MOV is a MPEG-4 digital video container format used on Apple’s QuickTime Player. It was developed in 1998 by Apple as the proprietary video format for Macintosh. On top of video data, MOV format can also store audio and text data, such as subtitles. It can open easily on both Macs and PCs, although Windows require 3vix codec.
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M4R is a filename extension for AAC format, which is developed by Apple Inc. It is typically used to save custom iPhone ringtones from Apple iTunes. M4R can only be created from iTunes purchased songs and is usually DRM protected. It can open on iTunes, VLC Media Player, Apple QuickTime Player, and more.