code given $\%\%$ Quantization$\_$SQNR $-$ Histogram of Sounds

$\%$ Evaluate the SQNR and sound volume distributions

clear; close all; clc;

isOctave $=$ exist$(\text{'}$OCTAVE$\_$VERSION', 'builtin'$)$ ~$=0$; $\%1$ if using Octave

if $($isOctave$)$ Fsize $=14$; else Fsize $=12$; end;

nbits $=8$; mu $=255$;

nbins $=30$;

$\%[$y$,$fs$]=$ audioread$(\text{'}$RockGuitar$.$wav'$)$;

$[$y$,$fs$]=$ audioread$(\text{'}/$home$/$cgreco$/$Music$/$Bach$/$Bach$\_$Prelude$\_$in$\_$E$.$wav'$)$;

y$1\_$max $=$ max$($abs$($y$($:$,1)))$;

y$2\_$max $=$ max$($abs$($y$($:$,2)))$;

$\%$ Scale signal

y$($:$,1)=$ y$($:$,1)/$y$1\_$max;

y$($:$,2)=$ y$($:$,2)/$y$2\_$max;

$\%$ Signal power

ndat $=$ length$($y$($:$,1))$;

py$1=$ sum$($y$($:$,1).^2)/$ndat;

py$1\_$dB $=$ pow$2$db$($py$1)$;

py$2=$ sum$($y$($:$,2).^2)/$ndat;

py$2\_$dB $=$ pow$2$db$($py$2)$;

$\%\%$ Histograms for each channel

if isOctave

$[$n$1,$h$1]=$ hist$($y$($:$,1),$nbins$)$;

n$1$sum $=$ sum$($n$1)$;

n$1=$ n$1/$n$1$sum;

$[$n$2,$h$2]=$ hist$($y$($:$,2),$nbins$)$;

n$2$sum $=$ sum$($n$2)$;

n$2=$ n$2/$n$2$sum;

else

$\%$ h$1=$ histogram$($y$($:$,1),$nbins$)$;

$\%$ h$2=$ histogram$($y$($:$,2),$nbins$)$;

$[$n$1,$h$1]=$ hist$($y$($:$,1),$nbins$)$; $\%$ Not tested in Matlab

n$1$sum $=$ sum$($n$1)$;

n$1=$ n$1/$n$1$sum;

$[$n$2,$h$2]=$ hist$($y$($:$,2),$nbins$)$;

n$2$sum $=$ sum$($n$2)$;

n$2=$ n$2/$n$2$sum;

end

$\%$ Display Histograms

figure$(\text{'}$position$\text{'},[10,10,900,400])$

subplot$(1,2,1)$; bar$($h$1,$n$1,1)$;grid;

xlabel$(\text{'}$Signal Magnitude'$)$;ylabel$(\text{'}$Count Frequency'$)$;

title$([\text{'}$Channel $1,$ P$\_\{$avg$\}=\text{'},$num$2$str$($py$1\_$dB$),\text{'}$ dB$\text{'}])$;

set$($gca$,$'Fontsize',Fsize$)$

subplot$(1,2,2)$;bar$($h$2,$n$2,1)$;grid;

xlabel$(\text{'}$Signal Magnitude'$)$;ylabel$(\text{'}$Count Frequency'$)$;

title$([\text{'}$Channel $2,$ P$\_\{$avg$\}=\text{'},$num$2$str$($py$2\_$dB$),\text{'}$ dB$\text{'}])$;

set$($gca$,$'Fontsize',Fsize$)$

$\%$ Quantization$\_$SQNR

SQNR$\_$uni $=10*$log$10(3*$py$1)+6*$nbits;

SQNR$\_$comp $=10*$log$10(3/($log$(1+$mu$)^2))+6*$nbits;

$\%\%$ Instantaneous Power Histogram

ycomb $=($y$($:$,1).^2+$ y$($:$,2).^2)/2$;

