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RECONSTRUCTION OF MISSING PACKETS FOR CELP-BASED SPEECH CODERS

RECONSTRUCTION OF MISSING PACKETS FOR CELP-BASED SPEECH CODERS. Aamir Husain and Vladimir Cuperman School of Engineering Science, Simon Fraser University 1995 IEEE. Hung, Kuo-En NTHU/CS, Visual Communication Lab. Outline. Introduction System Overview Packet Reconstruction model

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RECONSTRUCTION OF MISSING PACKETS FOR CELP-BASED SPEECH CODERS

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  1. RECONSTRUCTION OF MISSING PACKETS FOR CELP-BASED SPEECH CODERS Aamir Husain and Vladimir Cuperman School of Engineering Science, Simon Fraser University 1995 IEEE Hung, Kuo-En NTHU/CS, Visual Communication Lab.

  2. Outline • Introduction • System Overview • Packet Reconstruction model • Spectral extrapolation • Simulation results • Implementation

  3. Introduction • Jayant – odd-even sample interpolation in PCM and DPCM systems. • Goodman – waveform substitution techniques such as pattern matching in PCM systems. • Erdol – waveform substitution based on interpolative techniques on short-time energy parameters in PCM systems. • Leung – vector linear prediction in voiced frame reconstruction in CELP coders over frame relay networks.

  4. System Overview • Base on • LD-CELP 16kb/s standard (G.728) • Variable rate CELP coder (VAR-CELP) • Frame Classifier • voiced, unvoiced, transition, silence • Switch three distinct codec configuration • 8.0 kb/s for voiced and transition frames • 4.3 kb/s for unvoiced frames • 667 b/s for silence

  5. Packet Reconstruction Model

  6. Spectral Extrapolation

  7. Simulation Results

  8. Implementation • Pitch Estimation

  9. Recovery Method Frame(n-1) Frame(n)

  10. Simulation Result (original) Original Speech

  11. Simulation Result (erasure) Erasure Speech (20% lost rate)

  12. Simulation Result (recovery) Recovery Speech

  13. original erasure recovery Result Compare

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