9jacut

A Windows desktop app for manually cutting a recording into clips, reframing them into other aspect ratios for posting online, and mixing in your own audio. No AI model, no upload — everything runs locally through a bundled copy of ffmpeg.

What it does

• Open a local .mp4 / .mov / .mkv / .avi file, or just drag a video file onto the window.
• Scrub the timeline, hit Mark In / Mark Out (duration shows live), then + Add Clip to build a list of clips. Rename clips and hand-edit their start/end times directly.
• Pick an aspect ratio per clip: Original, Vertical 9:16, Square 1:1, Portrait 4:5, or Custom (type any W:H ratio). Click Reframe to drag the crop box over the frame and choose what stays in shot, then Done.
• Add Audio on any clip to import a local audio file (anything you already have downloaded/exported — the app can't pull tracks directly from Spotify or other streaming services, since they don't allow that) and mix it under the clip with a volume slider, or check Replace original audio to swap it out entirely.
• 😀 Stickers on any clip: pick a smiley/reaction from the picker, drag it anywhere on the frame, and set when it appears/disappears. Baked into the exported video, and correctly follows the frame if the clip is also reframed to a different aspect ratio.
• Undo reverses the last change — adding/deleting a clip, edits, reframe drags, audio changes, sticker placement.
• Switch between dark and light mode with the button in the top-right (dark brown is the default).
• Choose an export folder and hit Export All Clips — each one is cut and (if reframed) cropped/scaled with ffmpeg, saved as <name>_<aspect>.mp4.
• Multiple videos per session: open or drag in more than one source video; a row of pills lets you switch which one is active, and every clip remembers which video it came from (including on export).
• Clip thumbnails, a Duplicate button per clip, and full Save Project / Load Project (writes/reads a .json project file covering every loaded video, clip, crop, audio, and sticker) so you can pick up a project later without redoing anything.
• Promo Video tab (top of the window): a separate "CapCut-style" business promo maker. Fill in your business name/tagline/hours/address/contact, add photos and/or video clips (either from files or straight from whatever's loaded in the Clip Editor), then pick one of 52 named styles — 4 base layouts (Hero Card, Split Panel, Spotlight Grid, Side Strip) × 13 color themes — and export a vertical 9:16 promo video with your info baked in.

Running it (development)

Requires Node.js (LTS) installed on Windows.

cd 9jacut
npm install
npm start

Building the single shareable .exe

npm install
npm run dist

This uses electron-builder with the portable Windows target — one self-contained 9jacut.exe under dist/, no installer, no separate files. Anyone can download that one file and double-click it to run the app. Run this step on Windows — cross-building from another OS needs extra tooling (Wine) that isn't set up here.

Notes / known limits

• Preview relies on Chromium's built-in video support. Standard H.264 .mp4 files preview reliably; some .mov/.mkv files with unusual codecs may not preview inline, though export still works regardless.
• The reframe crop is a single position per clip (no animated pan over time). Say the word if you'd like the crop to move over the course of a clip and I'll add keyframed panning.
• Imported audio is trimmed to the clip's length (or looped/padded isn't done automatically — if your track is shorter than the clip, it'll just end early). Let me know if you'd like it to loop instead.
• Keyboard shortcuts (space to play/pause, I/O to mark in/out, Ctrl+Z, etc.) are intentionally not wired up yet — planned for later.
• Cuts re-encode (rather than stream-copy) so start/end points land exactly where you set them, at the cost of being a bit slower than a lossless cut.
• Stickers are a fixed size for their whole visible window (no grow/shrink or rotation animation) and use a bundled flat-style sticker set rather than your system's emoji font, so they render identically on every machine.
• If the source video has no audio track at all, exports now just skip audio entirely (or use only your imported audio, if you added one) instead of crashing.
• Promo videos are silent (no audio track) and use a fixed crossfade slideshow of your photos/clips rather than hand-animated transitions — say the word if you'd like background music or extra transition styles added.
• "+ From Loaded Videos" in the Promo tab adds every video currently open in Clip Editor; remove any you don't want with the × on that item afterward.

Project layout

9jacut/
  package.json      # electron-builder config (portable .exe target) lives here
  main.js           # Electron main process: file dialogs, ffmpeg export
  preload.js        # safe IPC bridge exposed to the renderer as window.nineJaCut
  promo-templates.js # Promo Video: 4 layouts x 13 themes = 52 named presets
  promo-export.js   # Promo Video: builds/runs the ffmpeg filter graph
  build/
    icon.ico        # app icon
  assets/
    stickers/       # bundled PNG sticker set used for the emoji overlay feature
    fonts/          # bundled Poppins font (OFL license) used by Promo Video
  renderer/
    index.html
    style.css       # dark/light theme via CSS variables
    renderer.js     # UI logic: timeline, clips, reframe drag, undo, audio, stickers, export, promo