Linear Predictive Coding in MixedExcitation Linear Predictive Coder

Linear Predictive Coding in Mixed-Excitation Linear Predictive Coder - MELP LPC LSFs demonstration Subject: Adaptive Digital Signal Processing Scientific Postgraduate Study of Electronics, FESB, University of Split Professor: dr. sc. Dinko Begušić Student: Zoran Sambol 9/9/2020 LPC impact on MELP 1

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 9/9/2020 LPC impact on MELP 2

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 10 th order ® My task was to show impact of LPC coder on overall MELP algorithm 9/9/2020 LPC impact on MELP 3

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? 9/9/2020 LPC impact on MELP 4

Encoder MELP – LPC 9/9/2020 LPC impact on MELP 5

Decoder MELP - LPC Parameters Voiced Unvoiced LSF’s 25 Fourier Magnitudes 25 8 Gain (2 per frame) 8 8 Pitch (overall voicing) 7 Bandpass voicing 7 4 Aperiodic Flag 1 - Error protection - 13 Sync Bit 1 1 Total bits/ 22. 5 ms Frame 54 54 - - 44/54 = 81. 48% 9/9/2020 LPC impact on MELP 6

MELP codec ® Windows console application ® What were changed? ® Command prompt – additional argument ® ® ® Console. Melp –a –i dam 9. bin –o dam 9. ccl –f 150 Parse function - void parse(int argc, char **argv) Clamping function (sort LSFs and minimum separation) l int lpc_clmp(float *w, float delta, int p); ® Minimum LSF separation ® ® 9/9/2020 #define BWMIN (50. 0*2/FSAMP) /* minimum LSF separation */ Changed with float f. LSFFrequency variable LPC impact on MELP 7

Recorder - Player ® Windows MELPCodec application ® Known interface ® Equalizer dialog ® 50 Hz default value ® Check button ® Log slider ® Easy canceling Equalizer 9/9/2020 LPC impact on MELP 8

Batch – Console applications ® Four different console application integrated using DOS Batch files ® ® Waveopt, Console. Melp, CCRemover and CCInserter Console applications with input and output parameters – files ® ® Console. Melp –a –i dam 9. bin –o dam 9. ccl –f 150 Waveopt syntax: ® ® Waveopt. exe [*. bin | *. wav] Easy deleting, renaming, directory creating – ® 9/9/2020 Read Me file. LPC impact on MELP 9

Testing ® Well known record ® Using Melp. Codec application as a recorder and my own voice. 9/9/2020 LPC impact on MELP 10

Results ® Subjective measurements ® Overvoicing ® Quality degradation – Male and Female ® 180 samples segments impact on parameters ® Real measurement – MOS (ITU) 9/9/2020 LPC impact on MELP 11

Windows – MELP Codec ® ® ® 9/9/2020 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 LPC impact on MELP 12

Melp. Codec 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, Soft. COM, ELMAR, Mi. PRO) Experience for some other voice and no-voice LP algorithms 9/9/2020 LPC impact on MELP 13

Thanks for your time! Contact: Zoran Sambol, Siemens d. d. Put Brodarice 6, 21000 Split Tel. +385 21 390 936 zoran. sambol@st. tel. hr, zoran. sambol@siemens. hr 9/9/2020 LPC impact on MELP 14