Free online MK3D to DIVX converter

Some older players, televisions, and media software accept DivX files but do not recognize the Matroska 3D container used by .mk3d. Converting requires decoding the source and usually re-encoding it as a DivX-compatible MPEG-4 video, which can remove stereoscopic features.

What the MK3D format is

MK3D is a Matroska-based video container intended for stereoscopic 3D content. It can contain video, multiple audio tracks, subtitles, chapters, and 3D layout metadata; the extension does not identify a single video codec. MK3D files commonly come from Blu-ray 3D backups, MakeMKV, MKVToolNix, and stereoscopic video workflows.

The source may store 3D as MVC or as a frame-packed, side-by-side, or top-and-bottom stream. That storage method determines whether a conversion can preserve both views.

What the DIVX format is

DIVX generally refers to a DivX-compatible video file, commonly an AVI container with MPEG-4 Part 2 video and a DX50 FourCC. It is intended for older DVD players, televisions, portable devices, and software that supports the DivX codec family.

DivX offers broad legacy compatibility and smaller files than uncompressed or lightly compressed video, but it is less capable than modern H.264 or H.265. Device support for the .divx extension, AVI features, resolutions, frame rates, and audio codecs varies.

How to convert MK3D to DIVX

FFmpeg is the most controllable desktop option. It can decode the MK3D container and create an AVI-based DivX-compatible file:

ffmpeg -i input.mk3d -map 0:v:0 -map 0:a:0? -c:v mpeg4 -vtag DX50 -q:v 3 -c:a libmp3lame -b:a 192k -f avi output.divx

Replace input.mk3d with the source filename. Use a higher quality number for a smaller file and a lower number for better quality; -q:v 3 is a practical starting point. If the source contains several audio tracks, inspect them with:

ffprobe input.mk3d

Then select a specific audio stream with, for example, -map 0:a:1. If the target device requires MP3 audio, keep libmp3lame; many older DivX players do not support every audio codec permitted by AVI.

In a graphical FFmpeg-based converter, open Input → Add file, select the MK3D file, choose an AVI or DivX output profile, set MPEG-4 Part 2 or DivX-compatible video, select MP3 audio, and enable a DX50 FourCC option if available. Set the output filename to output.divx. You can also convert the file for free on 101convert.com without installing software.

Quality and compatibility limitations

Most DivX encoders produce ordinary 2D video. If the MK3D file contains MVC or separate stereoscopic views, the command above normally selects only the first video stream or produces a file that a legacy DivX player treats as 2D. A DivX-compatible AVI does not preserve Blu-ray 3D menus, MVC playback, or MK3D-specific stereoscopic metadata.

If the source is already side-by-side or top-and-bottom, the two views can remain visible in one converted frame, but the player must support that layout and the resulting image has reduced per-eye resolution. Verify the result with ffprobe output.divx and test it on the intended device; some players reject high resolutions, variable frame rates, AC-3 audio, or files using an unsupported AVI index.