Use this skill to create burned-in social captions with word-level timing, pop/bounce/scale animations, karaoke highlighting, and platform-appropriate caption styles. This SKILL is a lean orchestrator; detailed ASS styles, scripts, formulas, and presets are preserved in references/caption-styles-and-generation.md.
When to Use
- Word-by-word or phrase-by-phrase social captions
- CapCut-style pop, bounce, sweep, karaoke, and typewriter captions
- Whisper transcript to animated ASS conversion
- TikTok, YouTube Shorts, Instagram Reels, and Facebook Reels caption styling
- Caption readability, safe zones, accessibility, and mobile typography
Caption Workflow
- Generate transcript with word-level timestamps using Whisper or another ASR tool.
- Convert word timings into ASS events and styles.
- Use ASS timing units correctly: karaoke tags use centiseconds; animation tags use milliseconds.
- Burn ASS into the video with FFmpeg.
- Verify readability, safe-zone placement, audio sync, and final platform specs.
Minimal Burn-In Command
ffmpeg -i input.mp4 \
-vf "ass=captions.ass" \
-c:v libx264 -preset fast -crf 23 \
-c:a copy \
output_captioned.mp4
If audio copy fails because the output container cannot accept the source audio, re-encode audio with -c:a aac -b:a 128k.
Quick Style Selection
| Style | Effect | Best for |
|---|---|---|
| Word Pop | Each word scales in with overshoot | High-energy hooks, gaming, comedy |
| Highlight Sweep | Full phrase visible, words highlight in sequence | Educational and professional explainers |
| Karaoke Fill | Progressive fill across words | Music, voiceover, lyric-style captions |
| Typewriter | Characters appear progressively | Dramatic storytelling |
| Bounce In | Words move/scale from below | Shorts/Reels emphasis beats |
Timing and Readability Rules
- Word-level animations usually need 80-250ms appear time and 200-600ms dwell, depending on platform.
- Keep 3-6 words on screen for vertical social video.
- Use large sans-serif fonts, high contrast, and a thick outline.
- Avoid excessive shake/flash; keep accessibility and readability ahead of novelty.
- Keep captions inside mobile safe zones; avoid the lower UI-heavy region.
Reference Map
references/caption-styles-and-generation.md- Full preserved reference: Whisper timestamp commands, ASS structure, WordPop/Sweep/Karaoke/Typewriter/Bounce examples, Python JSON-to-ASS script, bash pipeline, burn commands, style presets, color schemes, emoji integration, platform guidelines, troubleshooting, spring/easing/shake/pulse formulas, accessibility guidance, sources.
Related Skills
ffmpeg-captions-subtitles- Subtitle fundamentals and burn-inffmpeg-karaoke-animated-text- ASS karaoke and animated text patternsffmpeg-animation-timing-reference- Timing units, easing, readability, syncviral-video-platform-specs- Export specs and safe zonesviral-video-hook-templates- Hook and retention strategy