WALTR is a Mac & Windows app that's designed to make it easy to upload and convert any music or video file to an iPad or iPhone format for native playback. It supports a huge variety of media file types, including MP3, MP4, AVI, CUE, WMA, M4R, AAC, M4V, M4A, FLAC, ALAC, MKV, and more. It even supports file types that are not normally compatible with iOS, including MKV, AVI, FLAC, and CUE, allowing them to be played in the native Music and Movie apps on iOS.