Merge video with subtitles

[Pavel_47]

Well, taking into account the following shortcomings:

• changing subtitle color in VLC doesn't work
  
• GOOD subtitle file doesn't contain color-specific instructions (i.e. <c.cyan.bg_black>Une femme d'exception a su donner</c>
  <c.cyan.bg_black>une âme à ce havre de paix.</c>)
  

I guess before embedding subtitles in the video, I should process the .vtt file and embed color-specific instructions in it.
Then embed using python-ffmpeg. As I know, this is the only way to process subtitles in batch mode, although at the moment I don't know how to properly construct the command in order to embed the subtitles, not burn them.