How to repurpose a long youtube video into a shorts cut
- Step 1Find the moment worth repurposing — Scrub the long-form master for a self-contained 20–60 second hook — a punchline, a reveal, a tight tip. The formatter keeps the first 60 seconds, so you'll position this moment at the start in the next step.
- Step 2Cut the highlight first with the lossless trimmer — Use lossless-trimmer to extract your in/out range. It stream-copies (
-c copy) at the nearest keyframe, so it's instant and lossless — the perfect input for the formatter's-t 60. - Step 3Drop the trimmed clip onto the Shorts formatter — MP4, MOV, MKV, WebM, AVI, M4V, or TS. Loads into the in-browser FFmpeg.wasm filesystem — no upload. The size limit applies to this clip, not your full master.
- Step 4Run the reframe + format pass — JAD center-crops to 9:16, scales to 1080×1920 with Lanczos, re-applies
-t 60(harmless if your clip is already ≤60s), and encodes H.264 + AAC. - Step 5Add captions if the moment relies on dialogue — Sound-off viewing dominates Shorts. Burn captions onto the reframed clip with subtitle-burner so the repurposed hook lands without audio.
- Step 6Upload the Short and link the full video — Post the 1080×1920 MP4 as a Short and pin a comment or use the description to point viewers to the long-form upload — that's the discovery funnel the repurpose is for.
The repurposing pipeline (two tools)
Repurposing long-form to Shorts is a trim then a format. The formatter alone keeps only the first 60s, so the trim step chooses the moment.
| Step | Tool | What it does | Re-encode? |
|---|---|---|---|
| 1. Pick the moment | lossless-trimmer | Cut the exact highlight range, stream-copy at keyframe | No (-c copy, instant) |
| 2. Reframe + format | youtube-shorts-formatter (this tool) | Center-crop to 9:16, scale 1080×1920, -t 60 | Yes (one H.264 CRF20 pass) |
| 3. (optional) Captions | subtitle-burner | Hardcode SRT/VTT for sound-off viewing | Yes |
| Alt. 2 for off-center subjects | auto-reframe | Content-aware reframe before formatting | Yes |
What survives the repurpose
Quality and framing outcomes when reframing a long-form moment to a Short.
| Source trait | Outcome | Note |
|---|---|---|
| Centered host (talking head) | Kept intact | Center crop is exactly right |
| Host to one side | Cropped off | Use video-cropper or auto-reframe first |
| On-screen text in lower third | Kept (full height retained) | Edge text in side columns is lost |
| Highlight at 0:00 of the clip | Kept | -t 60 keeps the first minute |
| Highlight past 1:00 of the clip | Dropped | Trim it to the front first |
| 1080p / 4K master | Downscaled to 1080×1920 (sharp) | 720p sources may soften on upscale |
Cookbook
Repurposing workflows from real long-form content. Each shows the trim-then-format pattern and the center-crop result.
Pull a 45-second tip from a 22-minute tutorial
The actionable tip is at 8:30. Trim it losslessly, then format — the formatter sees a 45-second centered clip and reframes it cleanly.
Master: tutorial.mp4 1920×1080 22:14
Step 1 lossless-trimmer: 8:30–9:15 → tip.mp4 (45s, -c copy)
Step 2 shorts-formatter: tip.mp4
crop 607×1080 (center) → scale 1080×1920 → -t 60
Result: 1080×1920 Short, 45s, the tip front-loadedRepurpose a reaction beat from a centered webcam stream
A streamer's facecam sits centered in a 16:9 capture — the ideal case for the fixed center crop. No manual cropping needed.
Master: stream-vod.mkv 1920×1080 (facecam centered)
Step 1 trim 1:02:10–1:02:55 → beat.mp4 (45s)
Step 2 shorts-formatter → 1080×1920 H.264 CRF20
center crop keeps the facecam, sides (chat/game) droppedSide-framed interview moment (needs a manual crop)
The guest sits in the right third of the frame. A center crop would keep the empty middle, so swap step 2 for a manual crop.
Step 1 trim 14:00–14:50 → moment.mp4
Step 2a (wrong) shorts-formatter → center crop misses the guest
Step 2b (right) video-cropper → pick 607×1080 over the guest
then shorts-formatter re-scales the already-vertical cropRepurpose with burned captions for a dialogue-heavy clip
The hook is a quote. Format first, then burn captions so the line reads with sound off.
Step 1 trim → quote.mp4 (38s, centered speaker)
Step 2 shorts-formatter → quote-9x16.mp4 (1080×1920)
Step 3 subtitle-burner: quote.srt onto quote-9x16.mp4
→ captioned Short, sound-off readyTurn one long video into three Shorts
Batch the trims, then format each. The formatter does one file per run, so loop the format step.
Master: podcast-ep.mp4 (1:08:00, centered two-cam)
Step 1 trim 3 highlights → a.mp4, b.mp4, c.mp4
Step 2 shorts-formatter on each → a-9x16, b-9x16, c-9x16
(one run per clip; tool processes single files)
Result: 3 Shorts seeding the full episodeEdge cases and what actually happens
You feed the full long-form file directly to the formatter
By designThe formatter keeps only the first 60 seconds — so a 20-minute master becomes a Short of its intro, not its best moment. Always trim the highlight to the front first with lossless-trimmer.
