Before I show you the code, let me explain the format of the CSV files. Each line should have NOTE,DURATION,OCTAVE,ON/OFF as understood by Win32::MIDI.

I have added support for a rest. NOTE is R. OCTAVE and ON/OFF are ignored.

mary.txt

E,0.5,3,1
D,0.25,3,1
C,0.5,3,1
D,0.5,3,1
E,0.5,3,1
E,0.5,3,1
E,0.75,3,1
D,0.5,3,1
D,0.5,3,1
D,0.5,3,1
E,0.5,3,1
G,0.5,3,1
G,0.5,3,1
[download]

AC/DC - A Whole Lot of Rosie
song.txt

D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
G,0.25,3,1
D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
R,2,1,1
D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
G,0.25,3,1
D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
R,2,1,1
D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
G,0.25,3,1
D,0.25,3,1
F,0.25,3,1
D,0.25,3,1
[download]

And now for the code!

#!/perl/bin/perl -w
use strict;
use Win32::MIDI;

my $midi_obj = Win32::MIDI->new();
$midi_obj->openDevice(0);
if (scalar @ARGV == 0) {
  play_file("mary.txt");
  play_file("song.txt");
  melody(day_tripper(3));
} else {
  for my $song (@ARGV) {
    play_file($song);
  }
}
sleep(1);
$midi_obj->closeDevice();
exit(0);

sub note {
  # note(NOTE, DURATION, OCTAVE, ON/OFF);
  my ($note, $duration, $octave, $on) = @_;
  
  # play_note(NOTE, DURATION, VELOCITY, CHANNEL, ON/OFF, OCTAVE)
  if ($note ne 'R') {
    $midi_obj->play_note($note, $duration, 127, 1, $on, $octave)
     || print $midi_obj->error() . "\n" and $midi_obj->reset_error();
  } else {
    select(undef, undef, undef, $duration);  # Rest for this $duration
  }
}

sub melody {
  # ([NOTE, DURATION, OCTAVE, ON/OFF], [NOTE, DURATION, OCTAVE, ON/OFF
+],...)
  for my $melody (@_) {
    note(@$melody);
  }
  sleep(3);
}

sub play_file {
  my $file = shift;
  my @song;
  open(MID, "<", $file);
  for my $line (<MID>) {
    my ($note, $duration, $octave, $on) = split/,/, $line;
    push @song, [split /,/, $line];
  }
  close(MID);
  melody(@song);
}

sub day_tripper {
  # 'Day Tripper' by the Beatles
  my $octave = shift;
  my @song;
  for (0..2) {
    push @song, (
      ['E', 1.25, $octave, 1],
      ['G', 0.5, $octave, 1],
      ['G#', 0.25, $octave, 1],
      ['B', 0.25, $octave, 1],
      ['E', 0.25, $octave, 1],
      ['D', 0.25, $octave, 1],
      ['D', 1, $octave, 1],
      ['B', 0.25, $octave, 1],
      ['F#', 0.25, $octave, 1],
      ['F', 0.25, $octave, 1],
      ['B', 0.25, $octave, 1],
      ['D', 0.25, $octave, 1],
      ['E', 0.25, $octave, 1],
    );
  }
  return @song;
}
[download]

Update: all music was "transcribed" by LostS.

Update 2: Plays all song files listed on the command line or enters "demo" mode if you do not specify any files.