Allows you to convert .hwl to .funscript and back. Howl app: https://github.com/Amethyst-Sysadmin/Howl
Now also works with mp3. Due to browser limitations it's not the most precise method and some files are not supported. For more precise results see https://github.com/Amethyst-Sysadmin/Howl/wiki/HWL-files#how-to-convert-audio-files-to-hwl-format