Free lossy video compression format
Theora
is a
free
lossy
video compression format
.
[7]
It was 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.
The
libtheora
video codec
is the
reference implementation
of the Theora video compression format developed by the Xiph.Org Foundation.
[8]
[9]
Theora was derived from the formerly
proprietary
VP3
codec, released into the
public domain
by
On2 Technologies
. It is broadly comparable in design and bitrate efficiency to
MPEG-4 Part 2
, early versions of
Windows Media Video
, and
RealVideo
while it lacked some of the features present in some of these other codecs. It is comparable in open standards philosophy to the
BBC
's
Dirac
codec.
Theora was named after
Theora Jones
,
Edison Carter
's Controller on the
Max Headroom
television program.
[10]
Technical details
[
edit
]
Theora is a
variable-bitrate
,
DCT
-based video compression scheme. Like most common video codecs, Theora used
chroma subsampling
,
block
-based motion compensation and an 8-by-8 DCT block. Pixels are grouped into various structures, namely blocks, super blocks, and
macroblocks
. Theora supports intra-coded frames ("keyframes") and forward-predictive frames, but not
bi-predictive frames
which are found in
H.264
and
VC-1
. Theora also does not support
interlacing
, or bit-depths larger than 8 bits per component.
[2]
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. This combination provided a completely open, royalty-free multimedia format. It can also be used with the
Matroska
container.
[11]
The Theora video-compression format is compatible with the VP3 video-compression format, which consisted of a backward-compatible superset.
[12]
[13]
Theora is a superset of VP3, and VP3 streams (with some minor syntactic modifications) can be converted into Theora streams without recompression (but not vice versa).
[13]
VP3 video compression can be decoded using Theora implementations, but Theora video compression usually cannot be decoded using old VP3 implementations.
History
[
edit
]
Theora's predecessor
On2 TrueMotion VP3
was originally a
proprietary
and patent-encumbered
video codec
developed by
On2 Technologies
. VP3.1 was introduced in May 2000
[14]
and followed three months later by the VP3.2 release,
[15]
which was the basis for Theora.
Move to free software
[
edit
]
In August 2001, On2 Technologies announced that they would release an open source version of their VP3.2 video compression algorithm.
[16]
[17]
In September 2001, On2 Technologies published the
source code
of the VP3.2 codec under the VP3.2 Public License 0.1,
[18]
a custom open-source license.
[19]
[20]
The license only granted the right to modify the source code if the resultant larger work continued to support playback of VP3.2 data.
[18]
[21]
In March 2002, On2 responded to the public's reception by relicensing the VP3 codec under the
GNU Lesser General Public License
.
[22]
In June 2002, On2 donated VP3 to the Xiph.Org Foundation and offered it under the Ogg Vorbis
BSD
-style license.
[23]
[24]
[25]
[26]
On2 also made an irrevocable,
royalty-free
license grant for any patent claims it might have over the software and any derivatives,
[2]
allowing anyone to use any VP3-derived codec for any purpose.
[12]
[27]
In August 2002, On2 entered into an agreement with the Xiph.Org Foundation to make VP3 the basis of a new, free video codec, called Theora.
[28]
On2 declared Theora to be VP3's successor.
[
citation needed
]
On 3 October 2002, On2 and Xiph announced the completion and availability of the initial alpha code release of
libtheora
, Theora's reference implementation.
[29]
There is no formal specification for VP3's
bitstream format
beyond the VP3 source code published by On2 Technologies. In 2003, Mike Melanson created an incomplete description of the VP3 bitstream format and decoding process at a higher level than source code, with some help from On2 and Xiph.Org Foundation. The Theora specification adopted some portions of this VP3 description.
[2]
[30]
A successor to Theora,
Daala
, was later merged into
AV1
.
[31]
Theora I specification
[
edit
]
The Theora I bitstream format was
frozen
in June 2004 after the libtheora 1.0alpha3 release.
[1]
Videos encoded with any version of the libtheora since the alpha3 will be compatible with any future player.
[1]
[32]
This is also true for videos encoded with any implementation of the Theora I specification since the format freeze. The
Theora I Specification
was completely published in 2004.
[33]
Any later changes in the specification are minor updates.
The Theora reference implementation libtheora spent several years in
alpha
and beta status.
