Something Interesting about AI

Generate Music Algorithmically

Music Feature

Music is compose by lots of note.
The feature of note is frequece and length.

Markov Chain

The idea tech of Markov Chain is that, the next state (to us,it’s music note) is decided by the previous N states, only. That means:
the next note’s freq is decided by the previous’s. the next note’s length is decided by the previous’s.

Machine Learning

First, learn the trans probability throught lots of music sample.

Then, we got the probability from Freq A to Freq B, From length 1/2 to 1/4

Last, generate note by probability, random. Create music file according to the note data.

Code

The lib “pysynth.py” for gen music through two arg (freq and length)

The key program “MarkovBuilder.py” for TransArray&GenerateNote

'''
Created on May 14, 2009

@author: darkxanthos
'''
import random

class MarkovBuilder:
    def __init__(self, value_list):
        self._values_added = 0
        self._reverse_value_lookup = value_list
        self._value_lookup = {}
        for i in range(0, len(value_list)):
            self._value_lookup[value_list[i]] = i
        #Initialize our adjacency matrix with the initial
        #probabilities for note transitions.
        self._matrix=[[0 for x in range(0,len(value_list))] for i in range(0,len(value_list))]

    def add(self, from_value, to_value):
        """Add a path from a note to another note. Re-adding a path between notes will increase the associated weight."""
        value = self._value_lookup
        self._matrix[value[from_value]][value[to_value]] += 1
        self._values_added = self._values_added + 1

    def next_value(self, from_value):
        value = self._value_lookup[from_value]
        value_counts = self._matrix[value]
        value_index = self.randomly_choose(value_counts)
        if(value_index < 0):
            raise RuntimeError, "Non-existent value selected."
        else:
            return self._reverse_value_lookup[value_index]

    def randomly_choose(self, choice_counts):
        """Given an array of counts, returns the index that was randomly chosen"""
        counted_sum = 0
        count_sum = sum(choice_counts)
        selected_count = random.randrange(1, count_sum + 1)
        for index in range(0, len(choice_counts)):
            counted_sum += choice_counts[index]
            if(counted_sum >= selected_count):
                return index
        raise RuntimeError, "Impossible value selection made. BAD!"

Main Program “MarkovMusic.py”

'''
Created on May 12, 2009

@author: Justin Bozonier
'''
import pysynth
from MarkovBuilder import MarkovBuilder

class MusicMatrix:
    def __init__(self):
        self._previous_note = None
        self._markov = MarkovBuilder(["a", "a#", "b", "c", "c#", "d", "d#", "e", "f", "f#", "g", "g#"])
        self._timings = MarkovBuilder([1, 2, 4, 8, 16])

    def add(self, to_note):
        """Add a path from a note to another note. Re-adding a path between notes will increase the associated weight."""
        if(self._previous_note is None):
            self._previous_note = to_note
            return
        from_note = self._previous_note
        self._markov.add(from_note[0], to_note[0])
        self._timings.add(from_note[1], to_note[1])
        self._previous_note = to_note

    def next_note(self, from_note):
        return [self._markov.next_value(from_note[0]), self._timings.next_value(from_note[1])]

# Playing it comes next :)
#test = [['c',4], ['e',4], ['g',4], ['c5',1]]
#pysynth.make_wav(test, fn = "test.wav")

musicLearner = MusicMatrix()

# Input the melody of Row, Row, Row Your Boat
# The MusicMatrix will automatically use this to 
# model our own song after it.
musicLearner.add(["c", 4])
musicLearner.add(["c", 4])
musicLearner.add(["c", 4])
musicLearner.add(["d", 8])
musicLearner.add(["e", 4])
musicLearner.add(["e", 4])
musicLearner.add(["d", 8])
musicLearner.add(["e", 4])
musicLearner.add(["f", 8])
musicLearner.add(["g", 2])

musicLearner.add(["c", 8])
musicLearner.add(["c", 8])
musicLearner.add(["c", 8])

musicLearner.add(["g", 8])
musicLearner.add(["g", 8])
musicLearner.add(["g", 8])

musicLearner.add(["e", 8])
musicLearner.add(["e", 8])
musicLearner.add(["e", 8])

musicLearner.add(["c", 8])
musicLearner.add(["c", 8])
musicLearner.add(["c", 8])

musicLearner.add(["g", 4])
musicLearner.add(["f", 8])
musicLearner.add(["e", 4])
musicLearner.add(["d", 8])
musicLearner.add(["c", 2])

random_score = []
current_note = ["c", 4]
for i in range(0,100):
    print current_note[0] + ", " + str(current_note[1])
    current_note = musicLearner.next_note(current_note)
    random_score.append(current_note)

pysynth.make_wav(random_score, fn = "first_score.wav")