mux function could support a way to output its progress

[rvbg]

Is your enhancement request related to a problem? Please describe.
When muxing something with mkvmerge it outputs the current progress in percent.
The current implementation of mux does not seem to support that information, which would be great to have, especially when running async or when muxing large files.

Describe the solution you'd like
Having an event function in the main object, which returns the progress, which is called when new progress information arrives.

Example:

mkv = MKVFile('/path/to/file.mkv')
mkv.remove_track(0)
mkv.mux('/path/to/output.mkv', gui.set_current_progress)

or

mkv = MKVFile('/path/to/file.mkv')
mkv.remove_track(0)
mkv.connect_event_new_progress(gui.set_current_progress)
mkv.mux('/path/to/output.mkv')

Implementation steps

• Look at the output of mkvmerge and find a way to grab that information
• Interpret that data
• Add an event function which is called on new progress and returns that data
• Add a variable to hold the connected function and a setter function to connect an external function to that event function

Additional context
I implemented something similar a few years ago, which still works, but the code is more a proof of concept, than a good implementation. It can be found here.
That function is used in combination with a gui progress bar.

Let me know, if you want help implementing this and the enhancement request from yesterday.

[GitBib]

This is going to take more time. We need to figure out the best way to do it.

[rvbg]

Hi, I'm back to working on my project and will try to implement this. If I'm successful, I'll try to open a pull request.
But I've now come across another serious problem and will open a new issue for it.