TypesettingTools/Aegisub — reverse-engineered prompt

Build me a cross platform desktop subtitle editor like Aegisub.

I want it to let people open video and audio, create and edit subtitle lines, adjust timing accurately against the waveform or video, style subtitles, spell check text, and save common subtitle files. It should feel like a serious tool for fansubbers and typesetters, not just a basic text editor.

Please make it work on Windows, macOS, and Linux. Use a native desktop approach since this is a C++ style app, and include the build setup so I can compile it on each platform. Add support for translations if possible, and include tests for the important subtitle parsing and timing logic.

Keep the first version focused on a working editor with video preview, audio timing, subtitle grid, style editing, and file open or save. Look up current docs online if you need to.