Your highlight is past the 60-second mark of the trimmed clip
DroppedEven after trimming, anything beyond the first 60 seconds of the clip you give the formatter is cut. Trim tightly — aim for a clip that's already ≤60s so -t 60 is a no-op.
Subject is off-center in the source frame
Cropped outCenter crop keeps the middle column only. For a guest framed to one side or a moving presenter, use video-cropper (manual) or auto-reframe (tracking) for the reframe instead.
The long-form video had baked-in branding at a corner
Cropped outA logo or handle in a left/right corner sits in the discarded width and won't appear on the Short. If you want it on the Short, re-add it with watermark-engine after formatting.
Generation loss from re-encoding an already-compressed YouTube download
ExpectedRepurposing a re-downloaded YouTube file means encoding a lossy source again. CRF 20 keeps it high quality, but always repurpose from your original master if you have it, not a downloaded copy, to minimise generation loss.
Music or copyrighted audio in the highlight
Risk (off-tool)The formatter re-encodes audio to AAC but doesn't detect or strip copyrighted music — Shorts' Content ID may still flag it. To mute a span, use audio-mute-region before formatting; the formatter itself has no audio-removal option.
Mixed aspect ratios across a multi-cam master
SupportedThe formatter probes each input independently and computes the center 9:16 crop for that file's dimensions, so a 16:9 clip and a 4:3 clip both come out 1080×1920. Just run them one at a time.
Highlight is shorter than you'd like (e.g. 12s)
SupportedShort clips are fine — -t 60 only caps, it never pads. A 12-second highlight stays 12 seconds. To pace a snappy multi-beat Short you'd assemble clips first (the formatter doesn't concatenate).
Trimmed clip exceeds your tier file-size limit
RejectedThe size cap applies to the clip you hand the formatter (Free 1 GB, Pro 10 GB, Pro-media/Developer 100 GB). A high-bitrate 4K highlight can be large — trimming a shorter range or downscaling first keeps it under the ceiling.
You want the Short to keep the full landscape frame as context
Wrong toolThis formatter crops to fill vertical; it never letterboxes. If the wide framing is essential, the moment may work better as a standard landscape video or an X clip via twitter-x-formatter.
Frequently asked questions
Can I just upload my whole long video to the formatter?
You can, but you'll only get its first 60 seconds as a Short — the formatter keeps the opening minute. To repurpose a specific moment, cut it to the front first with lossless-trimmer, then format.
How do I pick the exact moment to repurpose?
The Shorts formatter doesn't have an in/out picker. Use lossless-trimmer to cut the highlight range (it stream-copies at a keyframe, so it's instant and lossless), then drop that clip onto the formatter.
Will repurposing degrade quality?
There's one H.264 CRF 20 re-encode in the format step (the trim step is lossless -c copy). CRF 20 is high quality, so the loss is minimal. The bigger factor is your source: repurpose from the original master, not a re-downloaded YouTube file, to avoid stacking generation loss.
My host is off to one side of the long-form frame. What then?
The fixed center crop would miss them. Use video-cropper to manually pick the 9:16 column over your host, or auto-reframe to track a moving subject, before this formatter re-scales.
Does it keep on-screen text from the long-form video?
Center crop keeps the full height, so lower-third captions survive — but text near the left/right edges falls in the discarded width and is lost. For Shorts you'll usually want fresh, larger captions via subtitle-burner anyway.
Can I repurpose members-only or unlisted content safely?
Yes. Processing runs entirely in-browser on FFmpeg.wasm, so your master never uploads. That makes it safe for members-only, sponsor-embargoed, or unpublished long-form.
What's the output of the repurpose?
A single 1080×1920 MP4 (9:16), H.264 CRF 20 + AAC 128 kbps, capped at 60 seconds, with +faststart. Source frame rate is preserved.
Can I make several Shorts from one long video at once?
Trim each highlight, then format them one at a time — the formatter runs a single file per pass. The trims are instant, so the loop is fast even for a dozen Shorts from one episode.
Should I add captions before or after formatting?
After. Format to 1080×1920 first, then burn captions onto the vertical output with subtitle-burner so the text is sized and positioned for the final 9:16 frame.
How do Shorts drive traffic to my long video?
That's a content strategy, not a tool feature — pin a comment or use the description to link the full upload, and pick highlights that leave viewers wanting the rest. The formatter just gets the clip Shorts-ready quickly so you can publish more of them.
What if my highlight has background music?
The formatter re-encodes audio to AAC but doesn't remove or detect music — Content ID may still flag it. Mute a span with audio-mute-region before formatting if needed.
Does the formatter add a #Shorts watermark or branding?
No — it outputs a clean 1080×1920 MP4 with no overlay. Add your own branding with watermark-engine after formatting if you want a consistent handle on every repurposed Short.
Privacy first
Every JAD Video tool runs entirely in your browser via WebCodecs and FFmpeg (WebAssembly). Your video files never leave your device — verified by zero outbound network requests during processing.