id	summary	reporter	owner	description	type	status	priority	component	version	resolution	keywords	cc	blockedby	blocking	reproduced	analyzed
2035	DVD subtitle from VOB does not contain CodecPrivate data	billie		"Summary of the bug:

When copying DVD subtitles from vob files into the matroska container the subtitles do not contain CodecPrivate data.

The subtitles play fine in vlc but mkvtoolnix has problems with editing the file. The header editor recognizes all tracks but mkvextract fails to extract the subtitles because of the missing data (Error: Track 5 with the CodecID 'S_VOBSUB' is missing the ""codec private"" element and cannot be extracted.). Also editing the file with mmg/mkvmerge does not work because the existing subtitles are ignored and not written to the output file because of the same reason (Warning: matroska_reader: The CodecID for track 5 is 'S_VOBSUB', but there was no private data found).

While I understand that the CodecPrivate data is not direct available when reading from VOB files as this information normally comes from the IDX part of extracted subtitles in vobsub format. However it would be nice if this information could be acquired somehow and written to the codec initialization part for the files to be editable by mkvtoolnix. This would save the additional step of extracting the subtitles to IDX/SUB. I guess that the ultimate solution would be to add a DVD reader who understands the dvd structure as I this information is stored in the IFO file.

How to reproduce:
{{{
% ffmpeg -i concat:VTS_01_1.VOB\|VTS_01_2.VOB\|VTS_01_3.VOB\|VTS_01_4.VOB \
-map 0:0 -map 0:1 -map 0:2 -map 0:6 -map 0:5 -map 0:4 \
-c:v libx264 -preset fast -crf 18 \
-c:a copy -metadata:s:a:0 language=ger \
-c:a copy -metadata:s:a:1 language=eng \
-c:s copy -metadata:s:s:0 language=eng \
-c:s copy -metadata:s:s:1 language=ger \
-c:s copy -metadata:s:s:2 language=ger \
-f matroska movie.mkv

ffmpeg version N-47903-gde89dff
built on Dec 16 2012 15:51:01
}}}
"	defect	open	normal	avcodec	git-master		dvdsub				0	0