Free online KUX to WMV converter

What the KUX format is

KUX is a proprietary video format associated mainly with Youku and Tudou downloads. Youku desktop software can save downloaded programs and movies as .kux files, which may contain proprietary headers, encryption, or stream structures that standard media players do not recognize.

KUX playback and conversion support varies by file source and by the version of the Youku software that created it. A file may also require an account, regional access, or the original application if it is DRM-protected.

What the WMV format is

WMV usually refers to Microsoft’s Windows Media Video codec, commonly stored in an .wmv container with WMA audio. It is supported by Windows Media Player, many Windows applications, older presentation software, and some legacy devices.

WMV is useful when compatibility with older Windows-based software matters. It is less suitable than H.264 MP4 for modern phones, browsers, and streaming platforms, and converting to WMV normally requires re-encoding rather than simply changing the filename.

How to convert KUX to WMV

Convert online on 101convert.com

1. Open the KUX converter on 101convert.com; the service can convert the file for free without installing software.
2. Choose .kux as the input file and upload the video.
3. Select WMV as the output format and start the conversion.
4. Download the resulting .wmv file and test it in Windows Media Player or the program that requires WMV.

Do not upload copyrighted or confidential video unless the service’s handling and retention terms are acceptable. Large files may take longer to upload and process, and protected KUX files may be rejected because conversion requires access to the video stream.

Convert locally with FFmpeg

FFmpeg can convert the file locally if the installed build recognizes the KUX container and can decode its streams. Run:

ffmpeg -i input.kux -c:v wmv2 -b:v 2M -c:a wmav2 -b:a 128k output.wmv

Replace input.kux with the actual filename. Increase or decrease -b:v to change video quality and file size; use -c:a copy only if the source audio is compatible with the WMV container, otherwise wmav2 re-encodes it for broader compatibility.

If FFmpeg reports an unknown format, invalid data, or an encrypted stream, it cannot decode that KUX file directly. Use the official Youku application to play or export the download where that function is available, or capture the permitted playback to a standard format before converting that file to WMV.

Quality and compatibility limits

WMV conversion cannot restore detail removed during the original Youku download. Re-encoding a compressed KUX video causes another generation of quality loss, so avoid unnecessarily low bitrates and keep the original file as an archive.

For general Windows playback, WMV2 video with WMA2 audio is a practical compatibility choice. Some applications instead require WMV9 or VC-1 specifically; if the output is rejected, check the application’s codec requirement and select a converter that can produce that codec rather than only a file with the .wmv extension.