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JVT Coding ITU-T H.26L; ISO MPEG-4, Part 10

JVT Coding ITU-T H.26L; ISO MPEG-4, Part 10. Thomas Wiegand Heinrich Hertz Institute, Berlin, Germany Associated Rapporteur ITU-T VCEG Co-Chair ITU-T/ISO JVT wiegand@hhi.de. JVT/ H.26L: History, Goals, Applications, Structure Video Coding Layer Syntax and Decoder Coder Control

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JVT Coding ITU-T H.26L; ISO MPEG-4, Part 10

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  1. JVT CodingITU-T H.26L; ISO MPEG-4, Part 10 Thomas Wiegand Heinrich Hertz Institute, Berlin, Germany Associated Rapporteur ITU-T VCEG Co-Chair ITU-T/ISO JVT wiegand@hhi.de

  2. JVT/H.26L: History, Goals, Applications, Structure Video Coding Layer Syntax and Decoder Coder Control Comparisons Network Adaptation Layer Outline

  3. The JVT Project • New ITU-T Q.6/SG16 (VCEG - Video Coding Experts Group) standardization activity for video compression • August 1999:1st test model (TML-1) • December 2001: Formation of the Joint Video Team (JVT) between VCEG and MPEG to finalize H.26L as a joint project: JVT Coding (similar to MPEG-2/H.262) • February 2002:WD-2 (11th test model: TML-11) • Schedule: • February 2002: Last major feature adoptions • November 2002: Final approval

  4. Goals of the JVT/H.26L Project • Simple syntax specification • Targeting simple and clean solutions • Avoiding any excessive quantity of optional features or profile configurations • Improved Coding Efficiency • Average bit rate reduction of 50% given fixed fidelity compared to any other standard • Improved Network Friendliness • Issues examined in H.263 and MPEG-4 are further improved • Major targets are mobile networks and Internet

  5. Applications • Conversational H.32X Services • H.320 Conversational • 3GPP Conversational H.324/M • 3GPP Conversational IP/RTP/SIP • H.323 Conversational Internet/unmanaged/best effort IP/RTP • Streaming Services • 3GPP Streaming IP/RTP/RTSP • Streaming IP/RTP/RTSP • Other Services • Entertainment Satellite/Cable/DVD, 0.5 – 8 Mbit/s • Digital Cinema Application • 3GPP Multimedia Messaging Services

  6. JVT/H.26L Layer Structure Control Data Video Coding Layer Macroblock Data Partitioning Slice/Partition Network Adaptation Layer H.320 H.324 H.323/IP H.324M etc.

  7. JVT/H.26L Layer Structure Control Data Video Coding Layer Macroblock Data Partitioning Slice/Partition Network Adaptation Layer H.320 H.324 H.323/IP H.324M etc.

  8. Entropy Coding H.26L Video Coding Layer Coder Control Control Data Transform/Quantizer Quant.Transf. coeffs - Decoder Deq./Inv. Transform 0 Motion- Compensated Predictor Intra/Inter Motion Data Motion Estimator

  9. 16x16 macroblocks Conventional sampling of chrominance and association of luminance and chrominance data Block motion displacement Motion vectors over picture boundaries Variable block-size motion Block transforms (not wavelets or fractals) Run-length coding of transform coefficients Scalar quantization I- and P-picture types Common Elements with other Standards

  10. Entropy Coding 16x16 8x8 16x8 8x16 0 MB 0 1 0 0 1 Modes 2 3 1 4x8 8x8 8x4 4x4 0 1 0 8x8 0 1 0 Modes 2 3 1 Motion Compensation Accuracy Coder Control Control Data Transform/Quantizer Quant.Transf. coeffs - Decoder Deq./Inv. Transform 0 Motion- Compensated Predictor Intra/Inter Motion Data Motion Estimator 1/4 (QCIF) or 1/8 (CIF) pel

  11. Tree-Structured MB Partition INTRA MB: INTRA 8x8: Allows motion segmentation shapes like INTRA

  12. Entropy Coding Multiple Reference Frames for Motion Compensation Multiple Reference Frames Coder Control Control Data Transform/Quantizer Quant.Transf. coeffs - Decoder Deq./Inv. Transform 0 Motion- Compensated Predictor Intra/Inter Motion Data Motion Estimator

  13. Entropy Coding Residual Coding • Residual coding is based on 4x4 blocks • Integer Transform Coder Control Control Data Transform/Quantizer Quant.Transf. coeffs - Decoder Deq./Inv. Transform 0 Motion- Compensated Predictor Intra/Inter Motion Data Motion Estimator

