RA (RealAudio) is an audio format released in 1995 by RealNetworks. It uses multiple audio codecs, including high-fidelity music formats and low-bitrate formats. Since its introduction, the RA format has been mainly used by radio stations to stream audio online. Also, up until 2009, the BBC has been using it to stream sounds online.
RealNetworks RealPlayer Cloud VLC Media Player Wensites with the RealPlayer Plugin
MKA is a free Matroska Multimedia Container format that can store multiple audio, video, image, and subtitle tracks. It’s used to save typical multimedia content such as TV shows and movies and comes with a .mkv for video files. When used on audio files, it features a .mka filename extension, .mks for subtitles, and .mk3d for stereoscopic video files.