Bookmarks/Chapter feature

[butterw]

Chapters embedded in mkv and mp4 files are widely supported in video players today. At their simplest form they are just a sequence of timestamps with optional title strings.

For editing/navigation purposes adding bookmark support to Avidemux project scripts makes a lot of sense. It would also be an intermediate step to supporting chapters in input and output video files.

Youtube Chapter format is a an easily user editable format for chapters (could something like this be added directly to a ##bookmarks section of the project .py script ?) :
 
00:00:00.000 Intro (the first chapter starts with 00:00)
00:30 Part 1. What Is Video Clip Chapter (simplified timestamp format can be used for videos shorter than 60 minutes)
01:20 Part 2. Why You Need to Add Chapter to YouTube Video
02:30 Part 3. How to Add Chapter to YouTube Video
03:50 Like & Subscribe

Note:
0. You can use spacing to separate the time and the chapter content. Dashes also work.
1. If you'd like to add a chapter to YouTube, please add at least 3 chapters.
2. 1K subscribers is a requirement for using YouTube chapter.
(3. You have to add a 0:00 timestamp.
4. Each chapter has to be more than 10 seconds.)
5. Please list the timestamps in chronological order.