Software mainly geared towards this codec is also welcome.
Theora is a free, lossy video compression format believed to be patent unencumbered. Originally based on TrueMotion VP3 from On2 Technologies which released it to the free software community, it is developed by the Xiph.Org Foundation and is comparable to Xvid regarding compression efficiency. Most of the time is it found muxed with Vorbis audio in an Ogg container with the .ogv file extension.
It is used for the video tag of HTML5 in several browsers such as Mozilla Firefox, Google Chrome, Chromium, Opera, SeaMonkey and can also be viewed in Safari if the Xiph QuickTime Components are installed.