subtitles framerate

Correcting subtitles framerate may be very important to sync it with audio/video. You can select all subtitles with an editor, and change framerate (for example to 25 from 23.976).

Thereby you should see the video correctly (with VLC or others).

how split a mkv with subtitles

You can use mkvtoolnix, then go to -> output, and -> splitting -> by parts based on timestamps -> and there you can write the beginning and the end of the poart you want extract (without spaces: like 1:02:07-1:04:40, for example).

How to change encodig of “.srt” Subtitle File in UTF-8

To encode your SRT file in UTF-8 (for instance: “video.srt”), please follow this process:

1. Rename (F2) the “video.srt” file with your PC in “video.srt.txt”.
2. Launch a text app, like Kate.
3. Click on the “File” menu then select “Save the file as…”.
4. In coding option, select “UTF-8”. Then save your file.
5. Rename (F2) the file “video.srt.txt” to “video.srt”.
Done!

from: Zappiti Player 4K [EN]

avidemux too slow

It’s better use (one of) the following codecs for encoding

  • x264
  • libavcodec MPEG-1/MPEG-2
  • libavcodec MPEG-4
  • Xvid 

so Avidemux will be able to optizmize the CPU usage and will be much faster. And the CPU temperature will be lower.
Cfr.here.