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whistle encoder
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| use warnings; | |
| use strict; | |
| my $data = $ARGV[0] // "OHAI!"; | |
| my $fs = 96000; | |
| my $fc = 2600; | |
| my $bps = 100; | |
| my $risetime = 0.09; | |
| my $padding = 0.5; | |
| my $f_am = 20; | |
| my $vol_am = 0.18; | |
| my $sig_vol = 1; | |
| my $noise_vol = 4; | |
| my $noise_shift = 1.0; | |
| my $lp_alfa_fm = 0.004; | |
| my $lp_alfa_noise = 0.009; | |
| my $fshift = 0.0769 * $fc; | |
| my $riseband = 0.7 * $fc; | |
| $data = "\xAA\xA7".chr(length($data)).$data; | |
| my $dur = length($data) * 8 / $bps; | |
| my @harmonics = (1, 0.141, 0.022, 0.0398, 0.0282, 0.0063); | |
| my @harmonics_noise = (1, 0.9, 0.8, 0.7, 0.6, 0.5); | |
| open my $stream, '|-', "sox -t .s16 -c 1 -r $fs - whistle.wav" | |
| or die $!; | |
| print $stream pack("s", 0) x ($padding * $fs); | |
| my $t = 0; | |
| my $prevy = 0; | |
| my $prev_f = $fc - $riseband; | |
| my $f, my $f_filt, my $vol; | |
| my $ph_am, my $ph_fm; | |
| for (0.. ($risetime+$dur+$risetime) * $fs) { | |
| $t += 1/$fs; | |
| if ($t < $risetime) { | |
| $f = $fc - $riseband + ($t/$risetime * $riseband); | |
| $vol = $t/$risetime; | |
| $harmonics[0] = ($t < $risetime * .66 ? 0 : | |
| ($t-$risetime * .66) / ($risetime * .66)); | |
| } elsif ($t > $risetime + $dur) { | |
| $f = $fc - ($t-$dur-$risetime) / $risetime * $riseband; | |
| $vol = 1 - ($t-$dur-$risetime) / $risetime; | |
| $harmonics[0] = ($t-$dur-$risetime > $risetime * .33 ? 0 : | |
| 1 - (($t-$dur-$risetime) * .33) / ($risetime * .33)); | |
| } else { | |
| $f = $fc; | |
| $harmonics[0] = 1; | |
| my $bitind = int(($t - $risetime) * $bps); | |
| my $byte = substr($data, int($bitind / 8),1); | |
| my $bit = ((ord($byte) >> ($bitind % 8)) & 1); | |
| $f = ($bit-.5)*$fshift + $fc; | |
| $vol = 1; | |
| } | |
| $f_filt = $lp_alfa_fm * $f + (1-$lp_alfa_fm) * $prev_f; | |
| $prev_f = $f_filt; | |
| my $noise = (rand()-.5); | |
| my $noise_filt = $lp_alfa_noise*$noise + (1-$lp_alfa_noise) * $prevy; | |
| $prevy = $noise_filt; | |
| $ph_fm += 2 * 3.14159 * $f_filt / $fs; | |
| $ph_am += 2 * 3.14159 * $f_am / $fs; | |
| my $total = 0; | |
| for (0..$#harmonics) { | |
| my $s = $harmonics[$_] * sin(($_+1) * $ph_fm); | |
| $total += $sig_vol * $s * (1 + $vol_am*sin($ph_am)); | |
| $total += $noise_vol * $noise_filt * $harmonics_noise[$_] * | |
| sin(($_+1) * ($ph_fm * $noise_shift)); | |
| } | |
| print $stream pack("s", 0.2 * $vol * $total * 0x7FFF); | |
| } | |
| print $stream pack("s", 0) x ($padding * $fs); | |
| close $stream; |
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