Hi,
To reduce buzzy sound, low/high pass filter are used for excitation in
HTS-2.2 normal demo scripts.
You can check the effect by removing following line.
$line .= "$DFS -b $lfil | $VOPR -a $gendir/$base.unv | ";
The filter coefficients are described in
Analog-to-Digital Conversion of Voice by 2,400 bit/second Mixed
Excitation Linear Prediction (MELP). United States Department of
Defense. Dec. 1999.
Regards,
Keiichiro Oura
2013/2/5 Csapo Tamas Gabor <csapot@xxxxxxxxxxx>:
Hi All,
I have seen that in the HTS-2.2 Normal demo (pulse-noise excitation) some
noise is added above 6 kHz in the voiced regions:
Training.pl, lines 1958 ... 1966
# synthesize waveform
$lfil = `$PERL $datdir/scripts/makefilter.pl $sr 0`;
$hfil = `$PERL $datdir/scripts/makefilter.pl $sr 1`;
$line = "$SOPR -m 0 $gendir/$base.pit | $EXCITE -p $fs | $DFS -b $hfil
$gendir/$base.unv";
shell($line);
$line = "$EXCITE -p $fs $gendir/$base.pit | ";
$line .= "$DFS -b $lfil | $VOPR -a $gendir/$base.unv | ";
[...]
Is there any reason for adding noise to higher frequencies of the
pulse-noise excitation? This part of Training.pl wasn't there in the
HTS-2.1.1 version, and I haven't found any changelog or paper that would
explain why this has been introduced.
Thanks and Best regards,
Tamas