THE H.264/MPEG4 AND ITS APPLICATIONS
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The document summarizes the H.264/MPEG4 Advanced Video Coding standard. It was developed by the Joint Video Team (JVT) which included the ITU-T Video Coding Experts Group and ISO/IEC Moving Picture Experts Group. The goals were to improve coding efficiency, enhance error robustness, simplify syntax, and increase flexibility. Key features of H.264 include enhanced motion prediction, small block size transforms, an adaptive in-loop deblocking filter, and improved entropy coding. These allow for approximately 50% bit rate savings over prior standards. Evaluation showed it can achieve near transparent quality at lower bit rates than previous standards.
THE H.264/MPEG4 AND ITS APPLICATIONS
- 1. THE H.264/MPEG4 ADVANCED VIDEO CODING STANDARD AND ITS APPLICATIONS DATA COMPRESSION ASSIGNMENT Aris C. Risdianto (20132095)
- 2. History of H.264/MPEG4-AVC •Project by JVT = Joint Video Team •ITU-T Q.6/SG16 (VCEG - Video Coding Expert Group) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG – Moving Picture Expert Group) •Approve on May 2003 (by ITU-T) and October 2003 (by ISO/IEC) •Fidelity Range Extension (FRExt)
- 3. The Goals of JVT •Improved Coding Efficiency •Enhanced Error Robustness •Simple Syntax Specification •Increase Flexibility and Scope of Applications
- 4. H.264/JVT Applications •Entertainment Video (Broadcast and Storage) •Conversational Services (H.323 and 3GPP) •Video Streaming (3GPP and IP/RTP/RTSP) •Other Applications (3GPP Messaging Services & Digital Camcorder)
- 5. H.264/AVC Video Encoder Structure • Needed for flexibility and customizability • Designed to cover : • VCL (Video Coding Layer) by efficiently represent content • NAL by providing header information for any transport layer or storage media
- 6. H.264/AVC Profiles •Baseline : core compression and error resilience •Main : high compression and quality •Extended : features for efficient streaming
- 7. Macro-Block (Picture Partitioning/Slice) •Slices • Pieces of picture splitting • Sequence of macroblock •Macroblock • 16x16 luma samples • 2x8x8 chroma samples • Depend on each other within a slice
- 8. Flexible Macroblock Ordering (FMO) •Slice Group • 1 or more slices • Pattern map by macroblock allocation map •Macroblock Allocation Map Types (Interleaved, Dispersed, Foreground/Leftover)
- 10. H.264 Intra Prediction • 8x8 spatial luma prediction – values predicted from neighboring decoded samples • 8 different prediction direction (mode 0,1,3-8) and averaging (mode 2)
- 11. Multi-Frame Motion-Compensated Prediction •Use for inter-frame prediction in P and B slices •Encoder and Decoder use more than one prior coded/decoded picture as reference •Inter-prediction of B slices : list0, list1, bi- predictive, direct prediction
- 12. H.264 4x4 Transform •Transform coding of the prediction residual •MxN transform stage depend on macroblock coding •Small block-size transform lower computation and reduce artifacts
- 13. Quantization •Scalar Quantization using URQ (Uniform- Reconstruction-Quantizers) with 52 steps •Logarithmic Step Size (6 increasing quantization parameter = double step size) •Step Size can be change at macroblock level •Transform Coefficients scanned in zig-zag fashion
- 14. Entropy Coding •Exponential-Golomb Code for all syntax elements •Context Adaptive Variable Length Coding (CAVLC) for coding transform coefficient • Change VLC tables depends various transmitted syntax elements •Context-Adaptive Arithmetic Coding (CABAC) • Binarization, context-modelling, binary arithmetic coding • Efficient implementation due to multiplication-free
- 15. In-loop de-blocking filter •Improve subjective quality and PSNR of decoded picture by adaptive filtering removes blocking artifacts •If absolute different between samples near block edge, it is blocking artifacts and should be reduced •Filtering affects the edges of 4x4 block structures
- 16. R-D Curve • HP = High Profile, MP = Main Profile • HP better than MP, better frequency selection in 8x8 luma transform • HP with CABAC achieves 59% over entire test
- 17. Average Bit Rate Savings
- 18. Mean Opinions Scores (MOS) • H.264/AVC almost the same quality based on user perspective with original video without compression
- 19. Conclusion •H.264/AVC enhanced coding efficiency and flexibility for effective usage •Important differences : • Enhanced motion prediction • Small block size transform • Adaptive in-loop deblocking filter • Enhanced entropy coding •Approx. 50% bit rate savings from prior standard
- 20. References • Thomas Wiegand, Gary J. Sullivan, Gisle Bjøntegaard, and Ajay Luthra, “Overview of the H.264/AVC Video Coding Standard”, IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 13, NO. 7, JULY 2003. • Detlev Marpe, Thomas Wiegand, and Gary J. Sullivan, “The H.264/MPEG4 Advanced Video Coding Standard and its Applications”, IEEE Communications Magazine, August 2006. • Bernd Girod, “Overview: Video Coding Standards”, EE398B Image Communication II, Lecture Notes,