DTS (Digital Theater Systems) is a standard home theater audio format developed in 1993 to compete with Dolby Digital. If used in your home theater system, it provides surround sound for 5.1, 6.1, and 7.1 setups. Compared to Dolby Digital, DTS uses higher bitrate, thereby offering superior sound quality.
Apple iTunes VLC Media Player File Viewer Plus Media Player Classic
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.