[32]
The first alpha version was released on 25 September 2002 and the first beta version was released on 22 September 2007.
[34]
The first stable release of libtheora was made in November 2008.
[35]
[36]
Work then focused on improving the codec's performance in the
"Thusnelda"
branch, which was released as version 1.1 in September 2009 as the second stable libtheora release.
[32]
[37]
This release brought some technical improvements and new features, such as the new rate control module and the
two-pass rate control
.
The codename for the next version of libtheora was
Ptalarbvorm
.
[38]
Theora was well established as a video format in
open-source applications
, and became the format used for
Wikipedia
's video content before replaced by
VP9
. However, the proposed adoption of Theora as part of the baseline video support in HTML5
resulted in controversy
.
[39]
Legacy
[
edit
]
In October 2023, Google announced intent to remove Theora support from Chromium (finalizing removal by Google Chrome 123),
[40]
with Firefox following suit. Google developers claimed that despite lack of adoption, Theora made a case for open and royalty-free codecs like
AV1
.
[41]
[
better source needed
]
Performance
[
edit
]
Encoding performance
[
edit
]
Evaluations of the VP3
[42]
and early Theora encoders
[43]
[44]
[45]
found that their subjective visual quality was inferior to that of contemporary video codecs. The performance characteristics of the Theora 1.0 reference implementation are dominated mostly by implementation problems inherited from the original VP3 code base.
[46]
Work that lead up to the 1.1 stable release focused on improving on or eliminating these. A May 2009 review of this work by Xiph developer Chris Montgomery claimed a considerable improvement in quality, both subjectively and as measured by
PSNR
, by improving the forward
DCT
and quantisation matrices.
[47]
More recently however,
[
when?
]
Xiph developers compared the 1.1 Theora encoder to
YouTube
's H.264 and
H.263+
encoders, in response to concerns raised in 2009 about Theora's inferior performance by
Chris DiBona
, a
Google
employee.
[48]
They found the results from Theora to be nearly the same as YouTube's H.264 output, and much better than the H.263+ output.
[49]
[50]
The differences in quality, bitrate and file size between a YouTube H.264 video and a transcoded Ogg video file are very small.
[51]
Playback performance
[
edit
]
There was an
open-source
VHDL
code base for a hardware Theora decoder in development.
[52]
[
needs update
]
It began as a 2006
Google
Summer of Code
project, and it has been developed on both the
Nios II
and
LEON
processors.
[53]
However, there are currently no Theora decoder chips in production, and
portable media players
,
smartphones
and similar devices with limited computing power rely on such chips to provide efficient playback.
Playback
[
edit
]
Web browsers
[
edit
]
As originally recommended by
HTML 5
, these browsers support Theora when embedded by the
video
element:
Supporting media frameworks
[
edit
]
Supporting applications
[
edit
]
Encoding
[
edit
]
There are several third-party programs that support encoding through libtheora:
Name
|
Description
|
Operating Systems Supported
|
Unix-like
|
OS X
|
Windows
|
- ffmpeg2theora
[71]
|
A command-line program that transcodes video by decoding with
FFmpeg
and reencoding with libtheora to encode it
|
Yes
|
Yes
|
Yes
|
- VLC
|
Can transcode to single-pass Theora 1.0 and optionally stream it
|
Yes
|
Yes
|
Yes
|
- FreeJ
|
"Video DJing" software that can encode to and stream Theora
|
Yes
|
Yes
|
?
|
- Kdenlive
|
The video editor supplied with
KDE
|
Yes
|
?
|
?
|
- Pitivi
|
The video editor supplied with
GNOME
|
Yes
|
?
|
?
|
- LiVES
|
Video editing software for Linux. Can edit, encode and stream theora.
|
Yes
|
Yes
|
?
|
- HandBrake
|
Can output to Theora only with the
Matroska
container
|
Yes
|
Yes
|
Yes
|
- RecordMyDesktop
|
Records the screen to Ogg Theora with optional Vorbis audio
|
Yes
|
?
|
?
|
The libtheora library contains the reference implementation of the Theora specification for encoding and decoding. libtheora was developed by the
Xiph.Org Foundation
. The library was released under the terms of a
BSD-style license
.
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.
[72]
[73]
[74]
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 are not available to the user in ffdshow's interface.
