Make editing the subtitles easier

[qgustavor]

An ideal interface would be one where...

1. Users can just open a video file and start working;
2. WYSIWYG;
3. It works directly in browser;
4. It supports MKV (which is the most common format);
5. MP4+ASS/SRT can also be supported (in fact it's simpler to implement);
6. It returns the fixed files;
7. It creates patch files;
8. It integrates with GitHub (so files can be commited directly from the editor);

The bottlenecks:

• Feature 2 requires loading the video file;
• Feature 3 requires JavaScript, but there aren't many subtitle editors in that language;
• Feature 4 requires a MKV demuxer, which was the focus of mkv-extract;
• Feature 5 is easier to implement as browsers support some kinds of MP4 and there are JavaScript libraries which can handle ASS and SRT;
• Feature 6 requires a MKV muxer, which seems hard to implement;
• Feature 6 and 7 seems resource heavy;

[qgustavor]

I don't remember if in 2017 GitHub had a good online editor, but currently it does (at least github.dev looks good) so I'm closing this issue.