Convert UNDF to WAV

Occasionally, the VLC Media Player will generate an error message stating that the UNDF multimedia format is not supported. This prompts some users to attempt converting their media files to a different format, although they are perfectly functional. Such error messages are displayed whenever the VLC Media Player is missing a suitable decoder for a specific video format.

WAV audio files can occasionally trigger such error messages, but there is no need to convert them. Simply look for a newer VLC Media Player version, or its codecs. Such issue can occasionally also be caused by partially downloaded files, which can be solved by either completing the download process or downloading the entire file again.

The UNDF file format is not supported by any software or file converter.

Simply put, it is impossible to convert UNDF to WAV directly.
Thus, there is no so-called undf to wav converter or a free online .undf to .wav converter to be found.