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Basic foilset Wavelet and H.263 Compression Technologies

Given by Tomasz Major at Rome Lab Quarterly Review for CIV on October 1 96. Foils prepared 22 February 97
Outside Index Summary of Material

H.263 standard
Improving H.263
Wavelet technology
Hybrid video codec System at NPAC
Video coder Architecture in NPAC System

Table of Contents for full HTML of Wavelet and H.263 Compression Technologies

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1 Wavelet+H.263 (1): H.263 standard
2 Wavelet+H.263 (2): improving H.263
3 Wavelet+H.263 (3): Wavelet technology
4 Wavelet+H.263 (4): Hybrid video codec
5 Wavelet+H.263 (5): Video coder scheme

Outside Index Summary of Material

HTML version of Basic Foils prepared 22 February 97

Foil 1 Wavelet+H.263 (1): H.263 standard

From Wavelet and H.263 Compression Technologies Rome Lab Quarterly Review for CIV -- October 1 96. *
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ITU-T Recommendation H.263 "Video Coding for Low Bitrate Communication", Dec. 1995
based on H.261 (MPEG-like method)
spectral redundancy: luminance + 2 color difference components - YUV (CCIR Recommendation 601)
spatial redundancy: blocked DCT transform coding (JPEG-like), Syntax-based Arithmetic Coding
temporal redundancy: half-pixel block motion prediction and compensation, Unrestricted Motion Vectors, Advanced Prediction, PB-frames
stream hierarchy: [I|P|PB]-frame, group of macroblocks, macroblock (motion vectors), block (8x8 DCT coefficients)
random access: to I-frame, implementor decides where to insert I-frame
HTML version of Basic Foils prepared 22 February 97

Foil 2 Wavelet+H.263 (2): improving H.263

From Wavelet and H.263 Compression Technologies Rome Lab Quarterly Review for CIV -- October 1 96. *
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Areas that still need improvement
  • robust video transmission (joint source/channel coding)
  • scalability (resolution, fidelity, framerate)
  • even lower bitrates (already low-motion P-frame requires only as little as ~300 bytes)
  • the method remains limited by the underlying block-based compression approach
H.263 implementation
  • public domain software from Lillevold, Telenor R&D
  • our enhancements:
    • periodical I-frame generation (random access, recovery from lost packets)
    • full motion vector search replaced with logarithmic search
    • most CPU time consuming routines optimized
  • result:
    • encoding time reduced 4x, real time operation (collaboratory applications)
    • very low bitrate, relatively good quality, one of the most advanced solutions for WWW
HTML version of Basic Foils prepared 22 February 97

Foil 3 Wavelet+H.263 (3): Wavelet technology

From Wavelet and H.263 Compression Technologies Rome Lab Quarterly Review for CIV -- October 1 96. *
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Compression algorithm:
  • separable, 2-dimmensional filtering: Discrete Wavelet Transform (DWT)
  • zerotree quantization: modified Embedded Zerotree Wavelet (EZW) of Shapiro (embedded bitstream)
  • adaptive arithmetic coding
  • luminance/chrominaces bitrates perfectly balanced through "passes"
Advantageous features:
  • scalability of quality(PSNR)/bitrate and embeded bitstream
  • universal code for a given feature, independent of magnification - frame size scalability
  • efficiency in terms of fidelity/comression ratio
  • support for watermarking, context based retrieval, robust channel coding
HTML version of Basic Foils prepared 22 February 97

Foil 4 Wavelet+H.263 (4): Hybrid video codec

From Wavelet and H.263 Compression Technologies Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
idea: periodical I-frames coded with wavelets
implementation:
  • codec/viewer running on CIF/QCIF formats
results for I-frame:
  • 0.75dB gain for QCIF,
  • 1.5dB for CIF
impact of I-frames on P-frames:
  • strong correlation for low-motion sequences, P-frame quality controlled with DCT quantization step
drawback:
  • decoding of wavelet-compressed frame takes ~2-3 times longer than decoding of DCT-compressed frame
possible enhancement:
  • transform speedup with all-pass filters (in progress)
HTML version of Basic Foils prepared 22 February 97

Foil 5 Wavelet+H.263 (5): Video coder scheme

From Wavelet and H.263 Compression Technologies Rome Lab Quarterly Review for CIV -- October 1 96. *
Full HTML Index
I-frames - DWT P-frames - DCT
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