I’m using mp4box for adding forced subtitles on a DolbyVison single layer mp4 done with DVDFab.
I’m using this command:
mp4box.exe -add “MovieDV.mp4” -add “ForcedSub.srt#1:txtflags=0xC0000000:enable:hdlr=sbtl:tx3g:layer=-1:group=2:delay=0:lang=FRE:name=sub forced” -new “MovieDVWithST.mp4”
txtflags=0xC0000000 is the flag for forced subtitles for mp4 and Mediainfo shows the result file correctly as “forced”.
The problem is that Infuse doesn’t play it as forced, you have to select it.
Unfortunately, Infuse does not currently support the forced flag for embedded subtitles, but this is something we have on our radar to investigate further.
Why doesn’t it show forced subtitles automatically in any .mp4 video? I have them configured correctly, marked as forced subtitles with Subbler and they work correctly in QuickTime.
After a little digging it appears that currently Infuse doesn’t support embedded forced subtitles on mp4 files but I moved your post to a suggestion thread for that feature.
Don’t forget that you need to click the like button on the first post in this thread to show your support for this suggestion!