vidpickr

Glossary · format

What is MKV (Matroska)?

MKV (Matroska) is an open, flexible container format that holds video, audio, subtitles, chapters, and metadata in a single file. It supports an unusually wide range of codecs and an unlimited number of audio and subtitle tracks. VLC plays MKV natively; native browser support is mixed.

Also called:matroska · .mkv · matroska multimedia container

MKV is the format of choice for high-quality video archives — Blu-ray rips, multi-language releases, anime fansubs. The format places no upper bound on tracks, supports embedded fonts and chapters, and survives codec churn well (you can mux a brand-new codec into MKV without changing anything else).

For YouTube downloads, MKV gives you flexibility (multi-language audio in one file, embedded subtitles) at the cost of compatibility (some smart TVs, mobile players, and editing tools choke on MKV). MP4 is safer for "I just want to play this anywhere"; MKV wins for "I want all tracks, all languages, archive-quality."

Common questions

Can I convert MKV to MP4 without quality loss?
Yes, if the codecs inside the MKV are MP4-compatible (H.264, H.265, AV1, AAC). The remux is byte-for-byte lossless and takes seconds. If the MKV uses MKV-only codecs, a remux fails and a (lossy) transcode is needed.

Related terms

WebM

WebM is an open container format developed by Google for the web.

Container (file format)

A container is the file format that wraps one or more audio and video streams into a single file.

Codec

A codec is the algorithm that encodes (compresses) and decodes raw audio or video into a smaller stream.

Mux (muxing)

Muxing is the process of combining separate audio and video streams into a single container file (MP4, MKV, WebM).

VidPickr is a free, browser-based YouTube downloader. Every term in this glossary either describes how YouTube delivers video or why your downloads behave the way they do. Try the downloader →