[FFmpeg-user] MKV muxer and ass subtitles issue

[ValdikSS]

Hello!

I have uploaded 2 files to FTP: mkv_subtitles.mkv and 
mkv_subtitles_ffmpeg.mkv.

The first file (mkv_subtitles.mkv) is splitted with mkvmerge, the second 
one (mkv_subtitles_ffmpeg.mkv) is remuxed with ffmpeg:
ffmpeg -i mkv_subtitles.mkv -map 0 -map_metadata 0 -c copy 
mkv_subtitles_ffmpeg.mkv

Subtitles in the first file are played correctly with all effects while 
subtitle effects in ffmpeg-remuxed file are not (in every player except 
mplayer).
If you extract subtitles with

mkvextract tracks mkv_subtitles.mkv 1:sub_orig.ass
mkvextract tracks mkv_subtitles_ffmpeg.mkv 1:sub_ffmpeg.ass

you can see the difference between them (with diff)
That's strange since -c copy is set and log clearly says it's copied.