Add TikTok video skills (caption-animation, countdown-video, lower-thirds, short-form-video)
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_011XhxckAYjGMLrLECWuKBzg
This commit is contained in:
18 files changed
+1842
No files matched your search
@@ -0,0 +1,254 @@
|
||||
# Word-Timed Captions — End-to-End Build
|
||||
|
||||
A complete, runnable path from audio/transcript to animated burn-in captions plus a sidecar SRT/VTT. Code targets Remotion for burn-in and plain JS for the web; the data shapes are framework-agnostic.
|
||||
|
||||
## 1. The one data shape
|
||||
|
||||
Everything normalizes to a flat array of word tokens. Get to this shape and the renderer never cares about the source.
|
||||
|
||||
```ts
|
||||
export type Token = { text: string; startMs: number; endMs: number };
|
||||
export type Page = { startMs: number; endMs: number; tokens: Token[] };
|
||||
```
|
||||
|
||||
Remotion's `@remotion/captions` uses a compatible `Caption` type:
|
||||
|
||||
```ts
|
||||
type Caption = { text: string; startMs: number; endMs: number; timestampMs: number | null; confidence: number | null };
|
||||
```
|
||||
|
||||
## 2. Transcribe to word-level timing (Whisper)
|
||||
|
||||
Word timestamps are non-negotiable for karaoke. Whisper produces them natively.
|
||||
|
||||
```bash
|
||||
npx @remotion/install-whisper-cpp # one-time: installs whisper.cpp + a model
|
||||
```
|
||||
|
||||
```ts
|
||||
import { transcribe, toCaptions } from "@remotion/install-whisper-cpp";
|
||||
|
||||
const { transcription } = await transcribe({
|
||||
inputPath: "voiceover.wav", // 16kHz mono WAV is ideal for whisper.cpp
|
||||
model: "medium.en", // medium.en ≈ 2x faster than large, accurate on clean voice
|
||||
tokenLevelTimestamps: true, // <-- the key flag: per-word, not per-line
|
||||
whisperPath: "./whisper.cpp",
|
||||
});
|
||||
const { captions } = toCaptions({ transcription }); // → Caption[]
|
||||
```
|
||||
|
||||
Tips:
|
||||
- Feed clean voice audio (denoise/normalize first). Background music wrecks word boundaries.
|
||||
- `large` is most accurate but 2–3x real-time on a laptop. Use `medium.en` unless accuracy is critical.
|
||||
- Cloud alternatives (AssemblyAI, Deepgram, OpenAI Whisper API) also return word timing — map their `words[]` into `Token` the same way.
|
||||
|
||||
Map any token shape into `Token`:
|
||||
|
||||
```ts
|
||||
const toTokens = (caps: Caption[]): Token[] =>
|
||||
caps.map(c => ({ text: c.text.trim(), startMs: c.startMs, endMs: c.endMs }));
|
||||
```
|
||||
|
||||
## 3. Parse an existing SRT into tokens
|
||||
|
||||
When handed an SRT, parse cues; if cues are sentence-level, re-transcribe for word timing rather than interpolating.
|
||||
|
||||
```ts
|
||||
const toMs = (t: string) => {
|
||||
const [h, m, rest] = t.trim().split(":");
|
||||
const [s, ms] = rest.split(",");
|
||||
return ((+h * 60 + +m) * 60 + +s) * 1000 + +ms;
|
||||
};
|
||||
|
||||
export function parseSrt(src: string): Token[] {
|
||||
return src.trim().split(/\n\s*\n/).map(block => {
|
||||
const lines = block.split("\n");
|
||||
const time = lines.find(l => l.includes("-->"))!;
|
||||
const [a, b] = time.split("-->");
|
||||
const text = lines.slice(lines.indexOf(time) + 1).join(" ").trim();
|
||||
return { text, startMs: toMs(a), endMs: toMs(b) };
|
||||
});
|
||||
}
|
||||
```
|
||||
|
||||
## 4. Page the tokens (1–4 words at a time)
|
||||
|
||||
Either use Remotion's helper or group manually. Manual grouping by gap + max-words keeps full control:
