Long Video → Vertical Short

Landscape clip → reframed 9:16 short ready for TikTok / Reels / Shorts.

Category: social · Difficulty: Intermediate · ~Time: 10 min

What you'll make

A platform-ready 9:16 vertical short cut from a wide 16:9 source clip, with the subject re-centered and optional AI-generated B-roll or an animated cover frame. Use this when you have one landscape recording (a talk, demo, or interview) and need a punchy mobile-first edit for short-form feeds.

Models used

💬 LLM — Claude (turn the transcript into hook + on-screen caption beats)
🎨 Image — Nano Banana Pro (resolve live; e.g. google/nano-banana-pro/text-to-image) for the 9:16 cover frame
🎬 Video — Seedance 2.5 i2v (resolve live; e.g. bytedance/seedance-2.5/image-to-video) or Kling 3 i2v (kwaivgi/kling-v3.0-pro/image-to-video) for animated cover / B-roll

Steps

Reframe to 9:16 — Ask the agent to crop/pan the source to vertical, keeping the speaker centered. This is a local ffmpeg/edit step (e.g. crop=ih*9/16:ih), not a model call — the AI models below add the cover and B-roll.
Write the hook + captions — "From this transcript, give me a 4-word hook and 6 short on-screen caption beats." → atlas_chat with Claude.
Generate a 9:16 cover frame — "Make a bold vertical cover, 9:16, big legible headline reading ''." → atlas_generate_image with Nano Banana Pro.

Tip: ask the agent to atlas_search_docs for the model first so it pulls the live aspect-ratio / size schema.
Animate the cover or add B-roll — "Add a slow push-in to this cover for a 3s intro." → atlas_generate_video with Seedance 2.5 i2v (use seedance-2.0-fast for drafts). For richer motion, see the Photo → Stylized Animated Clip (style-animate) motion recipe.
Assemble — concatenate intro cover clip → reframed body → end card locally.

Prompt starters

Hook (Claude): "Summarize this transcript into a 4-word curiosity hook + 6 caption beats (≤7 words each), punchy, no hashtags."
Cover (Nano Banana Pro): "Vertical 9:16 social cover, bold sans headline 'YOU'RE DOING THIS WRONG', high-contrast, mobile-safe margins, subject left, copy space right."
Cover animation (Seedance 2.5 i2v): "Subtle 3-second push-in on this cover, gentle parallax, no text distortion."

Tips & variations

Swap Seedance 2.5 i2v for Kling 3 i2v when you want stronger, more dramatic camera motion on the cover.
Keep all generated frames at a true 9:16 ratio (e.g. 1080×1920) so nothing gets letterboxed in-feed.
Draft with Seedance seedance-2.0-fast to preview pacing cheaply, then re-render the final cover at full quality.
Batch it: feed the LLM several transcript chunks at once to get multiple hook options, then pick the strongest before generating.