Free online KUX to VCD converter

What the KUX format is

KUX is a proprietary video container used by Youku's desktop and mobile applications for downloaded or offline-playback videos. Youku clients may store the video in segmented or encrypted form, so a KUX file is not necessarily a freely decodable media file. You normally encounter it in a Youku download folder rather than as a file exported by a general video editor.

Standard players and converters may reject KUX because support depends on the specific codec, container variant, and any download protection applied by the Youku software. A KUX file that cannot be decoded must first be re-exported by an authorized Youku application or converted to a normal format such as MP4; changing the extension does not remove encryption.

What the VCD format is

Video CD is a disc format based on MPEG-1 video and MPEG-1 Layer II audio. A VCD normally uses 352×288 pixels at 25 fps for PAL or 352×240 pixels at approximately 29.97 fps for NTSC. Its usual video rate is about 1,150 kbit/s, with 44.1 kHz stereo audio at 224 kbit/s.

VCD is useful for compatible older CD/DVD players, legacy disc collections, and hardware that does not read modern MP4 files. It has substantially lower resolution and compression efficiency than contemporary formats. A VCD video file is commonly stored inside the disc image as AVSEQ01.DAT; an ordinary MPEG file with a .dat extension is not automatically a valid VCD.

How to convert KUX to VCD

Using the built-in online converter

1. Open the KUX-to-VCD conversion page on 101convert.com.
2. Upload the KUX file, choose VCD as the output format, and start the conversion.
3. Download the result and check whether it is a VCD-ready MPEG file or a disc image. If it is an MPEG file, use a VCD authoring program before burning it.

This method works only when the service can decode that particular KUX variant. An encrypted or incomplete Youku download may fail and must be opened or exported through the Youku software that created it.

Using FFmpeg after obtaining a decodable video

Test the source first:

ffmpeg -i input.kux

If FFmpeg recognizes the file, create a PAL VCD-compliant MPEG stream with:

ffmpeg -i input.kux -target pal-vcd output.mpg

For an NTSC source or player, use:

ffmpeg -i input.kux -target ntsc-vcd output.mpg

If the KUX file is not recognized, convert it with an authorized Youku export function to an intermediate MP4, then replace input.kux in the command with that file. Do not use a simple filename rename.

Authoring and burning the VCD

An output.mpg file is VCD-compatible video, but it is not yet a complete VCD disc. Use a VCD authoring application to create a disc image, then burn the image to a blank CD-R. With vcdimager, a basic image can be created with:

vcdimager -t vcd2 -c videocd.cue -b videocd.bin output.mpg

Burn videocd.cue with a disc-burning program that supports cue/bin images. Burning the MPEG file as ordinary data will not create a playable VCD.

Quality, compatibility, and limitations

• VCD encoding cannot restore detail already lost in the KUX source. Video is reduced to VCD resolution and MPEG-1 quality, so text, fast motion, and widescreen material may look poor.
• Choose PAL or NTSC according to the target player and source frame rate. Converting between 25 and 29.97 fps can introduce duplicated or dropped frames.
• A VCD normally holds about 74–80 minutes because video is encoded at a fixed rate; longer videos must be split across discs or accepted as nonstandard VCDs.
• Some KUX downloads contain DRM or application-specific encryption. FFmpeg, VLC, and generic converters cannot bypass that protection; use an authorized export or a separately obtained unprotected source.
• For a file that only needs playback on a computer, retain the converted MP4 instead of creating a VCD. Authoring is necessary only for VCD hardware or disc-image compatibility.