ffmpeg-kinetic-captions

What this skill does

## CRITICAL GUIDELINES

### Windows File Path Requirements

**MANDATORY: Always Use Backslashes on Windows for File Paths**

When using Edit or Write tools on Windows, you MUST use backslashes (`\`) in file paths, NOT forward slashes (`/`).

### Documentation Guidelines

**NEVER create new documentation files unless explicitly requested by the user.**

---

# Kinetic Captions Master Guide (2025-2026)

## Quick Reference - Kinetic Effects

| Effect | ASS Code | Duration | Use Case |
|--------|----------|----------|----------|
| Word Grow | `{\fscx80\fscy80\t(0,200,\fscx120\fscy120)\t(200,400,\fscx100\fscy100)}` | 400ms | Karaoke highlight |
| Pop Bounce | `{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}` | 200ms | Word appear |
| Elastic | `{\fscx40\fscy40\t(0,100,\fscx130\fscy130)\t(100,200,\fscx90\fscy90)\t(200,350,\fscx100\fscy100)}` | 350ms | High energy |
| Spring Bounce | `{\move(540,1100,540,960,0,300)\t(0,150,\fscx110\fscy110)\t(150,300,\fscx100\fscy100)}` | 300ms | Entry from below |
| Shake | `{\t(0,50,\pos(545,960))\t(50,100,\pos(535,960))\t(100,150,\pos(540,960))}` | 150ms | Impact emphasis |
| Karaoke Fill | `{\kf100}Word` | 1000ms | Progressive highlight |
| Karaoke + Grow | `{\k80\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}` | 800ms | Highlight + scale |

---

## Why Kinetic Captions Matter

- **85% of social video** watched without sound
- **Word-level animation** increases retention by 25-40%
- **Scale/bounce effects** signal "this word matters NOW"
- **Karaoke highlighting** guides viewer timing with audio
- **Kinetic typography** is expected on TikTok/Shorts/Reels

---

# Section 1: Karaoke with Word-Grow Effect

The **word-grow highlight** is the most requested kinetic effect - words scale up when highlighted, then return to normal size.

## Basic Word-Grow Karaoke

```ass
[Script Info]
ScriptType: v4.00+
PlayResX: 1080
PlayResY: 1920
WrapStyle: 0

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: KaraokeGrow,Arial Black,80,&H00FFFFFF,&H0000FFFF,&H00000000,&H40000000,1,0,0,0,100,100,0,0,1,5,0,2,10,10,280,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
; Word grows when karaoke highlight reaches it
Dialogue: 0,0:00:01.00,0:00:05.00,KaraokeGrow,,0,0,0,,{\k80\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}This {\k60\t(0,150,\fscx115\fscy115)\t(150,300,\fscx100\fscy100)}is {\k100\t(0,250,\fscx120\fscy120)\t(250,500,\fscx100\fscy100)}AMAZING
```

### Understanding the Animation Tags

```ass
{\k80\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}Word

Breaking it down:
- \k80 = Karaoke duration (80 centiseconds = 0.8 seconds)
- \t(0,200,...) = Animation from 0-200ms
- \fscx115\fscy115 = Scale to 115% (grow)
- \t(200,400,...) = Animation from 200-400ms
- \fscx100\fscy100 = Scale back to 100% (shrink)
```

### Critical: Time Units Differ!

| Tag | Unit | 0.5 seconds = |
|-----|------|---------------|
| `\k` | Centiseconds | `\k50` |
| `\t()` | Milliseconds | `\t(0,500,...)` |

---

## Advanced Word-Grow Patterns

### Pattern 1: Grow + Color Change

Words grow AND change color when highlighted:

```ass
[V4+ Styles]
Style: GrowColor,Arial Black,80,&H00FFFFFF,&H0000FFFF,&H00000000,&H40000000,1,0,0,0,100,100,0,0,1,5,0,2,10,10,280,1
;                                 White     Yellow highlight

[Events]
; Karaoke fill (kf) + grow + color transition
Dialogue: 0,0:00:00.00,0:00:03.00,GrowColor,,0,0,0,,{\kf60\t(0,200,\fscx115\fscy115\c&H00FFFF&)\t(200,400,\fscx100\fscy100)}Check {\kf80\t(0,200,\fscx115\fscy115\c&H00FFFF&)\t(200,400,\fscx100\fscy100)}this {\kf100\t(0,250,\fscx120\fscy120\c&H00FFFF&)\t(250,500,\fscx100\fscy100)}out
```

### Pattern 2: Grow + Bounce (Overshoot)

Spring physics overshoot for more dynamic feel:

```ass
; Grows to 120%, bounces back to 95%, settles at 100%
Dialogue: 0,0:00:00.00,0:00:03.00,Style,,0,0,0,,{\k80\t(0,120,\fscx120\fscy120)\t(120,220,\fscx95\fscy95)\t(220,350,\fscx100\fscy100)}Bouncy
```

