DVR-MS, also called Microsoft Digital Video Recording, is a digital audio and video file container format introduced by Microsoft in 2004. It features a .dvr.ms filename extension and is used to save TV data recorded using Windows 7, Windows Vista, and Windows XP Media Center Edition. It stores both audio and video data wrapped inside an ASF container.
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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.