libtheora is a reference implementation of the Theora video compression format being developed by the Xiph.Org Foundation.

Theora is derived from the proprietary VP3 codec, released into the public domain by On2 Technologies. It is broadly comparable firstly in design and bitrate efficiency to MPEG-4 Part 2, early versions of Windows Media Video, and RealVideo, and secondly in open standards philosophy to the BBC’s Dirac codec.

Theora is named for Theora Jones, Edison Carter’s Controller on the Max Headroom television program.

Playback

Embedded by HTML 5

As originally recommended by HTML 5, these browsers support Theora when embedded by the video element:

• Mozilla Firefox 3.5 and later versions
• Google Chrome as of version 3.0.182.2
• SeaMonkey as of version 2.0
• Opera 9.5 experimental video builds and pre-alpha builds of Opera 10.50
• Future versions of Konqueror

Browser plugins

• Annodex plugin via OggPlay
• Cortado, a Java based applet
  • Itheora, a PHP wrapper for Cortado
• Mv Embed HTML 5 video tag wrapper for numerous plugin types.
• VLC media player browser plugin for IE or Firefox

Supporting media frameworks

• DirectShow with use of DirectShow filters
• GStreamer supported via Theora module, supports GStreamer based applications eg. Totem and Songbird
• Phonon
• QuickTime with use of Xiph QuickTime Components

Supporting applications

• FFmpeg (own implementation)
• Helix Player
• Miro Media Player (formerly known as Democracy Player)
• MPlayer and front-ends
• Songbird
• VLC (native support)
• xine and all libxine-based players like Kaffeine

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How to open files with the extension of

• .ogg (Ogg Vorbis)
• .oga (Vorbis)
• .ogv (Theora encoded video)
• .ogx
• .flac (Free Lossless Audio Codec)

In order to enable support for Ogg Vorbis, Ogg Theora, Ogg Speex and FLAC, user needs to download and install the appropriate codec, which allows players such as Media Player Classic, RealPlayer, WinAmp and so on to play the files with the above extensions.

These codecs are available from Xiph.org and are called DirectShow Filters.

The DirectShow Filters for Ogg Vorbis, Speex, Theora and FLAC is available from http://xiph.org/dshow/downloads/.

Downloads are available for both, 32 bit as well as 64 bit Windows. Download the file and follow the steps listed.

Then Windows Media Player or any other DirectShow application (e.g. BSPlayer) will be able to play Ogg Vorbis, Ogg Speex, Ogg Theora, Ogg FLAC and native FLAC files.

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1. Theora, the open video format
2. Firefox 3.5 supports open video formats
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Firefox now supports Theora, which is a truly free and open video format for the internet. This means that we would have to do away with proprietary plugins or restricted codecs and license fees and be able to embed videos in websites are truly free and viewable by everyone. Mozilla believes that the quality of Theora can be improved and is supporting the development of Theora by giving a US $100,000 grant. This grant is to be administered by the Wikimedia Foundation and will go towards improving Theora’s encoders and playback libraries.

So what is Theora ?

Theora is a free and open video compression format from the Xiph.org Foundation. The same guys who brought you the Ogg Vorbis open music format.

Theora can be used to distribute film and video online and on disc without the licensing and royalty fees or vendor lock-in associated with other formats. Theora scales from postage stamp to HD resolution, and is considered particularly competitive at low bitrates. It is in the same class as MPEG-4/DiVX, and like the Vorbis audio codec it has lots of room for improvement as encoder technology develops.

Theora is in full public release as of November 3, 2008. The bitstream format for Theora I was frozen Thursday, 2004 July 1. All bitstreams encoded since that date will remain compatible with future releases.

Theora comes without licensing fees. Neither commercial nor private use will make you owe money to us. The Theora specification is in the public domain, its reference implementation is open source and subject to a license which permits inclusion in proprietary commercial products. On2, which owns patents that apply to the technical foundations of Theora, granted an unrevocable free license regarding those patents.

Theora on the Internet

Theora, as every member of the Ogg family, can be streamed easily. Existing solutions do exist (e.g. Icecast or Flumotion streaming server) that have a proven track record and itself are free and open.

Theora also can be streamed from virtually any HTTP server, making it easy to provide static streams.

On the technological side Theora is well engineered for low-bitrate streaming. Its in-loop deblocking filter is efficient at preventing a distracting, blocky look of the encoded content. Thus perceived video quality usually degrades gracefully as bitrate decreases, which is an essential property for any video codec targeting web video.
Theora is cross-platform

Basically every major Linux distribution ships with support for Theora by default. The licensing terms of MPEG or e.g. VC-1 make those compression schemes inherently incompatible with the idea of truly free open source software. If you want to target the growing number of Linux users shipping your content as Theora is a good idea.

Apart from the Linux platform, where Theora is considered “standard”, there also exist easy to install solutions for Windows and Mac OS, making authoring and consuming of Theora encoded content easy.
Theora is reliable

In contrast to proprietary codecs with no public documentation available Theora is subject of a specification which is available to everyone at any time without restrictions. The open source nature of Theora makes it very unlikely it’ll simply disappear, which may happen to proprietary codecs once their developers decide to leave the codec business.

More about Xiph.org Foundation

Xiph.Org is a collection of open source, multimedia-related projects. The most aggressive effort works to put the foundation standards of Internet audio and video into the public domain, where all Internet standards belong.

The .ogv file

Theora uses the .ogv ( video/ogg ) file extension.

More reading about Open Video formats and Firefox support

Christopher Blizzard on “Why Open Video” : http://www.0xdeadbeef.com/weblog/2009/01/why-open-video/

Greg Maxwell compares the quality of Ogg Theora with real world examples: http://hacks.mozilla.org/2009/06/open-video-codecs-and-quality/

WebMonkey.com How Firefox is pushing open video onto the web : http://www.webmonkey.com/blog/How_Firefox_Is_Pushing_Open_Video_Onto_the_Web

What’s the ideal video quality for Theora : http://pacoup.com/2010/01/09/whats-the-ideal-video-quality-for-theora/

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