Free online KUX to M2V converter

What the KUX format is

KUX is a proprietary video format associated with Youku downloads and playback software. Youku applications create KUX files when they save certain videos for offline viewing; the files are commonly encountered in downloaded-video folders rather than in camera or editing workflows.

KUX files may use proprietary packaging or encryption. A file extension change does not convert the video, and many general-purpose players cannot decode every KUX variant.

What the M2V format is

M2V normally means an elementary MPEG-2 video stream. It is used by DVD and MPEG-2 authoring tools, broadcast-oriented workflows, and older playback systems that require raw MPEG-2 video.

An M2V file contains video only. Audio must be exported separately, commonly as an MPEG-1 Layer II, AC-3, or PCM file, and then combined with the M2V by the authoring application. M2V is less convenient than MP4 for ordinary sharing because it has no container metadata, subtitles, or synchronized audio track.

How to actually convert KUX to M2V

For an authorized KUX file that FFmpeg can decode, first inspect it:

ffprobe -hide_banner input.kux

If FFprobe reports a video stream, create an MPEG-2 elementary stream with:

ffmpeg -i input.kux -map 0:v:0 -an -c:v mpeg2video -q:v 2 -f mpeg2video output.m2v

-map 0:v:0 selects the first video stream, -an removes audio because M2V cannot store it, and -q:v 2 requests high MPEG-2 quality. For a smaller file, use a bitrate instead, for example:

ffmpeg -i input.kux -map 0:v:0 -an -c:v mpeg2video -b:v 6000k -maxrate 8000k -bufsize 1835k -f mpeg2video output.m2v

On Windows, macOS, or Linux, install FFmpeg, open a terminal in the folder containing the file, and replace the example filenames with the actual paths. If FFmpeg cannot identify the KUX stream, use the Youku software that created or downloaded it to export a standard video file first, then convert that exported file to M2V with FFmpeg. Do not bypass access controls or DRM.

You can also use the free converter on 101convert.com without installing software: choose the video conversion tool, upload the KUX file, select M2V if available, start the conversion, and download the result. A protected or unsupported KUX file may be rejected because browser-based conversion cannot decode its proprietary stream.

Quality, compatibility, and limitations

Conversion from KUX to M2V normally requires re-encoding because KUX video is not generally an MPEG-2 elementary stream. Re-encoding cannot restore detail already lost in the source; use a bitrate and frame size at least appropriate for the target authoring system, and avoid repeated conversions.

Check the output with:

ffprobe -hide_banner output.m2v

The result should report MPEG-2 video and no audio stream. Keep the original audio separately if the final application requires synchronized sound. Some DVD authoring tools require specific frame rates, interlacing, resolution, bitrate, or GOP structure, so apply that tool's MPEG-2 specification instead of relying on generic M2V settings.