MKV is a container format for holding multiple audio, video, picture, and text data such as subtitle tracks. It is similar to other common containers like MP4 and AVI, although MKV is open in the specification. For video contents, MKV uses a .mkv filename extension, .mka for audios, and .mks for subtitles.
MPC-HC, KMPlayer VLC Media Player MKV File Player MPV
APE (Monkey’s Audio) is a lossless audio file format released in 2000 by Matthew T. Ashland. Because it’s a lossless sound format, it doesn’t lose data during compression, unlike other standard formats like AAC, MP3, and Vorbis. However, Monkey’s Audio is available on PC only. To play APE on Mac OS X and Linux, you’ll need a third-party plugin like JRiver Media Center.