[FEATURE]

Problem

A minor issue is the lack of layer grouping; I suggest adding this feature along with an option to ungroup them. There's also a problem with captions for other languages ​​like Arabic and Chinese. In short, unsupported languages ​​have a clear issue with captioning not working when auto-detect is enabled.

Solution

I suggest adding a ready-made fade-in/fade-out option with a single click, similar to DaVinci Resolve, along with the option to merge and unmerge layers. This is crucial. You could also add fade-in/fade-out as an effect with blur. Currently, the work is excellent and relatively stable, but it lacks some finishing touches and a bit more power. When it reaches a point close to that, I suggest color grading.

Alternative

An additional suggestion: support for pre-made fonts would be a great option. Thank you for your efforts.

Anything else?

No response

The issue does not name files, tests, or entry points; start by splitting the requests into separate, scoped issues for layer grouping, caption auto-detection, fades and blur, color grading, and font support. Done is not measurable until one request has an agreed scope and acceptance criteria.