Free online KUX to XVID converter

Some older media players, editing applications, and hardware devices accept Xvid video in an AVI container but cannot open Youku’s KUX downloads. Converting the file produces a more widely supported MPEG-4 Part 2 video, although the KUX source may need to be decrypted or exported before conversion.

What the KUX format is

KUX is a proprietary video format used by Youku for downloaded or cached video content. You commonly encounter .kux files in Youku desktop or mobile download folders rather than as ordinary camera or screen-recording files.

KUX files can contain Youku-specific segmentation, metadata, or protection. As a result, many general-purpose players and converters cannot decode them directly, even when they can process standard MP4 or AVI files. A file that only plays inside the Youku application may need to be opened or exported there first.

What the XVID format is

Xvid is an MPEG-4 Part 2 video codec, not a complete container format. “XVID” output normally means an .avi file containing video encoded with the Xvid codec, often with MP3 audio.

Xvid is useful for older televisions, DVD players, media boxes, and editing software that support AVI but do not support newer H.264 or H.265 video. It usually provides smaller files than uncompressed video, but it is less efficient and less compatible with modern streaming devices than H.264.

How to convert KUX to XVID

Using the online converter

1. Open the KUX-to-XVID converter on 101convert.com.
2. Choose the Upload or file-selection control and select the .kux file.
3. Set the output format to XVID. If the service offers container choices, select AVI.
4. Start the conversion and download the resulting .avi file when processing finishes.

If the upload is rejected or conversion fails, the KUX file is probably protected or uses a KUX variant that the converter cannot decode. Play or export it with the official Youku software, then convert the resulting MP4 or other standard video file.

Using FFmpeg after obtaining a playable source

FFmpeg can create an AVI file with the Xvid encoder when the build includes libxvid. First test whether the input is readable:

ffmpeg -i input.kux

If FFmpeg can decode the KUX file, convert it with:

ffmpeg -i input.kux -c:v libxvid -q:v 4 -c:a libmp3lame -b:a 128k output.avi

The -q:v 4 setting gives a quality-based encode; lower values generally increase quality and file size. If the KUX file cannot be decoded, replace input.kux with the playable file exported by Youku, for example:

ffmpeg -i exported.mp4 -c:v libxvid -q:v 4 -c:a libmp3lame -b:a 128k output.avi

Quality and compatibility limitations

This conversion normally requires re-encoding the video because KUX video is not usually stored as Xvid. Re-encoding cannot restore detail already lost in the downloaded source, so use a moderate quality setting and avoid repeated conversions.

Some older devices require specific AVI settings, such as MP3 audio, standard-definition dimensions, or a frame rate below 30 fps. If the output fails on a hardware player, try -vf format=yuv420p and a compatible audio rate, for example -ar 44100. Xvid does not preserve modern codec features such as H.265 efficiency, HDR metadata, or some advanced subtitle and chapter data.