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 (/).

FFmpeg Kinetic Captions

Purpose

Create animated kinetic captions with professional effects like word-grow karaoke, bouncy text, elastic effects, and CapCut-style word pop animations for viral social media videos.

Workflow

1. Quick Effect Reference

Effect	Description	Best For
`pop`	Words pop in from small to normal with overshoot	TikTok, fast-paced content
`grow`	Words smoothly scale up when highlighted	Karaoke, music videos
`bounce`	Elastic bounce with multiple oscillations	YouTube Shorts, emphasis
`elastic`	Spring physics with natural damping	Professional, premium feel
`karaoke-grow`	Combined karaoke fill + grow animation	Lyric videos, singalongs

2. Generate Kinetic ASS Subtitles

Using the Script

# Basic kinetic captions
./generate-karaoke.sh kinetic lyrics.txt output.ass pop

# Platform-optimized
./generate-karaoke.sh kinetic lyrics.txt output.ass bounce tiktok
./generate-karaoke.sh kinetic lyrics.txt output.ass elastic youtube
./generate-karaoke.sh kinetic lyrics.txt output.ass karaoke-grow instagram

Manual ASS Creation

Pop Effect (CapCut-Style):

[Script Info]
ScriptType: v4.00+
PlayResX: 1080
PlayResY: 1920

[V4+ Styles]
Style: Kinetic,Montserrat,72,&H00FFFFFF,&H000000FF,&H00000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,2,50,50,30,1

[Events]
Dialogue: 0,0:00:01.00,0:00:02.00,Kinetic,,0,0,0,,{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}Hello
Dialogue: 0,0:00:02.00,0:00:03.00,Kinetic,,0,0,0,,{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}World

Word-Grow Karaoke Effect:

Dialogue: 0,0:00:01.00,0:00:05.00,Kinetic,,0,0,0,,{\k80\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}First {\k60\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}word {\k100\t(0,200,\fscx115\fscy115)\t(200,400,\fscx100\fscy100)}grows

Bounce Effect:

Dialogue: 0,0:00:01.00,0:00:02.00,Kinetic,,0,0,0,,{\fscx80\fscy80\t(0,100,\fscx120\fscy120)\t(100,200,\fscx95\fscy95)\t(200,300,\fscx100\fscy100)}Bounce

Elastic Effect:

Dialogue: 0,0:00:01.00,0:00:02.00,Kinetic,,0,0,0,,{\fscx60\fscy60\t(0,80,\fscx125\fscy125)\t(80,160,\fscx92\fscy92)\t(160,240,\fscx105\fscy105)\t(240,320,\fscx98\fscy98)\t(320,400,\fscx100\fscy100)}Elastic

3. Apply to Video

# Burn subtitles into video
ffmpeg -i input.mp4 -vf "ass=kinetic.ass" -c:v libx264 -crf 18 -c:a copy output.mp4

# With hardware acceleration (NVENC)
ffmpeg -i input.mp4 -vf "ass=kinetic.ass" -c:v h264_nvenc -preset p4 -cq 20 -c:a copy output.mp4

# 9:16 vertical with kinetic captions
ffmpeg -i input.mp4 -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2,ass=kinetic.ass" -c:v libx264 -crf 18 output.mp4

4. Platform-Specific Timing

Platform	Animation Speed	Recommended Effect
TikTok	Fast (100-200ms)	pop, bounce
YouTube Shorts	Medium (150-300ms)	grow, elastic
Instagram Reels	Stylish (200-400ms)	elastic, karaoke-grow

5. Critical ASS Timing Notes

IMPORTANT: ASS uses TWO different time units:

Karaoke tags (\k, \kf, \ko): Centiseconds (100 = 1 second)
Animation tags (\t): Milliseconds (1000 = 1 second)

Example combining both:

{\k80\t(0,200,\fscx115\fscy115)}Word

\k80 = word highlighted for 0.8 seconds (80 centiseconds)
\t(0,200,...) = animation over 200 milliseconds

6. Color Variations

# Yellow highlight on grow
{\k80\t(0,200,\fscx115\fscy115\c&H00FFFF&)\t(200,400,\fscx100\fscy100)}Word

# Gradient glow effect
{\k80\t(0,200,\fscx115\fscy115\3c&H0000FF&)\t(200,400,\fscx100\fscy100\3c&H000000&)}Word

7. Advanced: Python Generator

For complex projects, use the Python generator:

import json

def generate_kinetic_ass(words, effect="pop", platform="tiktok"):
    """Generate kinetic ASS subtitle file"""

    effects = {
        "pop": r"{\fscx50\fscy50\t(0,100,\fscx115\fscy115)\t(100,200,\fscx100\fscy100)}",
        "grow": r"{\fscx90\fscy90\t(0,150,\fscx110\fscy110)\t(150,300,\fscx100\fscy100)}",
        "bounce": r"{\fscx80\fscy80\t(0,100,\fscx120\fscy120)\t(100,200,\fscx95\fscy95)\t(200,300,\fscx100\fscy100)}",
        "elastic": r"{\fscx60\fscy60\t(0,80,\fscx125\fscy125)\t(80,160,\fscx92\fscy92)\t(160,240,\fscx105\fscy105)\t(240,320,\fscx98\fscy98)\t(320,400,\fscx100\fscy100)}"
    }

    header = """[Script Info]
ScriptType: v4.00+
PlayResX: 1080
PlayResY: 1920

[V4+ Styles]
Style: Kinetic,Montserrat,72,&H00FFFFFF,&H000000FF,&H00000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,2,50,50,30,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
"""

    effect_code = effects.get(effect, effects["pop"])
    lines = []

    for word_data in words:
        word = word_data["word"]
        start = word_data["start"]
        end = word_data["end"]
        lines.append(f"Dialogue: 0,{start},{end},Kinetic,,0,0,0,,{effect_code}{word}")

    return header + "\n".join(lines)

# Usage
words = [
    {"word": "Hello", "start": "0:00:01.00", "end": "0:00:02.00"},
    {"word": "World", "start": "0:00:02.00", "end": "0:00:03.00"}
]
ass_content = generate_kinetic_ass(words, effect="bounce", platform="tiktok")

Output

Provide:

Complete ASS subtitle file with kinetic effects
FFmpeg command to apply to video
Platform-specific optimization recommendations
Timing adjustments for audio sync
Color and style customization options

/ffmpeg-kinetic