Shorts Lab
長い動画をドロップ → AIが最良の 30秒フック を検出 → crop to 9:16 vertical → burn TikTok-style subtitles → download MP4. Everything runs in your browser. Free alternative to OpusClip and Munch.
動画をここにドロップ
MP4、MOV、WebM — ブラウザが再生できる任意の形式
最良の結果：2〜20分のトーキングヘッドまたはインタビューコンテンツ
Whisper AI 文字起こし
文字起こしにより最良のフックを検出し字幕を生成できます。 字幕が不要な場合はスキップ。
Select the spoken language for accurate subtitles.
First-time download only · cached in browser afterwards
Transcript
↕ Drag on preview to reposition crop
✨ AI-Suggested Hooks
Click to jump to the best 30s windows detected by AI.
Hooks appear after transcription.
🎬 Frame & Crop
Or drag the preview above to fine-tune manually.
💬 Subtitle Style
📝 Edit Subtitles
Click any segment to fix transcription errors.
Transcript appears here after transcription.
ショートをエクスポート
The free alternative to OpusClip and Munch
Tools like OpusClip and Munch charge $20–150/month to take a long video, find the best moments, reframe to 9:16 and add subtitles. They process everything on their servers with a monthly clip quota. Shorts Lab does the same workflow entirely in your browser, with no monthly limit and no server costs — because your CPU does all the work.
4ステップのワークフロー
- Upload — drop any video file. MP4, MOV, WebM — anything your browser can play.
- Transcribe — Whisper AI (same model used by OpenAI's API) transcribes the audio with word-level timestamps. Or skip this step if you just want the crop.
- Edit — the AI suggests the 3 most "hook-worthy" 30-second windows based on speech density. Pick one, or drag the timeline handles to any custom range. Preview with live subtitle rendering.
- Export — WebCodecs encodes a full-quality MP4 with subtitles burned in, ready to upload to TikTok, Instagram Reels or YouTube Shorts.
フック検出
We use a sliding-window algorithm that scores each 30-second segment by the number of words spoken per second. High speech density correlates with high-energy moments — the parts where the speaker is most engaged, making their point, or delivering value. The top 3 windows are ranked and shown as clickable suggestions.
字幕
Subtitles are rendered directly onto the video frames during export using the Canvas API. Three styles are available: TikTok (bold text on a semi-transparent box, yellow accent — the most viral-looking style), Minimal (white text with a drop shadow, clean and readable), and Solid Box (colorful background, high contrast).
プライバシー
Your video never leaves your device. All transcription, cropping and encoding happen locally using WebAssembly and WebCodecs. The only network requests are the one-time model downloads (Whisper model from HuggingFace, both cached by your browser after the first run).
制限事項
- Export requires WebCodecs — Chrome/Edge 94+ or Safari 16.4+.
- Transcription requires a model download (75–145 MB) on first use.
- Encoding speed depends on your CPU — expect 1–3 minutes per 30-second clip.
- Very long videos (>60 min) may run out of browser memory during audio decoding.
よくある質問
- Shorts Labとは何ですか？
- 横長の動画をYouTube Shorts、TikTok、Instagram Reels用の縦型9:16フォーマットに変換するツールです。
- 動画にウォーターマークは追加されますか？
- いいえ、出力はウォーターマークやブランディングなしのクリーンな状態です。
- エクスポート前にクロップをプレビューできますか？
- はい、縦型フォーマットでの動画の見え方をライブプレビューで確認できます。
- 動画をサーバーで処理しますか？
- いいえ、最大限のプライバシーのためにすべてブラウザ内でローカルに実行されます。
- Shorts Labは無料で使えますか？
- はい、コストやサインアップなしで無制限に変換できます。