PowerPoint-Pr

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Telematics/Network Engineering
Experimental study on scan order and motion
compensation in lossless video
coding
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Scan order and motion compensation in lossless
coding
Team

• School of Telematics and Network Engineering
• Carinthia Tech Institute, Austria
• Team of students Stefan A. Kramatsch
• Agnes Gruber, Alexander Krapesch, Stefan
  Matschitsch, Thomas Mayerdorfer,
• Stefan Miedl, Stefan Moser, Martin Tschinder,
  Stefan Zorn-Pauli
• Project leader
• Dr. Andreas Uhl
• Head of School
• Dr. Herbert Stögner

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Presentation Outline
Structure

• Motivation
• Basics
• Realization
• Results
• Conclusion

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Motivation
Project goals

• Semester Project in Compression Techniques 2
• Alternative way to view videos
• Make data compression more concrete
• Experience usage of programming languages in
• picture processing

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Basics(1)
Lossless video coding

• Mainly used in medical applications required
  by legal
• regulation
• JPEG, JPEG-LS, lossless JPEG 2000 on per-frame
  basis
• Temporal redundancy ignored
• ? no motion compensation
• ? limited compression performance

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Basics(2)
Classical view of video data
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Basics(3)
Classical view of video data

• Temporally ordered still images
• Frames are similar
• ? basis for motion compensated hybrid coding
• ? basis for application of 3D video techniques
• Possible to form a 3D block of video data

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Basics(4)
Different views on the video block
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Basics(5)
Different views on the video block

• Normal view Horizontal view Vertical view

Frame 40 Frame 112 Frame 112
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Basics(6)
Scan order
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Basics(7)
Streams stream compression

• File seen as a stream of gray values
• Written to a .txt file
• File compressors used
• - Arithmetical coder
• - Runlength Encoding (RLE)
• - Huffman Coding

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Basics(8)
Motion compensation Block matching

• Scene divided into non-overlapping block
  regions
• Compare blocks (current lt-gt reference frame)
• ? motion vector for each block
• Best match based on mean square error
• ? Stored as prediction
• Current frame prediction residual frame
• to be compressed
• Common for lossy compression

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Basics(9)
Motion compensation Block matching

• Usage in lossless coding
• Normally temporal based
• ? now spatially

Reference Frame 1 Residual Frame 40
Vertical View
Horizontal View
Frame 112 non BM and BM
Frame 112 non BM and BM
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Realization(1)
Implementation

• Input all frames of a video (in .pgm format)
• Build the 3D video block
• Cut normally, vertically and horizontally
• With or without blockmatching
• Frame based or stream based computing
• Implemented in c

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Realization(2)
Implementation of block matching

• Matlab application
• Based on one reference frame
• all remaining residual frames
• Searchwindow 32x32 Pixels
• Blocksize 16x16 Pixels
• Similar Block search based on Root Mean Square

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Realization(3)
Lossless frame compression

• JPEG 2000 Lossless mode
• Java Implementation JJ2000 (http//jj2000.epfl.ch
  )
• Standard options except
• Lossless Mode ( lossless on )
• Cancel console output ( verbose off )

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Realization(4)
Testvideos (Spatial x Temporal resolution)

• Akiyo (176 x 144 x 300) low movement
• Carphone (176 x 144 x 383) high movement
• Claire (176 x 144 x 494) low movement
• Football (720 x 486 x 60) high movement
• Foreman (176 x 144 x 49) high movement
• Grandma (176 x 144 x 871) low movement
• Mobile (720 x 576 x 40) high movement
• Mother and Daughter (176 x 144 x 962) low
  movement
• Salesman (176 x 144 x 449) low movement

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Results
Compression Ratio
Low movement High Movement Stream
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Conclusion(1)
Without Blockmatching

• Improved frame based compression by alternative
  views
• Exploitation of spatial instead of temporal
  redundancies through alternative scan order
• Little computational demand compared to BM
• Increased memory demand and coding delay
• Stream compression has little effect

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Conclusion(2)
With Blockmatching

• The increase of compression ratio does not
  justify the usage of BM algorithms in case of
  alternative views
• Superior results for 1D based compression
  algorithms

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Telematics/Network Engineering
Thank you for your attention!