$[$n$,$hpow$]=$ hist$($ycomb$,$nbins$)$;

nsum $=$ sum$($n$)$;

n $=$ n$/$nsum;

figure$(\text{'}$position$\text{'},[10,10,900,400])$

subplot$(1,2,1)$;bar$(($hpow$),$n$,1)$;grid;

xlabel$(\text{'}$Instantaneous Signal Power $($W$)\text{'})$;ylabel$(\text{'}$Count Frequency'$)$;

title$([\text{'}$Average Instantaneous Power $($Channels $1$ and $2)\text{'}])$;

set$($gca$,$'Fontsize',Fsize$)$

hpow$\_$dB $=$ pow$2$db$($hpow$)$;

subplot$(1,2,2)$;bar$($hpow$\_$dB$,$n$,10)$;grid;

xlabel$(\text{'}$Instantaneous Signal Power $($dB$)\text{'})$;ylabel$(\text{'}$Count Frequency'$)$;

title$([\text{'}$Average Instantaneous Power $($Channels $1$ and $2)\text{'}])$;

set$($gca$,$'Fontsize',Fsize$)$

$\%$ SQNR

sqnr $=6*$nbits $+10*$log$10(3*$hpow$)$;

figure$()$

bar$($sqnr$,$n$,10)$;grid;

xl $=$ xlim;

xval $=($xl$(2)-$ xl$(1))*0\mathrm{.}45+$ xl$(1)$;

xlabel$(\text{'}$SQNR $($dB$)\text{'})$;ylabel$(\text{'}$Count Frequency'$)$;

title$([\text{'}$Instantaneous SQNR $($uniform$)\text{'}])$;

text$($xval$,0\mathrm{.}8,[\text{'}$SQNR$\_\{$uniform$\}=\text{'},$num$2$str$($SQNR$\_$uni$)],$'Fontsize',Fsize$)$;

text$($xval$,0\mathrm{.}7,[\text{'}$SQNR$\_\{$compressed$\}=\text{'},$num$2$str$($SQNR$\_$comp$)],$'Fontsize',Fsize$)$;

text$($xval$,0\mathrm{.}6,[\text{'}$nbits $=\text{'},$int$2$str$($nbits$),\text{'},\backslash$mu $=\text{'},$int$2$str$($mu$)],$'Fontsize',Fsize$)$;

set$($gca$,$'Fontsize',Fsize$)$

$\%\%$ mu Law Compression

v$=$max$($abs$($y$($:$,1)))$;

xdmu$=$zeros$($length$($y$($:$,1)),2)$; $\%$ set up storage for decimated signal

xdmu$($:$,1)=$compand$($y$($:$,1),$mu$,$v$,\text{'}$mu$/$compressor$\text{'})$;

xdmu$($:$,2)=$compand$($y$($:$,1),$mu$,$v$,\text{'}$mu$/$compressor$\text{'})$;

$[$n$3,$h$3]=$hist$($xdmu$($:$,1),$nbins$)$;

n$3$sum $=$ sum$($n$3)$;

n$3=$ n$3/$n$3$sum;

$[$n$4,$h$4]=$hist$($xdmu$($:$,2),$nbins$)$;

n$4$sum $=$ sum$($n$4)$;

n$4=$ n$4/$n$4$sum;

figure$(\text{'}$position$\text{'},[10,10,900,400])$

subplot$(1,2,1)$;bar$(($h$3),$n$3,1)$;grid;

xlabel$(\text{'}$Compressed Signal Magnitude'$)$

ylabel$(\text{'}$Count Frequency'$)$

title$([\text{'}\backslash$mu Law Distribution. Channel $1(\backslash$mu $=\text{'},$int$2$str$($mu$),\text{'})\text{'}])$

set$($gca$,$'Fontsize',Fsize$)$

subplot$(1,2,2)$;bar$(($h$4),$n$4,1)$;grid;

xlabel$(\text{'}$Compressed Signal Magnitude'$)$

ylabel$(\text{'}$Count Frequency'$)$

title$([\text{'}\backslash$mu Law Distribution, Channel $2(\backslash$mu $=\text{'},$int$2$str$($mu$),\text{'})\text{'}])$

set$($gca$,$'Fontsize',Fsize$)$