|
||||
|
||||
```ts
|
||||
export function paginate(tokens: Token[], maxWords = 3, maxGapMs = 1200): Page[] {
|
||||
const pages: Page[] = [];
|
||||
let cur: Token[] = [];
|
||||
for (const t of tokens) {
|
||||
const span = cur.length ? t.endMs - cur[0].startMs : 0;
|
||||
if (cur.length >= maxWords || span > maxGapMs) {
|
||||
if (cur.length) pages.push(pageOf(cur)); cur = [];
|
||||
}
|
||||
cur.push(t);
|
||||
}
|
||||
if (cur.length) pages.push(pageOf(cur));
|
||||
return pages;
|
||||
}
|
||||
const pageOf = (ts: Token[]): Page => ({ startMs: ts[0].startMs, endMs: ts.at(-1)!.endMs, tokens: ts });
|
||||
```
|
||||
|
||||
Remotion equivalent:
|
||||
|
||||
```ts
|
||||
import { createTikTokStyleCaptions } from "@remotion/captions";
|
||||
const { pages } = createTikTokStyleCaptions({ captions, combineTokensWithinMilliseconds: 1200 });
|
||||
// 200–500ms → word-by-word; 1000–1500ms → short readable phrases
|
||||
```
|
||||
|
||||
## 5. Remotion component: word-timed with active highlight
|
||||
|
||||
```tsx
|
||||
import { AbsoluteFill, Audio, Sequence, useCurrentFrame, useVideoConfig,
|
||||
spring, interpolate, staticFile } from "remotion";
|
||||
|
||||
const CAPTION_STYLE: React.CSSProperties = {
|
||||
fontFamily: "Montserrat, Inter, sans-serif",
|
||||
fontWeight: 800,
|
||||
fontSize: 72, // ~8% of 1920px height
|
||||
color: "#fff",
|
||||
textAlign: "center",
|
||||
textTransform: "uppercase",
|
||||
WebkitTextStroke: "5px #000", // heavy outline survives any background
|
||||
paintOrder: "stroke fill", // stroke behind fill, not clipping glyphs
|
||||
textShadow: "0 4px 16px rgba(0,0,0,.55)",
|
||||
lineHeight: 1.1,
|
||||
padding: "0 80px", // keep inside center 80% width
|
||||
};
|
||||
|
||||
const Word: React.FC<{ token: Token; active: boolean }> = ({ token, active }) => {
|
||||
const frame = useCurrentFrame();
|
||||
const { fps } = useVideoConfig();
|
||||
const enter = (token.startMs / 1000) * fps;
|
||||
const p = spring({ frame: frame - enter, fps, config: { damping: 12, mass: 0.6 } });
|
||||
return (
|
||||
<span style={{
|
||||
display: "inline-block",
|
||||
transform: `scale(${interpolate(p, [0, 1], [0.6, 1])})`,
|
||||
opacity: interpolate(p, [0, 1], [0, 1]),
|
||||
color: active ? "#FFE45E" : undefined,
|
||||
transition: "color 80ms linear",
|
||||
}}>{token.text} </span>
|
||||
);
|
||||
};
|
||||
|
||||
export const Captions: React.FC<{ pages: Page[]; audio: string }> = ({ pages, audio }) => {
|
||||
const { fps } = useVideoConfig();
|
||||
const f = (ms: number) => Math.round((ms / 1000) * fps);
|
||||
const frame = useCurrentFrame();
|
||||
return (
|
||||
<AbsoluteFill>
|
||||
<Audio src={staticFile(audio)} /> {/* same audio the transcript came from */}
|
||||
{pages.map((pg, i) => (
|
||||
<Sequence key={i} from={f(pg.startMs)} durationInFrames={Math.max(1, f(pg.endMs - pg.startMs))}>
|
||||
<AbsoluteFill style={{ justifyContent: "flex-start", alignItems: "center", paddingTop: "62%" }}>
|
||||
<div style={CAPTION_STYLE}>
|
||||
{pg.tokens.map((t, j) => {
|
||||
const now = (frame / fps) * 1000;
|
||||
return <Word key={j} token={t} active={now >= t.startMs && now < t.endMs} />;
|
||||
})}
|
||||
</div>
|
||||
</AbsoluteFill>
|
||||
</Sequence>
|
||||
))}
|
||||
</AbsoluteFill>
|
||||
);
|
||||
};
|
||||
```
|
||||
|
||||
Because the `<Audio>` and the timestamps share one timebase, voice and captions stay locked with no manual nudging. Re-record the VO → re-transcribe → done.
