Why the files in this directory are considered invalid:

block_ends_beyond_cluster.mkv -
  File containing a single cluster with two simple blocks. One valid, and the
  second reporting a size that would cause the block to end far beyond the end
  of its parent cluster.

blockgroup_block_ends_beyond_blockgroup.mkv -
  File containing a single cluster and two blockgroups. The first blockgroup is
  valid. The second blockgroup contains a block reporting a size that spans well
  past the block and the end of the file.

chapters_truncated_chapter_string.mkv -
  File with a Chapters element that ends with a ChapterAtom whose ChapterDisplay
  element contains a truncated ChapterString.

chapters_truncated_chapter_string_2.mkv -
  Nearly identical to chapters_truncated_chapter_string.mkv, but with a void
  element and a partial cluster. Causes mkvparser to fail in a slightly
  different manner.

fixed_lacing_bad_lace_size.mkv -
  File containing a BlockGroup with fixed lacing, but reports a total laced size
  that is not evenly divisible by the number of laced frames.