Linear Predictive Coding in Mixed-Excitation Linear Predictive Coder - MELP

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Linear Predictive Coding in Mixed-Excitation
Linear Predictive Coder - MELP

• MELP LPC LSFs demonstration
• Subject Adaptive Digital Signal Processing
• Scientific Postgraduate Study of Electronics,
  FESB, University of Split
• Professor dr. sc. Dinko Begušic Student Zoran
  Sambol

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Adaptive DSP - Study

• Subject program
• Literature - Simon Haykin Adaptive filter
  theory,
• Prentice Hall, 1991.
• Practical work based on MELP codec
• Study subject Speech coding - Presentation
• Three phases
• Adaptive Filter theory Seminar documents
• MELP codec adjustment - coding
• LPC LSF impact on MELP today presentation

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LPC show impact on MELP

• Task was given during MELP codec presentation
  September 2002.
• MELP codec is based on Linear Predictive Coding.
• Its LPC coder has 10th order
• My task was to show impact of LPC coder on
  overall MELP algorithm

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LPC web resources

• MELP documents - MELP Presentation page 3.
• DDVPC Homepage, Standard draft, ASPI digital
  Polycom, Texas Instruments and Noam Amir
  educational site.
• Most of the resources has samples coded in Matlab
• Google groups search Line Spectrum Pairs (LSP)
• Cite William M. Wiese Jr. In the real world,
  if two adjoining LSF values are equal we separate
  them by some small value like 35 50 Hz.
• What will happen if I change LSF that minimum
• distance is greater or less than 50 Hz?

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Encoder MELP LPC
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Decoder MELP - LPC
44/54 81.48
 
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MELP codec

• Windows console application
• What were changed?
• Command prompt additional argument
• ConsoleMelp a i dam9.bin o dam9.ccl f 150
• Parse function - void parse(int argc,char argv)
• Clamping function (sort LSFs and minimum
  separation)
• int lpc_clmp(float w, float delta, int p)
• Minimum LSF separation
• define BWMIN (50.02/FSAMP) / minimum LSF
  separation /
• Changed with float fLSFFrequency variable

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Recorder - Player

• Windows MELPCodec application
• Known interface
• Equalizer dialog
• 50 Hz default value
• Check button
• Log slider
• Easy canceling

Equalizer
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Batch Console applications

• Four different console application integrated
  using DOS Batch files
• Waveopt, ConsoleMelp, CCRemover and CCInserter
• Console applications with input and output
  parameters files
• ConsoleMelp a i dam9.bin o dam9.ccl f 150
• Waveopt syntax
• Waveopt.exe .bin .wav
• Easy deleting, renaming, directory creating
• Read Me file.

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Testing

• Well known record
• Using MelpCodec application as a recorder and my
  own voice.

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Results

• Subjective measurements
• Overvoicing
• Quality degradation Male and Female
• 180 samples segments impact on parameters
• Real measurement MOS (ITU)

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Windows MELP Codec

• Opening WAV and MELP (Channel coded) files
• Playing files
• Recording and storing waves in MELP useful format
• Recording Channel coded and MELP files
• Size comparison - Explorer utility
• Useful Equalizer

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MelpCodec with Equalizer
Education

• Useful adjustable tool
• Statistics (MOS, DAM, DRT measurement)
• Vocoder example for FEC
• Internet and database connection
• Visualization, Skins and additional GUI
  components
• Laboratory exercise Voice Coding subject
• Digital Signal Adaptive Processing - Subject
• Gathering measurement results
• Symposium article (IEEE, SoftCOM, ELMAR, MiPRO)
• Experience for some other voice and no-voice LP
  algorithms

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Thanks for your time!

• Contact
• Zoran Sambol, Siemens d.d. Put Brodarice 6, 21000
  Split
• Tel. [phone]
• zoran.sambol_at_st.tel.hr, zoran.sambol_at_siemens.hr