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Theora

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Theora is a video codec being developed by the Xiph.org Foundation as part of their Ogg project. Based upon On2 Technologies' VP3 codec, and christened by On2 as the successor in VP3's lineage, Theora is targeted at competing with MPEG-4 video (e.g., H.264, Xvid and DivX), RealVideo, Windows Media Video, and similar lower-bitrate video compression schemes.

While VP3 is patented technology, On2 has irrevocably given royalty-free license of the VP3 patents to everyone, letting anyone use Theora and other VP3-derived codecs for any purpose.

In the Ogg multimedia framework, Theora provides a video layer, while Vorbis usually acts as the audio layer (Speex and FLAC can also act as audio layers).

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

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[edit] Technical details

Theora is a lossy video compression method derived from On2's VP3 Codec. The compressed video can be stored in any suitable container format. At the time of writing (June 2006), Theora video is generally included in Ogg container format. It is frequently paired with Vorbis audio.

The combination of the Ogg container format, Theora video and Vorbis audio allows for a completely open, royalty-free multimedia format. Thus, it is of great interest to the free software and Free Culture movements. Previous multimedia formats (e.g. MPEG-4 video and MP3 audio) were patented, meaning that Free Software players implementing them were legally vulnerable, because paying license fees for software freely available for everyone to use anywhere for anything is often hard, if not impossible to do, regardless of whether licensing fees are rarely collected or not.

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[edit] Encoding Theora videos

The libtheora library contains the reference implementations of both, the Theora encoder and decoder. libtheora is still under development by the Xiph.org Foundation, having made seven alpha releases thus far. The library is released under the terms of a BSD-style license.

As of 2006, Xiph.org has not developed any stand-alone programs to encode video in Theora, but there are several third-party programs that support encoding through libtheora:

  • ffmpeg2theora uses FFmpeg to decode video and libtheora to encode it. This is currently the most functional Theora encoder, and can be used for both creating stand-alone video files and to produce streaming video.
  • VLC is able to encode Theora video, from any of the video sources it supports, and also stream it.
  • The open-source 'Video DJ' program FreeJ can encode and stream ogg/theora. Video comes from one or more different video or image files/sources while audio is encoded from the soundcard.
  • The GNOME video editor Diva encodes to Ogg Theora.
  • The open-source Video Editing program LiVES can also encode to ogg theora at different quality settings.
  • There is also currently a beta-version of Thoggen [1] for Linux, a GTK+ and GStreamer based DVD-backup utility, which encodes to Ogg (Vorbis audio, Theora video).
  • The KungFu DVD Ripper is another GStreamer based DVD-backup application for Linux, which likewise encodes using the Ogg container, Vorbis audio, and Theora video.

Also, several media frameworks have support for Theora.

  • The open-source ffdshow audio/video decoder is capable of encoding Theora videos using its Video for Windows (VFW) multi-codec interface within popular AVI editing programs such as VirtualDub. It supports both encoding and decoding Theora video streams and uses Theora's alpha 4 libraries. However, many of the more refined features of Theora aren't available to the user in ffdshow's interface.
  • The GStreamer framework has support for Theora.

[edit] Editing Theora videos

CVS versions of the Cinelerra non-linear video editing system support Theora, as of August 2005.

[edit] Playing Theora videos

If you want to find videos to test out your new theora-enabled player, see the Theora test suite.

[edit] List of Theora video players

See also Wikipedia:Media help (Ogg)

[edit] Streaming Theora

The following streaming media servers are capable of streaming Theora video:

[edit] See also

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[edit] External links


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Xiph.org

Ogg Project
Vorbis • Theora • Speex • Tremor • Ghost • OggUVS • OggPCM • Xiph QuickTime Components

Other projects
FLAC • Annodex • cdparanoia • XSPF • Icecast • IceShare

Related articles
Ogg Media • CMML • Chris Montgomery

Multimedia compression formats
Video compression formats ISO/IEC MPEG-1 | MPEG-2 | MPEG-4 | MPEG-4/AVC ITU-T H.261 | H.262 | H.263 | H.264 Others AVS | Dirac | Indeo | MJPEG | RealVideo | VC-1 | Theora | VP6 | VP7 | WMV
Audio compression formats ISO/IEC MPEG MPEG-1 Layer III (MP3) | MPEG-1 Layer II | AAC | HE-AAC ITU-T G.711 | G.722 | G.722.1 | G.722.2 | G.723 | G.723.1 | G.726 | G.728 | G.729 | G.729.1 | G.729a Others AC3 | ATRAC | FLAC | iLBC | Monkey's Audio | Musepack | RealAudio | SHN | Speex | Vorbis | WavPack | WMA
Image compression formats ISO/IEC/ITU-T JPEG | JPEG 2000 | JPEG-LS | JBIG | JBIG2 -- -- Others BMP | GIF | ILBM | PCX | PNG | TGA | TIFF | WMP
Media container formats General 3GP | ASF | AVI | FLV | Matroska | MP4 | MXF | NUT | Ogg | Ogg Media | QuickTime | RealMedia Audio only AIFF | AU | WAV -- --
als:Theora

cs:Theora de:Theora es:Theora fr:Theora id:Theora it:Theora hu:Theora ja:Theora no:Theora pl:Theora pt:Theora sv:Ogg Theora

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