  14. Transform Based primarily on 4x4 transform (all prior standards: 8x8) Expanded to 8x8 for chroma by 2x2 transform of the DC values Intra Coding Structure Directional spatial prediction (6 types luma, 1 chroma) Expanded to 16x16 for luma intra by 4x4 transform of the DC values Residual and Intra Coding

  15. Quantization Two inverse scan patterns Logarithmic step size control Smaller step size for chroma (per H.263 Annex T) Deblocking Filter (in loop) Quantization and Deblocking

  16. Coder Control Control Data Transform/Quantizer Quant.Transf. coeffs - Decoder Deq./Inv. Transform Entropy Coding 0 Motion- Compensated Predictor Intra/Inter Motion Data Motion Estimator Entropy Coding

  17. Exp-Golomb Coding • One table that is used universally for all symbols • Simple, but has the following disadvantages • Probability distribution may not be a good fit • Probability distribution is static • Correlations between symbols are ignored, i.e. no conditional probabilities are used • Code words must have integer number of bits(Low coding efficiency for highly peaked pdfs)

  18. Context-based Adaptive Binary Arithmetic Codes (CABAC) • Usage of adaptive probability models • Exploiting symbol correlations by using contexts • Non-integernumber of bits per symbol by using arithmetic codes • Restriction to binary arithmetic coding • Simple and fast adaptation mechanism • Fast binary arithmetic coders are available • Binarization is done using the UVLC

  19. SP-Pictures SP-pictures are much smaller than I-pictures

  20. Both: Sequence structure IBBPBBP... Search range: 32x32 around 16x16 predictor Encoders use similar D+lR optimization techniques MPEG-4: Advanced Simple Profile (ASP) Motion Compensation: 1/4 pel Global Motion Compensation QPB=1.2 x QPP H.26L: Motion Compensation: 1/4 pel (QCIF), 1/8 pel (CIF) Using CABAC entropy coding 5 reference frames QPB=QPP+2 Comparison of JVT/H.26L and MPEG-4

  21. Left-hand side Right-hand side Comparison to MPEG-2, H.263, MPEG-4 ForemanQCIF 10Hz 39 38 37 36 JVT/H.26L 35 MPEG-4 34 MPEG-2 Quality Y-PSNR [dB] 33 H.263 32 31 30 29 28 27 0 50 100 150 200 250 Bit-rate [kbit/s]

  22. ???-hand side ???-hand side Comparison to MPEG-2, H.263, MPEG-4 Tempete CIF 30Hz 38 37 36 35 34 33 Quality Y-PSNR [dB] 32 31 30 29 JVT/H.26L 28 MPEG-4 27 MPEG-2 26 H.263 25 0 500 1000 1500 2000 2500 3000 3500 Bit-rate [kbit/s]

  23. Left-hand side Right-hand side Comparison to MPEG-2, H.263, MPEG-4 Tempete CIF 30Hz 38 37 36 35 34 33 Quality Y-PSNR [dB] 32 31 30 29 JVT/H.26L 28 MPEG-4 27 MPEG-2 26 H.263 25 0 500 1000 1500 2000 2500 3000 3500 Bit-rate [kbit/s]

  24. JVT/H.26L Layer Structure Control Data Video Coding Layer Macroblock Data Partitioning Slice/Partition Network Adaptation Layer H.320 H.324 H.323/IP H.324M etc.

  25. Network Adaptation Layer • Tasks • Mapping of slice structure on transport layer • Setup, framing, encapsulation, interleaving, logical channels, closing, timing issues, synchronization, etc. • Transport of control and header information • Further network specific issues (feedback, prioritization,…) • The specification for each NAL includes • Verbal description • Encapsulation process (processing of slice structure) • Header and parameter set specification

  26. Network Adaptation Features • Slice Structure Coding • Slices for a specified number of macroblocks • Slices for a specified number of Bytes • Data Partitioning: header, motion vectors, Intra, and Inter transform coefficients • Signalling of header info and parameter sets via appropriate means

  27. Conclusions • JVT/H.26Lcontains a video coding and a network adaptation layer • Video coding layer is based on hybrid video coding and similar in spirit to other standards but with important differences • Bit-rate savings up to 50 % against any other standard • Network adaptation layer and error resilience features consider transport over MPEG2/H.222.0 • IP and 3GPP networks • Download of documents and software via anonymous ftp to standard.pictel.com/video-site

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