Is there a way to get OMXPlayer to show the embedded subtitles in foo.mp4 without first extracting the subtitles with ffmpeg to foo.srt, and without hardcoding the subtitles into foo.mp4?
The problem was solved by adding SRT subtitles to a MKV-container instead of MP4:
ffmpeg -i infile.mp4 \
-f srt -i subtitles.srt \
-c:v copy -c:a copy -c:s srt \
-metadata:s:s:0 language=nor \
outfile.mkv
Subtitles can than be displayed by starting OMXPlayer with -t 0
omxplayer -t 0 outfile.mkv