| **1.0** | Standard I2V (no ID LoRA) | Proper start-frame anchoring. Confirmed clean in 2-clip test. |
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| **0.5-0.7** | I2V WITH ID LoRA (talking-head only) | Lower strength prevents LoRA interference |
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Verify after render:
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```bash
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ffprobe -v quiet -show_entries format_tags=prompt output.mp4 | grep -oP 'guide_strength.*?(\d+\.?\d*)'
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```
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## Common Mistakes
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| Mistake | Symptom | Fix |
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|---------|---------|-----|
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| guide_strength too low (0.5) | Identity drift, weak start-frame anchoring | 1.0 (safe with ID LoRA dropped) |
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| ID LoRA on action scenes | Frontal-face bias, fights camera motion | Drop ID LoRA entirely |
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| Transition LoRA on standard I2V | Wrong scene, hallucinated content | Remove Transition LoRA entirely |
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| zhuanchang on every scene | Model forces morphing everywhere | Only on actual transitions |
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| No camera direction | Static/random movement | Add dolly/pan/tracking |
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| Prompts too short (<30 words) | Model fills gaps with random data | 50-80 words minimum |
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| No motion detail | Character freezes | Sequential action in present tense |
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| Emotional labels | Abstract expressions | Physical cues only |
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| Conflicting descriptions | Averaged competing signals | One speed, one camera, one light |
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| euler_ancestral_cfg_pp on fp8 distilled | Catastrophic artifacts, hallucinated subjects | Plain euler only |
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