FHTW Wavelet Based Video Compression Using Long Term Memory Motion-Compensated Prediction and Context-based Adaptive Arithmetic Coding D.Marpe, H.L.Cycon, Th.Wiegand FHTW Berlin (University of Applied Sciences) Heinrich Hertz Institut Berlin Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Outline Introduction Wavelet-Based Transform Coding Video Coding Experimental Results Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Introduction Very Low Bit Video Codecs (< 64 kbit/s): MPEG-4 (ISO standard) H261/H263 (++) (ITU-T standard) H26L: about to be defined, (TML8/9 exists) DVC wavelet based codec proposed for new MPEG-4 Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand DVC Codec DVC is a new very low bit rate hybrid video coding scheme based on wavelet coding (DWT) effective entropy coding (PACC+AAC) Overlapped Block Motion Compensation (OBMC) Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Transform Coding Image Rec.Image compressed bit stream lossless decorelation lossy quantizer lossless entropy coder Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Discrete Wavelet Transform For DWT we use a new one-parametric family of biorthogonal filters defined by Petukhov, with: More degrees of freedom in the design than for commonly used biorthogonal FIR-filters Better performance than most frequently used biorthogonal 9/7-(FBI)-filter Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Biorthogonal Wavelet-Filters Optimal choice of parameters (obtained by numerical simulations): Analysis Filter Synthesis filter I-Frame a = 8 P-Frame a = 25 Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Quantizer scalar quantizer (replaces the continuous gray value function by step functions) uniform (equal bin sizes) with extended dead zone controls compression ratio Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Entropy Coder Precoder (PACC) binary adaptive arithmetic coding Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Precoding (PACC) Partitioning of quantized coefficients into 3 subsources: significance map, magnitude map and sign map Aggregation of zero quantized coefficients into „zerotrees“ or run length coding Conditional Coding of elements of each subsource using appropriately designed models Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Precoder encoding quantized data Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Conditional Coding significance maps use templates depending on scale and orientation of a band magnitude maps use estimations of the significance or their 8-neighborhood sign maps use contexts build of 2 preceding signs with respect to the orientation of a given band Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Context Templates for CC Significance CC using orientation & scale Magnitude CC using 8-Ngbhd Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Transform Coder DWT Q Arithmetic Coder Pre Bit Stream Video Input Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Video MC Prediction Coding DWT Q Arithmetic Coder Pre Bit Stream IDWT IQ + Reference Frame Buffer OBMC BME - Video Input Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand DVC Coding Scheme DWT Q Arithmetic Coder Pre Bit Stream IDWT IQ + Reference Frame Buffer OBMC BME - Video Input Inter/intra frame Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Motion Model Block Motion Estimation with different block sizes and macro block modes motion search by 1/4 pel accuracy OBMC using cosine shaped weight functions w = w1w2 Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Macro block partition modes Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Overlapped Block Matching w1 w2 Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Summary of Methods 3-level dyadic decomposition DWT (biorthogonal filter pairs) uniform quantization with central widened deadzone sophisticated entropy coder (PACC + binary adaptive arithmetic coder) sophisticated motion model (H26L) Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Experimental Results DVC codec outperforms optimized MPEG-4 codec by PSNR gains between 1 and 3 dB DVC shows comparable results to H26L TML8 (tops H26L in some cases by 0.5 dB) Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Test Conditions MPEG-4 coder: 1/4-pel motion vector accuracy search range 32 pels 2 B frames (IBBPBBP...) global MC DVC coder 1/4-pel motion vector accuracy search range 32 pels No B frames! 5 reference pictures arithmetic coding Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand DVC vs MPEG4 Fm Frame 22 Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Conclusions Wavelet video codecs are still in business! (for still images: JPEG 2000) DVC very low bit coder outperforms MPEG-4 (ASP) DVC has comparable results to H26L (TML8) presented as proposal for new MPEG4, Sidney 2001 (ranks 3rd after H26L w/o B frames) Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Future Work implementing B-frames real-time version of a very low bit rate codec DVC optimizing motion estimation process w.r.t. (OBMC) Waveletprojekt /HHI ,Cycon/Marpe/Wiegand

Waveletprojekt /HHI ,Cycon/Marpe/Wiegand Visual Demo ? Waveletprojekt /HHI ,Cycon/Marpe/Wiegand