Theora: Difference between revisions

Latest revision as of 14:48, 8 August 2014

Theora is a video codec, based on the VP3 codec donated by On2 Technologies. We've refined and extended it, giving it the same future scope for encoder improvement Vorbis has. See http://theora.org/ for more information.

Features

Features available in the Theora format (and a comparison to VP3 and MPEG-4 ASP):

8x8 Type-II Discrete Cosine Transform
block-based motion compensation
free-form variable bit rates (VBR)
adaptive in-loop deblocking applied to the edges of the coded blocks (not existing in MPEG-4 ASP)
block sizes down to 8x8 (MPEG-4 ASP supports 8x8 only with 4MV)
384 8x8 custom quantization matrices: intra/inter, luma/chroma and even each quant (more than VP3 and MPEG-4 ASP/AVC)
flexible entropy encoding (Theora supports 80 VLC tables selectable per-frame, MPEG-4 ASP has just one)
4:2:0, 4:2:2, and 4:4:4 chroma subsampling formats (VP3 and MPEG-4 ASP only support 4:2:0)
8 bits per pixel per color channel
multiple reference frames (not possible in MPEG-4 ASP)
pixel aspect ratio (eg for anamorphic signalling/playback)
non-multiple of 16 picture sizes (as possible in ASP, but not in VP3)
non-linear scaling of quants values (as done in MPEG-4 AVC)
adaptive quantization down to the block level (as possible in MPEG-4 ASP/AVC, but not in VP3)
intra frames (I-Frames in MPEG), inter frames (P-Frames), but no B-Frames (as supported in MPEG-4 ASP/AVC)
HalfPixel Motion Search Precision (MPEG-4 ASP/AVC supports HalfPixel or QuarterPixel)
technologies used already in Vorbis (decoder setup configuration, bitstream headers...) not available in VP3

Status

1.1.1 is the latest stable release (2009-10-01).
The bitstream format was frozen in 1.0 Alpha 3 on 2004-08-04: every file created with this encoder (and, of course, later encoders) will be playable by any compliant Theora decoder.
The decoder in 1.0 Alpha 8 implemented all features of the Theora Format Specification: every file created by any compliant Theora encoder will be playable by the decoder in 1.0 Alpha 8 (and, of course, later decoders).

Development

More information

Theora Hardware: List of hardware-players supporting Ogg Theora
TheoraSoftwarePlayers: List of media players that can play Ogg Theora
TheoraSoftwareEncoders: List of software that can encode to Ogg Theora
TheoraDecoders: List of decoder implementations
TheoraEncoders: List of encoder implementations
List of Theora videos: Get some files to see what the codec's like
Games that use Theora: List of known games that use Theora
TheoraTestsuite: Different samples to test player compliance

It's possible to convert VP3 video to Theora. See vp3toTheora.

External links

Theora homepage
Theora documentation daily builds
Wikipedia: Theora
VP3 homepage: The homepage of the codec Theora is based on
On2 Technologies: The authors of VP3
Ogg Theora Information on Doom9 Forum
HOWTO: Rip DVD to Theora using Linux
Codec shoot-out 2005 Comparison of many video codecs, including Theora

@@ Line 1: / Line 1: @@
-'''Theora''' is our video codec, based on the [[VP3]] codec donated by [[On2 Technologies]]. We've refined and extended it, giving it the same future scope for encoder improvement [[Vorbis]] has. See http://theora.org/ for more information.
+'''Theora''' is a video codec, based on the [[VP3]] codec donated by [[On2 Technologies]]. We've refined and extended it, giving it the same future scope for encoder improvement [[Vorbis]] has. See http://theora.org/ for more information.
 == Features ==
@@ Line 5: / Line 5: @@
 Features available in the Theora format (and a comparison to VP3 and MPEG-4 ASP):
+* 8x8 Type-II Discrete Cosine Transform
 * block-based motion compensation
-* 8x8 Type-II Discrete Cosine Transform
 * free-form variable bit rates (VBR)
 * adaptive in-loop deblocking applied to the edges of the coded blocks (not existing in MPEG-4 ASP)
@@ Line 22: / Line 22: @@
 * HalfPixel Motion Search Precision (MPEG-4 ASP/AVC supports HalfPixel or QuarterPixel)
 * technologies used already in Vorbis (decoder setup configuration, bitstream headers...) not available in VP3
-Note that not all of these features are already implemented in the reference encoder.
 == Status ==
-* 1.0 is the latest stable release (2008-11-03).
+* '''1.1.1''' is the latest stable release (2009-10-01).
-* The bitstream format was frozen in 1.0 Alpha 3 on 2004-08-04: every file created with this encoder (and, of course, later encoders, including Theora 1.1 in future) will be playable by any compliant Theora 1.x decoder.
+* The bitstream format was frozen in 1.0 Alpha 3 on 2004-08-04: every file created with this encoder (and, of course, later encoders) will be playable by any compliant Theora decoder.
-* The decoder in 1.0 Alpha 8 implements all planned features of the [http://theora.org/doc/Theora.pdf Theora Format Specification]: every file created by any compliant 1.x Theora encoder will be playable by the decoder in 1.0 Alpha 8 (and, of course, later decoders).
+* The decoder in 1.0 Alpha 8 implemented all features of the [http://theora.org/doc/Theora.pdf Theora Format Specification]: every file created by any compliant Theora encoder will be playable by the decoder in 1.0 Alpha 8 (and, of course, later decoders).
 == Development ==
 * [[OggTheora|Mapping in Ogg]]
-* [[TheoraTodo|Todo list for development]]
+* [[TheoraTodo|ToDo list for development]]
+* [[Cortado/release|Release checklist for the Cortado java applet]]
 ==  More information ==