How to disable Zlib compression on a PGS subtitles

Zlib reduces subtitle file size but uses more resources and can cause issues on older hardware. This guide shows how to disable it.

Tool needed

The steps

  1. Open MKVToolNix. Go to Preferences (or press Ctrl + P).

    Open Preferences

  2. Go to the "Default values" tab. Check the box for "Disable additional lossless compression for all track types". This turns off automatic compression.

    Disable compression

  3. Restart MKVToolNix. Verify the setting is active by checking the compression option for a new subtitle track; it should be set to "None" automatically.

Credits

Old owners - Simulping and an unknown person
New / Current owner - Clara

Fuck AI

(With <3)

If you have any feedback you want to give me, please fill in a form here.


Go back to the top

Edit

Pub: 27 Aug 2025 04:16 UTC

Edit: 02 Sep 2025 11:48 UTC

Auto Theme: Dark