Implementation of DTW and DDTW algorithm on Cell Broadband Engine - - PowerPoint PPT Presentation

IBM - CVUT Student Research Projects

Implementation of DTW and DDTW algorithm on Cell Broadband Engine

Pavel Bazika (bazikp1@fel.cvut.cz)

IBM - CVUT Student Research Projects 2

What do DTW and DDTW do?

• DTW (dynamic time warping) is dynamic

programming based algorithm

• compares two time series of different length and

computes similarity measure

• DDTW is an improved version of DTW algorithm

Corresponding points

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DTW and DDTW applications

• Speech recognition
• Handwritten signature verification

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DTW calculation scheme

Minimum evaluation Time seq 1 Time seq 2 SIMDized distance computation Computed relation between series (minimum cost path)

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Computing Euclidean distance

• Four distances in one step are computed
• Distance matrix is distributed across

available SPU's

• Each SPU then calculates part of the matrix

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Proposed SIMDization of DTW

• In one step four

new cells are computed

• Reading from

memory to register is done only once per matrix cell

Computation direction

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Job distribution

Pipeline processing Matrix transfer Control signals

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Platform comparison

1000 2000 3000 4000 5000 6000 7000 1000 2000 3000 4000 5000 6000 7000 8000 9000

Matrix size Processing time [ms]

PPU PPU SIMD SPU Pentium 4

from here SPU's are the best

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What I've done

• Distance matrix filling SIMDized
• Minimum computing also SIMDized
• Work distribution to pipelined SPU's
• Result backtracking in filled matrix by PPU
• Implemented on different platforms
• Implementations measured and compared

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Future work

• Asynchronous DMA transfers
• Tune up algorithms parameters