Cropbox

A lightweight desktop utility for trimming, cropping, previewing, and exporting video, GIF, and still-image media.

Features

• MP4, MOV, MKV, WebM, GIF, PNG, JPEG, WebP, and other Qt-readable still-image preview
• Interactive crop overlay with draggable edges and handles
• Ctrl-drag crop handles to preserve the crop aspect ratio
• Live resize, 90° rotation, and horizontal/vertical flip previews
• Toggleable crop-coordinate and trim annotations with time or frame display
• Thumbnail-strip timeline with trim in/out selection
• Exact timeline viewport start/end for precision trimming
• Draggable gray viewport handles, wheel zoom, and frame-step navigation
• Exact trim-in and trim-out entry by timecode or frame number
• Dockable Info panel with editable playback/trim/crop values and source metadata
• Frame stepping and trim-handle nudging from the keyboard
• Playback speed control for preview and export
• Export dialog with format, size, quality, audio, and PNG sequence padding controls
• Remembered export settings and output folder
• FFmpeg export to MP4, MOV, GIF, PNG stills, and PNG sequences
• Headless CLI export with media, trim, and crop options
• Python 3.8–3.12
• PySide6 desktop UI

Requirements

• Python 3.8 through 3.12
• ffmpeg
• ffprobe

CropBox checks for ffmpeg and ffprobe on startup and provides install guidance from Help -> Install FFmpeg.

Typical install on Ubuntu/Debian:

sudo apt install ffmpeg

Controls

• Space: play/pause
• Ctrl+I: toggle the Info panel
• Left/Right: step one frame
• Shift+Left/Right: nudge selected trim handle by one frame
• Ctrl+Left/Right: nudge selected timeline viewport handle by one frame
• Ctrl+Shift+D: open Resize
• Ctrl+Shift+L/R: rotate left/right 90°
• Ctrl+Shift+U: rotate 180° (upside down)
• Ctrl+Shift+H/V: toggle horizontal/vertical flip
• Ctrl+Shift+0: reset transforms

Menus

• File: Open, Export, Quit
• Edit: Set Trim In, Set Trim Out, Reset Trim, Reset Timeline, Create Crop, Reset Crop, Playback Speed, Loop Playback
• Transform: Resize, Rotate Left/Right/180°, Flip Horizontal/Vertical, Reset Transform
• View: Info Panel, Show Annotations
• Help: Install FFmpeg, About Cropbox

Install

Install the latest release from PyPI:

pip install cropbox

Or install from a local source checkout:

pip install .

Run

cropbox

Open media immediately:

cropbox input.mp4

Open with initial trim and crop values:

cropbox input.mp4 --trim-in 12.5 --trim-out 00:00:20.000 --crop 100 50 1280 720

Open at a specific time or frame:

cropbox input.mp4 --current-time 00:00:12.500
cropbox input.mp4 --current-frame 300

Export directly without opening the UI:

cropbox big_buck_bunny_1080p_h264.mov -o big_buck_bunny.mp4

Export with trim and crop values:

cropbox input.mp4 --out output.mp4 --trim-in 12.5 --trim-out 20 --crop 100 50 1280 720

CLI Options

• -o, --out PATH: export directly to MP4, MOV, GIF, or PNG without opening the UI
• -f, --force: overwrite an existing --out file
• --trim-in: initial trim-in time in seconds or HH:MM:SS.mmm
• --trim-out: initial trim-out time in seconds or HH:MM:SS.mmm
• --crop X Y WIDTH HEIGHT: initial crop rectangle in source pixels
• --current-time: initial current time in seconds or HH:MM:SS.mmm when launching the UI
• --current-frame: initial current frame number when launching the UI

Notes

• Playback speed affects both preview and export for timed media.
• Resize, rotation, and flip transforms are previewed live and applied to MP4, MOV, GIF, and PNG exports.
• Edit-stage resize is applied after crop; export size presets can optionally resize the transformed result again.
• Headless export defaults to the full media duration when --trim-out is omitted.
• Export size presets preserve the cropped aspect ratio and report the resulting dimensions.
• High, Balanced, and Smaller File presets control H.264 quality or GIF palette size.
• Exact trim-in and trim-out values can also be entered from the Edit menu.
• Press Enter in an Info panel field to apply current time/frame, playback FPS, trim, timeline viewport, or crop changes.
• Timeline Start and End zoom the visible timeline; expanding trim automatically expands the timeline viewport when needed.
• Gray viewport-handle drags preview against the current timeline and apply on mouse release.
• Mousewheel over the timeline zooms the visible range; when trim and view match, wheel zoom adjusts both together.
• Reset Timeline restores the full media duration.
• The playhead is constrained to the active trim range.
• View -> Show Frame Values toggles the transport and timeline labels between time and frame display.
• Still images disable playback and trim controls, but can still be cropped, transformed, and exported as PNG.
• PNG sequence export defaults to %08d frame padding and can be adjusted in the export dialog.