Free online KUX to OGG converter

What the KUX format is

KUX is a proprietary Youku video container used by the Youku desktop client and some Youku download tools. It can contain video and audio streams, and some files use Youku-specific encryption, segmentation, or download protection. A KUX file is not an audio format, so conversion to OGG requires extracting an audio stream rather than simply changing the filename extension.

What the OGG format is

OGG is a multimedia container most commonly associated with the lossy Vorbis audio codec. Ogg Vorbis provides adjustable quality, generally smaller files than uncompressed audio, and good support in VLC, Audacity, many Linux applications, and browser-based media workflows. Choose it when the receiving application specifically accepts OGG or when you need an open audio format; it is less compatible with some phones, car systems, and older hardware than MP3 or AAC.

How to convert KUX to OGG

Using the online converter

1. Open the KUX-to-OGG converter on 101convert.com.
2. Select the complete .kux file as the input.
3. Choose OGG as the output format and start the conversion.
4. Download the resulting .ogg file and test it in the intended player or editor.

This option requires no software installation. A protected, incomplete, or unsupported KUX file may still fail because conversion software cannot extract its streams.

Using FFmpeg on a computer

Install a current FFmpeg build, open a terminal in the folder containing the file, and run:

ffmpeg -i "input.kux" -vn -map 0:a:0 -c:a libvorbis -q:a 5 "output.ogg"

-vn discards the video, -map 0:a:0 selects the first audio stream, and -q:a 5 sets Vorbis quality. Use a lower value for a smaller file or a higher value for more audio quality, for example -q:a 7.

If the input contains several audio tracks, inspect them with ffmpeg -i "input.kux" and change the map value, such as -map 0:a:1. If the desired application requires Ogg Opus instead of Vorbis, use ffmpeg -i "input.kux" -vn -map 0:a:0 -c:a libopus -b:a 128k "output.ogg", provided the FFmpeg build includes libopus.

Quality and compatibility limitations

The output cannot restore quality that was removed from the original Youku audio. If the KUX contains AAC, MP3, or another lossy stream, encoding it as Vorbis performs another lossy conversion; keep the original KUX when archival quality matters.

FFmpeg support for KUX varies by version and by the specific Youku file. An Invalid data found when processing input error usually indicates an encrypted, incomplete, segmented, or unsupported KUX file rather than a bad OGG setting. Do not rename .kux to .ogg; that changes no container data and will not create a playable audio file.