File extension
.ogg
Ogg Encapsulation Format Version 0
.ogg files are Ogg container media: a free, open multimedia container from Xiph.Org that packages audio and video streams — most often Vorbis or Opus audio — into pages for streaming and storage.
Known meanings
Formats and reference material for .ogg
Details
Format notes
Ogg
Ogg is a free, open container format maintained by the Xiph.Org Foundation for packaging compressed multimedia streams. It is a container, not a codec: an Ogg file carries one or more logical bitstreams — commonly Vorbis or Opus audio, and also FLAC audio or Theora video — organized so they can be streamed and seeked efficiently. Because the format and its common codecs are royalty-free, Ogg is popular in open-source software, games, and web audio.
Internally, an Ogg stream is divided into “pages,” each beginning with the capture
pattern OggS and carrying a segment of one bitstream along with a granule
position (used for timing/seeking), a serial number identifying the stream, and a
CRC checksum. Multiple streams can be interleaved (multiplexed) so audio and video
play in sync. Conventionally, audio-only Vorbis files use .ogg or .oga, Opus
files use .opus, and video uses .ogv, though .ogg is still widely used
generically.
Preservation And Security Notes
Ogg is a strong choice for open, unencumbered distribution and archiving of
compressed audio; note that Vorbis and Opus are lossy, so a lossless master should
be retained where exact reproduction matters (FLAC-in-Ogg is a lossless option).
The common media type is audio/ogg (or video/ogg). As a paged container, an Ogg
demuxer should validate page and segment sizes and verify CRCs when handling
untrusted files.
Further Reading
- Ogg documentation (Xiph.Org):
https://xiph.org/ogg/ - RFC 3533 (Ogg encapsulation):
https://datatracker.ietf.org/doc/html/rfc3533