Quadrant Cropper

1 · Choose root folder

Choose the folder containing today's MP4 videos

All MP4 files in the selected folder are loaded automatically. Define the quadrants once on the first video and the same coordinates are used for every video in that folder.

2 · Quadrant names

Top-left

Top-right

Bottom-left

Bottom-right

3 · Define crop regions

Draw / adjust four boxes Split into four equal quadrants

Quadrants are defined from the first video and automatically reused for every video in this folder.

Preview video

Drag the center point to move the shared intersection; all four divider arms stay attached to it. Drag any green junction, including the center, edge points, and four corners. Only the selected junction moves; all connected lines remain attached. The same divider geometry is reused for every video in the folder.

4 · Crop videos

Quality (CRF)

Lower CRF = higher quality and larger files. 18 is the default. Source frame rate and crop resolution are preserved; no resizing is applied. Each source video is decoded once to create all four crops. Audio is removed. Results are packaged into one ZIP because browsers cannot silently write an output folder.

Ready.

Crop check

These previews show the regions used. Downloaded ZIP also contains rois.json.

Browser version notes

The original Python tool writes an autocropped videos folder. This HTML version instead creates a ZIP containing the cropped MP4s, crop-check PNGs, and rois.json. Video processing is local, but internet access is needed to load the browser FFmpeg engine. The FFmpeg worker is created from a same-origin blob URL to avoid CDN cross-origin Worker restrictions.