Audio Video coding Standard of (AVS) ChinaVideo coding standards [5]Video coding standards [4], [5]Development stages of AVS [3]Parts of AVS [3]Applications of the commonly used parts of AVS China [3]Major and Minor coding tools used in AVS part 2 [1]AVS encoder structure [1]Different picture types [2]MB level Adaptive frame coding [2]Intra Prediction [2]Luma Intra Prediction difference between AVS and H.264 [6]Intra prediction modes for Chroma [2]Inter Prediction and Motion Compensation [1]Reference Frame [1]Reference Index [1]Motion Vector Prediction [3]Slide 18Interpolation for Luma [3]Slide 20Interpolation for Chroma [3]Slide 22Forward and Backward Prediction [1]Slide 24Bi-directional Prediction [1]MV Derivation for Skip and Direct Mode [1]MV Derivation for Symmetric Mode [1]Pre-scale Transform [3]AVS 8×8 ICT Matrix [3]Context-based Adaptive 2D Variable Length Coding (CA-2D-VLC) [1]Slide 31Deblocking Filter [3]Slide 33AVS Part-2 vs H.264/AVC [4], [6]Slide 35AVS Part-2 performance [1], [A]Container.qcif sequence [A]Decoded frame [A]Claire.qcif sequence [A]Slide 40News.qcif sequence [A]Slide 42Slide 43Slide 44Audio Video coding Standard of (AVS) China Submitted by,Swaminathan SridharEE 5359 Multimedia Processing ProjectVideo coding standards [5]Video coding standards [4], [5]MPEG-2 (DVD, MPEG-2 (DVD, SDTV, HDTV)•More than 10 years old•Compression efficiency•4.7GB DVD – 2 hours movie (5.3Mbps)•18GB – 2 hours high definition movie (20Mbps)MPEG-4 AVC/H.264 (Multimedia applications)•Advanced coding techniques•Multiple-reference frame prediction•Context-based adaptive binary arithmetic coding•High compression efficiency•1.5~2Mbps for SD, 6~8Mbps for HD•Save storage space, channel bandwidth, and frequency spectrumDevelopment stages of AVS [3]December 2003•In the 7th AVS meeting, AVS-video (part-2) and AVS-system (part-1) was finalized.December 2004•In the 11th AVS meeting, AVS-M (part-7) was finalized March 2005•Authentication of ‘AVS101’ – high definition decoding chipMay 2005•AVS Industry Alliance was set up.June 2005•Joint AVS/ISMA workshop on IPTV standard and industry forumFebruary 2006•AVS part-2 was announced as a national standard.Parts of AVS [3]Applications of the commonly used parts of AVS China [3]AVS Part-2: HD/SD video•Jizhun Profile & Zengqiang Profile•HD broadcasting•High density storage media•Video surveillances•Video on demandAVS Part-7: Mobility video•Jiben Profile•Record and local playback on mobile devices•Multimedia Message Service (MMS)•Streaming and broadcasting•Real-time video conversationMajor and Minor coding tools used in AVS part 2 [1]Major tools•Interlace handling: Picture-level adaptive frame/field coding (PAFF)•Macroblock-level adaptive frame/field coding (MBAFF)•Intra prediction: 5 modes for luma and 4 modes for chroma•Motion compensation: 16x16/16x8/8x16/8x8 block size•Resolution of MV: 1/4-pel, 4-tap interpolation filter•Transform: 16bit-implemented 8x8 integer cosine transform•Quantization and scaling: scaling only in encoder•Entropy coding: 2D-VLC and Arithmetic Coding•In-loop deblocking filterMinor tools•Motion vector prediction•Adaptive scanAVS encoder structure [1]Different picture types [2]Three types of picture are defined by AVS namely • Intra pictures (I) •Predicted pictures (P)- At most two reference frames (P or I) •Interpolated pictures (B)- two reference frames (I or P or both)MB level Adaptive frame coding [2]MB-level adaptive frame/field coding (MBAFF)•The frame/field encoding decision is made independently for each vertical pair of macro blocks in a frame.•A frame consisting of both moving and non-moving regions is coded more efficiently by:•frame mode for the non-moving regions•field mode for the moving regions•MBAFF is much more complicated than PAFF– zig-zag scanning– motion vector prediction– intra prediction– deblocking– context modeling in entropy coding• The advantage compared with the MBAFF in H.264– A field-coded MB belonging to the bottom field CAN use the top field ofthe same frame as a reference for motion predictionIntra Prediction [2]• Five different modes for luma is as shown belowLuma Intra Prediction difference between AVS and H.264 [6]AVS•Block size: 8x8•5 modes•Reference pixels low pass filtered•Advantages: low complexity with less modesH.264•Block size: 4x4 or 16x16•9 modes for 4x4 and 4 modes for 16x16•Advantage: better prediction•Disadvantage: more complexIntra prediction modes for Chroma [2]• 4 Prediction modes for ChromaInter Prediction and Motion Compensation [1]•At most 2 frames can be stored as reference for motion prediction.•Block size of motion prediction and compensation– 16x16, 16x8, 8x16 and 8x8•In each MB, the number of MV pairs can be 1, 2 or 4, depending on the block size of MC.•MVD, the difference between the predicted MV and the real MV, is coded.•Resolution of MV– 1/4-pixel for luma– 1/8-pixel for chroma• Motion prediction modes•– Forward•– Backward (only applicable for B frame)•– Bi-directional (only applicable for B frame)•Skip•Direct•SymmetricReference Frame [1]•At most 2 reference frames are used. No matter•PAFF or MBAFF is used,– if the current MB is frame-coded, 2 frames can be used as reference for motion prediction.– if the current MB is field-coded, 4 fields can be used.• Reference index should be coded with every MC block to indicate which reference picture is usedReference Index [1]Motion Vector Prediction [3]Motion Vector Prediction [3]•Use A, B, C, D’s MV (MVA, MVB, MVC and MVD) to predict E’s MV (PredMVE)•Reason: reduce the bits for coding MV•Method:•Geometrical median of MVA, MVB, MVC•VAB = Dist(MVA, MVB)•VBC = Dist(MVB, MVC)•VCA = Dist(MVC, MVA)•FMV = Median(VAB, VBC, VCA) where Dist(MV1, MV2)=|x1-x2|+|y1-y2|.•Determine PredMVE•If FMV equals VAB, PredMVE=MVC.•If FMV equals VBC, PredMVE=MVA.•If FMV equals VCA, PredMVE=MVB.Interpolation for Luma [3]•Resolution– Quarter-pixel•Filter– Half-pixel•Blue: [-1, 5, 5, -1]– Quarter-pixel•White: [1, 7, 7, 1]•Red: bilinearInterpolation for Luma [3]Interpolation for Chroma [3]Interpolation for Chroma [3]•BilinearpredMatrix[x,y] = [(8–dx)×(8–dy)×A + dx×(8dy)×B + (8–dx)×dy×C + dx×dy×D]/64Forward and Backward Prediction [1]•Forward prediction•MV pointing only to the previous frame•Get reference block
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