Theora

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Theora
File extension : .ogv
MIME type : video / ogg
Developed by: Xiph.Org Foundation
Initial release: 2004 (Theora I specification)
Type: Video format , lossy video data compression
Contained in: Ogg
Extended by: VP3.2
Standard (s) : Specification (PDF; 857 kB)


libtheora

Theora logo 2007.svg
Basic data

developer Xiph.Org Foundation
Current  version 1.1.1
(October 1, 2009)
category free video codec (reference implementation)
License BSD license
theora.org

Theora is one of the Xiph.Org Foundation developed free video codec and video format of the Ogg - Container Format heard. Based on the VP3 .2 codec from On2 Technologies , a patent-free alternative to proprietary low-bit-rate video codecs such as RealVideo , DivX or Windows Media Video is to be offered.

Work is also currently underway to connect Theora to RTP in order to improve the streaming properties.

history

In June 2002 the company On2 Technologies handed over the video codec VP3.2 to the Xiph.Org Foundation in order to have it further developed under a BSD-like license. Although VP3.2 is patented, On2 had released the rights to use the respective patents free of charge, thus opening up the possibility of using Theora without patent problems or restrictions. The codec, further developed under the name Theora, was released on September 25, 2002 in a first alpha version . Compared to VP3, Theora is more flexible in terms of quantization. The name Theora came here from Theora Jones , a character from the Cyberpunk - television series Max Headroom .

Bitstream freeze was set on June 1st, 2004 (with libtheora 1.0alpha3), which meant that all videos created with codec versions from this point in time and later can also be read with future codec versions. In the summer of 2004, the first large-scale Theora streams of various open source conferences followed to demonstrate the capabilities of the codec. RealPlayer 10 was also released during this time . It was the first widely used video player to support Theora, but in some cases a plug-in had to be installed for Microsoft Windows.

On December 15, 2004 the Theora I specification was issued.

On April 17, 2005 it was announced that a C # port of the video codec for the OGRE graphics engine had been created. In June 2005, the Cinelerra software project implemented the ability to process Theora encoded videos.

On September 22nd, 2007 the first beta version of the Theora Reference Implementation (libtheora) was released. According to the developers, this version only differs from the final version in that the documentation is not yet complete and the project files are missing for various development environments.

On November 3rd, 2008 the final libtheora 1.0 was published.

The coding efficiency remained significantly behind the current commercial alternatives (a video encoded with the Theora Codec requires about 30% more storage space than one of comparable quality in H.264 format). With the support of Red Hat and Mozilla , work was carried out on a new reference encoder called Thusnelda . With improved motion search, use of the quantization options compared to VP3 and more intelligent bit allocation, it gets much more out of the format than the old encoder based on the VP3 encoder, which does not yet make use of the new possibilities of the Theora format. This encoder, rewritten from the ground up, was released in September 2009 as Theora 1.1. In addition to improved coding efficiency, which now makes Theora competitive, it is also much faster. Among other things, by estimating the expected movement of a block from past movements, a lot is saved in the computationally intensive movement search. Thereafter, libtheora 1.2 was worked on under the code name Ptalarbvorm.

With the release of VP8 under a free license by Google , it can be assumed that interest in Theora will be significantly lower in the future.

The Daala project is working on the successor to Theora.

reproduction

Embedding in HTML5

According to the original HTML5 draft, the following browsers support Theora for the videoelement:

Browser plugins

  • Annodex plugin from OggPlay
  • Cortado , a Java applet
  • 88Mv_Embed Mv Embed9 HTML 5 video element implementation for different plugin types.
  • VLC browser plugins for Internet Explorer and Firefox

Supporting media frameworks

Supporting Applications

Coding

There are several programs from other manufacturers that support coding using the libtheora program library:

description Supported Operating Systems
Linux Mac OS X Windows
ffmpeg2theora uses FFmpeg to decode videos and libtheora to encode. This robust Theora encoder can be used to create both individual video files and direct broadcasts (video streams). Yes Yes Yes
VLC can encode and stream Theora videos from all supported input formats. Yes Yes Yes
OggConvert (Open Source) Yes nearly
FreeJ ('Video DJ', Open Source) can encode and transmit (streaming) Theora. The video comes from one or more video or image files, while the sound source comes from the sound card. Yes Yes
PiTiVi (The Gnome video editing software). Yes
SUPER (freeware). Yes
LiVES (open source video editing software). Yes Yes
Recordmydesktop (records the active desktop as Ogg / Theora video, with optional Vorbis audio recording). Yes

The libtheora program library contains the reference implementation of the Theora specification for coding and decoding. It is still being developed by the Xiph.Org Foundation and can be used under the terms of the BSD license. Various media frameworks also provide support for Theora.

The open source direct show Audio / Video Codec ffdshow can encode and decode Theora videos via the Video for Windows (VFW) interface. Theoras alpha-4 libraries are used for this. However, not all setting options are accessible via the graphical user interface. Theora also supports the GStreamer framework.

Machining

description Supported Operating Systems
Linux Mac OS X Windows
PiTiVi (the Gnome video editor). Yes
Current versions of the non-linear video editing software Cinelerra support Theora. Yes Yes

Direct transmission (streaming)

The following programs can transfer Theora videos directly:

description Supported Operating Systems
Linux Mac OS X Windows
VLC Yes Yes Yes
Icecast Yes ? Yes
Flumotion Yes

Theora Streaming Studio allows you to connect to an Icecast server.

Libtheora versions

Versions of the Theora Reference Implementation (libtheora):

version date
Alpha 1 September 25, 2002
Alpha 2 June 9, 2003
Alpha 3 March 20, 2004
Alpha 4 December 15, 2004
Alpha 5 August 20, 2005
Alpha 6 May 30, 2006
Alpha 7 June 20, 2006
Alpha 8 September 18, 2007
Beta 1 September 22, 2007
Beta 2 October 12, 2007
Beta 3 April 16, 2008
1.0 November 3, 2008
1.1 September 24, 2009
1.1.1 October 1, 2009

See also

  • Dirac
  • Snow
  • Tarkin - wavelet-based video codec of the Xiph project abandoned in favor of Theora

Web links

Individual evidence

  1. ↑ Volker Zota: Open source competition for MPEG-4 . Heise online , August 8, 2001.
  2. ↑ Volker Zota: Truemotion VP7 video codec to try out . Heise online , March 9, 2005.
  3. ↑ Maik Merten: Theora 1.0beta1 released . Theora email list, September 22, 2007.
  4. ↑ Free video codec Ogg Theora is ready at Golem.de
  5. ↑ Massive improvements: Ogg Theora 1.1 released - Thusnelda: Better picture quality of the video codec at TecChannel.de.
  6. ↑ people.xiph.org