### Pattern 3: Grow + Outline Pulse

Outline expands during highlight:

```ass
; Border/outline grows with text
Dialogue: 0,0:00:00.00,0:00:02.00,Style,,0,0,0,,{\k100\t(0,200,\fscx115\fscy115\bord8)\t(200,400,\fscx100\fscy100\bord5)}IMPACT
```

---

## Word-Grow Timing by Platform

| Platform | Grow Duration | Shrink Duration | Max Scale | Animation Style |
|----------|---------------|-----------------|-----------|-----------------|
| **TikTok** | 100-150ms | 100-150ms | 115-120% | Fast, punchy |
| **YouTube Shorts** | 150-200ms | 150-200ms | 110-115% | Smooth, readable |
| **Instagram Reels** | 120-180ms | 120-180ms | 115-120% | Stylish, trendy |

### TikTok Optimized (Fast)

```ass
; Quick 200ms total animation
{\k60\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}Fast
```

### YouTube Shorts Optimized (Smooth)

```ass
; Smooth 350ms total animation
{\k80\t(0,175,\fscx112\fscy112)\t(175,350,\fscx100\fscy100)}Smooth
```

---

# Section 2: CapCut-Style Word Pop Effects

The **word pop** effect makes each word appear with a bounce, popularized by CapCut.

## Basic Word Pop

```ass
[V4+ Styles]
Style: WordPop,Arial Black,84,&H00FFFFFF,&H0000FFFF,&H00000000,&H40000000,1,0,0,0,100,100,0,0,1,6,0,2,10,10,280,1

[Events]
; Each word starts at 50% scale, pops to 115%, settles at 100%
Dialogue: 0,0:00:00.00,0:00:00.50,WordPop,,0,0,0,,{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}This
Dialogue: 0,0:00:00.30,0:00:00.80,WordPop,,0,0,0,,{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}is
Dialogue: 0,0:00:00.50,0:00:01.20,WordPop,,0,0,0,,{\c&H0000FFFF&\fscx50\fscy50\t(0,100,\fscx120\fscy120)\t(100,250,\fscx100\fscy100)}VIRAL
```

### Word Pop with Stagger Delay

Words appear sequentially with overlapping timing:

| Word | Start | End | Delay from Previous |
|------|-------|-----|---------------------|
| Word 1 | 0.00s | 0.50s | - |
| Word 2 | 0.25s | 0.75s | 250ms |
| Word 3 | 0.50s | 1.00s | 250ms |
| Word 4 | 0.75s | 1.25s | 250ms |

### Elastic Word Pop (Multiple Bounces)

```ass
; More dramatic with multiple oscillations
; 40% → 130% → 90% → 105% → 100%
Dialogue: 0,0:00:00.00,0:00:01.00,Style,,0,0,0,,{\fscx40\fscy40\t(0,100,\fscx130\fscy130)\t(100,200,\fscx90\fscy90)\t(200,350,\fscx105\fscy105)\t(350,500,\fscx100\fscy100)}ELASTIC
```

---

## Word Pop with Movement

### Pop In from Below

```ass
; Word moves up while popping
Dialogue: 0,0:00:00.00,0:00:01.00,Style,,0,0,0,,{\move(540,1100,540,960,0,200)\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}BounceUp
```

### Pop In from Side

```ass
; Word slides in from right while popping
Dialogue: 0,0:00:00.00,0:00:01.00,Style,,0,0,0,,{\move(1200,960,540,960,0,250)\fscx50\fscy50\t(0,120,\fscx110\fscy110)\t(120,250,\fscx100\fscy100)}SlideIn
```

### Pop with Rotation

```ass
; Word rotates while appearing
Dialogue: 0,0:00:00.00,0:00:01.00,Style,,0,0,0,,{\frz-15\fscx50\fscy50\t(0,150,\frz0\fscx115\fscy115)\t(150,300,\fscx100\fscy100)}Twist
```

---

# Section 3: Spring Physics Animation

Natural-feeling bounce using spring physics formulas.

## Spring Parameter Guide

| Parameter | Low Value | High Value | Effect |
|-----------|-----------|------------|--------|
| **Damping** | 2-3 | 5-8 | Less bouncy → More bouncy |
| **Frequency** | 8-10 rad/s | 15-20 rad/s | Slow oscillation → Fast oscillation |
| **Amplitude** | 5-10% | 15-25% | Subtle → Dramatic |

### Damping Ratio Interpretation

- **ζ < 0.5**: Very bouncy, multiple oscillations
- **ζ = 0.5-0.8**: Balanced bounce, 1-2 oscillations
- **ζ = 1.0**: Critical damping (no overshoot)
- **ζ > 1.0**: Over-damped (sluggish)

## Spring Bounce in ASS

### Low Damping (Bouncy)

```ass
; Multiple oscillations: 120% → 90% → 105% → 98% → 100%
{\fscx80\fscy80\t(0,100,\fscx120\fscy120)\t(