uncropMKV

uncropMKV is an advanced video processing tool that you can use to prepare MKV clips for compatibility with Blu-ray and AVCHD discs by resizing and cropping them, among other adjustments.
It features comprehensive functions dedicated to experienced users, so beginners will have a hard time figuring it out.

Classical-looking interface with advanced settings

The interface does not include visually attractive elements, but it as a neatly organized structure instead. MKV clips can be pointed out using either the file browser or drag-and-drop method, and they can be previewed in the main frame.

Examine clips information and specify the new properties

Video properties shown include the duration, number of frames, dimensions, frame rate and codec. You can modify it via AviSynth by resizing, cropping to a predefined dimension, changing the resolution, sharpening the image, or trimming it at a user-defined frame.
The bit rate is automatically set to the original value, so this cannot be changed, and it is possible to add each video to a queue list to start the processing for all of them at the same time.

Evaluation and conclusion

The tool runs on low CPU and RAM, so it shouldn't put a strain on computer performance. However, it popped up several errors during our tests and immediately crashed. Since it has not been updated for a while, uncropMKV may have compatibility issues with later operating systems.
To sum it up, uncropMKV comes bundled with some interesting options and configuration settings for making adjustments to MKV clips, but users may have problems running it on newer Windows editions.