How do I Mux subtitles into MP4 as a plain text

[limpo]

hey,guys

I've been using MP4Box to mux .srt subtitles into MP4 Files
but the default subtitle size is too small. If i playing external file sub, size it's normal.

Media Information (VLC default settings):

Stream 2
Type: Subtitle
Codec: tx3g

Stream 3
Type: Subtitle
Codec: Text subtitles with various tags (subt)


Stream 2 - internal sub, small size font
Stream 3 - external sub, sizw normal.

SRT files identical. Simple srt, only text (have not the tags)

How can mux srt and mp4 as normal size sub? Any idea's please

[limpo]

Here, a similar problem
https://forum.videohelp.com/threads/373857-Need-to-extract-convert-tx3g-subtitles?p=2407760


Interesting comment
There are slightly different tx3g/ ttxt formats . You might have to make some minor adjustments to get it working

How can i get "ttxt" srt with mp4?