WMV (Windows Media Video) is a collection of video codecs with their respective coding formats introduced by Microsoft on its Windows Media framework. Initially, it was designed to compete with RM format on online streaming apps. It stores compressed videos and is even used to deliver content on Blu-ray/DVDs.
VLC Media Player MPLayer Media Player Classic Windows Media Player
M4B is an audio filename extension for AAC format, which is developed by Apple Inc. It is mainly used on podcast and audiobook files. Typically, M4B files contain audio and other metadata like images, hyperlinks, and chapter markers. M4B files are DRM copy-protected and can be opened on Apple iTunes and QuickTime Player.