[Feature]: Video Cropping support with fixed aspect ratio presets (remove letterbox/black bars) #830

What would you like Filee to do?

Add a spatial Video Cropping feature (similar to the existing image crop feature) that allows users to crop video dimensions and remove unwanted borders/black bars, with fixed aspect ratio presets (such as 16:9, 4:3, 1:1, 9:16) and orientation toggle (Landscape / Portrait).

Note: This is spatial cropping (frame dimensions), not trimming (video duration cut).

Why / when would you use it?

Use Case:
Many recorded, downloaded, or shared videos come with embedded black bars (letterboxing/pillarboxing) due to improper resolution matching. For instance, a 4:3 landscape video (e.g., 960x720) often gets wrapped inside a vertical 9:16 container (e.g., 720x1280) with huge black bars on top and bottom.

Current Friction / What gets in the way:
Currently, Filee has a great drag-and-drop workflow and image cropping, but there is no built-in way to crop video borders. Today, to fix this issue, I have to rely on external manual scripts (e.g., placing videos into an input/ folder, running an FFmpeg/Python script, and retrieving them from output/). This interrupts the fast, seamless offline workflow that Filee is so great at. Having this natively in Filee would save a lot of time.

Ideas for how it could work

1. Crop Interface (similar to Image Crop):**

   • Provide a crop preview dialog when video processing is selected.
   • Fixed Aspect Ratio presets: 16:9, 4:3, 1:1, 9:16, 21:9.
   • Orientation switcher: Landscape / Portrait.
   • Unlike images, freeform crop is not strictly necessary; predefined aspect ratio boxes with an adjustable bounding box or center-crop would already cover 95% of use cases.

2. Under the hood (FFmpeg integration):**

   • Apply FFmpeg's video filter: -vf "crop=out_w:out_h:x:y".
   • Keep audio stream untouched (-c:a copy) to maintain conversion speed and original audio quality.
   • (Optional / Advanced idea): A 1-click "Auto-detect Black Bars" option using FFmpeg's built-in cropdetect filter (e.g., cropdetect=24:2).