Merge video with subtitles

[Pavel_47]

Here is a way with free tool Subtitle Edit 3.6.6.
Load .vtt file and now change to .ass(Advanced SubStation Alpha File), then save this .ass file.
Open MKVToolNix and the same,but now drag in the new .ass file generated with Subtitle Edit.
Now get transparent background with the right colors.

Well, here are my "updated" consideration concerning subtitles issue:
There are 3 ways to play a video with subtitles:

• hard embedding: this method involves rendering subtitles into particular frames, time-consuming process, requiring intensive processing
  
• soft embedding: fairly fast method, subtitles are embedded as metadata in the video file, then during playback smart video players (not all!) render the subtitles in particular frames
  
• do not embed any subtitles, just keep the subtitle file which can be read by smart player while the video is playing
  

The 2nd method appears to be the most effective because on the one hand it allows rapid processing on the other hand it avoids keeping two files (or more in the case of several languages) - video and subtitles.
The only issue with the 2nd method - there is no possibility to change subtitle color.
In VLC player, this option exists, but seems not to work, regardless specified color subtitles are always white ... at the same time, changing font works.
In another player "Videos" there is no option to work with subtitles... only enable them.
As I understood MKVToolNix do "hard embedding".
It will be nice to find a way to change the color of the subtitles. If this option in VLC is buggy, there are probably other smart players which have such option and this option works.