Ogg is a free, open container format, developed and maintained by the Xiph.Org Foundation is unrestricted by software patents and is designed to provide efficient flow diffusion and manipulation of high quality digital multimedia. The Ogg container format can multiplex a number of independent streams for audio, video, text (such as subtitles), and metadata. In the Ogg multimedia framework, Theora provides a layer of lossy video. The audio layer is most commonly provided by the music-oriented Vorbis format but other options include compression codecs Opus, FLAC lossless audio OggPCM.
RealAudio is a proprietary audio format developed by RealNetworks and first released in April 1995. It uses a variety of audio codecs, ranging from low-bitrate formats that can be used over dialup modems, to high-fidelity formats for music. It can also be used as a streaming audio format, that is played at the same time as it is downloaded. In the past, many internet radio stations used RealAudio to stream their programming over the internet in real time. In recent years, however, the format has become less common and has given way to more popular audio formats. RealAudio was heavily used by the BBC websites until 2009, though it was discontinued due to its declining use. BBC World Service, the last of the BBC websites to use RealAudio, discontinued its usage in March 2011.