I was wondering, as it’s not as easy to find software that does this, clip files to specific length, and also support AAC, MP3, M4A, MP4, WMD
Audacity is an audio editor. YouTube requires video format media.
YouTube supports most common video formats, and converts them if necessary.
See here for more information about formats supported by YouTube: https://support.google.com/youtube/troubleshooter/2888402