|
||||
|
||||
## 6. Web/CSS path (live DOM player)
|
||||
|
||||
```js
|
||||
function renderTrack(tokens, mountEl) {
|
||||
tokens.forEach(t => {
|
||||
const el = document.createElement("span");
|
||||
el.className = "word";
|
||||
el.textContent = t.text + " ";
|
||||
el.style.animationDelay = `${t.startMs}ms`; // each word pops on its own start
|
||||
mountEl.append(el);
|
||||
});
|
||||
}
|
||||
// drive .active off the media element's currentTime
|
||||
audio.addEventListener("timeupdate", () => {
|
||||
const ms = audio.currentTime * 1000;
|
||||
[...track.children].forEach((el, i) =>
|
||||
el.classList.toggle("active", ms >= tokens[i].startMs && ms < tokens[i].endMs));
|
||||
});
|
||||
```
|
||||
|
||||
```css
|
||||
.cap { font: 800 72px/1.1 Montserrat, sans-serif; text-transform: uppercase;
|
||||
color:#fff; -webkit-text-stroke:5px #000; paint-order:stroke fill;
|
||||
text-shadow:0 4px 16px rgba(0,0,0,.55); text-align:center; }
|
||||
.word { display:inline-block; opacity:0; animation: pop .26s cubic-bezier(.34,1.56,.64,1) forwards; }
|
||||
.word.active { color:#FFE45E; }
|
||||
@keyframes pop { from { opacity:0; transform:translateY(.18em) scale(.7) } to { opacity:1; transform:none } }
|
||||
```
|
||||
|
||||
## 7. Emit a sidecar SRT / VTT from the same tokens
|
||||
|
||||
Burn-in alone does not satisfy ADA/WCAG and many platforms ignore uploaded tracks — so ship both. Group tokens into readable cues and serialize:
|
||||
|
||||
```ts
|
||||
const pad = (n: number, w = 2) => String(n).padStart(w, "0");
|
||||
const stamp = (ms: number, sep: string) => {
|
||||
const h = Math.floor(ms / 3.6e6), m = Math.floor(ms % 3.6e6 / 6e4),
|
||||
s = Math.floor(ms % 6e4 / 1000), x = ms % 1000;
|
||||
return `${pad(h)}:${pad(m)}:${pad(s)}${sep}${pad(x, 3)}`;
|
||||
};
|
||||
|
||||
export const toSrt = (pages: Page[]) => pages.map((p, i) =>
|
||||
`${i + 1}\n${stamp(p.startMs, ",")} --> ${stamp(p.endMs, ",")}\n${p.tokens.map(t => t.text).join(" ")}`
|
||||
).join("\n\n") + "\n";
|
||||
|
||||
export const toVtt = (pages: Page[]) => "WEBVTT\n\n" + pages.map(p =>
|
||||
`${stamp(p.startMs, ".")} --> ${stamp(p.endMs, ".")}\n${p.tokens.map(t => t.text).join(" ")}`
|
||||
).join("\n\n") + "\n";
|
||||
```
|
||||
|
||||
Use SRT for the broadest platform support; VTT when styling/positioning cues or serving on the web.
|
||||
|
||||
## 8. Per-platform safe areas (1080×1920, 9:16)
|
||||
|
||||
| Platform | Bottom keep-clear | Top keep-clear | Side keep-clear | Notes |
|
||||
|---|---|---|---|---|
|
||||
| TikTok | ~340px | ~120px | ~110px right rail | Captions, audio title, action buttons crowd the bottom-right |
|
||||
| Instagram Reels | ~280px | ~130px | ~60px | Username/CTA bar at bottom |
|
||||
| YouTube Shorts | ~240px | ~100px | ~120px right rail | Title + channel at bottom-left |
|
||||
| Facebook Reels | ~300px | ~130px | ~80px | Similar to Reels |
|
||||
|
||||
Safe rule across all: place caption baseline at ~62–70% of frame height, keep text within the center 80% width, and never let it enter the bottom ~15%.
|
||||
|
||||
## 9. Readable-type spec sheet
|
||||
|
||||
| Property | Recommended | Floor |
|
||||
|---|---|---|
|
||||
| Weight | 800 (ExtraBold) | 700 |
|
||||
| Size @1080p | 56–80px | 45px |
|
||||
| Stroke | 4–6px solid #000 | 2px |
|
||||
| Shadow | `0 4px 16px rgba(0,0,0,.55)` | soft 1px |
|
||||
| Active accent | one color (e.g. #FFE45E) or filled box | — |
|
||||
| Lines on screen | 1–2 | 2 max |
|
||||
| Words per page | 1–4 | 5 max |
|
||||
|
||||
Set `paint-order: stroke fill` so a thick stroke sits behind the glyph instead of eating it. Test on a bright frame and a busy frame; if it survives both, it ships.
|
||||
|
||||
## 10. Render
|
||||
|
||||
```bash
|
||||
npx remotion render src/index.ts Captions out/captions.mp4 \
|
||||
--props='{"pages": ..., "audio": "voiceover.wav"}'
|
||||
```
|
||||
|
||||
A 10-minute video with animated captions can take 30–60 min to render locally; render long-form in segments, or render on Remotion Lambda for parallel speed.
|
||||
|
||||
---
|
||||
## Built by the team behind iart.ai
|
||||
|
||||
This skill is part of an open motion-graphics collection from iart.ai — the AI motion agent that turns data, scripts, and designs into editable motion graphics (Remotion → MP4). If you'd rather not hand-build this, iart.ai can auto-time captions to a narration track and one-click burn them in from a template — change the text/audio and re-export. → [iart.ai](https://iart.ai/?utm_source=github&utm_medium=reference&utm_campaign=tiktok-video-skills&utm_content=ref_footer&utm_term=caption-animation)
|
||||
Reference in new issue
Block a user