Theora

Ogg Theoralibtheora.ogvOGV
Theora is a free lossy video compression format.wikipedia
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Video coding format

video coding standardsvideo codingvideo coding standard
Theora is a free lossy video compression format.
Examples of video coding formats include H.262 (MPEG-2 Part 2), MPEG-4 Part 2, H.264 (MPEG-4 Part 10), HEVC (H.265), Theora, RealVideo RV40, VP9, and AV1.

Ogg

OGM.oggOgg Writ
It is developed by the Xiph.Org Foundation and distributed without licensing fees alongside their other free and open media projects, including the Vorbis audio format and the Ogg container. Theora video streams can be stored in any suitable container format, but they are most commonly found in the Ogg container with Vorbis or FLAC audio streams.
In the Ogg multimedia framework, Theora provides a lossy video layer.

Dirac (video compression format)

DiracVC-2Dirac (codec)
It is comparable in open standards philosophy to the BBC's Dirac codec.
Dirac supports resolutions of HDTV (1920×1080) and greater, and is claimed to provide significant savings in data rate and improvements in quality over video compression formats such as MPEG-2 Part 2, MPEG-4 Part 2 and its competitors, e.g. Theora, and WMV.

FLAC

Free Lossless Audio Codec.flacFLAC
Theora video streams can be stored in any suitable container format, but they are most commonly found in the Ogg container with Vorbis or FLAC audio streams.
Xiph.org is behind other free compression formats such as Vorbis, Theora, Speex and Opus.

Daala

Project Daala is working on the successor to Theora.
Like Theora and Opus, Daala is available free of any royalties and its reference implementation is being developed as free and open-source software.

Use of Ogg formats in HTML5

Ogg controversyresulted in controversyretracted
However, the proposed adoption of Theora as part of the baseline video support in HTML5 resulted in controversy.
The specification had formerly recommended support for playback of Theora video and Vorbis audio encapsulated in Ogg containers to provide for easier distribution of audio and video over the internet by using open standards, but the recommendation was soon after dropped.

Discrete cosine transform

DCTiDCTinverse discrete cosine transform
Theora is a variable-bitrate, DCT-based video compression scheme.
It is used in image compression standards such as JPEG, and video compression standards such as H.26x, MJPEG, MPEG, DV, Theora and Daala.

Lossy compression

lossylossy data compressioncompressed
Theora is a free lossy video compression format.

VP3

VP44
Theora is derived from the formerly proprietary VP3 codec, released into the public domain by On2 Technologies.
In June 2002 On2 donated VP3 to the Xiph.org Foundation under a BSD-like open source license to make VP3 the basis of a new, free (e.g. patent- and royalty-free) video codec, Theora.

Vorbis

Ogg VorbisOGGaoTuV
It is developed by the Xiph.Org Foundation and distributed without licensing fees alongside their other free and open media projects, including the Vorbis audio format and the Ogg container. Theora video streams can be stored in any suitable container format, but they are most commonly found in the Ogg container with Vorbis or FLAC audio streams.
Opera 10.5 browser has support for Vorbis audio, WAVE PCM audio and Theora video.

Variable bitrate

VBRvariable bit ratevariable
Theora is a variable-bitrate, DCT-based video compression scheme.
Variable bit rate encoding is also commonly used on MPEG-2 video, MPEG-4 Part 2 video (Xvid, DivX, etc.), MPEG-4 Part 10/H.264 video, Theora, Dirac and other video compression formats.

Digital container format

container formatcontainercontainer formats
Theora video streams can be stored in any suitable container format, but they are most commonly found in the Ogg container with Vorbis or FLAC audio streams.

Firefox 3.5

Mozilla Firefox 3.53.5
These include support for the and elements defined in the HTML 5 draft specification, including native support for Ogg Theora encoded video and Vorbis encoded audio.

Cortado (software)

CortadoItheora
Cortado is a streaming Java applet for Ogg formats Vorbis, Theora and Kate, μ-law, MJPEG and Smoke (a custom MJPEG variant), released under the GPL.

Advanced Video Coding

H.264H.264/MPEG-4 AVCMPEG-4 AVC
Theora supports intra-coded frames and forward-predictive frames, but not bi-predictive frames which are found in H.264 and VC-1. A flaw in the version of FFmpeg used in the test initially led to incorrect reports of Theora PSNR surpassing that of H.264.
In 2009, the HTML5 working group was split between supporters of Ogg Theora, a free video format which is thought to be unencumbered by patents, and H.264, which contains patented technology.

OggConvert

OggConvert is a free and open-source transcoder for digital audio and video files of various types into the free Ogg Vorbis audio format, and the Theora, VP8 and Dirac video formats.

Annodex

Annodex Association
By late 2004, Andre Pang developed the Annodex Plug-in for Mozilla Firefox Browsers, allowing for the playback of Annodex media encoded with the Ogg Theora video codec and the Ogg Vorbis audio codec.

FFmpeg

SnowLAV Filterslibavformat
A flaw in the version of FFmpeg used in the test initially led to incorrect reports of Theora PSNR surpassing that of H.264.

Miro (software)

MiroMiro Media PlayerDemocracy (video platform)
It is based on FFmpeg with profiles for the Theora (.ogv ), .mp4, and WebM video formats supported by various devices.

Thoggen

Thoggen can back up DVDs by re-encoding them using the Ogg Theora video codec.

FreeJ

The resulting video is accessible to any computer able to decode media encoded with the theora codec.

Icecast

IceStechnical component of Icecast software
The Icecast server is capable of streaming audio content as Opus or Vorbis over standard HTTP, video as WebM or Theora over HTTP, and MP3, AAC, and NSV over the SHOUTcast protocol.