- The
GStreamer
framework has support for parsing raw Theora streams, encoding and decoding raw Theora streams to/from YUV video
[75]
[76]
Editing
[
edit
]
Streaming
[
edit
]
The following streaming media servers are capable of streaming Theora video:
Name
|
Description
|
Operating Systems Supported
|
Unix-like
|
OS X
|
Windows
|
- VLC
|
|
Yes
|
Yes
|
Yes
|
- Icecast
|
|
Yes
|
?
|
Yes
|
- LiVES
|
Can stream ogg/theora/vorbis in realtime to a file or fifo.
|
Yes
|
Yes
|
?
|
Makers
[
edit
]
Elphel
is the main maker of cameras that record in theora.
See also
[
edit
]
References
[
edit
]
- ^
a
b
c
Giles, Ralph (1 June 2004).
"Theora I bitstream freeze"
.
theora-dev
(Mailing list)
. Retrieved
25 September
2009
.
- ^
a
b
c
d
"Theora Specification"
(PDF)
. Xiph.Org Foundation. 16 March 2011
. Retrieved
31 January
2012
.
- ^
"PlayOgg! ? FSF ? Free Software Foundation"
. 17 March 2010
. Retrieved
1 October
2013
.
- ^
"Theora FAQ"
.
Xiph.org
. 2016. Archived from
the original
on 26 September 2020
. Retrieved
1 December
2021
.
- ^
"Theora 1.1.1 release"
. Xiph.Org Foundation
. Retrieved
6 October
2009
.
- ^
"libtheora 1.2.0alpha1 release"
. Xiph.Org Foundation. September 2010
. Retrieved
10 October
2010
.
- ^
Theora
.
- ^
Xiph.Org Foundation.
"libtheora Documentation 1.1.0"
. Xiph.Org Foundation
. Retrieved
25 September
2009
.
- ^
ohloh
.
"libtheora"
.
ohloh
. Archived from
the original
on 10 October 2010
. Retrieved
25 September
2009
.
- ^
"Theora FAQ"
. Xiph.Org Foundation
. Retrieved
6 August
2009
.
- ^
"Matroska Codec Specs"
. Matroska
. Retrieved
6 August
2009
.
- ^
a
b
Xiph.org
libtheora license (Subversion ? Trunk)
, Retrieved on 16 August 2009
- ^
a
b
Xiph.org
FAQ ? Theora and VP3
. Retrieved 2 September 2009
- ^
On2 (17 May 2000),
On2.com Launches Next Generation of Revolutionary Broadband Video Technology
, archived from
the original
on 3 December 2007
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
On2 (16 August 2000),
On2 Introduces TrueMotion VP3.2
, archived from
the original
on 3 December 2007
, retrieved
23 August
2010
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
On2 (7 August 2001),
On2 Technologies to Open Source VP3.2 Video Compression Technology (archived website)
, archived from
the original
on 3 December 2007
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
Mariano, Gwendolyn (7 August 2001).
"On2's video codec to go open-source"
.
CNET
.
- ^
a
b
On2 Technologies (2001),
VP3.2 Public License 0.1
, Xiph.Org Foundation, archived from
the original
on 4 April 2016
, retrieved
10 February
2008
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
Bernat, Bill (7 September 2001).
"On2 Offers Up VP3.2 Source Code"
.
StreamingMedia.com
.
- ^
On2 (7 September 2001),
On2 Technologies Makes Video Compression Technology Available to Open-Source Community
, archived from
the original
on 7 December 2007
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
Seibert, Stan (September 2001).
"VP3.2 video codec open sourced"
.
vorbis
(Mailing list).
- ^
"On2 Alters Licensing Terms for VP3; Company Responds to Open Source Community Demands"
(Press release). On2 Technologies. 28 March 2002. Archived from
the original
on 4 December 2010
. Retrieved
16 August
2009
.
- ^
Xiph.Org Foundation (16 March 2011).
"Theora Specification"
(PDF)
. Xiph.Org Foundation. p. 1.
