AU is an audio format standard in early web pages NEXT systems. It is also called u-law or Sparc-audio format. Typically, AU files can store audio data and annotation blocks. Initially, it was a headerless audio format, but newer versions have a header, thanks to the six unsigned 32.bit words.
According to YouTube, MP4 video format with AAC audio codec and H.264 video codec is most recommended. However, this platform is also compatible with formats such as MOV, AVI, WebM, FLV, 3GPP, WMV, and more. Also, keep in mind that the maximum file size for YouTube is 128GB or 12 hours of playtime. So, you can use a video editor like Wondershare UniConverter to compress before uploading videos to YouTube.
VLC Media Player Windows Media Player Apple QuickTime Player 5KPlayer