2. INTRODUCTION
Owned by Xiph.org (http://xiph.org/)
Free, Open source video codec, distributed without
licensing fees
Initial software released in Oct 2002, the final / frozen
specification in Jun 2004
Named after Theora Jones from Televison program “Max
Headroom”
3. HISTORY & RELATION TO ON2 VP3
Derived from ON2”s TrueMotion VP3 Video codec
Based on ON2’s VP3.2 release in Sep 2000
ON2 later Donated to XIPH.org with BSD license in June
2002 to enable open source royalty free video codec
Theora is a superset of VP3, and VP3 streams (with some
minor syntactic modifications in frame header) can be
converted into Theora streams without recompression (but
not vice versa).
VP3 video compression can be decoded using Theora
implementations, but Theora video compression usually
cannot be decoded using old VP3 implementations.
4. RESOURCES
Theora web site : http://www.theora.org/
Specification: http://www.theora.org/doc/Theora.pdf
Conformance suite:
http://wiki.xiph.org/TheoraTestsuite
5. THEORA : DECODER ALGORITHM
Deblocking
Filtering
Motion
Compensation
Residual
Decoding
Picture
Buffering
Picture
Buffering
IQ
& IT
+
Bitstream
Input
Video
Output
Post-
processing
Mode &
MVD
Picture
Buffering
6. DETAILS OF TOOL SET FOR THEORA VIDEO
No Topic Tool Overview Not supported in
Theora
1 Content type Progressive Interlaced
2 Frame type I and P frames B frame
3 Chroma format YUV 4:2:0, YUV 4:2:2, YUV 4:4:4 YUV 4:0:0
4 Bit-depth 8 bit 10,12,14 bits
5 Resolution Stamp size to HD -
6 Frame rate Fixed frame rate Variable frame rate
7 Bit-rate free-form variable bit rates (VBR)
from few Kbps to Mbps
CBR
8 Coding unit Block (8x8), Macro-block (16x16)
and Super Block (32x32)
-
7. DETAILS OF TOOL SET (CONTD)
No Topic Overview Not supported
9 Entropy coding VLC (Huffman) coding, 80 Table
selectable per frame
CABAC, CAVLC,…
10 Motion
compensation
Block based MC with Half pel
accuracy, 1 MV and 4 MV per MB
Qpel, > 4 MV
11 Reference
frame
2 Reference frame (Previous and
Golden frame)
> 2, Referance frame
selection per MB basis
12 Quantization Adaptive quantization down to the
block level , Upto 384 Qmatrix
based mode, Qp and
luma/chroma and support for
Scaling Matrix
13 Transform 8x8 Type-II Discrete Cosine
Transform
Fixed point, Second
transform
14 Loop filter adaptive in-loop deblocking
applied to the edges of the coded
blocks
Not sophisticated
8. AUDIO, CONTAINER AND RTP FORMAT
Typically Theora video is used with Vorbis Audio in
Ogg Container format
Ogg container is a free, open container format
maintained by the Xiph.Org Foundation
Vorbis is a free software / open source audio codec
owned by Xiph.Org Foundation
RTL payload format:
http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-
theora-00.txt
9. VIDEO QUALITY
Comparable to MPEG part 2 (SP) based on specification
As per MSU shoot-out (Video quality, encoding, decoding
speeds, options etc)
http://compression.ru/video/codec_comparison/h264_2010/
X264 beats Theora more than 50% in bit-rate to achieve
video quality.
XVID (MP4) beats Theora than 10% in bit-rate to achieve
video quality
10. SW IMPLEMENTATION
PC : Provides source code to generate “libtheora”, that
enables other players e.g. FFMPEG, Helix, VLC,…
The SW API specification for “libtheorra”:
http://www.theora.org/doc/libtheora-1.2/
ARM Optimized version
1. Theoarm project: http://wss.co.uk/pinknoise/theorarm/
2. FFMPEG release:
DSP implementation
Available for C64x from VINJAY SOFTWARE
(http://www.vinjey.com/)
11. HW IMPLEMENTATION
Open source
RTL Availability :
http://wiki.xiph.org/index.php/TheoraHardware
Few Video IP and chip providers support it
12. KEY DRIVERS FOR THEORA
Most important driver Adopted in HTML5 as a video format along with
WebM
Video on Wikipedia project: http://www.videoonwikipedia.com/
Open video alliance : http://openvideoconference.org/
Mozilla support as default video codec in Firefox
List of content provider for Theora:
http://wiki.xiph.org/List_of_Theora_videos
13. THEORA ADOPTION
It remains low as MeFeedia on popularity of format
http://blog.mefeedia.com/html5-dec-2011
The maximum Thoera content is centered around CIF and below
WVGA resolution.
There is confusion to support Theora or move use directly WebM on
open source front for content creators.