- ^
"VP3 Combines with Vorbis to Create First Open-Source Multimedia Platform"
,
On2
, 24 June 2002, archived from
the original
on 3 December 2007
- ^
Linux.com (23 June 2002)
Ogg Vorbis, VP3 combining forces to create Open Source multimedia package
, Retrieved on 2009-08-16
- ^
InternetNews.com (24 June 2002)
On2 Throws More Open-Source at MPEG-4
, Retrieved on 16 August 2009
- ^
Xiph.org
VP32 codec license (Subversion ? Trunk)
, Retrieved on 16 August 2009
- ^
The Free Library (1 August 2002)
On2 Signs Pact With Xiph.org to Develop/Support VP3
, Retrieved on 16 August 2009
- ^
On2 (3 October 2002),
On2 and Xiph Announce Alpha Code Release of Theora, VP3-Vorbis-Based Multimedia Solution
, archived from
the original
on 4 December 2007
{{
citation
}}
: CS1 maint: numeric names: authors list (
link
)
- ^
Mike Melanson (mike at multimedia.cx) (8 December 2004),
VP3 Bitstream Format and Decoding Process
, Multimedia.cx, archived from
the original
on 6 January 2013
, retrieved
27 September
2009
- ^
Stephen Shankland (1 September 2015).
"Tech giants join forces to hasten high-quality online video"
.
CNET
. Retrieved
17 March
2021
.
- ^
a
b
c
Xiph.Org Foundation (24 September 2009),
Theora.org : news
, Xiph.Org Foundation
, retrieved
25 September
2009
- ^
Xiph.Org Foundation (17 September 2004).
"Theora I Specification, Xiph.org Foundation, September 17, 2004"
(PDF)
. Archived from
the original
(PDF)
on 28 September 2004
. Retrieved
26 September
2009
.
- ^
"CHANGES file"
. Retrieved
31 December
2022
.
- ^
Giles, Ralph (3 November 2008).
"Theora 1.0 final release!"
.
theora-dev
(Mailing list)
. Retrieved
4 November
2008
.
- ^
"The Xiph.Org Foundation announces the release of Theora 1.0"
(Press release). Xiph.Org Foundation. 3 November 2008
. Retrieved
6 August
2009
.
- ^
Giles, Ralph (24 September 2009).
"libtheora 1.1 (Thusnelda) stable release"
.
theora-dev
(Mailing list)
. Retrieved
24 September
2009
.
- ^
Monty (18 May 2010).
"Theora: Ptalarbvorm project update 20100518"
. Retrieved
1 July
2010
.
- ^
McLean, Prince (7 July 2009).
"Ogg Theora, H.264 and the HTML 5 Browser Squabble"
. AppleInsider
. Retrieved
1 November
2020
.
- ^
Larabel, Michael (29 October 2023).
"Google Chrome To Remove Theora Video Codec Support"
.
Phoronix
. Retrieved
1 November
2023
.
- ^
"Intent to Ship: Deprecate and remove Theora support"
.
groups.google.com
. Retrieved
1 November
2023
.
- ^
"MPEG-4 Codec shoot-out 2002 ? 1st installment"
.
Doom9
. 2002. Archived from
the original
on 23 February 2008
. Retrieved
19 December
2007
.
- ^
Codec shoot-out 2005 ? Qualification
,
Doom9
, 2005, archived from
the original
on 31 December 2007
, retrieved
19 December
2007
- ^
Loli-Queru, Eugenia (12 December 2007).
"Theora vs. h.264"
.
OSNews
. Retrieved
1 April
2008
.
- ^
Halbach, Till (March 2009).
"Dirac and Theora vs. H.264 and Motion JPEG2000"
. Archived from
the original
on 7 July 2012
. Retrieved
22 April
2008
.
- ^
Montgomery, Chris.
"Theora "the push for 1.0" update"
. Retrieved
19 December
2007
.
- ^
Blizzard, Christopher.
"Theora Update 7 May 2009"
. Retrieved
10 May
2009
.
- ^
DiBona, Chris (13 June 2009).
"H.264-in-<video> vs plugin APIs"
.
whatwg
(Mailing list)
. Retrieved
10 August
2009
.
- ^
Maxwell, Greg (13 June 2009).
"YouTube / Ogg/Theora comparison"
. Xiph.Org Foundation. Archived from
the original
on 9 July 2009
. Retrieved
10 August
2009
.
- ^
Merten, Maik (15 June 2009).
"Another online-video comparison"
. Xiph.Org Foundation. Archived from
the original
on 9 July 2009
. Retrieved
10 August
2009
.
