MPEG-4 Part 14 or MP4 is a digital multimedia format most commonly used to store video and audio, but can also be used to store other data such as subtitles and still images. Like most modern container formats, it allows streaming over the Internet. The only official filename extension for MPEG-4 Part 14 files is .mp4, but many have other extensions, most commonly .m4a and .m4p. M4A (audio only) is often compressed using AAC encoding (lossy), but can also be in Apple Lossless format. M4P is a protected format which employs DRM technology to restrict copying. MPEG-4 Part 14 (formally ISO/IEC 14496-14:2003) is a standard specified as a part of MPEG-4.
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.