Mkv: Index

mkvinfo your_video.mkv Look for a section labeled Cues . If it’s missing or very small relative to file size, your index is likely incomplete.

That map is the , officially called the Cues element (or Cueing Data ) in the MKV structure.

Thankfully, with free tools like MKVToolNix and FFmpeg, rebuilding the index is quick, lossless, and nearly always successful. Don’t tolerate frozen timelines—fix that index and take control of your MKV files. Have a stubborn MKV file that still won’t seek after remuxing? The issue may be corrupted video frames or missing keyframes—not just the index. Use ffmpeg -i broken.mkv -map 0 -c copy -f null - to detect frame-level errors.

You’ve downloaded a pristine MKV movie file. You double-click to play it. The player opens, the audio starts flawlessly, but the video is frozen on the first frame. Or worse—you can’t seek forward at all. Dragging the timeline slider does nothing.

The culprit? What is an MKV Index? The Matroska Multimedia Container ( .mkv ) is like a shipping crate. It holds video streams, audio tracks, subtitles, and chapters all in one file. But without a map, your video player would have to scan the entire crate to find anything.