- ^
Richmond, Gary.
"Firefogg: Transcoding videos to open web standards with Mozilla Firefox"
. Retrieved
2 November
2023
.
- ^
"Xiph Subversion repository: trunk/theora-fpga"
. Xiph.Org Foundation
. Retrieved
10 August
2009
.
- ^
"XiphWiki: Theora Hardware"
. Xiph.Org Foundation
. Retrieved
10 August
2009
.
- ^
MozillaWiki (18 March 2009),
Firefox3.5/Features
, MozillaWiki
, retrieved
11 October
2009
- ^
Mozilla Corporation (30 June 2009),
Mozilla Firefox 3.5 Release Notes
, Mozilla Corporation
, retrieved
11 October
2009
- ^
Mozilla Corporation (9 February 2010),
Firefox Mobile Features
, Mozilla Corporation
, retrieved
9 February
2010
- ^
"Mozilla Eyes Removal Of Theora Support In Firefox"
.
www.phoronix.com
. Retrieved
1 November
2023
.
- ^
"1860492 ? Investigate removing Theora support"
.
bugzilla.mozilla.org
. Retrieved
1 November
2023
.
- ^
Google Chrome to support HTML 5 video
, SoftSailor, 28 May 2009, archived from
the original
on 3 October 2009
, retrieved
11 October
2009
- ^
Shankland, Stephen (28 May 2009),
Google Chrome gets HTML video support
, cnet news
, retrieved
11 October
2009
- ^
Issue 16657: Ensure FFmpeg binaries end up in snapshots on all platforms
, Google Chromium, 14 July 2009
, retrieved
6 February
2010
- ^
Larabel, Michael (7 December 2023).
"Chrome 120 Released With Theora Support Evaporating, Adds WebGPU & CSS Improvements"
.
www.phoronix.com
. Retrieved
9 December
2023
.
- ^
"Deprecate and remove Theora support. ? Chrome Platform Status"
.
chromestatus.com
. Retrieved
24 October
2023
.
- ^
Kaiser, Robert (16 September 2009),
What's New in SeaMonkey 2.0 Beta 2
, seamonkey-project.org
, retrieved
11 October
2009
- ^
Bugreport: Wish for audio/video element support in Konqueror
, 13 May 2007, archived from
the original
on 28 December 2012
, retrieved
2 December
2009
- ^
Plans for Konqueror 4.4
, 26 November 2009, archived from
the original
on 17 July 2011
, retrieved
2 December
2009
- ^
Jagenstedt, Philip (31 December 2009).
"(re-)Introducing <video> ? Official blog for Core developers at Opera"
. Opera. Archived from
the original
on 4 January 2010
. Retrieved
2 January
2010
.
- ^
Arjan van Leeuwen (31 December 2009).
"Happy New Year! ? Official blog for Core developers at Opera"
. Opera. Archived from
the original
on 4 January 2010
. Retrieved
2 January
2010
.
- ^
Experimental Opera-video build with native Ogg Theora support
, Opera, 25 April 2007, archived from
the original
on 2 December 2007
, retrieved
11 October
2009
- ^
A call for video on the web ? Opera <video> release on Labs
, Opera, 7 November 2007
, retrieved
11 October
2009
- ^
"ffmpeg2theora"
.
v2v.cc
. Archived from
the original
on 11 March 2008
. Retrieved
2 June
2009
.
- ^
"ffdshow Summary"
. Retrieved
23 October
2009
.
- ^
Cutka, Milan (4 October 2002).
"Theora support in ffdshow a ffvfw"
.
theora-dev
(Mailing list).
- ^
"Theora in .ogg no only .avi ? ffdshow tryouts Forum"
. 15 January 2008
. Retrieved
23 October
2009
.
- ^
gstreamer.freedesktop.org.
"GStreamer Base Plugins 0.10 (0.10.24.1)"
. Retrieved
23 October
2009
.
- ^
gstreamer.freedesktop.org.
"GStreamer Base Plugins 0.10 Plugins Reference Manual ? Theora plugin library"
. Retrieved
23 October
2009
.
- ^
"Ogg Video Tools - Browse Files at SourceForge.net"
.
sourceforge.net
. Retrieved
6 November
2022
.
External links
[
edit
]