Do you know the of the file (e.g., a Blu-ray rip, a recording)?

If the file is not supported by a device, it can be "remuxed" (copied without re-encoding) into an MP4 container using tools like Xmedia Recode or Avidemux .

MKV files often include error detection and correction codes, allowing files to play smoothly even if they are not fully downloaded.

It acts as a "folder" that can hold video (H.264, H.265, AV1), audio (AC3, AAC, DTS), and subtitles, rather than being a video compression format itself. Common Uses and Tools

A single .mkv file can hold multiple video tracks, multiple audio tracks (e.g., different languages), and multiple subtitle streams.