OGA is a format of free container audio files, a kind of audio container. The developer is Xiph.Org. The full original name is Ogg Vorbis Audio File. This audio container runs on Ogg Vorbis, a widely used audio encoding and streaming technology. The container stores audio data with compression using Vorbis compression. OGA audio files can also use the .OGG extension because they are a standard Ogg container. Any Ogg-enabled media player must play OGA audio files.
RM is a video file format developed by RealNetworks. It uses the RealPlayer player, that is, a program for streaming audio and video files. The format contains audio and video data or links to streaming, which can be played back as it downloads. The RealMedia Player program was in great demand when they connected to the Internet using a modem, and when there was practically no broadband access to the global network. The large compression ratio of the format provided the opportunity to carry out online transmission of video and audio data. The quality of the output file, as a rule, was low. Today, such files are often used in order to broadcast Internet radio and Internet video. In the .RM format, music and video are found on the global network or on Western cable channels, on Internet radio stations. Support for this format is carried out by such mobile phones and smartphones as Nokia, Ericsson, Sony, iPhone, as well as mobile devices that operate on the Google Android operating system. Files with the extension .RM are compressed using proprietary codecs RealVideo and RealAudio. Individual Real Media files can be played using a VLC media player that partially supports RM files.