Rpi3 3D subtitles become twice as big at specific points in the movie

During playback of a 3D movie (in 3D and in monoscopic) the subtitles become now and then twice as big and jumps partialy of the screen.

  • A: The length of the subtitle sentence doesn’t matter, this can happen with short and long sentences
  • B: It happens always at the same spots in the movie (tested many movies), looks like something in the movie triggers this
  • C: It happens both on MKV and ISO movies
  • D: It looks like the font suddenly is projected twice (or more) bigger than the default
  • E: The language of the subtitle doesn’t matter (tested English and Dutch)
  • F: The 3D movie is projected correct
  • G: This can be verified by sample file number 2 on the Kodi website where this will also happen after about a minute: Samples - Official Kodi Wiki

Platform: RPI3
OS: OSCM 2020.10-1 (kernel 4.19.122-2)
Kodi: Version 18.8, compiled 2020-10-17

MMAL / OMX are deprecated now, and work on them has discontinued, at least from a Kodi perspective, with support dropped in Kodi v19.

Unfortunately this means it’s not likely to be looked in to.


Then I see possible options:

  • as the issue happens at always the same moments in the movie I guess someting in the subtitle triggers this (maybe a specific character). If we can discover what it is, a workaround can be made in Kodi or we can filter out that character in de subtitle stream while transcoding.
  • second option is to fix the source code. If you can give pointers to where to look I might spend some time on it.

Source is available on GitHub if you want to jump in, but keep in mind that Kodi v19 will probably be out within a month and a bit, so you are fixing something that will soon be deprecated.

This sounds like an issue which affected early 3D builds on the Vero 4K but which @tanio99 fixed. Don’t know if the fix is portable.

See also 3D subtitle bug on Raspberry Pi · Issue #16362 · xbmc/xbmc · GitHub

Yes, I think that one should be portable.

There are a couple of open PRs to address this on the xbmc Git, but they are pending approval. They should solve the issue, but 3D won’t be supported on Pi in the next version of Kodi unfortunately.

What is the reason 3D is not supported anymore on the RPi? I see Kodi 19.3 (OSMC) recognises it is a 3D movie, and for some movies it even asks if it should play them as 3D or not, but yeah, then whateven you select it just plays the movie in 2D, which is really really a shame.

This is because the V4L2/GBM stack which Raspberry Pi and Kodi moved to does not support it at this time.

You can use an older version of Kodi (v18.x or earlier) if you wish to retain this support.

This was outlined here: Kodi v19 Matrix is here. Here's what you need to know - OSMC