MKV
MKV (Matroska Video) is an open, free video container format that can hold many video, audio and subtitle tracks in a single file. It supports almost any codec, plus chapters and attachments such as fonts. MKV is popular for archiving films with several audio languages and subtitle options, but browsers and mobile devices support it less widely than MP4.
Why it matters
MKV files keep many audio languages and subtitles together, which is useful for archives and masters. But many phones and browsers will not play MKV directly. Platforms that accept uploads must convert MKV or risk files that users cannot watch.
How it works
- MKV stores data in EBML, a flexible structure that can be extended without breaking older players.
- Each video, audio and subtitle stream becomes its own track, with language and name labels.
- Chapters, fonts and other attachments can be stored in the same file.
- Players read the track list and let the viewer pick the audio or subtitle track they want.
MKV vs MP4: which is better?
MP4 is better for sharing and streaming, while MKV is better for archiving files with many tracks. Both can hold the same codecs, so picture quality can be identical. MKV supports more subtitle formats and attachments, but MP4 plays on far more phones, browsers and smart TVs.
Why does OBS record in MKV?
OBS Studio users often record in MKV because an MKV file stays readable if the recording crashes or the power cuts out. An interrupted MP4 recording can lose its index and become unplayable. After recording, OBS can remux the MKV to MP4 in seconds without re-encoding.
Can browsers play MKV files?
Most browsers do not officially support MKV, though some, like Chrome, can play certain MKV files that use web-friendly codecs. Support is inconsistent, so MKV is not a safe delivery format for websites or apps. Converting to MP4 or an adaptive streaming format is the reliable option.
Where it's used
Video platforms and creator apps receive MKV recordings from OBS Studio and convert them to MP4 or streaming formats. Archivists and media teams use MKV to keep films with several audio languages and subtitles in one file.
By the numbers
- The Matroska project was announced on December 6, 2002, and the format was published as an IETF standard, RFC 9559, in October 2024. (Matroska (Wikipedia))
