SubtitleEdit/subtitleedit ? reverse-engineered prompt

Build me a powerful desktop application for editing video subtitles. It needs to work across Windows, Mac, and Linux. The core idea is to let a user open a video file and a subtitle file together, then easily edit the subtitle text and timing while watching the video playback right in the app.

The app should have tools to fix common problems, like adjusting sync, correcting spelling, and converting between different subtitle formats. I also want some more advanced features. Let's include options to connect to online services for automatic translation and speech-to-text to generate subtitles from audio. It would also be great if it could use OCR to extract text from image-based subtitles.

Please build this as a C#/.NET application. It should be a self-contained utility. It'll need to integrate with something like mpv or ffmpeg to handle the video playback, so please make sure that's included.