INTRODUCTION Owned by Xiph.org (http://xiph.org/) Free, Open source video codec, distributed withoutlicensing fees Initial software released in Oct 2002, the final / frozenspecification in Jun 2004 Named after Theora Jones from Televison program “MaxHeadroom”
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 June2002 to enable open source royalty free video codec Theora is a superset of VP3, and VP3 streams (with someminor syntactic modifications in frame header) can beconverted into Theora streams without recompression (butnot vice versa). VP3 video compression can be decoded using Theoraimplementations, but Theora video compression usuallycannot be decoded using old VP3 implementations.
RESOURCES Theora web site : http://www.theora.org/ Specification: http://www.theora.org/doc/Theora.pdf Conformance suite:http://wiki.xiph.org/TheoraTestsuite
DETAILS OF TOOL SET FOR THEORA VIDEONo Topic Tool Overview Not supported inTheora1 Content type Progressive Interlaced2 Frame type I and P frames B frame3 Chroma format YUV 4:2:0, YUV 4:2:2, YUV 4:4:4 YUV 4:0:04 Bit-depth 8 bit 10,12,14 bits5 Resolution Stamp size to HD -6 Frame rate Fixed frame rate Variable frame rate7 Bit-rate free-form variable bit rates (VBR)from few Kbps to MbpsCBR8 Coding unit Block (8x8), Macro-block (16x16)and Super Block (32x32)-
DETAILS OF TOOL SET (CONTD)No Topic Overview Not supported9 Entropy coding VLC (Huffman) coding, 80 Tableselectable per frameCABAC, CAVLC,…10 MotioncompensationBlock based MC with Half pelaccuracy, 1 MV and 4 MV per MBQpel, > 4 MV11 Referenceframe2 Reference frame (Previous andGolden frame)> 2, Referance frameselection per MB basis12 Quantization Adaptive quantization down to theblock level , Upto 384 Qmatrixbased mode, Qp andluma/chroma and support forScaling Matrix13 Transform 8x8 Type-II Discrete CosineTransformFixed point, Secondtransform14 Loop filter adaptive in-loop deblockingapplied to the edges of the codedblocksNot sophisticated
AUDIO, CONTAINER AND RTP FORMAT Typically Theora video is used with Vorbis Audio inOgg Container format Ogg container is a free, open container formatmaintained by the Xiph.Org Foundation Vorbis is a free software / open source audio codecowned by Xiph.Org Foundation RTL payload format:http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt
VIDEO QUALITY Comparable to MPEG part 2 (SP) based on specification As per MSU shoot-out (Video quality, encoding, decodingspeeds, options etc) http://compression.ru/video/codec_comparison/h264_2010/ X264 beats Theora more than 50% in bit-rate to achievevideo quality. XVID (MP4) beats Theora than 10% in bit-rate to achievevideo quality
SW IMPLEMENTATION PC : Provides source code to generate “libtheora”, thatenables other players e.g. FFMPEG, Helix, VLC,… The SW API specification for “libtheorra”:http://www.theora.org/doc/libtheora-1.2/ ARM Optimized version1. Theoarm project: http://wss.co.uk/pinknoise/theorarm/2. FFMPEG release: DSP implementation Available for C64x from VINJAY SOFTWARE(http://www.vinjey.com/)
HW IMPLEMENTATION Open source RTL Availability :http://wiki.xiph.org/index.php/TheoraHardware Few Video IP and chip providers support it
KEY DRIVERS FOR THEORA Most important driver Adopted in HTML5 as a video format along withWebM 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
THEORA ADOPTION It remains low as MeFeedia on popularity of formathttp://blog.mefeedia.com/html5-dec-2011 The maximum Thoera content is centered around CIF and belowWVGA resolution. There is confusion to support Theora or move use directly WebM onopen source front for content creators.