Perl Synthsizer

synth.pl

$SPS = 16000;
$PI = 3.14159265359;
$PITCH_ROLL = 1;

$BPM = 170;

%FREQS = (
    A => 440.000,
    B => 493.883,
    C => 261.626,
    D => 293.665,
    E => 329.628,
    F => 349.228,
    G => 391.995
);

$HALF_STEP = 2. ** (1. / 12);

sub add_phrase{
    my ($track, $notes, $offset_bars, $inst) = @_;

    my $pos = $offset_bars * $SPS * 60 * 4 / $BPM;
    my $falloff_beats = $FALLOFF * $SPS * 60 * 4 / $BPM;
    my $attack_beats = $ATTACK * $SPS * 60 * 4 / $BPM;

    my @notes = split /\s+/, $notes;
    my $last_dur;
    for my $note(@notes){
        my ($key, $acc, $octave, $mult, $div) = $note =~ /([_A-G])([b#]?)(?:(-?\d+))?(?:[*](\d+))?(?:[\/](\d+))?/ or next;

        my $dur = $mult + $div? $SPS * 60 * 4 * ($mult||1) / $BPM / ($div||1): $last_dur;

        $pos += $dur, next if $key eq '_';

        $octave -= 4;

        $key = $FREQS{$key};
        my $freq = $key * (2 ** $octave);
        $freq *= $HALF_STEP if $acc eq '#';
        $freq /= $HALF_STEP if $acc eq 'b';


        $note_len = $falloff_beats && $falloff_beats > $dur ? $falloff_beats: $dur;

        if ($inst eq 'sine') {

            $pitch = 1.;

            for $i (0..$note_len){

                $pitch *= $PITCH_ROLL;
                my $h = sin( 1.0 * $i * $freq * 2 * $PI * $pitch/ $SPS);
                my $falloff = 1;
                $falloff = 1.0 - ($i / $note_len) ** .5 if $falloff_beats;
                $falloff *= $i / $attack_beats if $attack_beats && $i < $attack_beats;

                # prevent popping
                $falloff *= 1.0 * ($i) / 10 if $i < 10;
                $falloff *= 1.0 * ($note_len - $i) / 10 if $note_len - $i < 10;

                $track->[$pos + $i] += $VELOCITY * (2 ** 24) * $falloff * $h;
            }
        }

        elsif ($inst eq 'noise') {

            for $i (0..$note_len){

                my $falloff = 1;
                if($falloff_beats){
                    my $factor = $i / $falloff_beats;
                    next if $factor > 1.;
                    $falloff = 1.0 - $factor ** .5
                };
                $falloff *= $i / $attack_beats if $attack_beats && $i < $attack_beats;

                # prevent popping
                $falloff *= 1.0 * ($i) / 10 if $i < 10;
                $falloff *= 1.0 * ($note_len - $i) / 10 if $note_len - $i < 10;

                $track->[$pos + $i] += $VELOCITY * (2 ** 24) * $falloff * (rand() * 2 - 1);
            }

        }

        $pos += $dur;
        $last_dur = $dur;

    }
}

sub render_score{
    my (@tracks) = @_;
    print".snd",pack"N*",24,-1,5,$SPS,1;
    my $max = 0;
    for my $track (@tracks){
        $max = $#$track if $#$track > $max;
    }

    for my $i (0..$max){
        my $avg = 0.;
        for $track(@tracks){
            $avg += $track->[$i];
        }
        $avg /= $#tracks + 1;

        $avg = 2**31 - 1 if $avg > 2**31 - 1;
        $avg = - 2**31 if $avg < - 2**31;
        print pack("N", $avg);
    }
}