Free online MK3D to MTS converter

A device, editor, or authoring program may require the AVCHD-style MPEG transport stream used by .mts files instead of a Matroska 3D container. Converting usually requires remuxing compatible streams or re-encoding video and audio for broader MTS compatibility.

What the MK3D format is

.mk3d is the Matroska 3D container extension. It stores stereoscopic video, audio, subtitles, chapters, and Matroska metadata; the 3D picture may use side-by-side, top-and-bottom, or another layout, while the container can record stereoscopic flags.

MK3D files are created by Matroska muxing tools such as MKVToolNix, often from 3D Blu-ray or other stereoscopic video sources. Players including VLC, Kodi, and compatible MPC-based applications may open them, but support for the video codec and 3D metadata varies.

What the MTS format is

.mts is an MPEG-2 transport stream commonly associated with AVCHD camcorders and Blu-ray-compatible video. It normally contains H.264/AVC video with AC-3 or compatible audio, although the extension alone does not guarantee a particular codec, resolution, or profile.

MTS is useful when a camera workflow, video editor, Blu-ray tool, or television expects transport-stream input. It is less suited to Matroska-style features such as extensive subtitle formats, chapters, arbitrary attachments, and container-level stereoscopic metadata.

How to actually convert MK3D to MTS

FFmpeg is the most controllable desktop option. First inspect the streams and codecs:

ffprobe -hide_banner input.mk3d

If the MK3D already contains H.264 video and AC-3 audio, try a stream copy so the video is not degraded:

ffmpeg -i input.mk3d -map 0:v:0 -map 0:a:0? -c copy -f mpegts output.mts

This copies only the first video and optional first audio stream into an MPEG transport stream. If the source contains unsupported codecs, subtitles, or attachments, use an H.264/AC-3 transcode:

ffmpeg -i input.mk3d -map 0:v:0 -map 0:a:0? -c:v libx264 -preset medium -crf 18 -pix_fmt yuv420p -profile:v high -level 4.1 -c:a ac3 -b:a 448k -f mpegts output.mts

For an AVCHD-oriented workflow, match the destination device's required frame size, frame rate, H.264 level, audio format, and bitrate rather than relying on the defaults. FFmpeg can also perform the conversion on 101convert.com for free without installing software.

Quality, compatibility, and 3D limitations

Stream copying preserves encoded quality but works only when the codecs and stream structure are accepted by the MPEG-TS target. Transcoding changes quality and may alter frame-rate handling, interlacing, bitrate, or audio compatibility.

The stereoscopic presentation may not survive as container metadata. Side-by-side or top-and-bottom 3D remains visible because it is encoded in the video frame, but a player may no longer know how to interpret it automatically after conversion. MVC or other multi-view 3D streams are especially problematic: standard FFmpeg MTS output generally does not preserve the complete Blu-ray 3D structure, so a target that requires MVC may reject the result.

Check the resulting file before transferring it:

ffprobe -hide_banner output.mts