Theora video


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This foils gives overview of open source Thoera video codec.

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Theora video

  1. 1. THEORA VIDEOMihir Mody
  2. 2. INTRODUCTION Owned by ( 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”
  3. 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 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.
  4. 4. RESOURCES Theora web site : Specification: Conformance suite:
  5. 5. THEORA : DECODER ALGORITHMDeblockingFilteringMotionCompensationResidualDecodingPictureBufferingPictureBufferingIQ& IT+BitstreamInputVideoOutputPost-processingMode &MVDPictureBuffering
  6. 6. 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)-
  7. 7. 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
  8. 8. 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:
  9. 9. VIDEO QUALITY Comparable to MPEG part 2 (SP) based on specification As per MSU shoot-out (Video quality, encoding, decodingspeeds, options etc) X264 beats Theora more than 50% in bit-rate to achievevideo quality. XVID (MP4) beats Theora than 10% in bit-rate to achievevideo quality
  10. 10. SW IMPLEMENTATION PC : Provides source code to generate “libtheora”, thatenables other players e.g. FFMPEG, Helix, VLC,… The SW API specification for “libtheorra”: ARM Optimized version1. Theoarm project: FFMPEG release: DSP implementation Available for C64x from VINJAY SOFTWARE(
  11. 11. HW IMPLEMENTATION Open source RTL Availability : Few Video IP and chip providers support it
  12. 12. KEY DRIVERS FOR THEORA Most important driver Adopted in HTML5 as a video format along withWebM Video on Wikipedia project: Open video alliance : Mozilla support as default video codec in Firefox List of content provider for Theora:
  13. 13. THEORA ADOPTION It remains low as MeFeedia on popularity of format 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.
  14. 14. THANKS