The Matroska Video (.mkv) format is a highly flexible, open-standard container format. Unlike older formats like AVI that hardcoded a simple index at the end of the file, MKV uses a sophisticated, dynamically scaling indexing system.
Regenerating an Index: If a file is "unseekable," it can often be fixed by "remuxing"—running the file through tools like mkvmerge or MKVToolNix. This process doesn't re-encode the video (so there is no quality loss) but builds a fresh, accurate index for the container. mkv index
If you need to edit or repair the index of an MKV file, these are the industry standards: MKVToolNix: MKV index — Quick Guide What the MKV index is
Specialized Tools: Open-source programs like Meteorite are specifically designed to repair broken MKV headers and indexes. 2. The Search Index: "Index of /mkv" The MKV (Matroska) index maps timestamps to file