External vobsubs (.idx/.sub pairs) do not work with Libav

[ghost]

mpv dropped the internal vobsub demuxer and decoder in favor of using ffmpeg for this functionality. Unfortunately, Libav doesn't have a vobsub demuxer at all, so .idx/.sub files can't be opened when mpv is compiled with Libav.

Possible workarounds:
a) Created muxed subtitles with mkvmerge: mkvmerge -o foo.mks foo.idx ; mpv file.avi -sub foo.mks
b) use ffmpeg (requires latest release)

Libav bug: http://bugzilla.libav.org/show_bug.cgi?id=419