- In French, Italian and Portuguese, OGM is used to refer to genetically modified organisms ('organisme génétiquement modifié'/'organismi geneticamente modificati'/'organismo geneticamente modificado').
OGM, meaning Ogg Media File, is a container format (for video, audio and subtitle streams). It was developed by Tobias Waldvogel and can do a few things the common AVI format cannot, including:
- Chapter support
- Multiple subtitle tracks
- Multiple audio tracks of various formats (MP3, AC3, Vorbis, WAV)
- Vorbis audio support (although AVI can be made to support it in a way, there is no "correct" way to do it, making any attempt a potentially incompatible, unreliable hack)
OGM support for Windows (Including Microsoft's Windows Media Player) is available via Tobias's own OggDS or RadLight's Ogg Media filters (the latter of which can also decode Theora video, and is available on Unix-based systems with MPlayer).
Fundamentally, the format is a hack of the Ogg container format, which has only been designed to support encoders endorsed by Xiph.org (webpage). It is most likely going to be viewed as a temporary solution, to be phased out when other media container formats (for example, Matroska) mature and come to support the same services.
Originally, a major drawback of OGM was that it was not open source, even though it was based on the open source Ogg framework. The reason was that Tobias was embarrassed about the quick-dirty-hack quality of his code, wanting to improve it before releasing it to the keen eyes of the Xiph.org people. Tobias has officially joined the Xiph.org team (Who create both Ogg and Vorbis) since, and has donated all the code of his DirectShow filters — including format manipulation and playback — to their BSD-style open-source repository. It is available, though without documentation, in the "oggds" module of the repository.
OGMs most often carry video encoded in the XviD format and audio in Vorbis or AC-3 (Dolby Digital).