demux_mkv: check for valid track in video/audio switching

When switching audio or video tracks, demux_mkv only checked that the
new index fell in the range corresponding to tracks existing in the
file being played. However, if the demuxer can not recognize the
format of a track or detects an error, some of those tracks in the
file may not be exported from the demuxer and are not visible to the
rest of the player. Selecting such a track would cause a crash. Add
checks skip such tracks when cycling to next track and switch to
nosound instead if given an explicit track number corresponding to
such a track.

0 files changed, 0 insertions, 0 deletions