MK3D File

What are MK3D files and how to open them

Are you having problems opening a MK3D file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your MK3D files.

What is a MK3D file?

A .MK3D file is a Matroska 3D Video file.

Matroska 3D Video File (.mk3d) is a version of the Matroska multimedia container format designed specifically for stereoscopic 3D video. It can include video, audio tracks, subtitles, chapter data, and metadata - all wrapped together in one file. The "3D" part comes from support for multiple-eye rendering (stereo), which allows playback systems to display separate images for the left and right eye to create 3D depth effects. The file extension .mk3d signals to compatible players and devices that the video contains stereoscopic content rather than being a simple 2D video.

Files with the .mk3d extension are produced by any Matroska muxer following the Matroska specification when the included video track is stereoscopic. Typical uses of .mk3d files include archived 3D movies, home videos intended for 3D display, or streamed 3D content. Once created, they are played by any media player that supports Matroska 3D video (for example VLC, FFmpeg, or players that recognize the StereoMode field), which reads the StereoMode setting in the file to know how to display the two views (for example side-by-side or top-bottom).

Technical detail: the .mk3d format is defined by RFC 9559 as "video/matroska-3d" for files containing a stereoscopic video track. One mandatory element in such files is the StereoMode field (\Segment\Tracks\TrackEntry\Video\StereoMode), which is a uinteger that indicates how stereo content is packed (e.g. value 1 = side-by-side left-eye-first; value 2 = top-bottom right-eye-first; etc.).

How to open MK3D files

We have identified one MK3D opener that is compatible with this specific type of MK3D file.

Programs that open Matroska 3D Video files

Last updated: August 9, 2026

Various apps that use files with this extension

These apps are known to open certain types of MK3D files. Remember, different programs may use MK3D files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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